Low-cost intelligent forming manufacturing method based on shape memory alloy

Abstract

The invention discloses a low-cost intelligent forming manufacturing method based on a shape memory alloy, which relates to the technical field of low-cost intelligent manufacturing of large-size and complex components, and is characterized in that the shape memory alloy is made into a flexible metamaterial by adopting a curved bar dot matrix metamaterial and a curved edge stretchable net; then, the actuating function of the shape memory alloy is combined, and regionalized control, split control and compound control of superposition and lamination are carried out on the structure or performance of the shape memory alloy curved bar lattice metamaterial and the curved edge stretchable net; the shape memory alloy composite flexible metamaterial with different structures, non-uniform performance, non-simultaneous triggering actuating function and stress response can be constructed to serve as a flexible intelligent actuating body to act on a blank, and the blank is forced to deform and be attached to a mold to be formed into a component. The problems that an existing manufacturing method needs special, complex and expensive pressure generating equipment and pressure adjusting and controlling equipment, and the manufacturing cost is high are solved.

Description

Technical Field

[0001] This invention belongs to the field of forming and manufacturing, and is applicable to the low-cost intelligent manufacturing of complex-shaped and large-sized components in commercial aerospace and other fields. Specifically, it relates to a low-cost intelligent forming and manufacturing method based on shape memory alloys. Background Technology

[0002] With the development of aviation, aerospace, transportation, and weaponry, large-size thin-walled integral components and complex, difficult-to-deform components are increasingly being used to reduce the weight of these equipment and improve their reliability. Although 3D printing (additive manufacturing) can produce components of any shape and size, it requires specialized equipment and even raw materials, and the available materials are limited. Furthermore, the 3D printing process is slow, resulting in high manufacturing costs and long production cycles. Therefore, sheet metal forming remains a very valuable and attractive forming and manufacturing method. However, with the development of various fields and the demand for large-size thin-walled integral components and complex, difficult-to-deform components, the following new trends and challenges have emerged:

[0003] (1) More and more components with large thin-walled integral structures are being adopted. A typical example is the Ares-I rocket fuel tank bottom plate component with a diameter of 5.5m. In order to meet the needs of deep space exploration, the diameter of the rocket propellant tank bottom plate component of my country's latest high-thrust launch vehicle will reach 5 to 10m.

[0004] (2) The forming of large components with dimensions of several meters places extremely stringent requirements on forming equipment, and the equipment cost is extremely high. For example, spinning requires a special spinning machine, which is costly and time-consuming; welding requires the development of special welding equipment, such as a 10-meter-class plate component friction stir welding machine, which costs more than 100 million yuan; stamping requires the use of giant hydraulic presses, electromagnetic pulse generators and other pressure generating equipment, which requires huge investment and is extremely complex. For example, the 150MN (15,000 tons) double-action plate hydraulic forming equipment, which can achieve the integral forming of plate components with a diameter of 4 m, has a worktable of 4.5 m × 4.5 m, a height of 19.5 m, and weighs 1,900 tons. It also requires a very complex fluid high-pressure forming system, and the equipment manufacturing cost is very high.

[0005] (3) For ultra-large plate components, due to the limited size of existing plate blanks, it is necessary to weld the plate blanks together. This leads to the non-homogeneity of ultra-large component blanks, complex shapes, and non-homogeneity of welding, which requires specialized control equipment that can adjust the pressure in real time by region and stage.

[0006] (4) In the fields of automobiles, aviation, and aerospace, there are complex shapes and materials of different thicknesses, such as irregular and heterogeneous sheet metal components. The complex and irregular geometric shape and uneven sheet metal properties of the components often lead to complex sheet metal stress states. Components with large differences in the degree of deformation in different areas need to be subjected to regionalized forces, and the forming process needs to be finely controlled, which brings challenges to forming control.

[0007] (5) These irregular and heterogeneous plate components with different materials and thicknesses and complex shapes need to improve the formability of complex plate components through multi-regional coordination of stress state. It is necessary to adjust the pressure and loading sequence of each region of the plate and improve the formability of complex plate components through staged control of stress path. This generates a demand for multi-regional and multi-stage coordinated control of forming. Therefore, it is necessary to develop special control equipment that can adjust the pressure in real time by region and stage.

[0008] (6) In order to improve the formability of large-size sheet metal components or complex-shaped components that are difficult to deform, a method of covering the sheet metal blank with a cover plate or applying fluid back pressure on one side of the back of the sheet metal is generally adopted. However, whether it is applying fluid back pressure or covering the sheet metal blank with a cover plate, the forming force will be increased and the requirements for the pressure generating equipment will be increased. That is, some measures to improve the formability of sheet metal also increase the requirements for the pressure generating equipment.

[0009] In summary, the demand for forming and manufacturing large sheet metal components and complex, difficult-to-deform components requires the development of specialized, complex, and expensive pressure regulation and control equipment and pressure generating equipment. The equipment costs are extremely high, and the development cycle is long, resulting in high manufacturing costs and long manufacturing cycles, which seriously affects the development of fields such as commercial aerospace. Summary of the Invention

[0010] Plastic forming of thin-walled sheet metal components is a manufacturing method that uses pressure-generating equipment to apply pressure to the sheet metal, forcing it to deform into the desired shape. To successfully form the required component, pressure regulation and control equipment is generally required to control the deformation process. Existing technologies for forming complex, difficult-to-form, and large-sized components rely on specialized, complex, and expensive pressure regulation and control equipment and pressure-generating equipment, resulting in high costs and long production cycles.

[0011] To address this problem, this invention provides a technical solution: a low-cost intelligent forming manufacturing method based on shape memory alloys. This method utilizes curved rod lattice metamaterials and curved-edge stretchable meshes to transform shape memory alloys into flexible metamaterials. Combined with the actuation function of shape memory alloys and the regionalized, discrete, and superimposed layering control of the structure and properties of the curved rod lattice metamaterials and curved-edge stretchable meshes, a composite flexible metamaterial of shape memory alloys with non-uniform structures, non-uniform properties, and non-simultaneous triggering of actuation functions and stress responses can be constructed. This composite material serves as a flexible intelligent actuator whose stress response spatial distribution and time-varying characteristics can be designed. It forms a spatially non-uniformly distributed stress field and a time-varying adjustable stress response, acting on the blank to force it to deform and conform to the mold, forming a component.

[0012] Furthermore, the shape memory alloy can be of two types: one is a shape memory alloy with only single-pass shape memory function, and the other is a shape memory alloy with two-pass shape memory function. The material of the shape memory alloy can be selected from nickel-titanium shape memory alloys, copper-based shape memory alloys, and high-temperature shape memory alloys, such as Ti-Ni-Pd high-temperature shape memory alloys and Ti-Ni-Hf high-temperature shape memory alloys.

[0013] The beneficial effects of selecting shape memory alloys are as follows: they provide more reasonable choices for the forming and manufacturing of different components. Because the shapes of components are diverse and vary greatly, selection can be made according to the specific component. For example, single-pass shape memory alloys have a larger recoverable strain, stronger restoring force, and better fatigue resistance. Therefore, they can provide better forming force and form components with more complex shapes. However, it can only remember one shape. When deforming a shape memory alloy to store energy, an external force is needed to change its shape to store energy. On the other hand, two-pass shape memory alloys can remember two different shapes. Utilizing their own shape memory function, the shape can be transformed and changed through temperature changes. Thus, energy storage can be achieved through temperature control without the need for additional external force. The operation is simpler, but the recoverable deformation of two-pass shape memory alloys is smaller.

[0014] Furthermore, the method of transforming shape memory alloys into flexible metamaterials by employing curved rod lattice metamaterials and curved edge stretchable meshes involves using "flexible form" unit cells. The "flexible form" unit cells of the curved rod lattice metamaterials are composed of curved rods, and the "flexible form" unit cells of the curved edge stretchable meshes are composed of curved edges. This structural form of unit cells endows the curved rod lattice metamaterials and curved edge stretchable meshes with flexibility, stretchability, and the ability to adapt to large deformations required for complex shape forming.

[0015] The beneficial effects of the above-mentioned selection of shape memory alloy curved rod lattice metamaterials and curved stretchable mesh unit cell structures are: both the shape memory alloy curved rod lattice metamaterials and curved stretchable meshes can generate sufficiently large deformations, while the strain must be controlled within the recoverable strain range of the shape memory alloy. That is, by adopting a curved rod structure instead of the usual straight truss structure, the deformation of the lattice metamaterial's rods is dominated by bending or elongation deformation. This allows the curved rod lattice metamaterial to have large shrinkage and elongation expansion deformations, while the strain of the shape memory alloy itself is relatively small. By controlling the deformation within the recoverable range of shape memory alloys, shape memory alloy curved rod lattice metamaterials can become flexible metamaterials that can adapt to large deformations of complex shapes. Similarly, for stretchable meshes, the curved edges are used to form unit cells, so that the edges of the curved stretchable meshes are dominated by bending or elongation deformation. This allows the curved stretchable meshes to have both large shrinkage and elongation expansion deformations, while the shape memory alloy strain of the curved stretchable meshes is relatively small, controlled within the recoverable range of shape memory alloys, making shape memory alloy curved stretchable meshes a flexible metamaterial that can adapt to large deformations of complex shapes.

[0016] Furthermore, the shape memory alloy curved rod lattice metamaterial and the curved-edge stretchable mesh are "flexible" shape memory alloys that, as flexible intelligent actuators, force the blank to deform. Therefore, they need to be strengthened. The strengthening method is as follows:

[0017] Multiple flexible shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are stacked together. This stacking process gives them sufficient restoring force, enabling the "flexible" shape memory alloy to provide sufficient restoring force.

[0018] The beneficial effects of strengthening the shape memory alloy curved rod lattice metamaterial and the curved edge stretchable mesh mentioned above are: the shape memory alloy curved rod lattice metamaterial and the curved edge stretchable mesh, which are capable of large deformation to adapt to the need for deformation into complex shapes, are "flexible" enough to produce large deformation while also having sufficient restoring force to force the blank to deform or control the blank holder force, so as to form components of various shapes.

[0019] Furthermore, the aforementioned method of regionally controlling the structure or properties of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes is as follows:

[0020] In different regions of shape memory alloy curved rod lattice metamaterials or curved stretchable meshes, lattice unit cells or mesh unit cells with different structural parameters or properties are used. That is, the structural parameters or properties of unit cells in local regions are different from those in other regions. This non-identical layout of composite structure or composite performance unit cells makes shape memory alloy curved rod lattice metamaterials or curved stretchable meshes into flexible metamaterials with composite unit cells of different structural parameters or properties, generating non-uniform stress response and realizing regional control of the spatial distribution of stress response.

[0021] The beneficial effects of regional control over the structure or properties of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes to generate non-uniform stress responses are as follows: By simply changing the structural parameters or properties of the lattice unit cells of the curved rod lattice metamaterial or the mesh unit cells of the curved stretchable mesh in a local region, that is, making the structural parameters or properties of the unit cells in the local region different from those in other regions, the shape memory alloy curved rod lattice metamaterial or the curved stretchable mesh becomes a flexible metamaterial in the form of a composite of unit cells with different structural parameters or properties, generating non-uniform stress responses. This provides a basis for the construction of various complex stress fields and meets the needs of complex non-uniform pressure fields when forming complex and difficult-to-deform plates.

[0022] Furthermore, the aforementioned method of separately controlling the structure or properties of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes includes:

[0023] The spatial distribution of stress response can be controlled by splitting the layout of unit cells with different structural parameters or properties in each curved rod lattice metamaterial or curved edge stretchable mesh during regional control. That is, the layout of unit cells with different structural parameters or properties is controlled separately for each individual, resulting in multiple shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes with different spatial distributions of stress response.

[0024] The stress response is triggered asynchronously and controlled separately. By regulating the heat treatment specifications or the composition of the shape memory alloy material, the phase transition temperature of multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes is controlled to different temperature values. That is, the phase transition temperature is controlled separately for each individual, so that multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes produce staggered phase transition triggering and stress response.

[0025] Furthermore, the composite control of the structure or properties of the shape memory alloy curved rod lattice metamaterial and the curved edge stretchable mesh through superposition and lamination includes the following composite control methods:

[0026] By stacking multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different spatial distributions of stress response, structural parameters or performance, and different layouts of unit cells, complex structures or performance are formed by regional control of the structure. This results in shape memory alloy composite flexible metamaterials with non-uniform structures and performance, and produces complex spatial distributions of stress response.

[0027] By combining multiple separately controlled shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different phase transition temperatures and stress response triggered asynchronously, a shape memory alloy composite flexible metamaterial with asynchronous actuation function and stress response is formed.

[0028] By combining multiple spatially distributed and non-simultaneously triggered stress response control units with different structural parameters or performance, different layouts of unit cells, and different phase transition temperatures, shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are stacked together to obtain shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform performance, non-simultaneously triggered actuation function, and stress response.

[0029] Furthermore, the formable shape memory alloy composite flexible metamaterials include:

[0030] (1) Based on the regional control, split control, and composite control of the structure or properties of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes, complex regional control is formed to obtain shape memory alloy composite flexible metamaterials with non-uniform structures and non-uniform properties that can produce complex stress response spatial distributions. The method is as follows:

[0031] First, through regional control, lattice unit cells or mesh unit cells with different structural parameters or properties are used in different regions of shape memory alloy curved rod lattice metamaterials or curved stretchable meshes.

[0032] Secondly, modular control is implemented. By changing the layout of unit cells with different structural parameters or performances during regional control of each shape memory alloy curved rod lattice metamaterial or curved stretchable mesh, each individual is controlled separately, resulting in multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different stress response spatial distributions.

[0033] Then, composite control of superposition and layering is carried out. Multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different layouts of unit cells that have been separately controlled and have different structural parameters or performance are superimposed and layered to form complex regional control of structure or performance, resulting in shape memory alloy composite flexible metamaterials with non-identical structure and non-uniform performance.

[0034] (2) Based on the separate control and composite control of the structure or properties of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes, shape memory alloy composite flexible metamaterials with non-simultaneous triggering actuation function and stress response can be formed. The method is as follows:

[0035] First, separate control is achieved by adjusting the heat treatment specifications or the composition of the shape memory alloy material. The phase transition temperatures of multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are set to different values. By controlling the phase transition temperature of each individual, non-simultaneous phase transitions and shape recovery are generated, which in turn generate non-simultaneous actuation function triggering and stress response.

[0036] Then, the composite control of superposition and lamination is used to superimpose and laminate multiple curved rod lattice metamaterials or curved stretchable meshes with different phase transition temperatures after separate control, forming shape memory alloy composite flexible metamaterials with non-simultaneous triggering actuation function and stress response.

[0037] (3) Based on the regionalized control, split-type control, and composite control of the structure or properties of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes, shape memory alloy composite flexible metamaterials with non-uniform structures, non-uniform properties, and non-simultaneous triggering actuation functions and stress responses are formed. The method is as follows:

[0038] First, through regional control, lattice unit cells or mesh unit cells with different structural parameters or properties are used in different regions of shape memory alloy curved rod lattice metamaterials or curved stretchable meshes.

[0039] Secondly, the spatial distribution of stress response is controlled in a split manner. By changing the layout of unit cells with different structural parameters or performance in each curved rod lattice metamaterial or curved edge stretchable mesh during regional control, multiple shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes with different spatial distributions of stress response are obtained.

[0040] Then, the stress response is not triggered simultaneously and is controlled separately. By adjusting the heat treatment specifications or the composition of the shape memory alloy material, the phase transition temperatures of the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different structural parameters or performances and different layouts of the unit cells are set to different temperature values. This allows the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different structural parameters or performances and different layouts of the unit cells under regional control to generate non-simultaneous phase transition triggering and stress response.

[0041] Finally, composite control is carried out by superimposing and layering multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different layouts and phase transition temperatures, which have undergone regional and split control and have different structural parameters or performance. This results in shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform performance, and non-simultaneous triggering actuation function and stress response.

[0042] Furthermore, based on the aforementioned actuation function of shape memory alloys, the flexible metamaterial composite of shape memory alloys with non-uniform structure, non-uniform properties, and non-simultaneous triggering actuation functions and stress response is transformed into a flexible intelligent actuator with intelligently controllable spatial distribution and time-varying stress response. The specific method is as follows:

[0043] First, shape memory alloy curved rod lattice metamaterials and curved-edge stretchable meshes are fabricated.

[0044] Based on the design of different unit cell layouts according to structural parameters or performance, shape memory alloy blanks can be processed into curved rod lattice metamaterials and curved edge stretchable meshes with different unit cell layouts according to different structural parameters or performance through regional control and split control. Shape memory alloy blanks can be directly processed into curved rod lattice metamaterials and curved edge stretchable meshes with a set shape, or shape memory alloy blanks can be processed into flat curved rod lattice metamaterials and curved edge stretchable meshes.

[0045] Secondly, a shaping heat treatment is performed to set the shape and phase transition temperature.

[0046] When the shape memory alloy curved rod lattice metamaterial and the curved edge stretchable mesh are in the set shape, they are directly constrained and subjected to shaping heat treatment to fix them into the set shape and give them shape memory function. At the same time, split control is adopted, and the phase transition temperature of the shape memory alloy curved rod lattice metamaterial and the curved edge stretchable mesh is set by regulating the shaping heat treatment specifications or the shape memory alloy material composition. When the shape memory alloy curved rod lattice metamaterial and the curved edge stretchable mesh are in the shape of a flat plate, they are first deformed into a set shape and then constrained and subjected to shaping heat treatment to fix them into the set shape and give them shape memory function. Split control is adopted, and the phase transition temperature is set by regulating the shaping heat treatment specifications or the shape memory alloy material composition.

[0047] Then, the shape memory alloy curved rod lattice metamaterial and the curved stretchable mesh, which have been set with shape and phase transition temperature, are deformed into a temporary shape so that they can store energy, have actuation function, and become a flexible actuator;

[0048] Finally, a composite control method of superposition and layering is adopted. Multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different structural parameters or performances, different phase transition temperatures, and different actuation functions are superimposed and layered together. Because the structural parameters or performances of the various shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are different, the spatial distribution of stress response and its variation with temperature are also different. Superimposing and layering them transforms them into shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform performance, and non-simultaneous triggering of actuation functions and stress responses. This transforms them into flexible intelligent actuators with intelligent and controllable spatial distribution of stress response and its variation with time.

[0049] The aforementioned transformation of shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function, and stress response into flexible intelligent actuators with intelligently controllable spatial distribution and time-varying stress response has the following advantages: By simply taking shape memory alloy curved rod lattice metamaterials and curved stretchable meshes with different structural parameters or properties, different layouts of unit cells, and different phase transition temperatures, and performing simple shaping heat treatment and deformation, they can be made to have actuation functions. Stacking and layering them transforms them into shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function, and stress response, into flexible intelligent actuators with intelligently controllable spatial distribution and time-varying stress response. Then, by simply heating to trigger a phase transition, they recover to their original shape and generate an actuation effect for billet forming. This avoids the use of complex and expensive pressure generating and pressure control equipment. Moreover, through different combinations, they can be adapted to the forming of various components, with strong versatility and cost savings.

[0050] Furthermore, the aforementioned curved rod lattice metamaterial and curved stretchable mesh combined with shape memory alloy actuation function transform the curved rod lattice metamaterial and curved stretchable mesh into a flexible actuator that can act on the billet. This requires shaping heat treatment and deformation energy storage, and the methods and processes of shaping heat treatment and deformation energy storage are as follows:

[0051] When using single-pass shape memory alloys, the process of performing shaping heat treatment and storing energy is as follows:

[0052] When shape memory alloy curved rod lattice metamaterials and curved stretchable meshes are directly prepared into a set shape, they are constrained, heated, and transformed into the parent austenitic phase. They undergo shaping heat treatment to fix the shape and give it a single-pass shape memory function. Then they are cooled to transform into the low-temperature martensite phase. Deformation is performed in the low-temperature martensite phase to form a temporary shape. The temporary shape is determined by the blank of the forming component. As long as it is heated again to transform into the parent austenitic phase, it will restore the original shape. Therefore, this deformation induced by external force stores energy and transforms it into a flexible actuator with actuation properties.

[0053] When shape memory alloy curved bar lattice metamaterials and curved stretchable meshes are fabricated into simple flat plate shapes, the fabricated shape memory alloy curved bar lattice metamaterials and curved stretchable meshes need to be deformed to the set shape and constrained. They are then heated to transform into the parent austenitic phase, and subjected to shaping heat treatment to solidify their shape and give them a one-way shape memory function. Then they are cooled to transform into the low-temperature martensite phase. Deformation is then performed in the low-temperature martensite phase to form a temporary shape. The temporary shape is determined by the blank of the forming component. As long as it is heated again to transform into the parent austenitic phase, it will restore its original shape. Therefore, this deformation induced by external force stores energy, transforming it into a flexible actuator with actuation properties.

[0054] When using two-way shape memory alloys, the process of performing shaping heat treatment and storing energy is as follows:

[0055] First, when shape memory alloy curved rod lattice metamaterials and curved stretchable meshes are directly fabricated into a predetermined shape, they are constrained, heated, and transformed into the parent austenite phase. A shaping heat treatment is then performed to solidify the shape and enable it to possess single-pass shape memory functionality. Second, when shape memory alloy curved rod lattice metamaterials and curved stretchable meshes are fabricated into simple flat plate shapes, the fabricated shape memory alloy curved rod lattice metamaterials and curved stretchable meshes need to be first deformed into the predetermined shape and constrained, then heated, and transformed into the parent austenite phase. A shaping heat treatment is then performed to solidify the shape and enable it to possess single-pass shape memory functionality.

[0056] Secondly, the shape memory alloy curved rod lattice metamaterial and the curved edge stretchable mesh, which have been shaped and memorized, are cooled to transform into a low-temperature martensitic phase and deformed into a temporary shape. Under constrained conditions, they undergo thermomechanical treatment training involving heating and cooling to memorize the temporary shape of the low-temperature martensitic phase. This enables them to possess a two-way shape memory function, remembering not only the shaped high-temperature austenitic phase but also the temporary shape of the low-temperature martensitic phase. The temporary shape is determined by the blank of the forming component. By simply cooling it from the parent phase, the high-temperature austenitic phase, to the low-temperature martensitic phase, its shape is deformed from the originally set high-temperature austenitic phase shaped shape to the temporary shape of the low-temperature martensitic phase. Energy is stored through this temperature-induced deformation, enabling actuation and transforming it into a flexible actuator with actuation properties.

[0057] Furthermore, using shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function, and stress response as flexible intelligent actuators whose stress response spatial distribution and time-varying characteristics can be designed, acting on blanks and formed components, includes the following steps:

[0058] Step 1: Analyze the characteristics of the component to be formed and the distribution of the pressure load required for its forming, as well as the change of the pressure load over time;

[0059] Step 2: Based on the required pressure load distribution and pressure load variation over time obtained in Step 1, a composite control method is adopted to regionalize, split, and superimpose the structure or properties of shape memory alloy curved rod lattice metamaterials and curved edge stretchable meshes. Shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes with different structural parameters or properties, different unit cell layouts, and different phase transition temperatures are designed to form shape memory alloy composite flexible metamaterials with non-uniform structures, non-uniform properties, and non-simultaneous triggering actuation functions and stress responses.

[0060] Step 3: Prepare shape memory alloy curved rod lattice metamaterials or curved stretchable meshes.

[0061] Based on the design in step two, regional control methods and split control methods are used to process shape memory alloy billets into curved rod lattice metamaterials or curved edge stretchable meshes with different layouts of unit cells and different structural parameters or performance.

[0062] Step 4: Form shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response, and transform them into flexible intelligent actuators.

[0063] For shape memory alloy curved rod lattice metamaterials and curved stretchable meshes, the desired original and temporary shapes need to be determined based on the shape of the formed component, the required pressure load distribution and the change of pressure load over time, and the form of the sheet blank. Then, a split-control method is used to perform shaping heat treatment on the prepared shape memory alloy curved rod lattice metamaterial or curved stretchable mesh according to the determined original shape, setting the desired original shape and phase transition temperature. Finally, through actuation treatment, the shape memory alloy curved rod lattices with different structural parameters or properties, and different phase transition temperatures, are subjected to shaping heat treatment. Metamaterials or curved stretchable meshes are deformed into a temporary shape to store energy and enable actuation functions. Shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different structural parameters or properties and different phase transition temperatures become actuators. Then, using a composite method of superposition and lamination, multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different structural parameters or properties and different phase transition temperatures are superimposed and laminated in a composite control manner to form shape memory alloy composite flexible metamaterials with non-uniform structures, non-uniform properties, and non-simultaneous triggering of actuation functions and stress responses, which are then transformed into flexible intelligent actuators.

[0064] Step 5: Assembly

[0065] Shape memory alloy composite flexible metamaterials, which are transformed into flexible intelligent actuators with non-identical structures, non-uniform properties, non-simultaneous triggering actuation functions and stress responses, are assembled and fixed together with blanks, molds, auxiliary assembly and fixing components and heating devices.

[0066] Step Six: Heating triggers the shape memory alloy composite flexible metamaterial to recover its shape and form a component.

[0067] Heating triggering has been transformed into a flexible intelligent actuator using shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response. This allows the actuator to undergo a phase transformation, restore its original shape, generate actuation function, produce the required stress response, act on the billet, deform the billet, and form it into a component.

[0068] Furthermore, when the shape memory alloy composite flexible metamaterial, which has non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function, and stress response, is used as a flexible intelligent actuator to act on the blank for forming, it needs to be assembled with the blank and other components. Lubrication is required between the metals that come into contact with each other during assembly and forming. Graphite paper or a sprayed coating is filled into the pores of the shape memory alloy curved rod lattice metamaterial for lubrication. Graphite paper or a sprayed coating is placed between the superimposed shape memory alloy curved rod lattice metamaterial and the curved stretchable mesh, and between different shapes memory alloy curved stretchable meshes, for lubrication. Graphite paper or a sprayed coating is placed between the shape memory alloy flexible metamaterial composed of the shape memory alloy curved rod lattice metamaterial and the shape memory alloy curved stretchable mesh and the blank for lubrication.

[0069] The beneficial effects of using graphite paper or spray coating for lubrication are as follows: with the help of graphite paper or spray coating, friction between metals is reduced, ensuring that the recovery force of the shape memory alloy can be maximized and used for the deformation of the blank, ensuring the successful formation process. Otherwise, the porous shape memory alloy curved rod lattice metamaterial and the shape memory alloy curved edge stretchable mesh will generate severe friction during the process of restoring the original shape, dissipating the actuation energy of the shape memory alloy, resulting in insufficient energy and difficulty in successfully forming the component.

[0070] Furthermore, by employing a flexible metamaterial composed of shape memory alloys with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation functions, and stress response as a flexible intelligent actuator, when acting on a blank for forming, a rigid cover plate or a rigid-flexible composite cover plate can be placed on one side of the blank to improve formability, or a fluid back pressure can be applied to one side of the blank to improve formability, or an elastomer can be placed between the flexible metamaterial of the shape memory alloy with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation functions, and stress response and the blank to improve formability and the surface quality of the component.

[0071] The beneficial effects of covering one side of the billet with a rigid cover plate or a rigid-flexible composite cover plate, applying fluid back pressure, or placing an elastomer between the shape memory alloy composite flexible metamaterial with non-uniform structure, non-uniform properties, and non-simultaneous triggering of actuation functions and stress responses and the billet are as follows: The shape memory alloy composite flexible metamaterial with non-uniform structure, non-uniform properties, and non-simultaneous triggering of actuation functions and stress responses can generate intelligent pressure control that is adjustable in both spatial distribution and time variation, thereby improving the formability of the sheet metal and enhancing the forming quality of the components. Covering one side of the billet with a rigid cover plate or a rigid-flexible composite cover plate, or applying fluid back pressure, can further improve the formability. Alternatively, placing an elastomer between the shape memory alloy composite flexible metamaterial with non-uniform structure, non-uniform properties, and non-simultaneous triggering of actuation functions and stress responses and the billet can further enhance the formability of the billet and improve the forming quality of the billet components.

[0072] Furthermore, the shape memory alloy composite flexible metamaterial, which uses non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function, and stress response as a flexible intelligent actuator, is used as a blank to form a blank. The action on the blank is divided into two regions: one is the blank deformation region corresponding to the mold cavity, and the other is the blank edge region. In the blank deformation region corresponding to the mold cavity, the shape memory alloy composite flexible metamaterial is applied to generate a non-uniform pressure distribution and a pressure that changes over time. In the blanking region, the shape memory alloy composite flexible metamaterial is also used to adjust and control the blanking force acting on the blank edge.

[0073] The advantage of using shape memory alloy composite flexible metamaterials in the blanking area to adjust and control the blanking force acting on the blank edge is that it can adjust and control the blanking force acting on the blank edge without the need for complex blanking force adjustment equipment and devices. Otherwise, forming usually requires additional devices to apply and control the blanking force on the blank edge to control the flow of the blank and suppress the instability and wrinkling of the blank edge.

[0074] The method of the present invention has the following beneficial effects:

[0075] 1. Eliminating the need for specialized, complex, and expensive pressure regulation and control equipment and pressure generating equipment reduces costs. The method presented in this invention utilizes the actuation function of shape memory alloys to replace complex and expensive pressure generating equipment to force billet deformation. By employing shape memory alloy composite flexible metamaterials with non-uniform structures, non-uniform properties, non-simultaneous actuation triggering, and stress response, intelligent pressure regulation can be achieved in both spatial and temporal dimensions, replacing complex and expensive pressure regulation equipment to control the billet deformation process. Because the use of shape memory alloy composite flexible metamaterials with non-uniform structures, non-uniform properties, non-simultaneous actuation triggering, and stress response enables pressure regulation in both spatial and temporal dimensions, the deformation process of the billet can be intelligently controlled, eliminating the need to develop and apply specialized, complex, and expensive pressure regulation and control equipment and pressure generating equipment, thus reducing manufacturing costs and shortening the manufacturing cycle.

[0076] 2. By employing regionalized control, split-type control, and composite control through superposition and layering, shape memory alloy curved rod lattice metamaterials with non-uniform structures, non-uniform properties, non-simultaneous actuation functions, and stress responses, as well as different combinations of curved edge stretchable meshes, can be conveniently and cost-effectively formed into shape memory alloy composite flexible metamaterials with non-uniform structures, non-uniform properties, non-simultaneous actuation functions, and stress responses. This produces complex spatial distributions of stress responses and their changes over time, applicable to various complex-shaped and difficult-to-form components, as well as large-sized components. The operation is simple, convenient, widely applicable, and highly practical.

[0077] 3. It can improve the formability of sheet metal blanks and enhance the forming quality of components. Because it allows for intelligent control of the spatial distribution and temporal variation of forming forces, resulting in intelligent controllability of pressure in both spatial and temporal dimensions, it can specifically control the pressure load and its changes in various regions during sheet metal blank forming. This can effectively suppress instability, wrinkling, and localized thinning that are prone to occur during the forming of complex and difficult-to-deform components, thereby improving formability and forming quality. Attached Figure Description

[0078] Figure 1 This is a schematic diagram of a curved stretchable mesh;

[0079] Figure 2 This is a schematic diagram of a unit cell of a curved stretchable mesh, in which the shape, structure and parameters include the unit cell spans L1 and L2, the widths W1 and W2 of the curved edges, and the radii of curvature R1 and R2 of the curved edges.

[0080] Figure 3 This is a schematic diagram of a curved rod lattice metamaterial with a curved rod as the support.

[0081] Figure 4This is a schematic diagram of the lattice unit cell of a curved rod lattice metamaterial with a curved rod as the support.

[0082] Figure 5 This is a schematic diagram of the bending support of the lattice unit cell of the curved rod lattice metamaterial, where the shape, structure and parameters of the bending support include the unit cell span L (bending support length L), bending support diameter Φ, bending support radius of curvature R2, and bending support transition section radius of curvature R1.

[0083] Figure 6 This is a schematic diagram of a curved rod lattice metamaterial with springs as the support rod;

[0084] Figure 7 This is a schematic diagram of the lattice unit cell of a curved rod lattice metamaterial with springs as the support rod;

[0085] Figure 8 This is a schematic diagram of the spring support of a lattice unit cell of a curved rod lattice metamaterial with spring as the support rod. The shape, structure and parameters of the spring support rod include the unit cell span L1 (spring length L1), spring wire diameter Φ2, spring diameter Φ1, and spring pitch L2.

[0086] Figure 9 The following is a schematic diagram of stacking multiple flexible curved rod lattice metamaterials or curved stretchable meshes in sequence, using curved stretchable meshes as an example.

[0087] Figure 10 The diagram illustrates how multiple flexible curved bar lattice metamaterials or curved stretchable meshes are stacked together for reinforcement, using curved edge stretchable mesh as an example.

[0088] Figure 11 This is a schematic diagram of regional control of unit cell composite forms with different structural parameters (the layout is: the structural parameters of the curved stretchable mesh unit cells in one half of the region are different from those in the other half of the region). (The dashed box in the figure is used to indicate the region where the curved stretchable mesh uses unit cells with narrower curved widths).

[0089] Figure 12 This is a schematic diagram of regional control of unit cell composite forms with different structural parameters (the layout is: the structural parameters of the curved stretchable mesh unit cells in about a quarter of the edge region are different from those in other regions). (The dashed box in the figure is used to indicate the region where the curved stretchable mesh uses unit cells with narrower curved widths).

[0090] Figure 13 This is a schematic diagram of regional control of unit cell composite forms with different structural parameters (the layout is: the structural parameters of the unit cell of the curved stretchable mesh in the central region are different from those in other regions). (The dashed box in the figure is used to indicate the region where the curved stretchable mesh uses unit cells with narrower curved widths).

[0091] Figure 14 The example given is a curved stretchable mesh: multiple unit cells with different structural parameters or properties are stacked and layered to form a complex stress response spatial distribution, resulting in a shape memory alloy composite flexible metamaterial with non-uniform structure and non-uniform properties (the dashed box in the figure is used to indicate the area of ​​the unit cell with a narrower curved edge width of the curved stretchable mesh).

[0092] Figure 15 This is a schematic diagram of the regional control of the unit cell composite form of different structural parameters of the curved rod lattice metamaterial (layout mode: the structural parameters of the curved rod lattice metamaterial unit cell in about one-quarter of the edge region are different from those in other regions);

[0093] Figure 16 This is a schematic diagram of the split-type control of curved rod lattice metamaterials (coarse rod form: the diameter of the curved rod of the unit cell of the curved rod lattice metamaterial is relatively large);

[0094] Figure 17 This is a schematic diagram of the split-type control of curved rod lattice metamaterials (thin rod form: the diameter of the curved rod of the unit cell of the curved rod lattice metamaterial is small);

[0095] Figure 18 The following is a schematic diagram using a curved stretchable mesh as an example: By controlling the heat treatment specifications or the composition of the shape memory alloy material, the phase transition temperatures of multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are set to different temperature values ​​(T1, T2, T3, T4, T5, and T6 represent the phase transition temperature values ​​of shape memory alloy curved rod lattice metamaterials or curved stretchable meshes).

[0096] Figure 19 The following is a schematic diagram, using a curved stretchable mesh as an example: a stack of multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different phase transition temperatures (T1, T2, T3, T4, T5, and T6 represent the phase transition temperature values ​​of the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes).

[0097] Figure 20The following is an example using a curved stretchable mesh: By controlling the heat treatment specifications or the composition of the shape memory alloy material, the phase transition temperatures of shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different structural parameters or performances and different layouts of unit cells are controlled to different temperature values. These are then stacked together to obtain a schematic diagram of a shape memory alloy composite flexible metamaterial with non-uniform structure, non-uniform performance, and non-simultaneous triggering actuation function and stress response (the dashed box in the figure is used to indicate the area of ​​the unit cell with a narrower curved edge width of the curved stretchable mesh, and T1, T2 and T3 represent the phase transition temperature values ​​of the shape memory alloy curved rod lattice metamaterial and the curved stretchable mesh).

[0098] Figure 21 The following is an example of a curved stretchable mesh: a schematic diagram of a curved rod lattice metamaterial and a curved stretchable mesh fabricated from a shape memory alloy billet into a flat plate shape.

[0099] Figure 22 The following is a schematic diagram of the curved bar lattice metamaterial and the curved edge stretchable mesh, using curved edge stretchable mesh as an example.

[0100] Figure 23 The following is an example of a curved stretchable mesh: a curved rod lattice metamaterial that is shaped and then deformed into a temporary flat plate shape, and a schematic diagram of a curved stretchable mesh.

[0101] Figure 24 The following is a schematic diagram of a curved rod lattice metamaterial and a curved edge stretchable mesh, which is given as an example: after being shaped, it is deformed into a temporary flat plate shape, and then heated to trigger the restoration to the original shape.

[0102] Figure 25 The following is a schematic diagram showing the curved bar lattice metamaterial and the edge of the curved edge stretchable mesh in a flat state when the blank needs to be pressed; taking the curved edge stretchable mesh as an example.

[0103] Figure 26 This is a schematic diagram illustrating the influence of structural parameters on the performance of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable mesh, using a curved rod as an example (the two curved rod supports have the same span, but different diameters).

[0104] Figure 27 This is a schematic diagram illustrating the influence of structural parameters on the performance of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable mesh, using a curved rod as an example (the two curved rods have the same diameter, but the spans of the curved rods are different).

[0105] Figure 28 The following is a schematic diagram showing how a shape memory alloy curved rod lattice metamaterial or a curved stretchable mesh is processed into multiple parts, using a curved stretchable mesh as an example.

[0106] Figure 29 The following is a schematic diagram, using a curved stretchable mesh as an example: after shape memory alloy curved rod lattice metamaterial or curved stretchable mesh is processed into multiple parts, it is then shaped and heat-treated to set its shape, and then welded into a whole.

[0107] Figure 30 The following is a schematic diagram showing how a connector is fabricated at the edge of a shape memory alloy curved rod lattice metamaterial or a curved stretchable mesh, using curved edge stretchable mesh as an example.

[0108] Figure 31 The diagram shows a joint at the edge of a shape memory alloy curved rod lattice metamaterial or a curved stretchable mesh, using a curved stretchable mesh as an example.

[0109] Figure 32 The example given is a curved stretchable mesh: when the edges of the curved rod lattice metamaterial and the curved stretchable mesh are in a flat state, while the central region is a curved rod lattice metamaterial or a curved stretchable mesh, the central region is deformed into a set shape and shaped.

[0110] Figure 33 The example given is a curved stretchable mesh: when the edges of the curved rod lattice metamaterial and the curved stretchable mesh are in a flat state, while the central region is a curved rod lattice metamaterial or a curved stretchable mesh, the central region is deformed into a set shape and then shaped, and then deformed into a temporary flat shape.

[0111] Figure 34 The following is a schematic diagram, using a curved stretchable mesh as an example: When multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are stacked and layered, each shape memory alloy curved rod lattice metamaterial or curved stretchable mesh is rotated at an angle to stagger the connectors at their edges.

[0112] Figure 35 The following is a schematic diagram showing the result of stacking multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes together, with each shape memory alloy curved rod lattice metamaterial or curved stretchable mesh rotating at an angle to stagger the connectors at their edges.

[0113] Figure 36 This is a schematic diagram of the forming process of flexible metamaterials made of shape memory alloys with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response as flexible intelligent actuators (the forming start stage after assembly).

[0114] Figure 37This is a schematic diagram (forming completion stage) of a flexible metamaterial composed of shape memory alloys with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response as a flexible intelligent actuator.

[0115] Figure 38 This is a schematic diagram of the forming process of a flexible metamaterial composed of shape memory alloys with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response as a flexible intelligent actuator when applying a cover plate (the forming start stage after assembly).

[0116] Figure 39 This is a schematic diagram (forming completion stage) of a flexible metamaterial composed of shape memory alloys with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response, used as a flexible intelligent actuator when applying a cover plate.

[0117] Figure 40 This is a schematic diagram of the forming process of a flexible smart actuator using a shape memory alloy composite flexible metamaterial with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response when applying a rigid-flexible composite cover plate (the forming start stage after assembly).

[0118] Figure 41 This is a schematic diagram (forming completion stage) of a flexible intelligent actuator made of shape memory alloy composite flexible metamaterial with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response when applying rigid-flexible composite cover plate.

[0119] Figure 42 This is a schematic diagram of the forming process of a flexible smart actuator using a shape memory alloy composite flexible metamaterial with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response when applying elastic pads and cover plates (the forming start stage after assembly).

[0120] Figure 43 This is a schematic diagram (forming completion stage) of a flexible smart actuator using a shape memory alloy composite flexible metamaterial with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response when applying elastic pads and cover plates.

[0121] Figure 44 This is a schematic diagram of the forming process of a flexible metamaterial composed of shape memory alloys with non-uniform structure, non-uniform properties, and non-simultaneous triggering actuation function and stress response as a flexible intelligent actuator when applying fluid back pressure (the forming start stage after assembly).

[0122] Figure 45This is a schematic diagram (forming completion stage) of a flexible smart actuator made of shape memory alloy composite flexible metamaterial with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response, when applying fluid back pressure.

[0123] Figure 46 This is a schematic diagram of a flexible shape memory alloy metamaterial with different structures, properties, and phase transition temperatures when multiple shape memory alloy point-curved rod lattice metamaterials with different structures, properties, and actuation functions and stress responses are stacked together when applying a frame. (In the figure, T1, T2 and T3 represent the phase transition temperature values ​​of the shape memory alloy curved rod lattice metamaterial).

[0124] Figure 47 This is a schematic diagram of the forming process using shape memory alloy flexible metamaterials with non-uniform structure, non-uniform properties, and non-simultaneous triggering of actuation functions and stress responses when applying a frame (the initial stage of forming after assembly). In the diagram, T1, T2, T3, T4, and T5 represent different phase transformation temperatures. Because the phase transformation temperatures are different, the actuation function and stress response of the shape memory alloy are not triggered simultaneously. Therefore, the force exerted by the shape memory alloy on the billet is also non-simultaneous, thus applying pressure to the billet in different regions and stages.

[0125] Figure 48 This is a schematic diagram (forming completion stage) of the forming process using shape memory alloy flexible metamaterials with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response when applying a frame.

[0126] Figure 49 This is a schematic diagram of the forming process using shape memory alloy flexible metamaterials with non-uniform structure, non-uniform properties, and non-simultaneous triggering of actuation functions and stress responses when applying a housing, elastomer, and cover plate (the initial stage of forming after assembly). T1, T2, T3, T4, and T5 in the diagram represent different phase transformation temperatures. Due to the different phase transformation temperatures, the actuation function and stress response of the shape memory alloy are not triggered simultaneously. Therefore, the force exerted by the shape memory alloy on the billet is also non-simultaneous, thus applying pressure to the billet in different regions and stages.

[0127] Figure 50 This is a schematic diagram (forming completion stage) of a shape memory alloy flexible metamaterial with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response when using a housing, elastomer, and cover plate.

[0128] Figure 51This is a schematic diagram of the forming process using a flexible metamaterial composed of shape memory alloys with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response as a flexible intelligent actuator when using two-way shape memory alloys (the forming start stage after assembly).

[0129] Figure 52 This is a schematic diagram (forming completion stage) of a flexible metamaterial composed of shape memory alloys with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response, used as a flexible intelligent actuator when forming a two-way shape memory alloy. Detailed Implementation

[0130] This invention is based on shape memory alloys. Therefore, the specific embodiments of this invention will be further described below in conjunction with the characteristics of shape memory alloys, the ideas and principles of this invention, and the accompanying drawings.

[0131] Shape memory alloys exhibit two different phase morphologies at different temperatures: austenite and martensite. The temperature at which the austenite phase appears is higher than that at which the martensite phase appears; therefore, they are often referred to as the high-temperature austenite phase and the low-temperature martensite phase, respectively. The high-temperature austenite phase is generally referred to as the parent phase; therefore, in this application, the shape corresponding to the high-temperature austenite phase is referred to as the original shape.

[0132] Under different stress and deformation conditions, low-temperature martensite exists in two different forms. One is the existence of many different oriented martensite variants. The other is the formation of martensite monomers or preferred oriented martensite variants through self-cooperative merging and transformation under stress or the combined action of stress and temperature. Since martensite monomers or preferred oriented martensite variants can be transformed into the parent phase high-temperature austenite by heating, their shape will also be restored to the original shape corresponding to the parent phase high-temperature austenite. Therefore, in this application, the shape corresponding to the deformation-induced low-temperature martensite monomers or preferred oriented martensite variants is called the temporary shape, because it can be transformed into the original shape corresponding to the parent phase high-temperature austenite at any time by heating.

[0133] The shape memory function of shape memory alloys refers to the fact that when a shape memory alloy is fixed in an original shape in the high-temperature austenitic state of the parent phase, it will remember this original shape. When it is cooled down and transformed into low-temperature martensite, and then subjected to external forces, many low-temperature martensite variants with different orientations are formed through self-cooperative merging and transformation into martensite monomers or preferred orientation martensite variants. At the same time, the external forces change its shape into a temporary shape. When it is heated again, the martensite monomers or preferred orientation martensite variants will transform into the high-temperature austenitic parent phase, and the shape of the shape memory alloy will also recover from this temporary shape to the original shape. In other words, the shape memory alloy remembers the original shape and can recover its memory and return to its original shape after the shape is changed.

[0134] During the shape recovery process, a restoring force is generated, which produces an actuation effect. That is, through external induction, the shape memory alloy changes shape and can store energy. When the shape is restored to its original shape, this energy is released to generate a restoring force, thus possessing an actuation function.

[0135] The same applies to shape memory alloys with two-way shape memory. Two-way shape memory refers to the process where, through heat treatment, the parent phase of the shape memory alloy, high-temperature austenite, is shaped into a specific form, allowing it to "remember" this original shape. Then, through repeated cycles of thermodynamic "training," a specific stress field is created within the shape memory alloy. This stress field induces the shape memory alloy to automatically transform from high-temperature austenite to low-temperature martensite during cooling, resulting in a preferred orientation of the martensite. This low-temperature martensite phase is then shaped into a temporary shape and remembered, giving the shape memory alloy a two-way shape memory function. Finally, simply cooling is used to restore the shape memory. When the alloy cools down from the parent phase high-temperature austenite to low-temperature martensite, it automatically transforms into a low-temperature martensite with a preferred orientation. At the same time, the shape of the shape memory alloy changes from the original shape of the parent phase high-temperature austenite to the temporary shape of the parent phase low-temperature martensite. This provides a prerequisite for generating a restoring force when it is reheated to restore the original shape of the parent phase high-temperature austenite. That is, through this temperature-induced shape change from the original shape to the low-temperature temporary shape, the purpose of storing energy in the shape memory alloy is achieved. When the shape is restored to the original shape, this energy is released to generate a restoring force, thereby possessing an actuation function.

[0136] If a shape memory alloy curved rod lattice metamaterial or a curved stretchable mesh is shaped, transformed into low-temperature martensite, and then subjected to external forces to transform its shape from its original form to a temporary shape, and then heated, then, due to its shape memory function, it will restore its original shape and generate a restoring force. Furthermore, due to the flexibility and stretchability of the shape memory alloy curved rod lattice metamaterial and the curved stretchable mesh, during the expansion process of restoring its original shape after compression deformation, if it encounters a rigid, complex-shaped object, then the shape memory alloy curved rod lattice metamaterial or the curved stretchable mesh will actively adapt to and conform to this rigid, complex-shaped object. And due to the restoring force generated during the shape restoration process, the shape... Shape memory alloy curved rod lattice metamaterials or curved-edge stretchable meshes exert forces on rigid, complex-shaped objects that hinder their shape recovery. In other words, the shape memory alloy generates a stress response. At this point, the effect of the shape memory alloy curved rod lattice metamaterial or curved-edge stretchable mesh on the object hindering its movement is similar to that of a mechanical device, possessing an actuating function that generates force. However, if the shape memory alloy curved rod lattice metamaterial or curved-edge stretchable mesh encounters a relatively soft object during its expansion process after being compressed and deformed to restore its original shape, then the actuating function of the shape memory alloy curved rod lattice metamaterial or curved-edge stretchable mesh will drive and force this relatively soft object to deform until it encounters a rigid object. Therefore, the process of shape memory alloy curved rod lattice metamaterials or curved-edge stretchable meshes, after being shaped and possessing shape memory function, returning to its original shape after being deformed into a temporary shape, can act as a flexible actuator to drive and force the deformation of a blank into a component. If the structure or properties of a shape memory alloy are designed to be non-uniform, then the shape memory alloy can be transformed into a flexible metamaterial capable of generating non-uniform stress responses and time-varying stress responses. This can serve as a flexible intelligent actuator whose stress response spatial distribution and time-varying characteristics can be designed, and can be used for forming complex shaped components. Based on this, this invention proposes a low-cost intelligent forming manufacturing method based on shape memory alloys.

[0137] The implementation of this method mainly consists of two parts: first, transforming the shape memory alloy into a flexible metamaterial capable of generating non-uniform stress response and time-varying stress response, which serves as a flexible intelligent actuator; second, applying the shape memory alloy, which has been transformed into a flexible metamaterial capable of generating non-uniform stress response and time-varying stress response, and the flexible intelligent actuator, to the billet to form a component.

[0138] The specific implementation method is as follows.

[0139] (1) Implementation methods for achieving flexible shape memory alloy curved rod lattice metamaterials and curved-edge stretchable meshes with large deformation capabilities:

[0140] Lattice metamaterials and stretchable meshes inherently possess flexibility and large deformation capabilities. However, to ensure more uniform deformation, avoid stress and strain concentration, and prevent the deformation of the shape memory alloy from exceeding its recoverable strain, curved rod lattice metamaterials and curved edge stretchable meshes are employed. In other words, curved rods form the unit cells of the lattice metamaterials, and curved edges form the unit cells of the stretchable meshes. This gives the curved rod lattice metamaterials and curved edge stretchable meshes flexibility, extensibility, and the ability to adapt to the large deformation required for complex shape forming.

[0141] Figure 1 and Figure 2 These are schematic diagrams of a curved stretchable mesh and a schematic diagram of a curved stretchable mesh unit cell, respectively.

[0142] Besides the curved edges of the unit cells in the stretchable mesh to make it "flexible," the thickness of the stretchable mesh must also be "flexible," meaning it must be thin. This is because material thickness is related to the bend radius that can be formed. In practical applications, shape memory alloys can use "flexible" blanks—thin-walled sheets, thin-diameter wires or rods. The width and length of the sheet are much greater than its thickness, making it more "flexible" than bulk or rod-shaped blanks. However, thin sheets are only suitable for simple shape changes such as bending. To deform into more complex shapes, "flexible" shape memory alloy sheet blanks can be processed into stretchable meshes. Compared to continuous sheets, mesh structures can produce greater deformation. To control the deformation of the shape memory alloy within its recoverable deformation range, the unit cell structure of the stretchable mesh adopts a curved edge form, i.e., a flexible structure. One form of this curved edge stretchable mesh and its unit cell structure and dimensions are as follows... Figure 1 and Figure 2 As shown. A "flexible" shape memory alloy billet in the form of a curved, stretchable mesh, processed from sheet metal (such as...). Figure 1 It can produce a large amount of deformation, and therefore can be deformed into complex 3D shapes, forming complex 3D components.

[0143] The design of lattice unit cell structures and parameters for lattice metamaterials aims to enable significant shape changes while keeping the deformation within the recoverable range of shape memory alloys. Therefore, there are two types of lattice unit cells for lattice metamaterials, both employing curved rod forms. One type uses curved rods as the lattice supports (e.g.,...). Figure 3 , Figure 4 and Figure 5As shown), instead of the usual straight-bar truss structure, its deformation is dominated by the elongation and compression deformation of the curved rods. This allows the lattice metamaterial to have both large contraction and expansion deformations, while the strain of the shape memory alloy material itself is relatively small, controlled within the recoverable deformation range of the shape memory alloy material itself; another type is a structure that uses a spring-like structure as the lattice support (such as...). Figure 6 , Figure 7 and Figure 8 As shown, the spring-like structure also allows the lattice metamaterial to have large contraction and expansion deformations, while the strain of the shape memory alloy itself is small and controlled within the range of recoverable deformation of the shape memory alloy.

[0144] (2) Implementation methods for strengthening flexible metamaterials such as curved rod lattice metamaterials and curved edge stretchable mesh shape memory alloy flexible metamaterials:

[0145] By stacking multiple flexible form shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes, the forces are accumulated, enabling the "flexible form" curved rod lattice metamaterials and curved edge stretchable mesh shape memory alloy flexible metamaterials, which can undergo large deformations to adapt to complex shape deformations, to also have sufficient restoring force to force the blank to deform and form components. Figure 9 and Figure 10 Taking shape memory alloy curved stretchable mesh as an example, a schematic diagram is given of strengthening by stacking multiple flexible shape memory alloy curved rod lattice metamaterials or curved stretchable meshes.

[0146] (3) Implementation methods for regional control of the structure or properties of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes:

[0147] Regional control of unit cell composite forms with different structural parameters: In shape memory alloy curved rod lattice metamaterials or curved stretchable meshes, lattice unit cells or mesh unit cells with different structural parameters are used in different regions. That is, the structural parameters of unit cells in local regions differ from those in other regions, making the shape memory alloy curved rod lattice metamaterial or curved stretchable mesh a flexible metamaterial with unit cell composite forms of different structural parameters (e.g., Figure 11 As shown in the figure, this arrangement of non-uniform composite structural unit cells enables flexible metamaterials to produce non-uniform stress responses. The spatial distribution of stress response can be regionalized through the arrangement of non-uniform composite structural unit cells, for example... Figure 11 The image shows half of a curved stretchable mesh using mesh cells with smaller curved widths. Figure 11 The area within the dashed box is used, while the other half of the curved stretchable mesh uses mesh cells with larger curved widths, forming a regionalized control and layout of two different structural parameters of unit cell composite form.

[0148] Regional control of composite unit cells with the same structure but different properties is achieved by changing the material composition or properties of the lattice unit cells in lattice metamaterials and the mesh unit cells in stretchable meshes. Different lattice unit cells or mesh unit cells with different material compositions or properties are used in different regions of curved rod lattice metamaterials or curved edge stretchable meshes. That is, the material composition or properties of unit cells in local regions differ from those in other regions, making shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes flexible metamaterials with the same structure but different properties. This non-uniform composite property unit cell layout causes non-uniform stress response in flexible metamaterials. Regional control of the spatial distribution of stress response is achieved through the layout of non-uniform composite property unit cells; the layout method is similar to the layout of non-uniform structures (e.g., Figure 11 , Figure 12 and Figure 13 As shown), the only difference is that the material composition or properties of the unit cells in different regions are different; for this method of processing and preparing unit cells with the same structure but different material composition or properties, the regions of unit cells with the same structure but different material composition or properties can be processed and prepared separately, and then welded together.

[0149] (4) By regionalizing, splitting, and superimposing the structure or properties of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes, complex regional control can be achieved, resulting in shape memory alloy composite flexible metamaterials with non-uniform structures and properties, producing complex spatial distributions of stress response. The implementation method is as follows:

[0150] First, through regional control, lattice unit cells or mesh unit cells with different structural parameters or properties are used in different regions of shape memory alloy curved rod lattice metamaterials or curved stretchable meshes (e.g., Figure 11 As shown in the figure, the structural parameters or properties of the unit cell in a local region are different from those in other regions, resulting in a non-uniform stress response.

[0151] Secondly, modular control is implemented. By changing the structural parameters or the layout of unit cells with different properties during regional control of each curved rod lattice metamaterial or curved edge stretchable mesh, each individual is controlled separately, resulting in multiple shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes with different spatial distributions of stress response. That is, for each individual shape memory alloy curved rod lattice metamaterial or curved edge stretchable mesh, the layout of unit cells with different structural parameters or properties is different (e.g., Figure 11 , Figure 12 and Figure 13 As shown in the figure, the spatial distribution of stress response is different for each individual (as shown in the figure).

[0152] Then, composite control is performed, combining multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different structural parameters or performance of unit cells that have undergone separate control and have different layouts. That is, multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different stress response spatial distributions are stacked together (e.g., Figure 14 As shown, by forming a complex structure or regional control of properties, shape memory alloy composite flexible metamaterials are obtained, resulting in a complex spatial distribution of stress response.

[0153] For the fabrication of this non-identical composite structural unit cell layout, it can be fabricated directly according to different size and structural parameters, or it can be fabricated separately by processing parts with different structural parameters and then welding them together to form a complete non-identical composite structural unit cell layout of curved stretchable mesh.

[0154] Regional and discrete control of shape memory alloy curved rod lattice metamaterials, such as Figure 15 , Figure 16 and Figure 17 As shown, where Figure 15 and Figure 16 This is a schematic diagram of a lattice metamaterial for two curved struts with different bending parameters. Figure 17 This involves using lattice unit cells with different structural parameters or properties in different regions of a shape memory alloy curved rod lattice metamaterial. That is, the structural parameters or properties of unit cells in local regions differ from those in other regions, resulting in a non-uniform stress response. After regional and modular control, composite control is performed. Multiple shape memory alloy curved rod lattice metamaterials with different structural parameters or properties, after modular control, are arranged in different ways. This results in multiple shape memory alloy curved rod lattice metamaterials with different spatial distributions of stress response. These are then stacked together to form a complex structure or property through regional control, resulting in a non-uniform structure and non-uniform properties of a shape memory alloy composite flexible metamaterial, producing a complex spatial distribution of stress response.

[0155] (5) To achieve separate control and composite control of the structure or properties of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes, forming shape memory alloy composite flexible metamaterials with non-simultaneous triggering actuation function and stress response, the implementation method is as follows:

[0156] First, through modular control, by adjusting the heat treatment specifications or the composition of the shape memory alloy material, the phase transition temperatures of multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are set to different temperature values ​​(e.g., Figure 18 As shown), the phase transition temperature of each individual is controlled separately;

[0157] Then, through superposition and composite control, multiple curved rod lattice metamaterials or curved stretchable meshes with different phase transition temperatures, which have undergone separate control, are superimposed and layered together (e.g., Figure 19 As shown, a shape memory alloy composite flexible metamaterial with non-simultaneous triggering actuation function and stress response is obtained. Due to the different phase transition temperatures, the phase transition triggering times are not simultaneous. Therefore, multiple curved rod lattice metamaterials or curved edge stretchable meshes stacked together can generate non-simultaneous triggering actuation function and stress response. Thus, a stress response that varies with time can be generated. The separate control and composite control of the stacked form of curved rod lattice metamaterials or curved edge stretchable meshes with different phase transition temperatures are transformed into control that varies with time.

[0158] (6) By regionalizing, splitting, and composite controlling the structure or properties of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes, shape memory alloy composite flexible metamaterials with non-uniform structural layouts, non-uniform performance layouts, and non-simultaneous triggering of actuation functions and stress responses are formed. The implementation method is as follows:

[0159] First, through regional control, lattice unit cells or mesh unit cells with different structural parameters or properties are used in different regions of shape memory alloy curved rod lattice metamaterials or curved stretchable meshes. That is, the structural parameters or properties of the unit cells in local regions are different from those in other regions (e.g., Figure 11 As shown in the figure, a non-uniform stress response is generated;

[0160] Secondly, spatial distribution control of stress response is achieved through partitioned control. This is done by altering the layout of unit cells with different structural parameters or properties during regional control, specifically by changing the layout of unit cells with different structural parameters or properties (e.g., ...). Figure 11 , Figure 12 and Figure 13 As shown), by controlling each individual separately, multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different spatial distributions of stress response are obtained. That is, the layout of unit cells with different structural parameters or properties of each shape memory alloy curved rod lattice metamaterial or curved stretchable mesh is different, and the spatial distribution of stress response is also different.

[0161] Then, the stress response is controlled separately by non-simultaneous triggering. Through the regulation of heat treatment specifications or the composition of shape memory alloy materials, the phase transition temperatures of multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different structural parameters or performance layouts are set to different values. The phase transition temperature of each individual is controlled separately (e.g., ...). Figure 20As shown, since the phase transition temperatures are different, their phase transition triggering times are not simultaneous. This causes shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes with different layouts of multiple unit cells with different structural parameters or performance under regional control to generate non-simultaneous phase transition triggering and stress response, thereby generating a stress response that varies with time.

[0162] Finally, composite control is achieved through superposition and lamination. Multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes, with different structural parameters or performances and varying phase transition temperatures, which have undergone regional and discrete control, are superimposed and laminated together (e.g., Figure 20 As shown, a shape memory alloy composite flexible metamaterial was obtained. At this time, a composite control method of regional control, split control and layered superposition was comprehensively applied. It can not only generate a complex spatial distribution of stress response, but also generate a stress response that changes with time. Thus, a shape memory alloy composite flexible metamaterial with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response was formed.

[0163] (7) Combining the actuation function of shape memory alloys, the flexible metamaterials composited with shape memory alloys, which have non-uniform structures, non-uniform properties, and non-simultaneous triggering actuation functions and stress responses, are transformed into flexible intelligent actuators. The specific implementation method is as follows:

[0164] First, shape memory alloy curved rod lattice metamaterials and curved-edge stretchable meshes are fabricated.

[0165] Based on the design of different unit cell layouts according to structural parameters or performance, shape memory alloy blanks are processed into curved rod lattice metamaterials and curved-edge stretchable meshes; shape memory alloy blanks can be directly processed into curved rod lattice metamaterials and curved-edge stretchable meshes with a set shape, or shape memory alloy blanks can be processed into flat-shaped curved rod lattice metamaterials and curved-edge stretchable meshes (e.g., Figure 21 (as shown);

[0166] Secondly, a shaping heat treatment is performed to set the shape and phase transition temperature.

[0167] When the shape of the curved rod lattice metamaterial and the curved edge stretchable mesh is a set shape (such as...) Figure 22 When the shape is as shown, it is directly constrained and subjected to shaping heat treatment to shape it into a predetermined shape and give it shape memory function. Simultaneously, the phase transition temperature of the shape memory alloy curved rod lattice metamaterial and the curved stretchable mesh is set according to the shaping heat treatment specifications. When the curved rod lattice metamaterial and the curved stretchable mesh are in a flat plate shape, they are first deformed into a predetermined shape (e.g., Figure 22(As shown) Then constrain and perform shaping heat treatment to shape it into the set shape and give it shape memory function, and set its phase transformation temperature through shaping heat treatment specifications; for the desired original shape and temporary shape of curved bar lattice metamaterial and curved edge stretchable mesh, the shape of the formed component, the required pressure load distribution and the change of pressure load over time and the form of the sheet blank are determined. Then, the prepared shape memory alloy curved bar lattice metamaterial or curved edge stretchable mesh is subjected to shaping heat treatment according to the determined desired original shape to set the desired original shape;

[0168] Then, the shape memory alloy curved rod lattice metamaterial or curved stretchable mesh, with the original shape and phase transition temperature set as desired, is deformed into a temporary shape (such as...). Figure 23 As shown), this allows it to store energy, enabling it to have actuation functions, transforming it into a flexible actuator; then, it only needs to be heated to trigger a phase transition and return to its original shape (as shown). Figure 24 As shown in the figure, generating a restoring force can produce an actuation function;

[0169] Finally, multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes that already possess actuation functions and have been transformed into flexible actuators are stacked together. Since the structural parameters or properties of each shape memory alloy curved rod lattice metamaterial or curved stretchable mesh are different, the layout of the unit cells is different, and the phase transition temperature is different. Therefore, the spatial distribution of stress response is different, and the time of phase transition is also different. Stacking them together transforms them into shape memory alloy flexible metamaterials with non-identical structures, non-uniform properties, and non-simultaneous triggering of actuation functions and stress responses. This transforms them into flexible intelligent actuators with intelligent and controllable spatial distribution of stress response and changes over time.

[0170] In cases where blanks require edge pressing, the shape memory alloy curved bar lattice metamaterial and the curved stretchable mesh used for deforming the blanks have flat edges (e.g., Figure 25 As shown), the steps for transforming it into a flexible actuator are similar to... Figure 21 , Figure 22 , Figure 23 and Figure 24 The same as shown.

[0171] (8) Implementation methods for regional control of shape memory alloy curved bar lattice metamaterials and shape memory alloy curved edge stretchable meshes through structural parameter or performance design:

[0172] Regional control of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes involves applying lattice unit cells or stretchable mesh unit cells with different structural parameters or properties to different regions. This regional control is achieved through the design and modification of structural parameters or properties. These parameter designs are the control parameters for regional control of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes, specifically as follows... Figure 2 , Figure 5 and Figure 8 As shown.

[0173] Figure 2 This is a schematic diagram of the shape, structure, and parameters of a curved stretchable mesh unit cell. The shape, structure, and parameters include the unit cell spans L1 and L2, the widths W1 and W2 of the curved edges, and the radii of curvature R1 and R2 of the curved edges.

[0174] Figure 5 This is a schematic diagram of the shape, structure, and parameters of a curved rod lattice metamaterial unit cell in the form of a curved rod. The shape, structure, and parameters include the unit cell span L (length of the curved rod), the diameter Φ of the curved rod, the radius of curvature R2 of the curved rod, and the radius of curvature R1 of the transition section of the curved rod.

[0175] Figure 8 This is a schematic diagram of the shape, structure, and parameters of a curved rod lattice metamaterial unit cell spring support in the form of a curved support rod. The shape, structure, and parameters include the unit cell span L1 (spring length L1), spring wire diameter Φ2, spring diameter Φ1, and spring pitch L2.

[0176] Modifying structural parameters to achieve regionalized control over shape memory alloy curved rod lattice metamaterials and shape memory alloy curved stretchable meshes involves altering the shape, structure, and parameters of the aforementioned unit cells; specifically, it means changing... Figure 2 , Figure 5 and Figure 8 The parameters shown.

[0177] In practical implementation, these structural parameters are selected based on the performance requirements of the shape memory alloy curved rod lattice metamaterial and the shape memory alloy curved edge stretchable mesh. For example, taking a curved rod support as an example, the influence of structural parameters on the performance of the shape memory alloy curved rod lattice metamaterial and the shape memory alloy curved edge stretchable mesh is illustrated. When two curved rod supports have the same span, but the diameters of the curved rod supports are different (e.g., Figure 26 When subjected to the same force F, the curved rod with a smaller diameter deforms more and appears more "flexible," while the curved rod with a larger diameter deforms less and appears more "rigid." Therefore, this can be used to control the flexibility of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved stretchable meshes. When two curved rods have the same diameter but different spans (e.g.,...),... Figure 27When they are compressed to the same height (as shown), the deformation of the curved rod with a larger span is greater, while the deformation of the curved rod with a smaller span is smaller. Since the restoring force of shape memory alloy is related to the amount of deformation, this means that the restoring forces they can generate when compressed to the same height will be different. Therefore, the restoring force of shape memory alloy curved rod lattice metamaterial and shape memory alloy curved edge stretchable mesh can be controlled in this way.

[0178] Similar to the influence of structural parameters on the properties of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes, the properties of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes can also be controlled through material composition and heat treatment specifications. For example, the strength and phase transformation temperature of shape memory alloys are related to the material composition, and the material strength also affects the material deformation, thus affecting the flexibility of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes. The material strength also affects the material stress response, thus affecting the stress response of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes.

[0179] (9) Implementation methods for preparing shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes:

[0180] Since the composition of shape memory alloys affects their properties, such as phase transition temperature and strength, shape memory alloy curved rod lattice metamaterials and curved-edge stretchable meshes with different material compositions can be selected when designing and preparing shape memory alloy composite flexible metamaterials with different structures, non-uniform properties, and non-simultaneous triggering actuation functions and stress responses. This will produce shape memory alloy curved rod lattice metamaterials and curved-edge stretchable meshes with different properties, such as shape memory alloy curved rod lattice metamaterials and curved-edge stretchable meshes with different phase transition temperatures.

[0181] Depending on the requirements, select appropriate shape memory alloy raw materials or blanks, such as suitable shape memory alloy material composition. Then, according to the structural parameters of the unit cell of the designed shape memory alloy curved rod lattice metamaterial, use methods such as laser cutting, wire EDM, or 3D printing (additive manufacturing) to prepare curved rod lattice unit cells or curved rod supports of curved rod lattice unit cells with different structural parameters. Then, weld them together with laser welding to form shape memory alloy curved rod lattice metamaterials with different structures or properties. Alternatively, directly use 3D printing (additive manufacturing) to prepare integral shape memory alloy curved rod lattice metamaterials with different structures.

[0182] For shape memory alloy curved stretchable mesh, different structures of shape memory alloy curved stretchable mesh can be prepared by means of laser cutting, electrical discharge wire cutting or 3D printing (additive manufacturing).

[0183] For shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes with non-uniform properties, according to their properties, the parts with different properties are first processed and prepared by laser cutting, electrical discharge wire cutting or 3D printing (additive manufacturing), and then the parts are welded together by laser welding.

[0184] (10) Shape memory alloy curved rod lattice metamaterials and curved stretchable meshes are transformed into actuators by shaping heat treatment and deformation energy storage. The implementation method and process of shaping heat treatment are as follows:

[0185] When using single-pass shape memory alloys, the shaping heat treatment process is as follows:

[0186] When shape memory alloy curved rod lattice metamaterials and curved stretchable meshes are directly prepared into a set shape, they are constrained, heated, and transformed into the parent austenitic phase. They undergo shaping heat treatment to fix their shape and give them a one-way shape memory function. Then they are cooled to transform into the low-temperature martensite phase. Deformation is performed in the low-temperature martensite phase to form a temporary shape. As long as they are heated again to transform back into the parent austenitic phase, they will restore their original shape. Therefore, this deformation induced by external force stores energy, transforming them into a flexible actuator with actuation properties.

[0187] When shape memory alloy curved rod lattice metamaterials and curved stretchable meshes are fabricated into simple flat plate shapes, the prepared shape memory alloy curved rod lattice metamaterials and curved stretchable meshes need to be deformed to the set shape and constrained. They are then heated to transform into the parent austenitic phase, and subjected to shaping heat treatment to solidify their shape and give them a one-way shape memory function. Then they are cooled to transform into the low-temperature martensite phase. Deformation is then performed in the low-temperature martensite phase to form a temporary shape. As long as they are heated again to transform back into the parent austenitic phase, they will restore their original shape. Therefore, this deformation induced by external force stores energy, transforming it into a flexible actuator with actuation properties.

[0188] For smaller components, the required shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are also small in size. The shape memory alloy curved rod lattice metamaterials or curved stretchable meshes can be entirely bound to a single mold for shaping and heat treatment, shaping them into the desired shape and giving them shape memory function. For larger or extra-large components, the required shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are also large or extra-large. If the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are subjected to integral shaping and heat treatment, large or extra-large heating furnaces and molds are required, which is difficult to implement. Therefore, a split approach can be adopted, processing the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes into multiple parts (e.g., Figure 28 As shown), each component is bound to a corresponding mold, and after shaping and heat treatment, the individual components are welded together into a whole using laser welding (e.g., Figure 29 As shown), it has a set shape and a shape memory function.

[0189] When using two-way shape memory alloys, the shaping heat treatment process is as follows:

[0190] First, a shaping heat treatment is performed to remember the original shape of the high-temperature austenite phase:

[0191] When shape memory alloy curved rod lattice metamaterial and curved stretchable mesh are directly prepared into a set shape, they are constrained, heated to transform into the parent phase austenite phase, and then subjected to shaping heat treatment to fix the shape and give it the shape memory function of remembering the original shape of the high-temperature austenite phase.

[0192] When shape memory alloy curved bar lattice metamaterial and curved stretchable mesh are prepared into simple flat plate shapes, it is necessary to deform the prepared shape memory alloy curved bar lattice metamaterial and curved stretchable mesh into the set shape and constrain it, heat it to transform it into the parent phase austenite phase, and perform shaping heat treatment to shape it and give it the shape memory function of remembering the original shape of the high temperature austenite phase.

[0193] Secondly, a temporary shape for the low-temperature martensitic phase is established using a thermo-mechanical training method with constant deformation cyclic training under constrained conditions:

[0194] Shape memory alloy curved rod lattice metamaterials and curved stretchable meshes, whose original shapes are fixed and memorized in the high-temperature austenitic phase, are cooled to transform into a low-temperature martensitic phase and deformed into a temporary shape. Under constrained conditions, thermomechanical treatment training involving heating and cooling is performed: (a) The shape memory alloy curved rod lattice metamaterial or curved stretchable mesh, whose original shape is fixed to the set geometry, is fixed and heated above the high-temperature austenitic phase transformation temperature to transform it into a high-temperature austenitic phase; (b) The shape memory alloy in the high-temperature austenitic phase is loaded to deform it into the desired temporary shape; (c) The deformation loading is kept constant, and the shape memory alloy is cooled... (c) Increase the temperature of the shape memory alloy curved rod lattice metamaterial or curved edge stretchable mesh until the load applied to the shape memory alloy curved rod lattice metamaterial or curved edge stretchable mesh no longer decreases; (d) Keep the deformation load constant and increase the temperature of the shape memory alloy curved rod lattice metamaterial or curved edge stretchable mesh until the load applied to the shape memory alloy curved rod lattice metamaterial or curved edge stretchable mesh no longer increases; (e) Repeat steps (c) and (d) until the loading force no longer changes, until the shape memory alloy curved rod lattice metamaterial or curved edge stretchable mesh can not only remember the original set shape of the parent phase high-temperature austenite, but also remember the temporary shape of the low-temperature martensite phase, forming a two-way shape memory function.

[0195] For smaller components, the required shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are also small in size. The shape memory alloy curved rod lattice metamaterials or curved stretchable meshes can be entirely bound to a single mold for shaping and heat treatment, shaping them into the desired shape and giving them shape memory function. For larger or extra-large components, the required shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are also large or extra-large. If the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are subjected to integral shaping and heat treatment, large or extra-large heating furnaces and molds are required, which is difficult to implement. Therefore, a split approach can be adopted, processing the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes into multiple parts (e.g., Figure 28 As shown), each component is bound to a corresponding mold, and after shaping and heat treatment, the individual components are welded together into a whole using laser welding (e.g., Figure 29 As shown), it has a set shape and a shape memory function.

[0196] (11) Assembly Implementation Method

[0197] In order to assemble shape memory alloy composite flexible metamaterials, which are composed of shape memory alloy curved rod lattice metamaterials or curved stretchable meshes, with blanks to facilitate the forming of components, it is necessary to deform the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes into a temporary shape. This temporary shape is adapted to the shape of the blank used to form the component. For example, if the blank used to form the component is a sheet blank, then the shape memory alloy flexible metamaterial is deformed into a temporary flat shape.

[0198] During assembly, lubrication is required for all metals in contact. In the assembly process, graphite paper is filled into the pores of the shape memory alloy curved rod lattice metamaterial to reduce friction; graphite paper is placed between the stacked shape memory alloy curved rod lattice metamaterials or shape memory alloy curved stretchable meshes for lubrication and to reduce friction; graphite paper is placed between the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes and the blank to reduce friction.

[0199] (12) Implementation method of heating triggering

[0200] To heat-trigger a shape memory alloy composite flexible metamaterial composed of multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes, connectors (such as...) are fabricated at the edges of the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes. Figure 30 As shown), in Figure 30 The circular shape memory alloy curved stretchable mesh shown has a flat edge for applying a pressing force, while the central area is a curved stretchable mesh. Four connectors are machined on the edge of the circular flat plate, and holes are machined on the connectors for connecting resistance heating rods.

[0201] Figure 31 A schematic diagram is shown of a resistance heating rod connected to the edge connector of a shape memory alloy curved rod lattice metamaterial or a curved stretchable mesh. The resistance heating rod 2 is inserted into a copper sleeve 1, and then connected to the edge connector 4 of the shape memory alloy curved rod lattice metamaterial or curved stretchable mesh through the connector 3 at the end of the copper sleeve 1, and fixed together with bolts 7. When current is applied to the resistance heating rod 2, the heat is conducted through the copper sleeve 1, the connector 3 of the copper sleeve, the edge connector 4 of the shape memory alloy curved rod lattice metamaterial or curved stretchable mesh, and the edge plate portion 5 to the shape memory alloy curved rod lattice metamaterial or curved stretchable mesh area 6 in the center region.

[0202] When considering connecting a resistance heating rod to the edge of a shape memory alloy curved rod lattice metamaterial or a curved stretchable mesh for heating triggering, the method of transforming the shape memory alloy curved rod lattice metamaterial or curved stretchable mesh into an actuator also requires deforming and shaping it into a predetermined shape (e.g., Figure 32As shown), after being shaped and possessing shape memory function, it is then transformed into a temporary shape (such as...). Figure 33 As shown in the figure, multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes that have stored energy and transformed it into actuators are then stacked together to form a shape memory alloy composite flexible metamaterial.

[0203] To ensure smooth connection of the resistance heating rod to the connector at the edge of the shape memory alloy curved rod lattice metamaterial or the curved stretchable mesh, each shape memory alloy curved rod lattice metamaterial or curved stretchable mesh is rotated at an angle during stacking, staggering the connectors at their edges (e.g., Figure 34 and Figure 35 (As shown), this ensures that the resistance heating rods do not interfere with each other when connected. This heating method allows for individual control of the heating of each shape memory alloy curved rod lattice metamaterial or curved stretchable mesh.

[0204] Alternatively, the flexible heating wire can be insulated and then directly wound onto a shape memory alloy curved rod lattice metamaterial or a shape memory alloy curved edge stretchable mesh. By energizing the heating wire, the heat can be directly transferred to the shape memory alloy curved rod lattice metamaterial or the shape memory alloy curved edge stretchable mesh. In this way, the shape memory alloy curved rod lattice metamaterial or the shape memory alloy curved edge stretchable mesh can heat up faster.

[0205] Example 1

[0206] Example 1 is a hemispherical component (e.g.) Figure 36 and Figure 37 As shown, the blank used to form the hemispherical component is a 2mm thick aluminum alloy sheet, or it can be a pure titanium or other materials, or it can be a welded plate of two materials, such as a welded plate of aluminum alloy and steel.

[0207] The shape memory alloy material used is nickel-titanium shape memory alloy.

[0208] The rigid mold 1 used for forming the component is machined from 45 steel. Holes are machined into the edges of the mold 1 for assembly via bolts 7 (e.g., ...). Figure 36 and Figure 37 (As shown).

[0209] Shape memory alloy composite flexible metamaterial 3, with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function, and stress response, is used to apply pressure to the sheet blank 2 to deform it. Shape memory alloy composite flexible metamaterial 4 is used for edge clamping force control to suppress wrinkling of the sheet blank 2 (e.g., Figure 36 and Figure 37 (As shown).

[0210] Based on the characteristics of the components to be formed, shape memory alloy composite flexible metamaterials 3 and 4 are designed and fabricated to process non-uniform structures, non-uniform properties, and non-simultaneously triggered actuation functions and stress responses. Other auxiliary tools and molds are also processed and prepared, and then... Figure 36 As shown, assemble and form the component. The specific steps are as follows:

[0211] Step 1:

[0212] The sheet metal components to be formed are analyzed or numerically simulated. Based on the instability, wrinkling or cracking that may occur during the deformation of the sheet metal blank, the appropriate spatial distribution of the stress field acting on the sheet metal blank and its change over time are determined.

[0213] The pressure field acting on the sheet blank is divided into two parts: one part corresponds to the deformation part of the mold cavity, and the other part corresponds to the edge pressing part outside the mold cavity of the sheet blank. Therefore, the analysis or numerical simulation to determine the appropriate spatial distribution of the stress field acting on the sheet blank and its change over time is also divided into two parts. Then, the corresponding shape memory alloy composite flexible metamaterials 3 and 4 are designed and fabricated respectively.

[0214] Step Two:

[0215] Based on the spatial distribution of stress field and its change over time obtained from the analysis in step one, we first designed a flexible shape memory alloy-shape memory alloy curved rod lattice metamaterial and a curved stretchable mesh. Then, we applied a composite control method of regional control, split control, and superposition and layering to design a shape memory alloy composite flexible metamaterial with non-uniform structure, non-uniform performance, non-simultaneous triggering actuation function and stress response.

[0216] First, flexible design is implemented. Shape memory alloy composite flexible metamaterials employ two forms of flexible structures: curved rod lattice metamaterials and curved-edge stretchable meshes. To ensure that the flexible structure and parameters of the unit cells of the shape memory alloy curved rod lattice metamaterials and curved-edge stretchable meshes can provide sufficient force and produce large shape changes, while controlling the deformation within the recoverable deformation range of the shape memory alloy, the lattice unit cells of the curved rod lattice metamaterials adopt a lattice structure where the supports are curved rods (bent rods) (e.g., Figure 3 , Figure 4 and Figure 5 As shown in the diagram, instead of the usual straight-bar truss structure, its deformation is dominated by the elongation and compression deformation of the curved bars. This allows the lattice metamaterial to have both large contraction and expansion deformations, while the strain of the shape memory alloy itself is relatively small, controlled within the recoverable deformation range of the shape memory alloy. The curved-edge stretchable mesh uses... Figure 1The curved edge structure is shown. Since the blank thickness is related to the formable bending radius, in practical applications, shape memory alloys can use "flexible" blanks—sheets. The width and length of the sheet are much greater than its thickness, making it more "flexible" than block or rod blanks. However, thin sheets are only suitable for simple shape changes such as bending. To deform into more complex shapes, the "flexible" shape memory alloy sheet blank needs to be processed into a stretchable mesh. Compared to a continuous sheet, the mesh structure can produce greater deformation. To control the deformation of the shape memory alloy within its recoverable deformation range, the unit cell structure of the stretchable mesh also adopts a curved edge form, i.e., a flexible structure. One form of this stretchable mesh and its unit cell structure are shown below. Figure 1 and Figure 2 As shown, the "flexible" shape memory alloy, which is made from sheet metal and can be in the form of a stretchable mesh, can produce a large amount of deformation. Therefore, it can be deformed into complex 3D shapes to form complex 3D components.

[0217] Secondly, after determining the flexible form of the unit cell of the shape memory alloy curved rod lattice metamaterial and the curved edge stretchable mesh, the structural parameters or properties of the unit cell are changed, and regional control method, split control method and superimposed layering composite method are adopted to design and determine the shape memory alloy composite flexible metamaterial with non-identical structure, non-uniform properties, non-simultaneous triggering actuation function and stress response.

[0218] Designing shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes by changing the structural parameters of the unit cells and the layout of unit cells with different structural parameters involves altering the shape, structure, and parameters of the unit cells in the shape memory alloy curved rod lattice metamaterials and curved edge stretchable meshes, as well as the layout of unit cells with different structural parameters. For curved edge stretchable mesh unit cells, the shapes, structures, and parameters that can be designed and modified include (e.g., Figure 2 (As shown): the unit cell spans L1 and L2, the widths W1 and W2 of the curved edges, and the radii of curvature R1 and R2 of the curved edges; for curved rod lattice metamaterial unit cells in the form of curved supports, the designable and modifiable shapes, structures, and parameters include (e.g.) Figure 5(As shown): The unit cell span L (bending rod length L), bending rod diameter Φ, bending rod radius of curvature R2, and bending rod transition section radius of curvature R1. Using these parameters, based on the required pressure load distribution and pressure load variation over time obtained in step one, regional control methods or split-type control methods can be used to design shape memory alloy curved rod lattice metamaterials or curved-edge stretchable meshes with different structural parameters or performance, and different unit cell layouts and phase transition temperatures. These are then stacked and layered to form shape memory alloy composite flexible metamaterials with non-uniform structures, non-uniform properties, and non-simultaneous triggering actuation functions and stress responses.

[0219] In practical implementation, these structural parameters are selected based on the performance requirements of the shape memory alloy curved rod lattice metamaterial and the shape memory alloy curved edge stretchable mesh. For example, taking a curved rod support as an example, the influence of structural parameters on the performance of the shape memory alloy curved rod lattice metamaterial and the shape memory alloy curved edge stretchable mesh is illustrated. When two curved rod supports have the same span, but the diameters of the curved rod supports are different (e.g., Figure 26 When subjected to the same force F, the curved rod with a smaller diameter deforms more and appears more "flexible," while the curved rod with a larger diameter deforms less and appears more "rigid." Therefore, this can be used to control the flexibility of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved stretchable meshes. When two curved rods have the same diameter but different spans (e.g.,...),... Figure 27 When they are compressed to the same height (as shown), the deformation of the curved rod with a larger span is greater, while the deformation of the curved rod with a smaller span is smaller. Since the restoring force of shape memory alloy is related to the amount of deformation, this means that the restoring forces they can generate when compressed to the same height will be different. Therefore, the restoring force of shape memory alloy curved rod lattice metamaterial and shape memory alloy curved edge stretchable mesh can be controlled in this way.

[0220] Similar to the influence of structural parameters on the properties of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes, the properties of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes can also be controlled through material composition and heat treatment specifications. For example, the strength and phase transformation temperature of shape memory alloys are related to the material composition, and the material strength also affects the material deformation, thus affecting the flexibility of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes. The material strength also affects the material stress response, thus affecting the stress response of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes.

[0221] For regional control by changing the performance of unit cells, the approach is to apply unit cells with different properties to different regions of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes. Then, based on the required pressure load distribution and the change of pressure load over time obtained in step one, shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different unit cell layouts and phase transition temperatures are designed using regional control methods and split control methods. Then, they are stacked together to form shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform performance, non-simultaneous triggering actuation function and stress response.

[0222] Step 3: Fabrication of shape memory alloy curved rod lattice metamaterial and curved-edge stretchable mesh.

[0223] Based on the design in step two, regional control methods and split control methods are used to process shape memory alloy billets into curved rod lattice metamaterials and curved edge stretchable meshes with different structures or properties.

[0224] Select suitable shape memory alloy raw materials or blanks, and then, according to the structural parameters of the unit cell of the designed shape memory alloy curved rod lattice metamaterial, use methods such as laser cutting, electrical discharge wire cutting or 3D printing (additive manufacturing) to prepare curved rod lattice units or curved rod lattice units of shape memory alloy curved rod lattice metamaterials with different structural parameters. Then, weld them together with laser welding to form shape memory alloy curved rod lattice metamaterials with different structures, or directly use 3D printing (additive manufacturing) to prepare integral curved rod lattice metamaterials with different structures.

[0225] For shape memory alloy curved stretchable mesh, curved stretchable meshes with different structures can be prepared by means of laser cutting, electrical discharge wire cutting or 3D printing (additive manufacturing);

[0226] For shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes with non-uniform properties, according to the performance distinction, the parts of each unit cell with the same performance are first processed and prepared by laser cutting, electrical discharge wire cutting or 3D printing (additive manufacturing), etc., and then the parts are welded together by laser welding.

[0227] Step 4: Form shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response, and transform them into flexible intelligent actuators.

[0228] The desired original and temporary shapes for shape memory alloy curved bar lattice metamaterials and curved stretchable meshes are determined based on the shape of the formed component, the required pressure load distribution and the change of pressure load over time, and the form of the sheet blank. Then, using a split control method, the prepared shape memory alloy curved bar lattice metamaterial or curved stretchable mesh is subjected to shaping heat treatment according to the determined original shape, setting the desired original shape and phase transition temperature. In this embodiment, the component shape is a hemisphere, and the blank is a sheet blank. Therefore, the original shape of the shape memory alloy curved bar lattice metamaterial or curved stretchable mesh needs to be set as a hemisphere, while the temporary shape is a flat plate. That is, the original shape of the shape memory alloy curved bar lattice metamaterial or curved stretchable mesh is first set as a hemisphere, and after shaping, it needs to be deformed into a flat plate shape to facilitate assembly with the blank. The restoring force of shape memory alloys is related to the strain during shape recovery. The greater the strain, the greater the restoring force. Therefore, when determining the original shape of shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes, it is necessary to ensure that during the process of shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes restoring from a temporary flat shape to the original hemispherical shape, when the sheet blank is forced to deform and fit into the mold, there is still a deformation amount that is not fully recovered. That is, the sheet blank is still subjected to the restoring force of shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes until it fits into the mold.

[0229] In this embodiment, the process and method for shaping and transforming the shape memory alloy composite flexible metamaterial used for deforming sheet metal blanks into an actuator are as follows:

[0230] The prepared shape memory alloy curved rod lattice metamaterial and curved stretchable mesh are deformed into the desired shape and constrained. They are then subjected to heat treatment to set their original shape and phase transition temperature. Next, the already-formed shape memory alloy curved rod lattice metamaterial and curved stretchable mesh, with different unit cell layouts and phase transition temperatures, are deformed into a temporary shape to store energy and enable actuation. This allows the shape memory alloy curved rod lattice metamaterial and curved stretchable mesh with different unit cell layouts and phase transition temperatures to become actuators. Then, using a composite method of superposition and lamination, the shape memory alloy curved rod lattice metamaterial and curved stretchable mesh with different unit cell layouts and phase transition temperatures, already possessing actuation functions, are superimposed and laminated in a composite control manner. This results in a shape memory alloy composite flexible metamaterial with non-uniform structure, non-uniform properties, and non-simultaneous triggering of actuation functions and stress responses, which is then transformed into a flexible intelligent actuator.

[0231] For the shape memory alloy curved rod lattice metamaterial used for the edge clamping part, it is first subjected to a shaping heat treatment to give it shape memory function. Then, the shaped shape memory alloy curved rod lattice metamaterial is compressed and deformed to give it actuation function so that when it is heated and restores its original shape, it can generate a restoring force, which acts on the sheet blank and applies an edge clamping force to the sheet blank.

[0232] Step 5: Assembly

[0233] Once the shape memory alloy composite flexible metamaterial is prepared and formed into a shape memory alloy composite flexible metamaterial with non-uniform structure, non-uniform properties, and non-simultaneous triggering actuation function and stress response, and transformed into a flexible intelligent actuator, it is ready for assembly. This involves assembling the shape memory alloy composite flexible metamaterial with blanks, molds, etc., such as... Figure 36 As shown.

[0234] The sheet blank 2 is placed on the mold 1, and then the shape memory alloy composite flexible metamaterial 3, which is transformed into an actuator, is placed on the sheet blank 2. In order to control the blank blank's blank blank pressure, the shape memory alloy composite flexible metamaterial 4, which is transformed into an actuator, is placed at the edge of the shape memory alloy composite flexible metamaterial 3 and the sheet blank 2. Then, the pressure plate 6 is placed on the shape memory alloy composite flexible metamaterial 4, and the shape memory alloy composite flexible metamaterial 4 is placed in the cavity at the end of the pressure plate 6. A support body 5 made of 45 steel is placed at the edge of the mold 1 to support and adjust the distance between the pressure plate 6 and the mold 1. This allows control of the height of the shape memory alloy composite flexible metamaterial 4, thereby controlling the shape recovery and restoring force of the shape memory alloy composite flexible metamaterial 4. Finally, bolts 7 are used to assemble and fix the various parts together through the holes on the mold 1 and the pressure plate 6.

[0235] To heat-trigger shape memory alloys to restore their original shape and generate restoring force and actuation function, the heating component needs to be connected to a shape memory alloy composite flexible metamaterial. This can be achieved by employing... Figure 31 As shown in the diagram, another method is to insulate the surface of a flexible heating wire and then directly wind it onto a shape memory alloy curved rod lattice metamaterial or a shape memory alloy curved edge stretchable mesh. By energizing the heating wire, the heat is directly transferred to the shape memory alloy curved rod lattice metamaterial or the shape memory alloy curved edge stretchable mesh. This method allows the shape memory alloy curved rod lattice metamaterial or the shape memory alloy curved edge stretchable mesh to heat up faster.

[0236] During assembly, lubrication is required between the various metals. In the assembly process, graphite paper is filled into the pores of the shape memory alloy curved rod lattice metamaterial to reduce friction; graphite paper is placed between the stacked shape memory alloy curved rod lattice metamaterials or shape memory alloy curved stretchable meshes to reduce friction; graphite paper is placed between the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes and the blank to reduce friction.

[0237] Step 6: Heating triggers the shape memory alloy composite flexible metamaterial to recover its shape and form a component.

[0238] After assembly, heating is performed to soften the blank and trigger the shape memory alloy composite flexible metamaterial to recover its shape (e.g., Figure 37 (As shown).

[0239] The shape memory alloy composite flexible metamaterial 3, transformed into an actuator, undergoes a phase transition sequentially as the temperature rises after being heated, changing its shape from a flat plate shape (such as...) to a completely different shape. Figure 36 (As shown) it gradually returns to its original, fixed shape (such as) Figure 37 As shown, by utilizing the restoring force generated during the shape recovery process, the stored energy is released, producing an actuation effect that forces the blank 2 of the formed component to deform along with it. The spatial distribution and time-varying stress acting on the blank 2 are determined by the non-identical structure, non-uniform properties, and non-identical phase transition temperatures of the various curved rod lattice metamaterials and curved edge stretchable meshes that make up the shape memory alloy composite flexible metamaterial body 3. That is, through the regionalized control, split control, and composite control of the structure and properties of the shape memory alloy curved rod lattice metamaterials and curved edge stretchable meshes, a non-identical structure, non-uniform properties, and non-simultaneously triggered actuation function are formed. A flexible metamaterial composited with a shape memory alloy, which is designed to respond to stress, serves as a flexible intelligent actuator whose stress response spatial distribution and time-varying characteristics can be designed. This enables intelligent pressure control in both spatial and temporal dimensions, acting on the billet to deform it. Simultaneously, the flexible metamaterial 4, which is transformed into an actuator, also recovers its shape, generating a restoring force that acts on the edge of the sheet billet 2, suppressing instability and wrinkling at the edge. Ultimately, under the combined action of the flexible metamaterials 3 and 4, which are transformed into actuators, the sheet billet 2 gradually deforms, conforming to the surface of the mold 1, and transforming into component 8 (such as...). Figure 37 (As shown).

[0240] When using shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response for component forming, in addition to the method given above of directly assembling the shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response with sheet blanks and molds, there are other methods.

[0241] Implementation methods of applying cover plates (e.g.) Figure 38 and Figure 39 (As shown).

[0242] Figure 38 and Figure 39 The paper presents a method for assembling a flexible metamaterial composed of shape memory alloys with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response with sheet blanks, cover plates of sheet blanks and molds. Specifically, a cover plate is placed on the other side of the sheet, which can further improve the formability of the sheet by means of the effect of the cover plate on the sheet. Figure 38 and Figure 39 The given implementation methods and Figure 36 and Figure 37 The proposed implementation is similar. The difference is that a cover plate 2 is placed under the sheet metal blank 3. For example... Figure 38 As shown, firstly, the cover plate 2 is placed on the mold 1, then the sheet blank 3 is placed on the cover plate 2, and then the shape memory alloy composite flexible metamaterial 4, which is transformed into an actuator, is placed on the sheet blank 3. In order to control the blanking force of the sheet blank 3, the shape memory alloy composite flexible metamaterial 5, which is transformed into an actuator, is placed at the edge of the shape memory alloy composite flexible metamaterial 4 and the sheet blank 3. Then, the pressure plate 7 is placed on the shape memory alloy composite flexible metamaterial 5, and the shape memory alloy composite flexible metamaterial 5 is placed in the cavity at the end of the pressure plate 7. A support body 6 made of 45 steel is placed at the edge of the mold 1 to support and adjust the distance between the pressure plate 7 and the mold 1. This allows control of the height of the shape memory alloy composite flexible metamaterial 5, thereby controlling the shape recovery and restoring force of the shape memory alloy composite flexible metamaterial 5. Finally, bolts 8 are used to assemble and fix the various parts together through the holes on the mold 1 and the pressure plate 7.

[0243] To heat-trigger shape memory alloys to restore their original shape and generate restoring force and actuation function, the heating component needs to be connected to a shape memory alloy composite flexible metamaterial. This can be achieved by employing... Figure 31As shown in the diagram, another method is to insulate the surface of a flexible heating wire and then directly wind it onto a shape memory alloy curved rod lattice metamaterial or a shape memory alloy curved edge stretchable mesh. By energizing the heating wire, the heat is directly transferred to the shape memory alloy curved rod lattice metamaterial or the shape memory alloy curved edge stretchable mesh. This method allows the shape memory alloy curved rod lattice metamaterial or the shape memory alloy curved edge stretchable mesh to heat up faster.

[0244] After assembly, heating is performed to soften the blank and trigger the shape memory alloy composite flexible metamaterial to recover its shape (e.g., Figure 39 (As shown).

[0245] The shape memory alloy composite flexible metamaterial 4, which transforms into an actuator, undergoes a phase transition sequentially as the temperature rises after being heated, changing its shape from a flat plate shape (such as...) to a flat plate shape. Figure 38 (As shown) it gradually returns to its original, fixed shape (such as) Figure 39 As shown), by utilizing the restoring force generated during the shape recovery process, the stored energy is released, producing an actuation effect that forces the blank 3 and the cover plate 2 of the formed component to deform together. The spatial distribution and time-varying changes of the stress acting on the blank 3 are determined by the non-identical structure, non-uniform performance unit cell layout, and non-identical phase transition temperature of the various curved rod lattice metamaterials and curved edge stretchable meshes that make up the shape memory alloy composite flexible metamaterial body 4. That is, through the regionalized control, split control, and composite control of the structure and performance of the shape memory alloy curved rod lattice metamaterials and curved edge stretchable meshes, a non-identical structure, non-uniform performance, and non-simultaneously triggered actuation function are formed. The stress-responsive shape memory alloy composite flexible metamaterial serves as a flexible intelligent actuator whose stress response spatial distribution and temporal variation can be designed. This enables intelligent pressure control in both spatial and temporal dimensions, acting on the billet to deform it. Simultaneously, the shape memory alloy composite flexible metamaterial 5, transformed into an actuator, also recovers its shape, generating a restoring force that acts on the edge of the sheet billet 3, suppressing instability and wrinkling at the edge. Ultimately, under the combined action of the shape memory alloy composite flexible metamaterials 4 and 5, the sheet billet 3 gradually deforms, conforming to the surface of the mold 1, transforming into component 10. The cover plate 2 also deforms accordingly into 9 (e.g., Figure 39 (As shown).

[0246] Implementation methods of applying rigid-flexible composite cover panels (e.g.) Figure 40 and Figure 41 (As shown).

[0247] On the other side of the sheet material, place a rigid-flexible composite cover panel, that is, a rigid-flexible composite cover panel consisting of a metal sheet and an elastic sheet (e.g., Figure 40 and Figure 41As shown in the diagram, this allows for the improvement of the sheet's formability through the action of the rigid-flexible composite cover plate. Polyurethane rubber can be used as the elastomer. Figure 40 and Figure 41 The given implementation methods and Figure 36 and Figure 37 , Figure 38 and Figure 39 The proposed implementation is similar. The difference lies in the placement of rigid-flexible composite cover plates 2 and 3 beneath the sheet metal blank 4; that is, a rigid-flexible composite cover plate consisting of a metal sheet cover plate 2 and a polyurethane elastic sheet plate 3. Figure 40 As shown, firstly, a rigid-flexible composite cover plate consisting of a metal sheet cover plate 2 and a polyurethane elastic sheet 3 is placed on the mold 1. Then, the sheet blank 4 is placed on the rigid-flexible composite cover plate consisting of the metal sheet cover plate 2 and the polyurethane elastic sheet 3. Next, a shape memory alloy composite flexible metamaterial 5, which is transformed into an actuator, is placed on the sheet blank 4. In order to control the blank blank 4, a shape memory alloy composite flexible metamaterial 6, which is transformed into an actuator, is placed at the edge of the shape memory alloy composite flexible metamaterial 5 and the sheet blank 4. Finally, a pressure plate 8 is placed on the mold 1. The shape memory alloy composite flexible metamaterial 6, which is converted into an actuator, is placed on top of the mold 1 and is located in the cavity at the end of the pressure plate 8. A support body 7 made of 45 steel is placed at the edge of the mold 1 to support and adjust the distance between the pressure plate 8 and the mold 1. This allows control of the height of the shape memory alloy composite flexible metamaterial 6, which is converted into an actuator, thereby controlling the shape recovery and restoring force of the shape memory alloy composite flexible metamaterial 6. Then, bolts 9 are used to assemble and fix the various parts together through the holes on the mold 1 and the pressure plate 8.

[0248] To heat-trigger shape memory alloys to restore their original shape and generate restoring force and actuation function, the heating component needs to be connected to a shape memory alloy composite flexible metamaterial. This can be achieved by employing... Figure 31 As shown in the diagram, another method is to insulate the surface of a flexible heating wire and then directly wind it onto a shape memory alloy curved rod lattice metamaterial or a shape memory alloy curved edge stretchable mesh. By energizing the heating wire, the heat is directly transferred to the shape memory alloy curved rod lattice metamaterial or the shape memory alloy curved edge stretchable mesh. This method allows the shape memory alloy curved rod lattice metamaterial or the shape memory alloy curved edge stretchable mesh to heat up faster.

[0249] After assembly, heating is performed to soften the blank and trigger the shape memory alloy composite flexible metamaterial to recover its shape (e.g., Figure 41 (As shown).

[0250] The shape memory alloy composite flexible metamaterial 5, transformed into an actuator, undergoes a phase transition sequentially as the temperature rises after being heated, changing its shape from a flat plate shape (such as...) to a completely different shape. Figure 40 (As shown) it gradually returns to its original, fixed shape (such as) Figure 41 As shown), by utilizing the restoring force generated during the shape recovery process, the stored energy is released, generating an actuation effect. This forces the blank 4 of the formed component and the rigid-flexible composite cover plate composed of the metal sheet cover plate 2 and the polyurethane elastic sheet 3 to deform together. The spatial distribution and time-varying changes of the stress acting on the sheet blank 4 are determined by the non-identical structure, non-uniform performance unit cell layout, and non-identical phase transition temperature of the various curved rod lattice metamaterials and curved edge stretchable meshes that make up the shape memory alloy composite flexible metamaterial body 5. That is, through regional control, split control, and superposition and layering control of the structure and performance of the shape memory alloy curved rod lattice metamaterials and curved edge stretchable meshes, a non-identical structure, non-uniform performance, and non-simultaneously triggered actuation function and stress response are formed. Shape memory alloy composite flexible metamaterials are used as flexible intelligent actuators whose stress response spatial distribution and time-varying characteristics can be designed. This enables intelligent pressure control in both spatial and temporal dimensions, acting on the billet to deform it. Simultaneously, the shape memory alloy composite flexible metamaterial 6, transformed into an actuator, also recovers its shape, generating restoring force that acts on the edge of the sheet billet 4, suppressing instability and wrinkling at the edge. Ultimately, under the combined action of the shape memory alloy composite flexible metamaterials 5 and 6, the sheet billet 4 gradually deforms, conforming to the surface of the mold 1, transforming into component 12. A rigid-flexible composite cover plate composed of a metal sheet cover plate 2 and a polyurethane elastic sheet 3 deforms accordingly into 10 and 11 (e.g., Figure 41 (As shown).

[0251] Implementation methods using elastic pads and cover plates (e.g.) Figure 42 and Figure 43 (As shown).

[0252] A cover plate is placed on one side of the sheet material. This allows the cover plate to further improve the formability of the sheet material. Furthermore, to improve the surface quality and formability of the sheet material components, an elastic pad can be placed between the sheet material blank and the shape memory alloy composite flexible metamaterial composed of shape memory alloy curved rod lattice metamaterials or curved stretchable meshes. Polyurethane elastomers are generally used as the elastic pad (e.g., ...). Figure 42 and Figure 43 (As shown). Figure 42 and Figure 43 The given implementation methods and Figure 36 and Figure 37 , Figure 40 and Figure 41The proposed implementation is similar. The difference is that, in addition to placing a cover plate 2 under the sheet blank 3, an elastic pad 4 is placed between the sheet blank 3 and the shape memory alloy composite flexible metamaterial 5, which is composed of shape memory alloy curved rod lattice metamaterial or curved edge stretchable mesh. Figure 42 As shown, first, the cover plate 2 is placed on the mold 1, then the sheet blank 3 is placed on the cover plate 2, and then an elastic pad 4 is placed on the sheet blank 3. The elastic pad 4 is constrained by the pad plate 13, and a spring washer 14 is placed under the pad plate 13. Then, the shape memory alloy composite flexible metamaterial 5, which is transformed into an actuator, is placed on the pad plate 13 and the elastic pad 4. In order to control the blanking force of the sheet blank 3, the shape memory alloy composite flexible metamaterial 6, which is transformed into an actuator, is placed at the edge of the elastic pad 4 and the shape memory alloy composite flexible metamaterial 5. Then, the pressure plate 8 is placed on the edge of the mold 1. The shape memory alloy composite flexible metamaterial 6 is placed on top of the body, and the shape memory alloy composite flexible metamaterial 6, which is converted into an actuator, is placed in the cavity at the end of the pressure plate 8. A support body 7 made of 45 steel is placed at the edge of the mold 1 to support and adjust the distance between the pressure plate 8 and the mold 1. This allows control of the height of the shape memory alloy composite flexible metamaterial 6, which is converted into an actuator, thereby controlling the shape recovery and restoring force of the shape memory alloy composite flexible metamaterial 6. Then, bolts 9 are used to assemble and fix the various parts together through holes in the mold 1, holes in the pressure plate 8, holes in the pad 13, and spring washers 14.

[0253] To heat-trigger shape memory alloys to restore their original shape and generate restoring force and actuation function, the heating component needs to be connected to a shape memory alloy composite flexible metamaterial. This can be achieved by employing... Figure 31 As shown in the diagram, another method is to insulate the surface of a flexible heating wire and then directly wind it onto a shape memory alloy curved rod lattice metamaterial or a shape memory alloy curved edge stretchable mesh. By energizing the heating wire, the heat is directly transferred to the shape memory alloy curved rod lattice metamaterial or the shape memory alloy curved edge stretchable mesh. This method allows the shape memory alloy curved rod lattice metamaterial or the shape memory alloy curved edge stretchable mesh to heat up faster.

[0254] After assembly, heating is performed to soften the blank and trigger the shape memory alloy composite flexible metamaterial to recover its shape (e.g., Figure 43 (As shown).

[0255] The shape memory alloy composite flexible metamaterial 5, transformed into an actuator, undergoes a phase transition sequentially as the temperature rises after being heated, changing its shape from a flat plate shape (such as...) to a completely different shape. Figure 42 (As shown) it gradually returns to its original, fixed shape (such as) Figure 43As shown), by utilizing the restoring force generated during the shape recovery process, the stored energy is released, generating an actuation effect that forces the elastic pad 4, the blank 3 of the formed component, and the cover plate 2 to deform together. The spatial distribution and time-varying changes of the stress acting on the elastic pad 4 and the blank 3 are determined by the non-identical structure, non-uniform performance unit cell layout, and non-identical phase transition temperature of the various curved rod lattice metamaterials and curved edge stretchable meshes that make up the shape memory alloy composite flexible metamaterial body 5. That is, through the regionalized control, split control, and composite control of the structure and performance of the shape memory alloy curved rod lattice metamaterials and curved edge stretchable meshes, a non-identical structure, non-uniform performance, and non-simultaneous triggering actuation function are formed. The stress-responsive shape memory alloy composite flexible metamaterial serves as a flexible intelligent actuator whose stress response spatial distribution and temporal variation can be designed. This enables intelligent pressure control in both spatial and temporal dimensions, acting on the billet to deform it. Simultaneously, the shape memory alloy composite flexible metamaterial 6, transformed into an actuator, also recovers its shape, generating a restoring force that acts on the edge of the sheet billet 3, suppressing instability and wrinkling at the edge. Ultimately, under the combined action of the shape memory alloy composite flexible metamaterials 5 and 6, the sheet billet 3 gradually deforms, conforming to the surface of the mold 1, transforming into component 11. The rigid cover plate 2 deforms accordingly to 10, and the elastic pad 4 deforms to 12 (e.g., ...). Figure 43 (As shown).

[0256] Implementation methods using fluid back pressure (e.g.) Figure 44 and Figure 45 (As shown).

[0257] To adjust and control the back pressure acting on the sheet metal blank—that is, the pressure in the opposite direction to the pressure applied to the sheet metal by the shape memory alloy composite flexible metamaterial—fluid back pressure can be applied to the other side of the sheet metal blank, such as... Figure 44 and Figure 45 As shown. Figure 44 and Figure 45 The given implementation methods and Figure 36 and Figure 37 The proposed implementation is similar. The difference lies in applying fluid 2 to the other side of the sheet metal blank. For example... Figure 44As shown, sheet metal blank 3 is placed on mold 1, and then shape memory alloy composite flexible metamaterial body 4, which is transformed into an actuator, is placed on sheet metal blank 3. In order to control the blanking force of sheet metal blank 3, shape memory alloy composite flexible metamaterial body 5, which is transformed into an actuator, is placed at the edge of shape memory alloy composite flexible metamaterial body 4 and sheet metal blank 3. Then, pressure plate 7 is placed on shape memory alloy composite flexible metamaterial body 5, and shape memory alloy composite flexible metamaterial body 5 is placed in the cavity at the end of pressure plate 7. Support body 6, made of 45 steel, is placed at the edge of mold 1 to support and adjust the distance between pressure plate 7 and mold 1. This allows control of the height of shape memory alloy composite flexible metamaterial body 5, thereby controlling the shape recovery and restoring force of shape memory alloy composite flexible metamaterial body 5. Then, bolts 8 are used to assemble and fix the various parts together through holes in mold 1 and pressure plate 7. Then, fluid 2 is filled into the cavity of mold 1 through the hole at the bottom of mold 1. Depending on the fluid material and fluid pressure used, a sealing groove is machined on the surface of the mold 1 that is in contact with the blank 3 and is located in the pressing area, for installing a sealing ring in order to seal the fluid 2.

[0258] To heat-trigger shape memory alloys to restore their original shape and generate restoring force and actuation function, the heating component needs to be connected to a shape memory alloy composite flexible metamaterial. This can be achieved by employing... Figure 31 As shown in the diagram, another method is to insulate the surface of a flexible heating wire and then directly wind it onto a shape memory alloy curved rod lattice metamaterial or a shape memory alloy curved edge stretchable mesh. By energizing the heating wire, the heat is directly transferred to the shape memory alloy curved rod lattice metamaterial or the shape memory alloy curved edge stretchable mesh. This method allows the shape memory alloy curved rod lattice metamaterial or the shape memory alloy curved edge stretchable mesh to heat up faster.

[0259] After assembly, heating is performed to soften the blank and trigger the shape memory alloy composite flexible metamaterial to recover its shape (e.g., Figure 45 (As shown).

[0260] The shape memory alloy composite flexible metamaterial 4, which transforms into an actuator, undergoes a phase transition sequentially as the temperature rises after being heated, changing its shape from a flat plate shape (such as...) to a flat plate shape. Figure 44 (As shown) it gradually returns to its original, fixed shape (such as) Figure 45As shown), by utilizing the restoring force generated during the shape recovery process, the stored energy is released, producing an actuation effect that forces the blank 3 of the formed component to deform along with it. The spatial distribution and time-varying changes of the stress acting on the blank 3 are determined by the non-identical structure, non-uniform performance unit cell layout, and non-identical phase transition temperature of the various curved rod lattice metamaterials and curved edge stretchable meshes that make up the shape memory alloy composite flexible metamaterial body 4. That is, by regionalizing, splitting, and superimposing the structure and properties of the shape memory alloy curved rod lattice metamaterials and curved edge stretchable meshes, a shape memory alloy composite flexible metamaterial with non-identical structure, non-uniform performance, and non-simultaneous triggering actuation function and stress response is formed, so as to serve as A flexible intelligent actuator, designed to accommodate both spatial and temporal stress response variations, enables intelligent pressure control in both spatial and temporal dimensions. This actuator deforms the billet. Simultaneously, the shape memory alloy composite flexible metamaterial 5, transformed into the actuator, recovers its shape, generating a restoring force that acts on the edge of the sheet billet 3, suppressing instability and wrinkling at the edge. Furthermore, by controlling the flow rate of fluid 2 within the mold cavity 1, the back pressure on the sheet billet 3 is controlled. Ultimately, under the combined action of the shape memory alloy composite flexible metamaterials 4 and 5 (transformed into actuators) and the back pressure of fluid 2, the sheet billet 3 gradually deforms, conforming to the surface of the mold 1, transforming into component 9 (e.g., Figure 45 (As shown).

[0261] Implementation methods when applying a frame (e.g.) Figure 46 , Figure 47 and Figure 48 (As shown).

[0262] For component forming, the force applied to the blank can be controlled in stages and regions. A specific area of ​​the blank is deformed first, followed by other areas. This achieves staged pressure loading, allowing control over the stress and deformation states of the blank and more effectively preventing instability, wrinkling, and cracking. In this embodiment using a container frame, the blank is a welded plate of two materials, such as aluminum alloy and steel. Due to the different materials and properties, a staged load application method is used to ensure successful forming. Therefore, a container frame is used. Multiple shape memory alloy point-curved rod array metamaterials with different structures, properties, and phase transition temperatures undergo shape-setting heat treatment to establish their shapes and set different phase transition temperatures. Then, they are compressed and deformed to store energy, and then... Figure 46 The shapes are superimposed and combined in the manner shown to form a shape memory alloy composite flexible metamaterial 3 with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response, and then placed in a container 6 (e.g. Figure 47As shown), after being transformed into a flexible intelligent actuator, it is ready for assembly. The shape memory alloy composite flexible metamaterial is assembled with the blank, mold, etc., such as... Figure 47 As shown, Figure 47 T1, T2, T3, T4, and T5 in the figure represent different phase transformation temperatures. Because the phase transformation temperatures are different, the actuation function and stress response of the shape memory alloy are not triggered simultaneously. Therefore, the force exerted by the shape memory alloy on the billet is also not simultaneous, thus applying pressure to the billet in different regions and stages.

[0263] The sheet blank 2 is placed on the mold 1, and then the shape memory alloy composite flexible metamaterial 3, which is transformed into an actuator, is placed on the sheet blank 2. In order to control the blank blank's blank pressure, the shape memory alloy composite flexible metamaterial 4, which is transformed into an actuator, is placed on the edge of the blank 2. Then, the frame 6 is placed on the shape memory alloy composite flexible metamaterial 4, which is transformed into an actuator, and the shape memory alloy composite flexible metamaterial 4 is placed in the cavity of the frame 6 corresponding to the end of the sheet blank. The shape memory alloy composite flexible metamaterial 3, which is transformed into an actuator, is placed in the cavity of the frame 6 corresponding to the mold cavity. A support body 5 made of 45 steel is placed at the edge of the mold 1 to support and adjust the distance between the frame 6 and the mold 1. This allows control of the height of the shape memory alloy composite flexible metamaterial 4, which is transformed into an actuator, thereby controlling the shape recovery and restoring force of the shape memory alloy composite flexible metamaterial 4. Finally, bolts 7 are used to assemble and fix the various parts together through the holes on the mold 1 and the frame 6.

[0264] In order to heat-trigger shape memory alloys to restore their original shape and generate restoring force and actuation function, surface-insulated electric heating wires can be directly wound around the rods and nodes connecting the rods of the shape memory alloy curved rod lattice metamaterial.

[0265] During assembly, lubrication is required between the various metals. In the assembly process, graphite paper is filled into the pores of the shape memory alloy curved rod lattice metamaterial to reduce friction; graphite paper is placed between the stacked shape memory alloy curved rod lattice metamaterials or shape memory alloy curved stretchable meshes to reduce friction; graphite paper is placed between the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes and the blank to reduce friction.

[0266] After assembly, heating is performed to soften the blank and trigger the shape memory alloy composite flexible metamaterial to recover its shape (e.g., Figure 48 (As shown).

[0267] The shape memory alloy composite flexible metamaterial 3, which transforms into an actuator, is composed of multiple layers stacked together. Because the phase transition temperatures of each part are different, the phase transition triggering of the actuation function is not simultaneous. Therefore, upon heating, as the temperature rises, each part undergoes a phase transition sequentially, generating restoring forces in different regions and stages, acting on the sheet blank 2 and forcing the blank 2 of the formed component to deform accordingly. Simultaneously, the shape memory alloy composite flexible metamaterial 4, which has also transformed into an actuator, undergoes shape recovery, generating restoring forces that act on the edges of the sheet blank 2, suppressing instability and wrinkling at the edges. Ultimately, under the combined action of the shape memory alloy composite flexible metamaterials 3 and 4, the sheet blank 2 gradually deforms, conforming to the surface of the mold 1, and transforms into component 8 (e.g., Figure 48 (As shown).

[0268] Implementation methods when using frames, elastomers, and cover plates (e.g.) Figure 49 and Figure 50 (As shown).

[0269] When using a frame, a cover plate and an elastomer can also be placed on one side of the blank to improve formability and forming quality. In this embodiment, when using a frame, elastomer, and cover plate, the blank is a welded plate of two materials. Due to the different materials, their properties are different. In order to make it form smoothly, a method of applying load in sections and stages is adopted.

[0270] Using a frame-like approach, shape memory alloy point-curved rod array metamaterials with non-uniform structures, properties, and phase transition temperatures are first subjected to shape-setting heat treatment to define their shapes and set different phase transition temperatures. Then, they are compressed and deformed to store energy, and then... Figure 46 The methods shown are superimposed and combined to form a shape memory alloy composite flexible metamaterial 5 with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response, and then placed in a container 8 (such as...). Figure 49 As shown), after being transformed into a flexible intelligent actuator, it is ready for assembly. The shape memory alloy composite flexible metamaterial is assembled with the blank, mold, etc., such as... Figure 49 As shown, Figure 49 T1, T2, T3, T4, and T5 in the figure represent different phase transformation temperatures. Because the phase transformation temperatures are different, the actuation function and stress response of the shape memory alloy are not triggered simultaneously. Therefore, the force exerted by the shape memory alloy on the billet is also not simultaneous, thus applying pressure to the billet in different regions and stages.

[0271] A cover plate is placed on one side of the sheet material. This allows the cover plate to further improve the formability of the sheet material. Furthermore, to improve the surface quality of the sheet material components, an elastic gasket can be placed between the sheet material blank and the flexible metamaterial composed of shape memory alloy curved rod lattice metamaterial or curved stretchable mesh. Polyurethane elastomers are generally used as the elastic gasket (e.g., ...). Figure 49 and Figure 50 As shown), that is, in addition to placing a cover plate 2 under the sheet blank 3, an elastic pad 4 is placed between the sheet blank 3 and the shape memory alloy composite flexible metamaterial 5, which has a non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function, and stress response. Figure 49 As shown, firstly, the cover plate 2 is placed on the mold 1, then the sheet blank 3 is placed on the cover plate 2, and then an elastic pad 4 is placed on the sheet blank 3. Next, a shape memory alloy composite flexible metamaterial 5, which transforms into an actuator with non-identical structure, non-uniform properties, non-simultaneous triggering actuation function, and stress response, is placed on the elastic pad 4. To control the blank holder force of the sheet blank 3, a shape memory alloy composite flexible metamaterial 6, which transforms into an actuator, is placed at the edge of the sheet blank 3. Then, a frame 8 is placed on the shape memory alloy composite flexible metamaterial 6, which transforms into an actuator, and the shape memory alloy composite material 5, which transforms into an actuator with non-identical structure, non-uniform properties, non-simultaneous triggering actuation function, and stress response. A shape memory alloy composite flexible metamaterial 6, which is transformed into an actuator, is placed on top of the flexible metamaterial 5 and is placed in the cavity of the frame 8 corresponding to the end of the plate blank. The shape memory alloy composite flexible metamaterial 5 and the elastic body 4, which are transformed into actuators, are placed in the cavity of the frame 8 corresponding to the mold cavity. A support body 7 made of 45 steel is placed at the edge of the mold 1 to support and adjust the distance between the frame 8 and the mold 1. This allows control of the height of the shape memory alloy composite flexible metamaterial 6, which is transformed into an actuator, thereby controlling the shape recovery and restoring force of the shape memory alloy composite flexible metamaterial 6. Then, bolts 9 are used to assemble and fix the various parts together through the holes on the mold 1 and the frame 8.

[0272] In order to heat-trigger shape memory alloys to restore their original shape and generate restoring force and actuation function, surface-insulated electric heating wires can be directly wound around the rods and nodes connecting the rods of the shape memory alloy curved rod lattice metamaterial.

[0273] During assembly, lubrication is required between the various metals. In the assembly process, graphite paper is filled into the pores of the shape memory alloy curved rod lattice metamaterial to reduce friction; graphite paper is placed between the stacked shape memory alloy curved rod lattice metamaterials or shape memory alloy curved stretchable meshes to reduce friction; graphite paper is placed between the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes and the blank to reduce friction.

[0274] After assembly, heating is performed to soften the blank and trigger the shape memory alloy composite flexible metamaterial to recover its shape (e.g., Figure 50 (As shown).

[0275] The shape memory alloy composite flexible metamaterial 5, which transforms into an actuator, is composed of multiple layers stacked together. Because the phase transition temperatures of each part are different, the phase transition triggering of the actuation function is not simultaneous. Therefore, upon heating, as the temperature rises, each part undergoes a phase transition sequentially, generating restoring forces in different regions and stages, acting on the sheet blank. Using the restoring forces generated during shape recovery, the stored energy is released, producing an actuation effect that forces the elastic pad 4 and the blank 3 of the formed component to deform together (e.g., ...). Figure 49 and Figure 50 As shown, the spatial distribution and time-varying stress acting on the elastic pad 4 and the sheet blank 3 are determined by the non-identical structure, non-uniform performance unit cell layout, and non-identical phase transition temperature of the various curved rod lattice metamaterials and curved edge stretchable meshes constituting the shape memory alloy composite flexible metamaterial body 5. That is, through regionalized control, split control, and composite control of the structure and performance of the shape memory alloy curved rod lattice metamaterials and curved edge stretchable meshes, a shape memory alloy composite flexible metamaterial with non-identical structure, non-uniform performance, and non-simultaneous triggering actuation function and stress response is formed, which serves as the spatial distribution and time-varying stress response. The flexible intelligent actuator, which can be designed by Huadu, achieves intelligent pressure control in both spatial and temporal dimensions. It acts on the sheet metal blank 3 and the elastic pad 4, causing them to deform. Simultaneously, the shape memory alloy composite flexible metamaterial 6, transformed into an actuator, also recovers its shape, generating a restoring force that acts on the edge of the sheet metal blank 3, suppressing instability and wrinkling at the edge. Ultimately, under the combined action of the shape memory alloy composite flexible metamaterials 5 and 6, the sheet metal blank 3 gradually deforms, conforming to the surface of the mold 1, transforming into component 11. The rigid cover plate 2 deforms accordingly to 10, and the elastic pad 4 deforms to 12 (e.g., ...). Figure 49 and Figure 50 (As shown).

[0276] Example 2

[0277] Example 2 is a box-like component (e.g.) Figure 51 and Figure 52 As shown, the blank used for forming box-shaped components is a 2mm thick aluminum alloy sheet.

[0278] The shape memory alloy material used is nickel-titanium shape memory alloy.

[0279] The rigid mold 1 used for forming the component is machined from 45 steel. Holes are machined into the edges of the mold 1 for assembly via bolts 7 (e.g., ...). Figure 51 (As shown).

[0280] Shape memory alloy composite flexible metamaterial 3, characterized by non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function, and stress response, is used to apply pressure to the sheet blank 2 to deform it. Shape memory alloy composite flexible metamaterial 4, also characterized by non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function, and stress response, is used for edge clamping force control to suppress wrinkling of the sheet blank 2 (e.g., ...). Figure 51 and Figure 52 (As shown).

[0281] Based on the characteristics of the components to be formed, shape memory alloy composite flexible metamaterials 3 and 4 are designed and fabricated to process non-uniform structures, non-uniform properties, and non-simultaneously triggered actuation functions and stress responses. Other auxiliary tools and molds are also prepared and processed according to... Figure 51 As shown, assemble and form the component. The specific steps are as follows:

[0282] Step 1:

[0283] The sheet metal components to be formed are analyzed or numerically simulated. Based on the instability, wrinkling or cracking that may occur during the deformation of the sheet metal blank, the appropriate spatial distribution of the stress field acting on the sheet metal blank and its change over time are determined.

[0284] The pressure field acting on the sheet blank is divided into two parts: one part corresponds to the deformation part of the mold cavity, and the other part corresponds to the edge pressing part outside the mold cavity of the sheet blank. Therefore, the analysis or numerical simulation to determine the appropriate spatial distribution of the stress field acting on the sheet blank and its change over time is also divided into two parts. Then, the corresponding shape memory alloy composite flexible metamaterials 3 and 4 are designed and fabricated respectively.

[0285] Step Two:

[0286] Based on the spatial distribution of the stress field and its changes over time obtained from the analysis in step one, a composite control method involving regional control, split control, and superposition and layering is applied to design a shape memory alloy composite flexible metamaterial with non-uniform structure, non-uniform performance, non-simultaneous triggering actuation function and stress response.

[0287] First, flexible design is implemented. The shape memory alloy composite flexible metamaterial employs two forms of flexible structures: curved rod lattice metamaterials and curved-edge stretchable meshes. To ensure that the flexible structure and parameters of the unit cells of the shape memory alloy curved rod lattice metamaterials and curved-edge stretchable meshes can provide sufficient force and produce large shape changes, while controlling the deformation within the recoverable deformation range of the shape memory alloy, the lattice unit cell form of the curved rod lattice metamaterials is used, and the supports adopt a curved rod (bent rod) lattice structure (such as...). Figure 3 , Figure 4 and Figure 5 As shown in the diagram, instead of the usual straight-bar truss structure, its deformation is dominated by the elongation and compression deformation of the curved bars. This allows the lattice metamaterial to have both large contraction and expansion deformations, while the strain of the shape memory alloy itself is relatively small, controlled within the recoverable deformation range of the shape memory alloy. The curved-edge stretchable mesh uses... Figure 1 The curved edge structure is shown. Since the blank thickness is related to the formable bending radius, in practical applications, shape memory alloys can use "flexible" blanks—sheets. The width and length of the sheet are much greater than its thickness, making it more "flexible" than block or rod blanks. However, thin sheets are only suitable for simple shape changes such as bending. To deform into more complex shapes, the "flexible" shape memory alloy sheet blank needs to be processed into a stretchable mesh. Compared to a continuous sheet, the mesh structure can produce greater deformation. To control the deformation of the shape memory alloy within its recoverable deformation range, the unit cell structure of the stretchable mesh also adopts a curved edge form, i.e., a flexible structure. One form of this stretchable mesh and its dimensions are shown below. Figure 1 and Figure 2 As shown, the "flexible" shape memory alloy, which is made from sheet metal and can be in the form of a stretchable mesh, can produce a large amount of deformation. Therefore, it can be deformed into complex 3D shapes to form complex 3D components.

[0288] Secondly, after determining the flexible form of the unit cell of the shape memory alloy curved rod lattice metamaterial and the curved edge stretchable mesh, the structural parameters or properties of the unit cell are changed, and regional control method, split control method and superimposed layering composite method are adopted to design and determine the shape memory alloy composite flexible metamaterial with non-identical structure, non-uniform properties, non-simultaneous triggering actuation function and stress response.

[0289] Designing shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes by changing the structural parameters of the unit cells and the layout of unit cells with different structural parameters involves altering the shape, structure, and parameters of the unit cells in the shape memory alloy curved rod lattice metamaterials and curved edge stretchable meshes, as well as the layout of unit cells with different structural parameters. For curved edge stretchable mesh unit cells, the shapes, structures, and parameters that can be designed and modified include (e.g., Figure 2 (As shown): the unit cell spans L1 and L2, the widths W1 and W2 of the curved edges, and the radii of curvature R1 and R2 of the curved edges; for curved rod lattice metamaterial unit cells in the form of curved supports, the designable and modifiable shapes, structures, and parameters include (e.g.) Figure 5 (As shown): The unit cell span L (bending rod length L), bending rod diameter Φ, bending rod radius of curvature R2, and bending rod transition section radius of curvature R1. Using these parameters, based on the required pressure load distribution and pressure load variation over time obtained in step one, regional control methods or split-type control methods can be used to design shape memory alloy curved rod lattice metamaterials or curved-edge stretchable meshes with different structural parameters or performance, and different unit cell layouts and phase transition temperatures. These are then stacked and layered to form shape memory alloy composite flexible metamaterials with non-uniform structures, non-uniform properties, and non-simultaneous triggering actuation functions and stress responses.

[0290] In practical implementation, these structural parameters are selected based on the performance requirements of the shape memory alloy curved rod lattice metamaterial and the shape memory alloy curved edge stretchable mesh. For example, taking a curved rod support as an example, the influence of structural parameters on the performance of the shape memory alloy curved rod lattice metamaterial and the shape memory alloy curved edge stretchable mesh is illustrated. When two curved rod supports have the same span, but the diameters of the curved rod supports are different (e.g., Figure 26 When subjected to the same force F, the curved rod with a smaller diameter deforms more and appears more "flexible," while the curved rod with a larger diameter deforms less and appears more "rigid." Therefore, this can be used to control the flexibility of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved stretchable meshes. When two curved rods have the same diameter but different spans (e.g.,...),... Figure 27 When they are compressed to the same height (as shown), the deformation of the curved rod with a larger span is greater, while the deformation of the curved rod with a smaller span is smaller. Since the restoring force of shape memory alloy is related to the amount of deformation, this means that the restoring forces they can generate when compressed to the same height will be different. Therefore, the restoring force of shape memory alloy curved rod lattice metamaterial and shape memory alloy curved edge stretchable mesh can be controlled in this way.

[0291] Similar to the influence of structural parameters on the properties of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes, the properties of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes can also be controlled through material composition and heat treatment specifications. For example, the strength and phase transformation temperature of shape memory alloys are related to the material composition, and the material strength also affects the material deformation, thus affecting the flexibility of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes. The material strength also affects the material stress response, thus affecting the stress response of shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes.

[0292] For regional control by changing the performance of unit cells, the approach is to apply unit cells with different properties to different regions of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes. Then, based on the required pressure load distribution and the change of pressure load over time obtained in step one, shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different unit cell layouts and phase transition temperatures are designed using regional control methods and split control methods. Then, they are stacked together to form shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform performance, non-simultaneous triggering actuation function and stress response.

[0293] Step 3: Fabrication of shape memory alloy curved rod lattice metamaterial and curved-edge stretchable mesh.

[0294] Based on the design in step two, regional control methods and split control methods are used to process shape memory alloy billets into curved rod lattice metamaterials and curved edge stretchable meshes with different structures or properties.

[0295] Select suitable shape memory alloy raw materials or blanks, and then, according to the structural parameters of the unit cell of the designed shape memory alloy curved rod lattice metamaterial, use methods such as laser cutting, electrical discharge wire cutting or 3D printing (additive manufacturing) to prepare curved rod lattice units or curved rod lattice units of shape memory alloy curved rod lattice metamaterials with different structural parameters. Then, weld them together with laser welding to form shape memory alloy curved rod lattice metamaterials with different structures, or directly use 3D printing (additive manufacturing) to prepare integral curved rod lattice metamaterials with different structures.

[0296] For shape memory alloy curved stretchable mesh, curved stretchable meshes with different structures can be prepared by means of laser cutting, electrical discharge wire cutting or 3D printing (additive manufacturing);

[0297] For shape memory alloy curved rod lattice metamaterials and shape memory alloy curved edge stretchable meshes with non-uniform properties, according to the performance distinction, the parts of each unit cell with the same performance are first processed and prepared by laser cutting, electrical discharge wire cutting or 3D printing (additive manufacturing), etc., and then the parts are welded together by laser welding.

[0298] Step 4: Form shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response, and transform them into flexible intelligent actuators.

[0299] The desired original and temporary shapes for shape memory alloy curved bar lattice metamaterials and curved stretchable meshes are determined based on the shape of the formed component, the required pressure load distribution and the change of pressure load over time, and the form of the sheet blank. Then, using a split control method, the prepared shape memory alloy curved bar lattice metamaterial or curved stretchable mesh is subjected to shaping heat treatment according to the determined original shape, setting the desired original shape and phase transition temperature. In this embodiment, the component shape is a box-shaped component, and the blank is a sheet blank. Therefore, the original shape of the shape memory alloy curved bar lattice metamaterial or curved stretchable mesh needs to be set as a box shape, while the temporary shape is a flat plate shape. That is, the original shape of the shape memory alloy curved bar lattice metamaterial or curved stretchable mesh is first set as a box shape, and after shaping, it needs to be deformed into a flat plate shape to facilitate assembly with the blank. The restoring force of shape memory alloys is related to the strain during shape recovery. The greater the strain, the greater the restoring force. Therefore, when determining the original shape of shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes, it is necessary to ensure that during the process of shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes restoring from a temporary flat shape to the original hemispherical shape, when the sheet blank is forced to deform and fit into the mold, there is still a deformation amount that is not fully recovered. That is, the sheet blank is still subjected to the restoring force of shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes until it fits into the mold.

[0300] In this embodiment, the process and method of shaping and transforming into an actuator are as follows:

[0301] First, a high-temperature heat treatment is performed to fix the original shape of the austenitic phase.

[0302] The prepared shape memory alloy curved rod lattice metamaterial and curved edge stretchable mesh are deformed into the desired shape and constrained, then heated for shaping heat treatment to set their original shape and phase transition temperature;

[0303] Secondly, a temporary shape for the low-temperature martensitic phase is established using a thermo-mechanical training method with constant deformation cyclic training under constrained conditions:

[0304] (a) Fix the shape memory alloy curved stretchable mesh whose original shape is fixed to the set geometric shape, and heat it to above the high temperature austenite phase transformation temperature to transform it into the high temperature austenite phase; (b) Load the shape memory alloy in the high temperature austenite phase to deform it into the desired temporary shape; (c) Keep the deformation load unchanged and reduce the temperature of the shape memory alloy curved stretchable mesh until the load applied to the shape memory alloy curved stretchable mesh no longer decreases; (d) Keep the deformation load unchanged and increase the temperature of the shape memory alloy curved stretchable mesh until the load applied to the shape memory alloy curved stretchable mesh no longer increases; (e) Repeat steps (c) and (d) until the loading force no longer changes, until the shape memory alloy curved stretchable mesh can not only remember the original set shape of the parent phase high temperature austenite, but also remember the temporary shape of the low temperature martensite phase, forming a two-way shape memory function.

[0305] In this embodiment, the original shape is a box-like shape of the component, and the temporary shape is a flat plate shape of the sheet blank. This facilitates the assembly of the composite flexible metamaterial composed of shape memory alloy curved rod lattice metamaterial and curved edge stretchable mesh with the sheet blank. After forming a two-way shape memory function, the shape memory alloy composite flexible metamaterial is transformed into a flat plate shape through temperature control. At this time, the shape memory alloy has stored energy due to temperature-induced deformation and has been transformed into an actuator.

[0306] Then, by using a composite method of superposition and lamination, shape memory alloy curved rod lattice metamaterials with different layouts and phase transition temperatures of unit cells that already have actuation functions, structural parameters or performance are superimposed and laminated with curved stretchable meshes to form shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform performance, and non-simultaneous triggering of actuation functions and stress responses, and transform them into flexible intelligent actuators.

[0307] Step 5: Assembly

[0308] Once the shape memory alloy composite flexible metamaterial is prepared, assembly is carried out. This involves assembling the shape memory alloy composite flexible metamaterial with the blank, mold, etc., such as... Figure 51 As shown.

[0309] After pre-treating the shape memory alloy curved rod lattice metamaterial and the curved stretchable mesh with energy stored by inducing deformation through external force or temperature, they are then assembled (e.g. Figure 51 (As shown).

[0310] The sheet blank 2 is placed on the mold 1, and then the shape memory alloy composite flexible metamaterial 3, which is transformed into an actuator, is placed on the sheet blank 2. In order to control the blank blank's blanking force, the shape memory alloy composite flexible metamaterial 4, which is transformed into an actuator, is placed on the edge of the shape memory alloy composite flexible metamaterial 3. Then, the pressure plate 6 is placed on the shape memory alloy composite flexible metamaterial 4, which is transformed into an actuator, and the shape memory alloy composite flexible metamaterial 4 is placed in the cavity at the end of the pressure plate 6. A support body 5 made of 45 steel is placed at the edge of the mold 1 to support and adjust the distance between the pressure plate 6 and the mold 1. This allows control of the height of the shape memory alloy composite flexible metamaterial 4, which in turn controls the shape recovery of the shape memory alloy composite flexible metamaterial 4. Finally, bolts 7 are used to assemble and fix the various parts together through the holes on the mold 1 and the pressure plate 6.

[0311] To heat-trigger shape memory alloys to restore their original shape and generate restoring force and actuation function, the heating component needs to be connected to a shape memory alloy composite flexible metamaterial. This can be achieved by employing... Figure 31 As shown in the diagram, another method is to insulate the surface of a flexible heating wire and then directly wind it onto a shape memory alloy curved rod lattice metamaterial or a shape memory alloy curved edge stretchable mesh. By energizing the heating wire, the heat is directly transferred to the shape memory alloy curved rod lattice metamaterial or the shape memory alloy curved edge stretchable mesh. This method allows the shape memory alloy curved rod lattice metamaterial or the shape memory alloy curved edge stretchable mesh to heat up faster.

[0312] During assembly, lubrication is required between the various metals. In the assembly process, graphite paper is filled into the pores of the shape memory alloy curved rod lattice metamaterial to reduce friction; graphite paper is placed between the stacked shape memory alloy curved rod lattice metamaterials or shape memory alloy curved stretchable meshes to reduce friction; graphite paper is placed between the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes and the blank to reduce friction.

[0313] Step 6: Heating triggers the shape memory alloy composite flexible metamaterial to recover its shape and form a component.

[0314] After assembly, heating is performed to soften the blank and trigger the shape memory alloy composite flexible metamaterial to recover its shape (e.g., Figure 52 (As shown).

[0315] The shape memory alloy composite flexible metamaterial 3, transformed into an actuator, undergoes a phase transition sequentially as the temperature rises after being heated, changing its shape from a flat plate shape (such as...) to a completely different shape. Figure 51 (As shown) it gradually returns to its original, fixed shape (such as) Figure 52 As shown), by utilizing the restoring force generated during the shape recovery process, the stored energy is released, producing an actuation effect that forces the blank 2 of the formed component to deform along with it. The spatial distribution and time-varying changes of the stress acting on the blank 2 are determined by the non-identical structure, non-uniform performance unit cell layout, and non-identical phase transition temperature of the various curved rod lattice metamaterials and curved edge stretchable meshes that make up the shape memory alloy composite flexible metamaterial body 3. That is, through the regionalized control, split control, and composite control of the structure and performance of the shape memory alloy curved rod lattice metamaterials and curved edge stretchable meshes, a non-identical structure, non-uniform performance, and non-simultaneous triggering actuation effect are formed. The shape memory alloy composite flexible metamaterial, which combines dynamic function and stress response, serves as a flexible intelligent actuator whose stress response spatial distribution and temporal variation can be designed. This enables intelligent pressure control in both spatial and temporal dimensions, acting on the billet to deform it. Simultaneously, the shape memory alloy composite flexible metamaterial 4, transformed into an actuator, also recovers its shape, generating a restoring force that acts on the edge of the sheet billet 2, suppressing instability and wrinkling at the edge. Ultimately, under the combined action of the shape memory alloy composite flexible metamaterials 3 and 4, which have been transformed into actuators, the sheet billet 2 gradually deforms, conforming to the surface of the mold 1, and transforming into component 8 (such as...). Figure 52 (As shown).

[0316] While the present invention has been disclosed above, it provides only a few typical examples and specific embodiments, and the scope of protection of the present invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A low-cost intelligent forming manufacturing method based on shape memory alloys, characterized in that, By employing curved rod lattice metamaterials and curved edge stretchable meshes, shape memory alloys can be transformed into flexible metamaterials. Combined with the actuation function of shape memory alloys and the regionalized, discrete, and composite control of the structure and properties of the curved rod lattice metamaterials and curved edge stretchable meshes, it is possible to construct flexible shape memory alloy composite metamaterials with non-uniform structures, non-uniform properties, and non-simultaneous triggering of actuation functions and stress responses. These can serve as flexible intelligent actuators whose stress response spatial distribution and time-varying characteristics can be designed, forming a spatially non-uniformly distributed stress field and a time-varying adjustable stress response. This stress field acts on the billet, forcing the billet to deform and conform to the mold, forming a component.

2. The low-cost intelligent forming and manufacturing method based on shape memory alloys according to claim 1, characterized in that, The shape memory alloy can be of two types: one is a shape memory alloy with only single-pass shape memory function, and the other is a shape memory alloy with two-pass shape memory function.

3. The low-cost intelligent forming and manufacturing method based on shape memory alloys according to claim 1, characterized in that, The method of making shape memory alloys into flexible metamaterials by using curved rod lattice metamaterials and curved edge stretchable meshes involves using "flexible form" unit cells to make shape memory alloys into flexible metamaterials. The "flexible form" unit cells of the curved rod lattice metamaterials are composed of curved rods forming the unit cells of the shape memory alloy curved rod lattice metamaterials, and the "flexible form" unit cells of the curved edge stretchable meshes are composed of curved edges forming the unit cells of the shape memory alloy curved edge stretchable meshes.

4. The low-cost intelligent forming and manufacturing method based on shape memory alloy according to claim 1, characterized in that, The shape memory alloy curved rod lattice metamaterial and the curved edge stretchable mesh described herein are "flexible" shape memory alloys. As flexible intelligent actuators, they force the blank to deform, requiring reinforcement. The reinforcement method is as follows: Multiple flexible shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are stacked together. This stacking process gives them sufficient restoring force, enabling the "flexible" shape memory alloy to provide sufficient restoring force.

5. The low-cost intelligent forming and manufacturing method based on shape memory alloy according to claim 1, characterized in that, The aforementioned method for regional control of the structure or properties of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes is as follows: In different regions of shape memory alloy curved rod lattice metamaterials or curved stretchable meshes, lattice unit cells or mesh unit cells with different structural parameters or properties are used.

6. The mechanical cloning manufacturing method based on shape memory alloy composite flexible metamaterials according to claim 1, characterized in that, The aforementioned method of separately controlling the structure or properties of shape memory alloy curved rod lattice metamaterials and curved edge stretchable meshes includes: The spatial distribution of stress response can be controlled by splitting the layout of unit cells with different structural parameters or performances when each curved rod lattice metamaterial or curved edge stretchable mesh is controlled in a regionalized manner, thereby obtaining multiple shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes with different spatial distributions of stress response. The separate control of non-simultaneous stress response triggering, through the regulation of heat treatment specifications or the regulation of shape memory alloy material composition, controls the phase transition temperature of multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes to different temperature values, so that multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes produce non-simultaneous phase transition triggering and stress response.

7. The mechanical cloning manufacturing method based on shape memory alloy composite flexible metamaterials according to claim 1, characterized in that, The composite control of the structure or properties of shape memory alloy curved rod lattice metamaterials and curved edge stretchable meshes through superposition and lamination includes the following composite control methods: By stacking multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different spatial distributions of stress response, structural parameters or performance, and different layouts of unit cells, complex structures or performance are formed by regional control of the structure. This results in shape memory alloy composite flexible metamaterials with non-uniform structures and performance, and produces complex spatial distributions of stress response. By combining multiple separately controlled shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different phase transition temperatures and stress response triggered asynchronously, a shape memory alloy composite flexible metamaterial with asynchronous actuation function and stress response is formed. By combining multiple spatially distributed and non-simultaneously triggered stress response control units with different structural parameters or performance, different layouts of unit cells, and different phase transition temperatures, shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are stacked together to obtain shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform performance, non-simultaneously triggered actuation function, and stress response.

8. The low-cost intelligent forming manufacturing method based on shape memory alloy according to claim 1, characterized in that, Formable shape memory alloy composite flexible metamaterials include: (1) Based on the regional control, split control, and composite control of the structure or properties of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes, complex regional control is formed to obtain shape memory alloy composite flexible metamaterials with non-uniform structures and non-uniform properties that can produce complex stress response spatial distributions. The method is as follows: First, through regional control, lattice unit cells or mesh unit cells with different structural parameters or properties are used in different regions of shape memory alloy curved rod lattice metamaterials or curved stretchable meshes. Secondly, modular control is implemented. By changing the layout of unit cells with different structural parameters or performances during regional control of each shape memory alloy curved rod lattice metamaterial or curved stretchable mesh, each individual is controlled separately, resulting in multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different stress response spatial distributions. Then, composite control of superposition and layering is carried out. Multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different layouts of unit cells that have been separately controlled and have different structural parameters or performance are superimposed and layered to form complex regional control of structure or performance, resulting in shape memory alloy composite flexible metamaterials with non-identical structure and non-uniform performance. (2) Based on the separate control and composite control of the structure or properties of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes, shape memory alloy composite flexible metamaterials with non-simultaneous triggering actuation function and stress response can be formed. The method is as follows: First, separate control is achieved by adjusting the heat treatment specifications or the composition of the shape memory alloy material. The phase transition temperatures of multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes are set to different values. By controlling the phase transition temperature of each individual, non-simultaneous phase transitions and shape recovery are generated, which in turn generate non-simultaneous actuation function triggering and stress response. Then, the composite control of superposition and lamination is used to superimpose and laminate multiple curved rod lattice metamaterials or curved stretchable meshes with different phase transition temperatures after separate control, forming shape memory alloy composite flexible metamaterials with non-simultaneous triggering actuation function and stress response. (3) Based on the regionalized control, split-type control, and composite control of the structure or properties of shape memory alloy curved rod lattice metamaterials and curved stretchable meshes, shape memory alloy composite flexible metamaterials with non-uniform structures, non-uniform properties, and non-simultaneous triggering actuation functions and stress responses are formed. The method is as follows: First, through regional control, lattice unit cells or mesh unit cells with different structural parameters or properties are used in different regions of shape memory alloy curved rod lattice metamaterials or curved stretchable meshes. Secondly, the spatial distribution of stress response is controlled in a split manner. By changing the layout of unit cells with different structural parameters or performance in each curved rod lattice metamaterial or curved edge stretchable mesh during regional control, multiple shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes with different spatial distributions of stress response are obtained. Then, the stress response is not triggered simultaneously and is controlled separately. By adjusting the heat treatment specifications or the composition of the shape memory alloy material, the phase transition temperatures of the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different structural parameters or performances and different layouts of the unit cells are set to different temperature values. This allows the shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different structural parameters or performances and different layouts of the unit cells under regional control to generate non-simultaneous phase transition triggering and stress response. Finally, composite control is carried out by superimposing and layering multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different layouts and phase transition temperatures, which have undergone regional and split control and have different structural parameters or performance. This results in shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform performance, and non-simultaneous triggering actuation function and stress response.

9. The low-cost intelligent forming and manufacturing method based on shape memory alloys according to claim 1, characterized in that, Based on the aforementioned actuation function of shape memory alloys, a flexible metamaterial composite of shape memory alloys with non-uniform structures, non-uniform properties, and non-simultaneous triggering actuation functions and stress response is transformed into a flexible intelligent actuator with intelligently controllable spatial distribution and time-varying stress response, capable of acting on a billet. The specific method is as follows: First, shape memory alloy curved rod lattice metamaterials and curved-edge stretchable meshes are fabricated. Based on the design of different unit cell layouts according to structural parameters or performance, shape memory alloy blanks can be processed into curved rod lattice metamaterials and curved edge stretchable meshes with different unit cell layouts according to different structural parameters or performance through regional control and split control. Shape memory alloy blanks can be directly processed into curved rod lattice metamaterials and curved edge stretchable meshes with a set shape, or shape memory alloy blanks can be processed into flat curved rod lattice metamaterials and curved edge stretchable meshes. Secondly, a shaping heat treatment is performed to set the shape and phase transition temperature. When the shape memory alloy curved rod lattice metamaterial and the curved edge stretchable mesh are in the set shape, they are directly constrained and subjected to shaping heat treatment to fix them into the set shape and give them shape memory function. At the same time, split control is adopted, and the phase transition temperature of the shape memory alloy curved rod lattice metamaterial and the curved edge stretchable mesh is set by adjusting the shaping heat treatment specifications or the shape memory alloy material composition. When the curved rod lattice metamaterial and the curved edge stretchable mesh are in the shape of a flat plate, they are first deformed into a set shape and then constrained and subjected to shaping heat treatment to fix them into the set shape and give them shape memory function. Split control is adopted, and the phase transition temperature is set by adjusting the shaping heat treatment specifications or the shape memory alloy material composition. Then, the shape memory alloy curved rod lattice metamaterial and the curved stretchable mesh, which have been set with shape and phase transition temperature, are deformed into a temporary shape. The temporary shape is determined by the blank of the forming component, so that it stores energy, has actuation function, and is transformed into a flexible actuator. Finally, a composite control method of superposition and layering is adopted to combine multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes that have undergone regional and split control, have different structural parameters or performance, different phase transition temperatures, and have actuation functions and can be transformed into flexible actuators. These are superimposed and layered together to form a shape memory alloy composite flexible metamaterial with non-uniform structure, non-uniform performance, and non-simultaneous triggering of actuation functions and stress response. This becomes a flexible intelligent actuator with intelligent controllable spatial distribution of stress response and changes over time.

10. The low-cost intelligent forming and manufacturing method based on shape memory alloys according to claim 1, characterized in that, The shape memory alloy curved rod lattice metamaterial and the curved stretchable mesh, combined with the shape memory alloy actuation function, transform the curved rod lattice metamaterial and the curved stretchable mesh into a flexible actuator that can act on the billet. This is achieved through shaping heat treatment and deformation energy storage. The methods and processes of shaping heat treatment and deformation energy storage are as follows: When using single-pass shape memory alloys, the process of performing shaping heat treatment and storing energy is as follows: Shape memory alloy curved rod lattice metamaterials and curved stretchable meshes can be directly fabricated into the desired shape, or shape memory alloy curved rod lattice metamaterials and curved stretchable meshes can be fabricated into simple flat plate shapes, deformed into the desired shape, constrained, heated to transform into the parent austenitic phase, and subjected to shaping heat treatment to solidify the shape and give it a one-way shape memory function. Then, it can be cooled to transform into a low-temperature martensitic phase, and deformed in the low-temperature martensitic phase to a temporary shape. The temporary shape is determined by the blank of the forming component. This deformation induced by external force stores energy, transforming it into a flexible actuator with actuation properties. When using two-way shape memory alloys, the process of performing shaping heat treatment and storing energy is as follows: First, shape memory alloy curved rod lattice metamaterials and curved edge stretchable meshes can be directly prepared into the desired shape, or shape memory alloy curved rod lattice metamaterials and curved edge stretchable meshes can be prepared into simple flat plate shapes, deformed into the desired shape, constrained, heated to transform into the parent phase austenite phase, and then subjected to shaping heat treatment to shape it and give it shape memory function. Secondly, the shape memory alloy curved rod lattice metamaterial and curved stretchable mesh, which have been shaped and memorized, are cooled to transform into a low-temperature martensitic phase and deformed into a temporary shape. The temporary shape is determined by the blank of the forming component. Under constrained conditions, thermomechanical treatment training of heating and cooling is carried out to enable it to memorize the temporary shape of the low-temperature martensitic phase, thus possessing a two-way shape memory function. It can not only memorize the shaped high-temperature austenitic phase but also the temporary shape of the low-temperature martensitic phase. Energy is stored through temperature-induced deformation between the original shape and the temporary shape, transforming it into a flexible actuator with actuation properties.

11. The low-cost intelligent forming and manufacturing method based on shape memory alloy according to claim 1, characterized in that, A flexible metamaterial composed of shape memory alloys with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function, and stress response is used as a flexible intelligent actuator whose spatial distribution and time-varying stress response can be designed. This actuator acts on blanks and formed components, including the following steps: Step 1: Analyze the characteristics of the component to be formed and the distribution of the pressure load required for its forming, as well as the change of the pressure load over time; Step 2: Based on the required pressure load distribution and pressure load variation over time obtained in Step 1, a composite control method is adopted to regionalize, split, and superimpose the structure or properties of shape memory alloy curved rod lattice metamaterials and curved edge stretchable meshes. This method designs shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes with different structural parameters or properties, different unit cell layouts, and different phase transition temperatures. This results in the formation of shape memory alloy composite flexible metamaterials with non-uniform structures, non-uniform properties, and non-simultaneous triggering actuation functions and stress responses. Step 3: Prepare shape memory alloy curved rod lattice metamaterials or curved stretchable meshes. Based on the design in step two, shape memory alloy blanks are processed into shape memory alloy curved rod lattice metamaterials or curved edge stretchable meshes with different structural parameters or performance unit cell layouts using regional control methods and split control methods. Step 4: Form shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response, and transform them into flexible intelligent actuators. A modular control method is employed to perform shaping heat treatment on the prepared shape memory alloy curved rod lattice metamaterial or curved stretchable mesh, setting its original shape and phase transition temperature. Then, by deforming the already shaped shape memory alloy curved rod lattice metamaterial or curved stretchable mesh with different unit cell layouts and phase transition temperatures to a temporary shape, energy is stored, enabling it to have actuation function. Next, a composite method of superposition and lamination is used to superimpose and laminate multiple shape memory alloy curved rod lattice metamaterials or curved stretchable meshes with different unit cell layouts and phase transition temperatures, resulting in a composite flexible shape memory alloy metamaterial with non-uniform structure, non-uniform properties, and non-simultaneous triggering of actuation function and stress response, which is then transformed into a flexible intelligent actuator. Step 5: Assembly Shape memory alloy composite flexible metamaterials, which are transformed into flexible intelligent actuators with non-identical structures, non-uniform properties, non-simultaneous triggering actuation functions and stress responses, are assembled and fixed together with blanks, molds, auxiliary assembly and fixing components and heating devices. Step Six: Heating triggers the shape memory alloy composite flexible metamaterial to recover its shape and form a component. Heating triggering has been transformed into a flexible intelligent actuator using shape memory alloy composite flexible metamaterials with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response. This allows the actuator to undergo a phase transformation, restore its original shape, generate actuation function, produce the required stress response, act on the billet, deform the billet, and form it into a component.

12. The low-cost intelligent forming manufacturing method based on shape memory alloys according to claim 1 or 11, characterized in that, The flexible metamaterial, which combines shape memory alloys with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response, is used as a flexible intelligent actuator. When it is applied to the blank for forming, it needs to be assembled with the blank and other materials. Lubrication is required between the metals that come into contact with each other during assembly and forming.

13. The low-cost intelligent forming manufacturing method based on shape memory alloys according to claim 1 or 11, characterized in that, The shape memory alloy composite flexible metamaterial, which has non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response, is used as a flexible intelligent actuator. When it is applied to a blank for forming, a rigid cover plate or a rigid-flexible composite cover plate can be covered on one side of the blank to improve formability, or a fluid back pressure can be applied to one side of the blank to improve formability, or an elastomer can be placed between the shape memory alloy composite flexible metamaterial, which has non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function and stress response, and the blank to improve formability and surface quality of the component.

14. The low-cost intelligent forming manufacturing method based on shape memory alloys according to claim 1 or 11, characterized in that, The aforementioned flexible metamaterial, a composite of shape memory alloys with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function, and stress response, is used as a flexible intelligent actuator. When applied to a blank for forming, the action on the blank is divided into two regions: one is the blank deformation region corresponding to the mold cavity, and the other is the region at the edge of the blank. In the blank deformation region corresponding to the mold cavity, the flexible metamaterial, a composite of shape memory alloys with non-uniform structure, non-uniform properties, non-simultaneous triggering actuation function, and stress response, is applied to generate a non-uniform pressure distribution and a pressure that changes over time. In the edge-pressing region, the flexible metamaterial, a composite of shape memory alloys, is also used to adjust and control the edge-pressing force acting on the blank.

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