Phase change flexible mechanical metamaterial with adjustable deformation

Abstract

The invention discloses a phase change flexible mechanical metamaterial with adjustable and controllable deformation. The phase change flexible mechanical metamaterial comprises a plurality of lattice units which are mainly composed of a series of basic driving units arranged in a set pattern and first configuration connecting pieces or second configuration connecting pieces, the basic driving units are bonded and fixed to the first configuration connecting pieces or the second configuration connecting pieces, and the first configuration connecting pieces are of L-shaped structures. The first configuration connecting piece is of a plate-shaped structure, the second configuration connecting piece is of a plate-shaped structure, each basic driving unit is provided with a fixed side and a deformation side, the fixed side is fixedly bonded with the first configuration connecting piece or the second configuration connecting piece, the deformation side is used for generating deformation, and each basic driving unit can be independently controlled. The deformation-controllable phase change flexible mechanical metamaterial can repeatedly and reversibly realize abundant and diversified controlled deformation, can keep deformation without power consumption, greatly expands the deformation form of limited liquid-gas phase change flexible driving in the prior art, and has a relatively great application prospect.

Description

Technical Field

[0001] This invention relates to an active mechanical metamaterial in the field of soft robotics, specifically to a deformable phase change flexible mechanical metamaterial.

[0002] Mechanical metamaterials, composed of periodically arranged structural units, exhibit superior properties compared to natural materials, but their characteristics cannot be altered after fabrication. In recent years, combining mechanical metamaterials with flexible actuation technology has led to the development of active mechanical metamaterials capable of deforming in response to stimuli and thus changing their properties. Among various flexible actuation technologies, liquid-gas phase change flexible actuation technology boasts advantages such as small size, noiselessness, and high output, and holds promise for further expanding the properties, functions, and applications of active mechanical metamaterials. However, existing liquid-gas phase change flexible actuation technologies suffer from limitations such as a relatively singular deformation pattern, the inability to change the deformation pattern after fabrication, and the inability to achieve uniform overall deformation rather than localized deformation control at specific locations. Furthermore, it has not yet been used to develop active mechanical metamaterials with periodic lattice structures and complex deformation capabilities. Summary of the Invention

[0003] The technical problem solved by this invention is to provide a deformable phase change flexible mechanical metamaterial that combines two phase change mechanisms: solid-liquid phase change and liquid-gas phase change. It regulates the deformation generated by liquid-gas phase change through locally controlled solid-liquid phase change and adopts a lattice metamaterial configuration to solve the problem of the limited deformation forms of existing liquid-gas phase change flexible driving technology. This invention provides a phase change flexible mechanical metamaterial technical solution with rich and adjustable deformation forms, realizing reversible and diverse deformation control and local deformation control.

[0004] The technical solution adopted in this invention is: The deformable phase change flexible mechanical metamaterial comprises multiple lattice units, mainly consisting of a series of basic driving units arranged in a set pattern and a first configuration connector or a second configuration connector. The basic driving units are bonded and fixed to the first configuration connector or the second configuration connector. The first configuration connector is an L-shaped structure, and the second configuration connector is a plate-like structure. The basic driving unit has a fixed side and a deformable side. The fixed side is bonded and fixed to the first configuration connector or the second configuration connector, and the deformable side is used to generate deformation.

[0005] Phase change flexible mechanical metamaterials are classified into two configurations: in-plane deformation configuration and out-of-plane deformation configuration; The in-plane deformable phase change flexible mechanical metamaterial includes a series of basic drive units arranged in a set pattern and a first configuration connector.

[0006] The out-of-plane deformable phase change flexible mechanical metamaterial includes a series of basic drive units and a second configuration connector arranged in a set pattern.

[0007] The in-plane deformable phase change flexible mechanical metamaterial mainly consists of multiple closely arrayed in-plane lattice units. Each in-plane lattice unit includes four basic driving units and four first configuration connectors, which are arranged alternately in a square ring along the circumference. The fixed ends of each basic driving unit are connected to one of the first configuration connectors. The four basic driving units are located at the four sides of the in-plane lattice unit, and the four first configuration connectors are located at the four corners of the in-plane lattice unit. The deformable sides of two basic driving units on one pair of opposite sides of the in-plane lattice unit are arranged towards the center of the plane of the in-plane lattice unit, and the fixed sides of two basic driving units on another pair of opposite sides are arranged towards the center of the plane of the in-plane lattice unit. For two adjacent in-plane lattice units, the orientation of the basic driving units on the side along one direction of the array arrangement of one in-plane lattice unit is always opposite to that of the basic driving units on the side along the same direction of the array arrangement of the other in-plane lattice unit.

[0008] The phase change flexible mechanical metamaterial with the out-of-plane deformation configuration is mainly composed of multiple closely connected out-of-plane lattice units. Each out-of-plane lattice unit includes six basic driving units and a second configuration connector with a plate-like structure.

[0009] The fixed sides of the six basic drive units are all fixedly connected to the second configuration connector; the six basic drive units are divided into two groups of strip-shaped basic drive unit groups, which are respectively arranged on the two side surfaces of the second configuration connector, and the strip-shaped directions of the two groups of basic drive unit groups are perpendicular to each other.

[0010] Each group of basic drive units mainly consists of three strip-shaped basic drive units. The three basic drive units are arranged in parallel and spaced apart on the surface of the second configuration connector. The three basic drive units and the surface of the second configuration connector have the same length along the strip direction of the basic drive units and are flush with each other. One basic drive unit is located in the middle of the surface of the second configuration connector, and the other two basic drive units are located at the edge of the surface of the second configuration connector and are aligned with their own sides and edges.

[0011] For two adjacent out-of-plane lattice units, the basic driving unit orientation of one out-of-plane lattice unit on the side along one direction of the array arrangement is perpendicular to the basic driving unit orientation of the other out-of-plane lattice unit on the side along the same direction of the array arrangement.

[0012] In the case of an initially undeformed metamaterial, the two configurations are determined as follows: When the normal of the plane connecting each layer of the basic driving unit is perpendicular to the normal direction of the overall plane of the metamaterial, the metamaterial has an in-plane deformation configuration. When the normal direction of the plane connecting each layer of the basic driving unit is parallel to the normal direction of the overall plane of the metamaterial, the metamaterial has an out-of-plane deformation configuration.

[0013] The basic driving unit includes a driving layer, a heat insulation layer, and a variable stiffness layer, all of which are strip-shaped and arranged in close succession. Each pair of adjacent driving layers, heat insulation layers, and variable stiffness layers are connected and fixed. Both the driving layer and the variable stiffness layer are equipped with electrically heated components. The driving layer is driven to deform by the electrically heated components, and the variable stiffness layer adjusts the stiffness of the deformation at different positions of the driving layer by the electrically heated components. The driving layer and the variable stiffness layer work together to achieve arbitrary shape deformation and adjustment of the basic driving unit.

[0014] The basic drive unit has a fixed side and a deformable side. The side where the drive layer of the basic drive unit is located serves as the deformable side of the basic drive unit, and the side where the variable stiffness layer of the basic drive unit is located serves as the fixed side.

[0015] The driving layer mainly consists of a first driving layer shell, a liquid-gas phase change working fluid, a driving heating wire, a second driving layer shell, and a sheet-like fabric restraint layer, all arranged in a tightly stacked manner and in strip shape. The second driving layer shell is bonded to the fabric restraint layer, and the first driving layer shell is arranged on top of the second driving layer shell. A relatively closed strip-shaped driving cavity is formed between the first driving layer shell and the second driving layer shell. The driving heating wire is disposed in the strip-shaped driving cavity and filled with the liquid-gas phase change working fluid. The first driving layer shell is configured as a toothed shell structure. The driving heating wire extends and is arranged entirely within the strip-shaped driving shell and bends through each tooth of the toothed shell structure. The liquid-gas phase change working fluid fills the space inside the strip-shaped driving cavity except for the driving heating wire. The upper surface of the second driving layer shell has a strip-shaped groove parallel to its own strip direction.

[0016] The strip-shaped grooves on the upper surface of the second driving layer shell are used to connect the various toothed cavities in the first driving layer shell, allowing the liquid-gas phase change working fluid to flow freely within them. The fabric restraining layer is used to restrict the elongation of the driving layer in the length direction, ensuring that the bending deformation occurs biased towards the fabric restraining layer.

[0017] The first driving layer shell has hollow hole structures at both ends. The driving heating wire passes through the hole structures at both ends of the first driving layer shell and is connected to an external power source, and is used to heat the liquid-gas phase change working fluid.

[0018] The variable stiffness layer includes a first variable stiffness layer shell, a stiffness-regulating heating wire, a solid-liquid phase-change working fluid, and a second variable stiffness layer shell, all of which are strip-shaped. The top surface of the second variable stiffness layer shell has a strip-shaped groove along the strip-shaped direction of the variable stiffness layer. The first variable stiffness layer shell is connected to the opening of the strip-shaped groove of the second variable stiffness layer shell. A relatively closed strip-shaped variable stiffness cavity is formed between the first and second drive layer shells. The first and second drive layer shells, outside the strip-shaped variable stiffness cavity, are each internally fitted with a stiffness-regulating heating wire. The strip-shaped variable stiffness cavity is filled with a solid-liquid phase-change working fluid. The stiffness-regulating heating wire consists of multiple annular heating wires arranged at equal intervals along the strip-shaped direction of the variable stiffness layer, each annular heating wire arranged circumferentially around the outer periphery of the strip-shaped variable stiffness cavity. Each stiffness-regulating heating wire is... Each of the aforementioned stiffness-regulating heating wires is used to independently control the temperature of the solid-liquid phase change working fluid, and each of these wires passes through the outer shell of the variable stiffness layer and is connected to an external power source. By energizing and heating a stiffness-regulating heating wire at a certain location, a local solid-liquid phase change occurs in the solid-liquid phase change working fluid at that location, thereby softening the position of the stiffness-regulating heating wire in the variable stiffness layer. This softening is used to regulate the deformation stiffness of the basic driving unit at each position in the strip direction when the driving layer deforms. After the driving heating wire is energized and heated, it drives the liquid-gas phase change working fluid in the strip-shaped driving cavity to undergo a liquid-gas phase change for driving, thereby driving the overall deformation of the basic driving unit. The variable stiffness layer uses the local solid-liquid phase change of the solid-liquid phase change working fluid to control the stiffness at various positions in the strip direction, thereby regulating the deformation stiffness of the basic driving unit.

[0019] The upper surface of the insulation layer is provided with a column group on each side along its strip direction. Each column group includes multiple columns. The columns in each column group are symmetrically distributed and extend along its strip direction at equal intervals to form a column array structure. The insulation layer is used to reduce thermal interference between the driving layer and the variable stiffness layer.

[0020] The phase change flexible mechanical metamaterial deforms through the deformation of a basic driving unit, which achieves four different working modes: Deformation control working mode: First, the variable stiffness layer is electrically heated to control the deformation stiffness of the basic driving unit at various positions in the strip direction. Then, the driving layer is electrically heated to drive the overall deformation of the basic driving unit, so as to achieve any expected deformation state.

[0021] Rapid deformation working mode: First, the driving layer is energized and heated to regulate the basic driving unit to store energy. Then, the variable stiffness layer is energized and heated to regulate the deformation stiffness of the basic driving unit at various positions in the strip direction. The driving layer rapidly deforms in the area softened by the energized and heated variable stiffness layer, so that the basic driving unit rapidly deforms in the area softened by the energized and heated variable stiffness layer, and the basic driving unit achieves rapid deformation working mode.

[0022] Shape-locking working mode: For the basic drive unit in a deformed state, the temperature of the variable stiffness layer is first cooled to solidify the variable stiffness layer, and then the drive layer is cooled and liquefied, so that the shape protection of the basic drive unit is locked, thereby realizing the shape-locking working mode.

[0023] Restoring the initial working mode: For the basic drive unit that is in a deformed state, first cool the drive layer to liquefy it and restore its initial shape, and then cool the temperature of the variable stiffness layer to solidify it, thereby restoring the initial working mode.

[0024] More specifically, the controlled deformation working mode is as follows: by heating the stiffness control heating wire of the variable stiffness layer at a certain position, the solid-liquid phase change working medium at the position of the stiffness control heating wire is further controlled to undergo solid-liquid phase change, and then the driving heating wire is heated to control the liquid-gas phase change working medium of the driving layer to undergo liquid-gas phase change as a whole, so that the basic driving unit is deformed as a whole, and the basic driving unit realizes the controlled deformation working mode.

[0025] More specifically, the rapid deformation working mode involves heating the driving heating wire of the driving layer to control the liquid-gas phase change working medium to undergo a liquid-gas phase change, thereby regulating the driving layer to enable the basic driving unit to store energy. Then, heating the stiffness regulating heating wire at a certain position further controls the solid-liquid phase change working medium at the location of the stiffness regulating heating wire to undergo a solid-liquid phase change, causing the variable stiffness layer to soften at this location. The driving layer then rapidly deforms in the area softened by the electric heating of the variable stiffness layer, causing the basic driving unit to rapidly deform in the area softened by the electric heating of the variable stiffness layer, thus enabling the basic driving unit to achieve the rapid deformation working mode.

[0026] More specifically, the shape locking working mode is as follows: for the basic drive unit in a deformed state, while maintaining the liquid-gas phase change working medium of the drive layer in a vaporized drive state, the solid-liquid phase change working medium of the variable stiffness layer is cooled and solidified, and then the liquid-gas phase change working medium of the drive layer is cooled and liquefied, so that the shape locking of the drive layer leads to the shape protection locking of the basic drive unit, thereby realizing the shape locking working mode.

[0027] More specifically, the restoration of the initial working mode is as follows: for the basic drive unit in a deformed state, while maintaining the solid-liquid phase change working medium of the variable stiffness layer in a liquefied drive state, the liquid-gas phase change working medium of the drive layer is cooled and liquefied, so that the drive layer restores its initial shape. Then, the solid-liquid phase change working medium of the variable stiffness layer is cooled and solidified, thereby realizing the restoration of the initial working mode.

[0028] The beneficial effects of this invention are: 1. The phase change flexible mechanical metamaterial of the present invention is a deformable phase change flexible mechanical metamaterial. It utilizes local controllable solid-liquid phase change to regulate liquid-gas phase change deformation. Compared with existing liquid-gas phase change flexible driving structures, it can repeatedly and reversibly regulate deformation according to needs, freely set the deformation position, and can only control deformation at the required position to achieve local deformation regulation, thereby realizing a variety of deformation forms.

[0029] 2. The phase change flexible mechanical metamaterial of the present invention has a customizable lattice design, which can distribute and control the deformation of basic driving units at different locations, further expanding the ability of liquid-gas phase change flexible driving technology to achieve complex deformation.

[0030] 3. The phase change flexible mechanical metamaterial of the present invention can utilize the reversible solid-liquid phase change of the variable stiffness layer to lock the deformation generated by the liquid-gas phase change of the driving layer. Compared with the existing liquid-gas phase change flexible driving structure, it achieves deformation retention without power consumption and overcomes the problem of high energy consumption for deformation retention in the existing liquid-gas phase change flexible driving technology. Attached Figure Description

[0031] Figure 1 A schematic diagram of a phase change flexible mechanical metamaterial with an in-plane deformation configuration; Figure 2 This is a schematic diagram of the composition of an in-plane lattice unit. Figure 3 A schematic diagram of a partial cross-sectional structure of a phase change flexible mechanical metamaterial with an out-of-plane deformation configuration; Figure 4 This is a schematic diagram of the composition of an out-of-plane lattice unit; Figure 5 This is a structural outline diagram of the basic drive unit; Figure 6 An exploded view of the basic driving unit structure; Figure 7 This is a schematic diagram illustrating the deformation control principle of the basic driving unit. Figure 8 A schematic diagram of a deformation control scheme for an in-plane lattice unit; Figure 9 A schematic diagram of a deformation control scheme for an out-of-plane lattice unit; Figure 10 Experimental images showing the design for different deformation control of a single triangular lattice; Figure 11 Experimental images showing the design for different deformation control of a single quadrilateral lattice; Figure 12 Experimental images showing the achievement of deformable shape locking for a single quadrilateral lattice; Figure 13 Experimental images show the design for different deformation control of phase change flexible mechanical metamaterials with out-of-plane deformation configurations.

[0032] In the figure: basic drive unit 1, drive layer 11, first drive layer shell 111, liquid-gas phase change working medium 112, drive heating wire 113, second drive layer shell 114, fabric confinement layer 115, heat insulation layer 12, variable stiffness layer 13, first variable stiffness layer shell 131, stiffness adjustment heating wire 132, solid-liquid phase change working medium 133, second variable stiffness layer shell 134, first configuration connector 2, second configuration connector 3. Detailed Implementation

[0033] To illustrate the technical solution and objectives of this invention, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0034] The specific design of the phase change flexible mechanical metamaterial structure is as follows: like Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, the deformable phase-change flexible mechanical metamaterial comprises multiple lattice units, mainly consisting of a series of basic driving units 1 arranged in a predetermined pattern and either a first configuration connector 2 or a second configuration connector 3. The basic driving units 1 are bonded and fixed to the first configuration connector 2 or the second configuration connector 3. The first configuration connector 2 has an L-shaped structure, and the second configuration connector 3 has a plate-like structure. The basic driving unit 1 has a fixed side and a deformable side. The fixed side is bonded and fixed to the first configuration connector 2 or the second configuration connector 3, and the deformable side is used to generate deformation.

[0035] Phase change flexible mechanical metamaterials are classified into two configurations: in-plane deformation configuration and out-of-plane deformation configuration.

[0036] The in-plane deformable phase change flexible mechanical metamaterial includes a series of basic drive units 1 arranged in a set pattern and a first configuration connector 2, while the out-of-plane deformable phase change flexible mechanical metamaterial includes a series of basic drive units 1 arranged in a set pattern and a second configuration connector 3.

[0037] In phase transition flexible mechanical metamaterials with in-plane deformation configurations, they are mainly composed of multiple closely connected in-plane lattice units. Each in-plane lattice unit includes four basic driving units 1 and four first configuration connectors 2, which are arranged alternately in a square ring along the circumference.

[0038] Each basic driving unit 1 has its fixed side ends connected to a first configuration connector 2. The four basic driving units 1 are located at the four sides of the in-plane lattice unit, and the four first configuration connectors 2 are located at the four corners of the in-plane lattice unit. The deformable sides of the two basic driving units 1 located on one pair of opposite sides of the in-plane lattice unit are arranged towards the center of the in-plane lattice unit plane, and the fixed sides are arranged away from the center of the in-plane lattice unit plane. The fixed sides of the two basic driving units 1 located on the other pair of opposite sides are arranged towards the center of the in-plane lattice unit plane, and the deformable sides are arranged away from the center of the in-plane lattice unit plane.

[0039] The first configuration connector 2 is shared by adjacent in-plane lattice units that are in contact with each other.

[0040] The array is a matrix array, that is, arranged along two orthogonal directions. Furthermore, the basic driving unit 1 of two adjacent in-plane lattice units is arranged in opposite directions on the same side of the array arrangement. Specifically, for two adjacent in-plane lattice units, the basic driving unit 1 of one in-plane lattice unit is always arranged in opposite directions on the same side of the array arrangement as the basic driving unit 1 of the other in-plane lattice unit.

[0041] like Figure 1 As shown, for two adjacent in-plane lattice units, the array is arranged in two orthogonal directions, horizontal x and vertical y. In one in-plane lattice unit, the basic driving units 1 on the two sides along the x direction are both oriented towards the center of the in-plane lattice unit plane, and the basic driving units 1 on the two sides along the y direction are both away from the center of the in-plane lattice unit plane. In the other in-plane lattice unit, the basic driving units 1 on the two sides along the x direction are both far from the center of the in-plane lattice unit plane, and the basic driving units 1 on the two sides along the y direction are both oriented towards the center of the in-plane lattice unit plane.

[0042] like Figure 3As shown, the phase change flexible mechanical metamaterial with out-of-plane deformation configuration is mainly composed of multiple closely arrayed out-of-plane lattice units. Each out-of-plane lattice unit includes six basic driving units 1 and a plate-shaped second configuration connector 3. The fixed sides of the six basic driving units 1 are all fixedly connected to the second configuration connector 3. The six basic driving units 1 are divided into two groups of strip-shaped basic driving unit groups. The two groups of basic driving unit groups are respectively arranged on the two side surfaces of the second configuration connector 3, and the strip directions of the two groups of basic driving unit groups are perpendicular to each other.

[0043] Each group of basic drive units mainly consists of three strip-shaped basic drive units 1. The three basic drive units 1 are arranged in parallel and spaced apart on the surface of the second configuration connector 3. The three basic drive units 1 and the surface of the second configuration connector 3 have the same length along the strip direction of the basic drive unit 1 and are flush with each other. One basic drive unit 1 is located in the middle of the surface of the second configuration connector 3, and the other two basic drive units 1 are located at the edge of the surface of the second configuration connector 3 and are aligned with their own sides and edges.

[0044] Specifically, a set of basic drive units is fixedly connected to the second configuration connector 3, wherein two basic drive units 1 are arranged along the edge of a pair of opposite sides of the second configuration connector 3, and another basic drive unit 1 is arranged at the center of the second configuration connector 3 and parallel to the other two basic drive units 1; the length of the three basic drive units 1 is the same as the side length of the opposite sides of the second configuration connector 3.

[0045] Another set of basic drive units is fixedly connected below the second configuration connector 3. Two basic drive units 1 are arranged along the other pair of opposite sides of the second configuration connector 3, and another basic drive unit 1 is arranged at the center of the second configuration connector 3 and parallel to the other two basic drive units 1. The length of the three basic drive units 1 is the same as the side length of the other pair of opposite sides of the second configuration connector 3, and is perpendicular to the basic drive units 1 arranged above the second configuration connector 3.

[0046] The array is a matrix array, that is, arranged along two orthogonal directions. Furthermore, the basic driving units 1 of two adjacent out-of-plane lattice units are arranged perpendicularly to each other on the side of the same direction along the array arrangement. Specifically, for two adjacent out-of-plane lattice units, the basic driving units 1 of one out-of-plane lattice unit are arranged perpendicularly to each other on the side of the same direction along the array arrangement, and the basic driving units 1 of the other out-of-plane lattice unit are arranged perpendicularly to each other on the side of the same direction along the array arrangement.

[0047] In the case of an initially undeformed metamaterial, the two configurations are determined as follows: When the normal of the plane connecting each layer of the basic driving unit 1 is perpendicular to the normal direction of the overall plane of the metamaterial, the metamaterial has an in-plane deformation configuration.

[0048] When the normal direction of the bonding plane of each layer of the basic driving unit 1 is parallel to the normal direction of the overall plane of the metamaterial, the metamaterial has an out-of-plane deformation configuration.

[0049] like Figure 5 , Figure 6 , Figure 7 As shown, the basic driving unit 1 includes a driving layer 11, a heat insulation layer 12, and a variable stiffness layer 13, all of which are strip-shaped and arranged in close succession. Each pair of adjacent layers in the driving layer 11, heat insulation layer 12, and variable stiffness layer 13 are connected and fixed. Both the driving layer 11 and the variable stiffness layer 13 are equipped with electrically heated components. The driving layer 11 is driven to deform by the electrically heated components, and the variable stiffness layer 13 adjusts the stiffness of the deformation of the driving layer 11 at different positions by the electrically heated components. The driving layer 11 and the variable stiffness layer 13 work together to realize the deformation and adjustment of the basic driving unit 1 in any shape.

[0050] The basic drive unit 1 has a fixed side and a deformable side. The side where the drive layer 11 of the basic drive unit is located is the deformable side of the basic drive unit 1, and the side where the variable stiffness layer 13 of the basic drive unit 1 is located is the fixed side.

[0051] The driving layer 11 mainly consists of a first driving layer shell 111, a liquid-gas phase change working medium 112, a driving heating wire 113, a second driving layer shell 114, and a sheet-like fabric restraint layer 115, all arranged in a tightly stacked manner and in strip shape. The second driving layer shell 114 is bonded to the fabric restraint layer 115, and the first driving layer shell 111 is arranged on top of the second driving layer shell 114. A relatively closed strip-shaped driving cavity is formed between the first driving layer shell 111 and the second driving layer shell 114. The driving heating wire 113 is arranged in the strip-shaped driving cavity and filled with the liquid-gas phase change working medium 112. The first driving layer shell 111 is configured as a toothed shell structure. The driving heating wire 113 extends and is arranged inside the strip-shaped driving shell and bends through each tooth of the toothed shell structure. The liquid-gas phase change working medium 112 fills the space inside the strip-shaped driving cavity except for the driving heating wire 113. The upper surface of the second driving layer shell 114 has a strip-shaped groove parallel to its own strip direction.

[0052] The strip-shaped groove on the upper surface of the second drive layer shell 114 is used to connect the various toothed cavities in the first drive layer shell 111, so that the liquid-gas phase change working medium 112 can flow freely therein. The fabric restricting layer 115 is used to restrict the elongation of the drive layer 11 in the length direction, and to ensure that the bending deformation that occurs is biased towards the side of the fabric restricting layer 115.

[0053] The first driving layer shell 111 has hollow perforated structures at both ends. The driving heating wire 113 passes through the perforated structures at both ends of the first driving layer shell 111 and is connected to an external power source to heat the liquid-gas phase change working medium 112.

[0054] The variable stiffness layer 13 includes a first variable stiffness layer shell 131, a stiffness-regulating heating wire 132, a solid-liquid phase change working fluid 133, and a second variable stiffness layer shell 134, all of which are strip-shaped. A strip-shaped groove along the strip-shaped direction of the second variable stiffness layer shell 134 is formed on the top surface of the second variable stiffness layer shell 134. The first variable stiffness layer shell 131 is connected to the opening of the strip-shaped groove of the second variable stiffness layer shell 134. A relatively closed strip-shaped variable stiffness cavity is formed between the first drive layer shell 111 and the second drive layer shell 114. The first drive layer shell 111 and the second drive layer shell 114, located outside the strip-shaped variable stiffness cavity, have the stiffness-regulating heating wire 132 embedded inside them. The strip-shaped variable stiffness cavity is filled with the solid-liquid phase change working fluid 133. The stiffness-regulating heating wire 132 consists of multiple annular heating wires arranged at equal intervals along the strip direction of the variable stiffness layer 13 and each annular heating wire is arranged circumferentially around the outer periphery of the strip-shaped variable stiffness cavity. Each stiffness-regulating heating wire 132 is used to independently control the temperature of the solid-liquid phase change working medium 133. Each stiffness-regulating heating wire 132 passes through the outer shell of the variable stiffness layer 13 and is connected to an external power source. By energizing and heating the stiffness-regulating heating wire 132 at a certain position, a local solid-liquid phase change occurs in the solid-liquid phase change working medium 133 at that stiffness-regulating heating wire 132, thereby softening the position of the stiffness-regulating heating wire 132 in the variable stiffness layer 13. This is used to regulate the deformation stiffness of the basic driving unit 1 at each strip direction position when the driving layer 11 deforms. After the driving heating wire 113 is energized and heated, the liquid-gas phase change working medium 112 in the driving strip cavity undergoes a liquid-gas phase change for driving, thereby driving the overall deformation of the basic driving unit 1; the variable stiffness layer 13 uses the local solid-liquid phase change of the solid-liquid phase change working medium 133 to control the stiffness at various positions in the strip direction, thereby regulating the deformation stiffness of the basic driving unit 1.

[0055] The upper surface of the insulation layer 12 has a column group on each side along its strip direction. Each column group includes multiple columns. The columns in each column group are symmetrically distributed and extend along its strip direction at equal intervals to form a column array structure. The insulation layer 12 is used to reduce thermal interference between the driving layer 11 and the variable stiffness layer 13.

[0056] The phase change flexible mechanical metamaterial deforms through the deformation of the basic driving unit 1, and the basic driving unit 1 achieves four different working modes: Deformation control mode: First, the variable stiffness layer 13 is energized and heated to control the deformation stiffness of the basic drive unit 1 at various positions in the strip direction. Then, the drive layer 11 is energized and heated to drive the overall deformation of the basic drive unit 1, so as to achieve any expected deformation state.

[0057] Rapid deformation working mode: First, the driving layer 11 is energized and heated to regulate the basic driving unit 1 to store energy. Then, the variable stiffness layer 13 is energized and heated to regulate the deformation stiffness of the basic driving unit 1 at various positions in the strip direction. The driving layer 11 deforms rapidly in the area softened by the energized and heated variable stiffness layer 13, so that the basic driving unit 1 deforms rapidly in the area softened by the energized and heated variable stiffness layer 13, and the basic driving unit 1 achieves rapid deformation working mode.

[0058] Shape locking working mode: For the basic drive unit 1 in the deformed state, the temperature of the variable stiffness layer 13 is first cooled to solidify the variable stiffness layer 13, and then the drive layer 11 is cooled and liquefied to lock the shape protection of the basic drive unit 1, thereby realizing the shape locking working mode.

[0059] Restoring the initial working mode: For the basic drive unit 1 that is in a deformed state, first cool the drive layer 11 to liquefy the drive layer 11 and restore its initial shape, then cool the temperature of the variable stiffness layer 13 to solidify the variable stiffness layer 13, thereby realizing the restoration of the initial working mode.

[0060] More specifically, the deformation control working mode is as follows: by heating the stiffness control heating wire 132 of the stiffness control layer 13 at a certain position, the solid-liquid phase change working medium 133 at the position of the stiffness control heating wire 132 is further controlled to undergo solid-liquid phase change, and then the driving heating wire 113 is heated to control the liquid-gas phase change working medium 112 of the driving layer 11 to undergo liquid-gas phase change as a whole, so that the basic driving unit 1 deforms as a whole, and the basic driving unit 1 realizes the deformation control working mode.

[0061] More specifically, the rapid deformation working mode involves heating the driving heating wire 113 of the driving layer 11 to control the liquid-gas phase change working medium 112 to undergo a liquid-gas phase change, thereby regulating the driving layer 11 to enable the basic driving unit 1 to store energy. Then, heating the stiffness regulating heating wire 132 at a certain position further controls the solid-liquid phase change working medium 133 at the location of the stiffness regulating heating wire 132 to undergo a solid-liquid phase change, causing the variable stiffness layer 13 to soften at this location. The driving layer 11 rapidly deforms in the area softened by the electric heating of the variable stiffness layer 13, causing the basic driving unit 1 to rapidly deform in the area softened by the electric heating of the variable stiffness layer 13, thus enabling the basic driving unit 1 to achieve the rapid deformation working mode.

[0062] More specifically, in the shape-locking working mode, for the basic drive unit 1 in a deformed state, while maintaining the liquid-gas phase change working medium 112 of the drive layer 11 in a vaporized drive state, the solid-liquid phase change working medium 133 of the variable stiffness layer 13 is cooled and solidified, and then the liquid-gas phase change working medium 112 of the drive layer 11 is cooled and liquefied, so that the shape of the drive layer 11 is locked, resulting in the shape protection lock of the basic drive unit 1, thereby realizing the shape-locking working mode.

[0063] To restore the initial working mode, more specifically: for the basic drive unit 1 in a deformed state, while maintaining the solid-liquid phase change working medium 133 of the variable stiffness layer 13 in a liquefied drive state, the liquid-gas phase change working medium 112 of the liquefied drive layer 11 is cooled, so that the drive layer 11 returns to its initial shape. Then, the solid-liquid phase change working medium 133 of the variable stiffness layer 13 is cooled, so that the solid-liquid phase change working medium 133 solidifies, thereby realizing the restoration of the initial working mode.

[0064] The first driving layer shell 111 and the second driving layer shell 114 are made of low-hardness bicomponent silicone rubber, the first variable stiffness layer shell 131 and the second variable stiffness layer shell 134 are made of high-hardness bicomponent silicone rubber, the heat insulation layer 12 is made of high-hardness bicomponent silicone rubber, the first configuration connector 2 is made of high-hardness bicomponent silicone rubber, and the second configuration connector 3 is made of low-hardness bicomponent silicone rubber. The low-hardness bicomponent silicone rubber is a bicomponent silicone rubber with a Shore hardness between 0A and 5A, and the mixing mass ratio of components A and B in the low-hardness bicomponent silicone rubber is 1:1; the high-hardness bicomponent silicone rubber is a bicomponent silicone rubber with a Shore hardness between 10A and 50A, and the mixing mass ratio of components A and B in the high-hardness bicomponent silicone rubber is 1:1; the liquid-gas phase change working medium 112 is a fluid with a boiling point between 20℃ and 100℃, and the solid-liquid phase change working medium 133 is an alloy with a melting point between 30℃ and 150℃.

[0065] like Figure 10 , Figure 11 As shown, phase change flexible mechanical metamaterials can be designed to achieve two-dimensional in-plane deformation or two-dimensional to three-dimensional out-of-plane deformation; in phase change flexible mechanical metamaterials, the type of a single lattice unit composed of multiple basic driving units 1 is customizable, including various shapes such as quadrilaterals and triangles; for example... Figure 8 , Figure 9 As shown, in the phase change flexible mechanical metamaterial, each basic driving unit can be independently controlled, and the deformation of each basic driving unit 1 can be independently adjusted. The driving layer 11 based on liquid-gas phase change is used to drive the overall deformation of the basic driving unit, and the variable stiffness layer 13 based on solid-liquid phase change is used to adjust the deformation generated by the driving layer. The heat insulation layer 12 with a column array structure is used to reduce the thermal interference between the two layers. A series of independently controlled stiffness-adjusting heating wires 132 are arranged at different positions along the long axis of the variable stiffness layer 13, which can control the phase change and stiffness change at different positions of the variable stiffness layer 13 as needed.

[0066] like Figure 12As shown, the controlled deformation of each basic driving unit 1 is reversible, and after deformation, the deformation of the basic driving unit can be locked after the solid-liquid phase change working medium 133 condenses using a reversible solid-liquid phase change. By repeatedly and reversibly controlling the deformation generated by the liquid-gas phase change through solid-liquid phase change, a rich variety of deformation forms of the phase change flexible mechanical metamaterial can be achieved, enabling power-free deformation retention. The deformation generated by the phase change flexible mechanical metamaterial can also be locked through reversible solid-liquid phase change. For example... Figure 10 , Figure 11 , Figure 13 As shown, deformable phase change flexible mechanical metamaterials can achieve repeated reversible controlled deformation and a wide variety of deformation forms, and can maintain the deformation without power consumption, which greatly expands the deformation forms of existing liquid-gas phase change flexible actuation limited by the existing deformation forms and has great application prospects.

[0067] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A deformable phase-change flexible mechanical metamaterial, characterized in that: It includes multiple lattice units mainly composed of a series of basic driving units (1) arranged in a set pattern and a first configuration connector (2) or a second configuration connector (3). The basic driving unit (1) is bonded and fixed to the first configuration connector (2) or the second configuration connector (3). The first configuration connector (2) is an L-shaped structure and the second configuration connector (3) is a plate-shaped structure. The basic driving unit (1) has a fixed side and a deformable side. The fixed side is bonded and fixed to the first configuration connector (2) or the second configuration connector (3), and the deformable side is used to generate deformation.

2. The deformable phase change flexible mechanical metamaterial according to claim 1, characterized in that: Phase change flexible mechanical metamaterials are classified into two configurations: in-plane deformation configuration and out-of-plane deformation configuration; The in-plane deformable phase change flexible mechanical metamaterial includes a basic driving unit (1) and a first configuration connector (2). The out-of-plane deformable phase change flexible mechanical metamaterial includes a basic drive unit (1) and a second configuration connector (3).

3. The deformable phase change flexible mechanical metamaterial according to claim 2, characterized in that: The in-plane deformable phase change flexible mechanical metamaterial is mainly composed of multiple closely arrayed in-plane lattice units. Each in-plane lattice unit includes four basic driving units (1) and four first configuration connectors (2). The four basic driving units (1) and four first configuration connectors (2) are arranged alternately in a square ring along the circumference. The fixed ends of each basic driving unit (1) are connected to one first configuration connector (2). The four basic driving units (1) are located at the four sides of the in-plane lattice unit. The configuration connectors (2) are located at the four corners of the in-plane lattice unit. The two basic driving units (1) of one pair of opposite sides of the in-plane lattice unit are arranged with their deformation sides facing the center of the plane of the in-plane lattice unit, and the two basic driving units (1) of the other pair of opposite sides are arranged with their fixed sides facing the center of the plane of the in-plane lattice unit. For two adjacent in-plane lattice units, the basic driving units (1) of one in-plane lattice unit on the side along the direction of the array arrangement are always arranged in opposite directions to the basic driving units (1) of the other in-plane lattice unit on the side along the same direction of the array arrangement.

4. The deformable phase change flexible mechanical metamaterial according to claim 2, characterized in that: The phase change flexible mechanical metamaterial with out-of-plane deformation configuration is mainly composed of multiple closely connected out-of-plane lattice units. Each out-of-plane lattice unit includes six basic driving units (1) and a second configuration connector (3) with a plate-like structure. The fixed sides of the six basic drive units (1) are all fixedly connected to the second configuration connector (3); the six basic drive units (1) are divided into two groups of strip-shaped basic drive unit groups, and the two groups of basic drive unit groups are respectively arranged on the two sides of the second configuration connector (3), and the strip-shaped directions of the two groups of basic drive unit groups are perpendicular to each other. Each group of basic drive units mainly consists of three strip-shaped basic drive units (1). The three basic drive units (1) are arranged in parallel and spaced apart on the surface of the second configuration connector (3). The three basic drive units (1) and the surface of the second configuration connector (3) have the same length along the strip direction of the basic drive unit (1) and are flush with each other. One of the basic drive units (1) is located in the middle of the surface of the second configuration connector (3), and the other two basic drive units (1) are located at the edge of the surface of the second configuration connector (3) and are aligned with their own sides and edges. For two adjacent out-of-plane lattice units, the basic driving unit (1) of one out-of-plane lattice unit on the side where it is located along the direction of the array arrangement is arranged perpendicularly to the basic driving unit (1) of the other out-of-plane lattice unit on the side where it is located along the same direction of the array arrangement.

5. The deformable phase change flexible mechanical metamaterial according to claim 2, characterized in that: In the case of an initially undeformed metamaterial, the two configurations are determined as follows: When the normal of the plane of each layer of the basic driving unit (1) is perpendicular to the normal direction of the overall plane of the metamaterial, the metamaterial is an in-plane deformation configuration; When the normal of the plane of each layer of the basic driving unit (1) is parallel to the normal direction of the overall plane of the metamaterial, the metamaterial is an out-of-plane deformation configuration.

6. The deformable phase change flexible mechanical metamaterial according to claim 1, characterized in that: The basic driving unit (1) includes a driving layer (11), a heat insulation layer (12), and a variable stiffness layer (13), all of which are strip-shaped and arranged in close succession. Each pair of adjacent layers in the driving layer (11), the heat insulation layer (12), and the variable stiffness layer (13) are connected and fixed. Both the driving layer (11) and the variable stiffness layer (13) are equipped with electrically heated components. The driving layer (11) is driven to deform by the electrically heated components, and the variable stiffness layer (13) adjusts the stiffness of the driving layer (11) at different positions by the electrically heated components. The driving layer (11) and the variable stiffness layer (13) work together to realize the deformation and adjustment of the basic driving unit (1) in any shape. The basic drive unit (1) has a fixed side and a deformable side. The side where the drive layer (11) of the basic drive unit is located is the deformable side of the basic drive unit (1), and the side where the variable stiffness layer (13) of the basic drive unit (1) is located is the fixed side. The driving layer (11) mainly consists of a first driving layer shell (111), a liquid-gas phase change working medium (112), a driving heating wire (113), a second driving layer shell (114), and a sheet-like fabric restraint layer (115), all arranged in close succession and in strip shape. The second driving layer shell (114) is bonded to the fabric restraint layer (115), and the first driving layer shell (111) is arranged on top of the second driving layer shell (114). A relatively closed strip-shaped driving cavity is formed between the first driving layer shell (111) and the second driving layer shell (114). The driving heating wire (113) is disposed in the strip-shaped driving cavity and filled with the liquid-gas phase change working medium (112). The first driving layer shell (111) is configured as a toothed shell structure. The driving heating wire (113) extends and is arranged inside the strip-shaped driving shell and bends through each tooth of the toothed shell structure. The liquid-gas phase change working medium (112) fills the space inside the strip-shaped driving cavity except for the driving heating wire (113). The upper surface of the second driving layer shell (114) is provided with a strip-shaped groove parallel to its own strip direction. The first driving layer shell (111) has hollow hole structures at both ends. The driving heating wire (113) passes through the hole structures at both ends of the first driving layer shell (111) and is connected to an external power source, and is used to heat the liquid-gas phase change working medium (112).

7. The deformable phase change flexible mechanical metamaterial according to claim 6, characterized in that: The variable stiffness layer (13) includes a first variable stiffness layer shell (131) that is strip-shaped, a stiffness-regulating heating wire (132), a solid-liquid phase change working fluid (133), and a second variable stiffness layer shell (134). The top surface of the second variable stiffness layer shell (134) has a strip-shaped groove along the strip-shaped direction of the variable stiffness layer (13). The first variable stiffness layer shell (131) is connected to the groove opening of the second variable stiffness layer shell (134). The first driving layer shell (111) and the second driving layer shell (114) are also mentioned. The interior forms a relatively closed strip-shaped variable stiffness cavity. The first driving layer shell (111) and the second driving layer shell (114) outside the strip-shaped variable stiffness cavity are each internally fitted with a stiffness-regulating heating wire (132). The strip-shaped variable stiffness cavity is filled with a solid-liquid phase change working fluid (133). The stiffness-regulating heating wire (132) consists of multiple annular heating wires arranged at equal intervals along the strip-shaped direction of the variable stiffness layer (13) and are independent of each other. Each annular heating wire is arranged circumferentially around the outer periphery of the strip-shaped variable stiffness cavity. Each stiffness-regulating heating wire... Each of the stiffness-regulating heating wires (132) is used to independently control the temperature of the solid-liquid phase change working medium (133), and each of the stiffness-regulating heating wires (132) passes through the outer shell of the variable stiffness layer (13) and is connected to an external power source. By energizing and heating a stiffness-regulating heating wire (132) at a certain position, a local solid-liquid phase change occurs in the solid-liquid phase change working medium (133) at that stiffness-regulating heating wire (132), thereby softening the position of that stiffness-regulating heating wire (132) in the variable stiffness layer (13), which is used to regulate the temperature of the solid-liquid phase change working medium (133). When the driving layer (11) deforms, the deformation stiffness of the basic driving unit (1) at each strip direction position; after the driving heating wire (113) is energized and heated, it drives the liquid-gas phase change working medium (112) in the strip driving cavity to undergo liquid-gas phase change for driving, thereby driving the overall deformation of the basic driving unit (1); the variable stiffness layer (13) uses the local solid-liquid phase change of the solid-liquid phase change working medium (133) to control the stiffness at each position in the strip direction, thereby regulating the deformation stiffness of the basic driving unit (1).

8. The deformable phase change flexible mechanical metamaterial according to claim 6, characterized in that: The upper surface of the heat insulation layer (12) is provided with a column group on each side along its strip direction. Each column group includes multiple columns. The columns in each column group are symmetrically distributed and extend along its strip direction at equal intervals to form a column array structure. The heat insulation layer (12) is used to reduce thermal interference between the driving layer (11) and the variable stiffness layer (13).

9. A method for controlling the deformation of a phase change flexible mechanical metamaterial according to any one of claims 6-8, characterized in that: The phase change flexible mechanical metamaterial is deformed by the deformation of a basic driving unit (1), which achieves four different working modes: Deformation control mode: First, the variable stiffness layer (13) is heated by electricity to control the deformation stiffness of the basic driving unit (1) at various positions in the strip direction. Then, the driving layer (11) is heated by electricity to drive the overall deformation of the basic driving unit (1) so as to achieve any expected deformation state. Rapid deformation working mode: First, the driving layer (11) is energized and heated to regulate the basic driving unit (1) to store energy. Then, the variable stiffness layer (13) is energized and heated to regulate the deformation stiffness of the basic driving unit (1) at various positions in the strip direction. The driving layer (11) rapidly deforms in the area softened by the energized and heated variable stiffness layer (13), so that the basic driving unit (1) rapidly deforms in the area softened by the energized and heated variable stiffness layer (13), and the basic driving unit (1) achieves rapid deformation working mode. Shape locking working mode: For the basic drive unit (1) in the deformed state, first cool the temperature of the variable stiffness layer (13) to solidify the variable stiffness layer (13), and then cool and liquefy the drive layer (11) to lock the shape protection of the basic drive unit (1), thereby realizing the shape locking working mode. Restoring the initial working mode: For the basic drive unit (1) in the deformed state, first cool the drive layer (11) to liquefy and restore the initial shape, then cool the temperature of the variable stiffness layer (13) to solidify the variable stiffness layer (13), thereby realizing the restoration of the initial working mode.

10. The method for controllable deformation of phase change flexible mechanical metamaterials according to claim 9, characterized in that: More specifically, the deformation control working mode is as follows: by heating the stiffness control heating wire (132) of the variable stiffness layer (13) at a certain position, the solid-liquid phase change working medium (133) at the position of the stiffness control heating wire (132) is further controlled to undergo solid-liquid phase change, and then the driving heating wire (113) is heated to control the liquid-gas phase change working medium (112) of the driving layer (11) to undergo liquid-gas phase change as a whole, so that the basic driving unit (1) is deformed as a whole, and the basic driving unit (1) realizes the deformation control working mode. More specifically, the rapid deformation working mode is as follows: by heating the driving heating wire (113) of the driving layer (11) to control the liquid-gas phase change working medium (112) to undergo liquid-gas phase change, thereby regulating the driving layer (11) to make the basic driving unit (1) store energy, and then heating the stiffness regulating heating wire (132) at a certain position to further control the solid-liquid phase change working medium (133) at the position of the stiffness regulating heating wire (132) to undergo solid-liquid phase change, so that the variable stiffness layer (13) softens at this position, and the driving layer (11) rapidly deforms in the area softened by the electric heating of the variable stiffness layer (13), so that the basic driving unit (1) rapidly deforms in the area softened by the electric heating of the variable stiffness layer (13), and the basic driving unit (1) realizes the rapid deformation working mode. More specifically, the shape locking working mode is as follows: for the basic drive unit (1) in the deformed state, while maintaining the liquid-gas phase change working medium (112) of the drive layer (11) in the vaporization drive state, the solid-liquid phase change working medium (133) of the variable stiffness layer (13) is cooled and solidified, and then the liquid-gas phase change working medium (112) of the drive layer (11) is cooled and liquefied, so that the shape locking of the drive layer (11) causes the shape protection locking of the basic drive unit (1), thereby realizing the shape locking working mode; More specifically, the restoration of the initial working mode is as follows: for the basic drive unit (1) in the deformed state, while maintaining the solid-liquid phase change working medium (133) of the variable stiffness layer (13) in the liquefied drive state, the liquid-gas phase change working medium (112) of the drive layer (11) is cooled and liquefied, so that the drive layer (11) restores its initial shape. Then, the solid-liquid phase change working medium (133) of the variable stiffness layer (13) is cooled and the solid-liquid phase change working medium (133) is solidified, thereby realizing the restoration of the initial working mode.

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