A composite combination shell structure embedded with reticulated NiTi shape memory alloy wires and a preparation method thereof

Abstract

The application discloses a composite material combined shell structure embedded with net-shaped NiTi shape memory alloy wires, relates to the technical field of aviation composite material structures, and comprises a first layer shell part and a second layer shell part which are symmetrically arranged, and horizontal clamping molds and vertical clamping molds, wherein a net-shaped alloy wire surface is arranged between the first layer shell part and the second layer shell part; the net-shaped alloy wire surface is formed by orthogonal weaving of circumferentially arranged horizontal NiTi shape memory alloy wires and radially arranged vertical NiTi shape memory alloy wires; the first layer shell part and the second layer shell part adopt a symmetric layering angle design and form an integral laminated structure with the net-shaped alloy wire surface through hot pressing and curing; the horizontal NiTi shape memory alloy wires are circumferentially positioned through the horizontal clamping molds, and the vertical NiTi shape memory alloy wires are radially positioned through the vertical clamping molds; the first / second shell part adopts a layering design which is symmetric about the net-shaped layer and effectively balances thermal-mechanical stress in the curing process in combination with the neutral layer wire embedding layout.

Description

Technical Field

[0001] This invention relates to the field of aerospace composite material structure technology, specifically to a composite material composite shell structure embedded with mesh-like NiTi shape memory alloy wires and its preparation method. Background Technology

[0002] With the widespread application of composite materials in aerospace equipment, vibration control of composite shell structures under dynamic loads has become a key challenge. Taking the fairing of a new energy aircraft as an example, its streamlined curved surface structure is prone to broadband vibration under aerodynamic excitation. Traditional solutions often fall into a dilemma: adding a constraint damping layer can improve the vibration reduction effect, but it significantly increases the structural weight and destroys the aerodynamic shape; pre-embedded discrete reinforcing fibers can improve stiffness, but it is difficult to achieve directional dissipation of vibration energy.

[0003] In existing technologies, shape memory alloy reinforcement schemes mostly employ linear arrangement or partial wire embedding designs, which reveal significant defects during curved surface forming: First, rigid wires are difficult to fit complex curved surfaces, leading to geometric mismatch between the reinforcing unit and the matrix structure; second, asymmetric layup causes interfacial stress concentration during the curing process, weakening the structural integrity of the composite material. More importantly, traditional wire embedding processes rely on manual positioning, which easily leads to wire mesh misalignment during curved shell forming, severely affecting vibration suppression effectiveness.

[0004] To address the aforementioned issues, this invention proposes an innovative solution based on a braided mesh alloy wire layout. By using a conformal mold system to achieve precise positioning of the alloy wire mesh and the curved shell, and combining it with a symmetrical layup design to reduce residual stress, this invention significantly improves the vibration resistance and process reliability of the composite material structure while ensuring lightweight characteristics. This effectively overcomes the challenge of synergistic optimization of vibration suppression and structural strengthening of the curved shell. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a composite shell structure with embedded mesh NiTi shape memory alloy wires and its preparation method. This solves the problems in existing technologies, such as the difficulty of rigid wires fitting complex curved surfaces, leading to geometric mismatch between reinforcing units and matrix structures, and the stress concentration at the interface during curing caused by asymmetric layup, which weakens the structural integrity of the composite material. It also addresses the issues of traditional wire embedding processes relying on manual positioning, which can easily cause wire mesh displacement during the forming of curved shells, severely affecting vibration suppression performance.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: a composite material combined shell structure embedded with mesh NiTi shape memory alloy wire, comprising: a first shell part and a second shell part symmetrically arranged, a horizontal clamping mold and a vertical clamping mold, wherein a mesh alloy wire surface is provided between the first shell part and the second shell part;

[0007] The mesh alloy wire surface is formed by orthogonally weaving together circumferentially arranged horizontal NiTi shape memory alloy wires and radially arranged vertical NiTi shape memory alloy wires;

[0008] The first and second shell layers adopt a symmetrical layup angle design and form an integral laminated structure with the mesh alloy wire surface through hot pressing and curing.

[0009] The horizontal NiTi shape memory alloy wire is circumferentially positioned by a horizontal clamping mold, and the vertical NiTi shape memory alloy wire is radially positioned by a vertical clamping mold.

[0010] Preferably, the circumferential spacing of the horizontal NiTi shape memory alloy wires is 20-30 mm, the radial angle of the vertical NiTi shape memory alloy wires is 30°, the diameter of the horizontal and vertical NiTi shape memory alloy wires is 0.1-0.4 mm, and the nickel-titanium mass ratio is 60:40.

[0011] Preferably, both the first and second shell layers contain 1-5 layers of fiber composite prepreg with layup angles selected from a combination of 0°, 90°, or ±45°, and the layup sequence of the first and second shell layers is symmetrical about the mesh alloy wires.

[0012] Preferably, the horizontal clamping mold includes: a fixing strip and a top strip that fit together with a concave-convex shape, wherein the contact surfaces of the fixing strip and the top strip are provided with mutually cooperating U-shaped semi-cylindrical channels; the vertical clamping mold is an annular concave-convex module composed of: a vertical upper fixing ring and a vertical upper fixing block, and a vertical lower fixing ring and a vertical lower fixing block, wherein the inner surface of the annular concave-convex module is provided with a V-shaped positioning channel.

[0013] The method for preparing a composite shell structure includes the following steps:

[0014] Step 1: Lay the first layer of shell prepreg on the molding die;

[0015] Step 2: Fix the mesh alloy wire surface with an embedded wire clamping mold, and achieve pre-positioning by epoxy resin bonding;

[0016] Step 3: Symmetrically lay the second layer of shell prepreg on the surface of the mesh alloy wire, and apply a pre-pressure of 100-200N to form a preform;

[0017] Step 4: Insert the conical cylinder mold and cure it in an autoclave at 4-5 atm and 100-150℃ for 4-6 hours;

[0018] Step 5: After demolding, a vibration-resistant composite shell with a mesh-like NiTi shape memory alloy wire inlay structure is obtained.

[0019] Preferably, in step 2, the epoxy resin and curing agent are mixed at a mass ratio of 3.3:1, and after curing at room temperature for 4-6 hours, excess alloy wire is cut off; the combined mold is a conical shell-cylindrical shell-conical shell type combined structure, with a conical groove inside.

[0020] Preferably, the upper diameter of the conical cylindrical mold is 96mm, the lower diameter is 80mm, and the height is 230mm; the pre-pressure application time is not less than 30 minutes.

[0021] Preferably, the fiber composite prepreg adopts a T700 grade carbon fiber / epoxy resin system, with a single layer thickness of 0.1 mm and an angle difference between adjacent layers ≥ 45°.

[0022] Preferably, before the high temperature and high pressure curing in step 4, the preform is subjected to a gradient temperature increase treatment: the temperature is increased to 80°C at a rate of 2°C / min and held for 30 minutes, and then increased to 120°C at a rate of 1.5°C / min to start curing. The gradient temperature increase treatment process is combined with a synchronous pressure increase operation of 0.5 atm / min.

[0023] This invention provides a composite shell structure with embedded mesh-like NiTi shape memory alloy wires and its preparation method, which has the following beneficial effects:

[0024] In the field of aerospace composite material structure technology, a special mold system composed of U-shaped semi-cylindrical channels and V-shaped positioning channels is used to achieve orthogonal positioning of circumferential and radial alloy wires, completely solving the offset problem of traditional wire embedding process.

[0025] In the field of aerospace composite material structure technology, symmetrical layup stress control is achieved by adopting a symmetrical layup design about the mesh layer for the first / second shell, combined with a neutral layer embedded wire layout, which effectively balances the thermo-mechanical stress during the curing process.

[0026] In the field of aerospace composite material structure technology, orthogonally braided NiTi alloy wires form a continuous reinforcing network, and the vibration resistance is improved through the synergistic effect of the superelastic phase transformation of the alloy wires and the matrix.

[0027] In the field of aerospace composite material structure technology, lightweight thin-walled structure design is achieved by combining ultra-thin prepreg (T700 carbon fiber / epoxy resin system, single layer 0.1mm) with fine-diameter alloy wire (0.1-0.4mm) to maintain the lightweight characteristics of aerospace components.

[0028] In the field of aerospace composite material structure technology, gradient curing process control involves staged heating (2℃ / min) and simultaneous pressurization (0.5atm / min) to ensure the coordination between resin flow and alloy wire displacement.

[0029] Modular mold adaptability in the field of aerospace composite material structure technology: Conical shell-cylindrical shell-conical shell combined mold structure with detachable clamping components, adaptable to complex curved surface components such as fairings.

[0030] In the field of aerospace composite material structure technology, the fatigue resistance of the material system is demonstrated by a shape memory alloy wire with a nickel-titanium ratio of 60:40 combined with a symmetrical layup design. The structural integrity has been verified through cyclic load testing. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the mold for preparing the composite shell structure of the present invention, which is embedded with mesh NiTi shape memory alloy wire.

[0032] Figure 2 This is a schematic diagram of the composite shell structure with embedded mesh NiTi alloy wires before curing, as per the present invention.

[0033] Figure 3 This is a schematic diagram of the design of the combined shell mesh embedding process and the wire clamping mold of the present invention.

[0034] Figure 4 This is a partial schematic diagram showing the vertical clamping of the upper mold and the fixing relationship of the insert wire.

[0035] Figure 5 This is a partial schematic diagram showing the vertical clamping of the lower mold and the fixing relationship of the insert wire.

[0036] Figure 6 This is a partial schematic diagram of the horizontal clamping mold and the wire fixing relationship.

[0037] In the diagram: 101: Horizontal clamping mold, 102: Vertical clamping mold, 201: Horizontal NiTi shape memory alloy wire, 202: Vertical NiTi shape memory alloy wire, 203: First shell layer, 204: Second shell layer, 301: Fixing strip, 302: Top strip, 303: Vertical upper fixing ring, 304: Vertical upper fixing block, 305: Vertical lower fixing ring, 306: Vertical lower fixing block. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Please see Figure 1-6 The present invention provides a technical solution: a composite material combined shell structure embedded with mesh NiTi shape memory alloy wire, comprising: a first shell part 203 and a second shell part 204 symmetrically arranged, a horizontal clamping mold 101 and a vertical clamping mold 102, wherein a mesh alloy wire surface is provided between the first shell part 203 and the second shell part 204.

[0040] The mesh alloy wire surface is formed by orthogonally weaving together circumferentially arranged horizontal NiTi shape memory alloy wires 201 and radially arranged vertical NiTi shape memory alloy wires 202;

[0041] The first shell 203 and the second shell 204 adopt a symmetrical layup angle design and form an integral laminated structure with the mesh alloy wire surface through hot pressing and curing.

[0042] The horizontal NiTi shape memory alloy wire 201 is circumferentially positioned by the horizontal clamping mold 101, and the vertical NiTi shape memory alloy wire 202 is radially positioned by the vertical clamping mold 102.

[0043] Furthermore, the circumferential spacing of the horizontal NiTi shape memory alloy wire 201 is 20-30 mm, the radial angle of the vertical NiTi shape memory alloy wire 202 is 30°, the diameter of the horizontal NiTi shape memory alloy wire 201 and the vertical NiTi shape memory alloy wire 202 is 0.1-0.4 mm, and the nickel-titanium mass ratio is 60:40.

[0044] Furthermore, both the first shell portion 203 and the second shell portion 204 contain 1-5 layers of fiber composite prepreg with layup angles selected from a combination of 0°, 90° or ±45°, and the layup sequence of the first shell portion 203 and the second shell portion 204 is symmetrical about the mesh alloy wire face.

[0045] Furthermore, the horizontal clamping mold 101 includes: a fixing strip 301 and a top strip 302 that fit together with a concave-convex shape, and the contact surfaces of the fixing strip 301 and the top strip 302 are provided with mutually cooperating U-shaped semi-cylindrical channels; the vertical clamping mold 102 is an annular concave-convex module composed of: a vertical upper fixing ring 303 and a vertical upper fixing block 304, and a vertical lower fixing ring 305 and a vertical lower fixing block 306, and the inner surface of the annular concave-convex module is provided with a V-shaped positioning channel.

[0046] The method for preparing a composite shell structure includes the following steps:

[0047] Step 1: Lay the first layer of shell prepreg on the molding die;

[0048] Step 2: Fix the mesh alloy wire surface with an embedded wire clamping mold, and achieve pre-positioning by epoxy resin bonding;

[0049] Step 3: Symmetrically lay the second layer of shell prepreg on the surface of the mesh alloy wire, and apply a pre-pressure of 100-200N to form a preform;

[0050] Step 4: Insert the conical cylinder mold and cure it in an autoclave at 4-5 atm and 100-150℃ for 4-6 hours;

[0051] Step 5: After demolding, a vibration-resistant composite shell with a mesh-like NiTi shape memory alloy wire inlay structure is obtained;

[0052] Horizontal wire embedding processing flow:

[0053] First, the horizontal clamping and fixing strip 301 is tightly attached to the first shell portion 203; then, the horizontal NiTi shape memory alloy wire 201 is passed through the horizontal clamping and fixing strip 301 and placed in the semi-cylindrical groove on one side of the first shell portion 203; then, a NiTi shape memory alloy wire ring is formed around the first shell portion 203 by the molding die; next, the two ends of the horizontal NiTi shape memory alloy wire ring are placed in the semi-cylindrical groove on the other side of the horizontal clamping and fixing strip 301, and this process is repeated to wind the NiTi shape memory alloy wire ring according to the set number and position; finally, the U-shaped semi-cylindrical protrusion on the horizontal clamping top strip 302 is aligned with the semi-cylindrical groove on the fixing strip and fastened by bolts. In this way, the horizontal NiTi wire embedding process is completed.

[0054] Vertical wire embedding processing flow:

[0055] The vertical lower fixing ring 305 is slid to the bottom along the conical groove in the molding die, fitting against the inner side of the die. One end of the vertical NiTi shape memory alloy wire 202 is then placed into the V-shaped groove inside the vertical lower fixing ring 305. The V-shaped protrusion in the vertical lower fixing block 306 is aligned with the V-shaped groove, tightening one end of the vertical NiTi shape memory alloy wire 202. The vertical lower fixing block 306 is then fixed to the vertical lower fixing ring 305 with bolts, clamping the lower end of the vertical NiTi shape memory alloy wire 202. The vertical upper fixing ring 303 is then... The conical groove in the molding die slides in, but because of its large diameter, it can only slide to the top of the conical groove before getting stuck. The vertical NiTi shape memory alloy wire 202 is placed in the V-shaped groove inside the vertical upper fixing ring 303. The NiTi wire is pulled tight, and the V-shaped protrusion in the vertical upper fixing block 304 fits against the V-shaped groove, pressing one end of the vertical NiTi shape memory alloy wire 202. Then, the vertical upper fixing block 304 is fixed to the vertical upper fixing ring 303 by bolts, thus clamping the upper end of the vertical NiTi shape memory alloy wire 202.

[0056] Thus, the process of vertically embedding NiTi shape memory alloy wire is completed;

[0057] To further verify the vibration reduction effect of the composite shell structure with embedded mesh NiTi shape memory alloy wires prepared by the design scheme, the vibration resistance of the transverse embedding scheme with 13 transverse wires and the longitudinal embedding scheme with 12 longitudinal wires were further tested. This design scheme provides a theoretical analysis method for vibration suppression scheme based on NiTi shape memory alloy wires, and provides a theoretical research approach for the design of embedded wire layout for reinforced structures.

[0058] Based on Donnell's thin-shell assumption, the strain and curvature of the neutral surface of the composite shell structure can be derived as follows:

[0059]

[0060] in, , , , represents the strain of the shell structure; , , , where is the curvature of the shell structure, and z is the displacement along the z-axis.

[0061] The stiffness matrix S of the composite shell is further expressed as:

[0062]

[0063] Wherein, the ABD term is the classical ABD stiffness term in composite material mechanics, the T matrix is ​​a matrix related to the layup angle, β is the layup angle of the modified layer, and Q is the stiffness matrix of the stress-strain relationship of the composite material. The above formulas can be used to solve for the structural kinetic energy T and structural potential energy U of the composite shell. Using Hamilton's principle, the dynamic equations of the reinforced composite shell with embedded mesh NiTi shape memory alloy wires are established:

[0064]

[0065] in, For variational notation, It is the virtual work done by external forces on the laminated shell structure. It is the virtual work of the damping vibration provided by the enhanced vibration damping part composed of mesh NiTi shape memory alloy wires.

[0066] Virtual Work and writing:

[0067]

[0068] in, A function representing the location of force application; preferably, the Dirac function is used. This represents the nonlinear restoring force of the NiTi shape memory alloy wire; here, the harmonic force acting on the cylindrical shell is set as... ,in and These are the amplitude and frequency of the harmonic excitation, respectively. It is the correction factor for NiTi shape memory alloy wire; where, and These are the linear stiffness coefficient and the damping coefficient, respectively; It is a nonlinear stiffness coefficient; and is the coupling damping coefficient. Table 1 lists the stiffness and damping parameters of the NiTi polynomial fit.

[0069] Table 1 Material parameters of NiTi shape memory alloy wire

[0070] Parameter 1 170.2 <![CDATA[7.60×10 5 ]]> 8.04 <![CDATA[6.83×10 4 ]]> -1170 0.5 Parameter 2 513.2 <![CDATA[2.29×10 5 ]]> 17.83 <![CDATA[7.29×10 4 ]]> -15294 0.5

[0071] Furthermore, in step 2, the epoxy resin and curing agent are mixed at a mass ratio of 3.3:1, cured at room temperature for 4-6 hours, and the excess alloy wire is cut off; the combined mold is a conical shell-cylindrical shell-conical shell type combined structure, with a conical groove inside.

[0072] Furthermore, the upper diameter of the conical cylindrical mold is 96mm, the lower diameter is 80mm, and the height is 230mm; the pre-pressure application time is not less than 30 minutes.

[0073] Furthermore, the fiber composite prepreg adopts a T700 grade carbon fiber / epoxy resin system, with a single layer thickness of 0.1 mm and an angle difference between adjacent layups ≥ 45°;

[0074] T700 carbon fiber composite material, model T700-12K, with a resin content of 36%, was selected.

[0075] Furthermore, before the high temperature and high pressure curing in step 4, the preform is subjected to a gradient temperature increase treatment: the temperature is increased to 80°C at a rate of 2°C / min and held for 30 minutes, and then increased to 120°C at a rate of 1.5°C / min to start curing. The gradient temperature increase treatment process is combined with a synchronous pressure increase operation of 0.5 atm / min.

[0076] The vertical upper fixing ring has an outer frustum-shaped profile, slightly smaller than the upper end of the molded conical cylinder. Its upper diameter is 94mm, lower diameter is 93mm, and height is 15.4mm. During installation, it slides down into the molded composite shell mold. Its inner side is a concave mold with a semi-cylindrical hollow section. Three threaded holes are opened on the inner side of the ring, with an angle of 120° between each hole.

[0077] Vertical upper fixing block: It has a U-shaped semi-cylindrical protrusion, which is a punch that cooperates with the upper clamping fixing ring to clamp the vertically embedded NiTi shape memory alloy wire. The upper clamping fixing block and the fixing ring are connected by threads.

[0078] The vertical lower fixing ring has an outer frustum-shaped profile, slightly larger than the lower end of the molded conical cylinder. It has an upper diameter of 79mm, a lower diameter of 78mm, and a height of 15.4mm. During installation, it slides down into the molded composite shell mold. Furthermore, its inner side is a concave mold with a semi-cylindrical hollow section. The inner side of the ring has three threaded holes, each at a 120° angle to the next hole.

[0079] Vertical lower fixing block: It has a U-shaped semi-cylindrical protrusion, which is a punch that cooperates with the lower clamping fixing ring to clamp the vertically embedded NiTi shape memory alloy wire. The lower clamping fixing block and the fixing ring are connected by threads.

[0080] Those skilled in the art will be able to operate the technology in this case sequentially, and the specific operating sequence should refer to the following working principle. The detailed connection means are well-known in the art. The following mainly introduces the working principle and process.

[0081] Example:

[0082] The compression molding assembly mold includes a horizontal clamping mold 101 and a vertical clamping mold 102, which together form a compression molding assembly mold in the shape of a conical shell-cylindrical shell-conical shell. The compression molding assembly mold is placed on a horizontal platform, and carbon fiber prepreg is sequentially laid on the mold according to the layup design scheme of the composite material assembly shell to form the first shell layer 203.

[0083] In a specific implementation, the first shell 203 includes 5 layers of fiber composite material with a layup angle of [0° / 90° / 0° / 90° / 0°]. Similarly, the second shell 204 also includes 5 layers of fiber composite material with layup angles symmetrical about the central plane as the first shell.

[0084] In specific implementation, the fiber composite material layer described in this embodiment is made of unidirectional carbon fiber prepreg purchased from Shanghai Xin'ao Composite Materials Technology R&D Center, with specific specifications of T700-12K / 100g / resin 36% and a single layer thickness of 0.1mm.

[0085] In step 2, the mesh alloy wire surface includes embedded horizontal NiTi shape memory alloy wires 201 and embedded vertical NiTi shape memory alloy wires 202, and the mesh alloy wire surface is a woven shape.

[0086] The first direction of the mesh alloy wire surface is circumferential, that is, the horizontal embedding direction, and the second direction of the mesh alloy wire surface is radial, that is, the vertical embedding direction.

[0087] In specific implementation, this embodiment uses several NiTi shape memory alloy wires, including 13 in the horizontal direction and 12 in the vertical direction.

[0088] The mesh-embedded NiTi shape memory alloy wire solution requires the use of a wire-embedding clamping mold, which includes a horizontal clamping mold 101 and a vertical clamping mold 102.

[0089] The horizontal clamping mold 101 includes a horizontal clamping fixing strip 301 and a horizontal clamping top strip 302. The horizontal wire embedding process is as follows: First, the horizontal clamping fixing strip 301 is tightly attached to the first shell portion 203; then, the horizontal NiTi shape memory alloy wire 201 is passed through the horizontal clamping fixing strip 301 into the semi-cylindrical groove on one side of the first shell portion 203; then, a NiTi shape memory alloy wire ring is formed around the first shell portion 203 by the molding and forming assembly mold; next, the two ends of the horizontal NiTi shape memory alloy wire ring are placed in the semi-cylindrical groove on the other side of the horizontal clamping fixing strip 301, and this process is repeated to wind the NiTi shape memory alloy wire ring according to the set number and position; finally, the U-shaped semi-cylindrical protrusion on the horizontal clamping top strip 302 is aligned with the semi-cylindrical groove on the fixing strip and fastened by bolts. In this way, the horizontal NiTi wire embedding process is completed. The vertical clamping mold 102 includes a vertical upper clamping mold and a vertical lower clamping mold. The upper vertical clamping mold includes an upper vertical fixing ring 303 and an upper vertical fixing block 304. The lower vertical clamping mold includes a lower vertical fixing ring 305 and a lower vertical fixing block 306.

[0090] The vertical wire insertion process includes upper and lower clamping processes. The lower clamping must be performed first, as follows:

[0091] The first step is to slide the vertical lower fixing ring 305 down to the bottom along the conical groove in the molding die and fit it against the inner side of the die.

[0092] The second step is to insert one end of the vertical NiTi shape memory alloy wire 202 into the V-shaped groove inside the vertical lower fixing ring 305.

[0093] The third step is to fit the V-shaped protrusion in the vertical lower fixing block 306 with the V-shaped groove mentioned above, tighten one end of the vertical NiTi shape memory alloy wire 202, and then fix the vertical lower fixing block 306 to the vertical lower fixing ring 305 with bolts to achieve the clamping of the lower end of the vertical NiTi shape memory alloy wire 202.

[0094] The fourth step is to slide the vertical upper fixing ring 303 into the conical groove in the molding die. Because of its large diameter, it can only slide to the top of the conical groove and then get stuck.

[0095] Fifth step, place the vertical NiTi shape memory alloy wire 202 in the V-shaped groove inside the vertical upper fixing ring 303 and tighten the NiTi wire;

[0096] The sixth step is to fit the V-shaped protrusion in the vertical upper fixing block 304 with the V-shaped groove to tighten one end of the vertical NiTi shape memory alloy wire 202, and then fix the vertical upper fixing block 304 to the vertical upper fixing ring 303 with bolts to achieve the upper end clamping of the vertical NiTi shape memory alloy wire 202.

[0097] This completes the process of vertically embedding NiTi shape memory alloy wire.

[0098] In step 3, the alloy wire laying route is the location of the aforementioned mesh alloy wire. Then, an appropriate amount of epoxy resin curing agent is applied to the alloy wire and cured at room temperature.

[0099] The epoxy resin bonding process uses an epoxy resin to hardener in a mass ratio of 3.3:1, with a curing time of 4-6 hours at room temperature. Preferably, the epoxy resin hardener weighs 5-10g, the epoxy resin is bisphenol A type E51, and the hardener is polyetheramine D230.

[0100] (Purpose of adhesive bonding: Since the diameter of the NiTi shape memory alloy wires in the mesh alloy wire surface is between 0.1 and 0.4 mm, they are very prone to curling during the preparation of the composite shell structure. This results in the embedding position of the NiTi wires in the composite shell structure not matching the design, reducing the predicted vibration damping performance. Therefore, adhesive bonding is required first, and the position of the alloy wires is determined after room temperature curing before laying the second shell layer 204.)

[0101] In the preparation method, the mesh alloy wire surface is bonded to the first shell by using epoxy resin, so that the curved structure is basically maintained after the exposed NiTi shape memory alloy wire is cut. By applying a first pressure to the second shell, the alloy wire is embedded in the flexible first and second shells, which can also ensure that the cut NiTi shape memory alloy wire maintains the curved state.

[0102] In step 4, the number of layers and the layup angle of the second shell 204 have been explained above. The first pressure, through the combined action of the wire clamping mold provided by this invention and the first pressure, positions the alloy wire layer in the middle of the two composite shells and parallel to the composite shells. Since NiTi shape memory alloy wire and composite prepreg are two different materials with different densities, if the NiTi wire layer is not in the middle position (that is, the composite shell is not symmetrical along the alloy wire mesh), it will cause the center of gravity of the laminated shell to shift, affecting the dynamic stability of the structure. In addition, the NiTi wire layer cannot move with the laminated shell, resulting in a displacement difference between the NiTi wire and the composite structure. In severe cases, this may cause delamination of the laminated shell, affecting its service life.

[0103] In step 5, after high temperature and high pressure curing, the present invention can maintain the mechanical properties of the composite shell structure with embedded mesh NiTi shape memory alloy wires.

[0104] In order to better shape the composite shell structure with embedded NiTi shape memory alloy wire mesh, this embodiment further limits the pressure and temperature of the autoclave and the processing time. The high temperature and high pressure curing molding pressure is 4 atm, the temperature is 120°C, and the processing time is 5 hours.

[0105] The first pressure is an external force of 100N, and the duration of applying the first pressure to the second shell is 30 minutes.

[0106] As a possible implementation method, the pressure for high-temperature and high-pressure curing can also be 5 atm.

[0107] As a possible implementation method, the temperature of the high-temperature and high-pressure curing molding can be any value between 100-150°C.

[0108] As a possible implementation method, the processing time for the high-temperature and high-pressure curing molding can be any value between 4 and 6 hours.

[0109] As a possible implementation, the first pressure is an external force of 100-200N.

[0110] As a possible implementation, the duration for which the first pressure is applied to the second shell layer is >30 minutes.

[0111] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, the phrase "comprising an element defined as..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0112] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite shell structure with embedded mesh-like NiTi shape memory alloy wires, characterized in that, include: A first shell portion (203) and a second shell portion (204) are symmetrically arranged, along with a horizontal clamping mold (101) and a vertical clamping mold (102). A mesh alloy wire surface is provided between the first shell portion (203) and the second shell portion (204). The mesh alloy wire surface is formed by orthogonally weaving together circumferentially arranged horizontal NiTi shape memory alloy wires (201) and radially arranged vertical NiTi shape memory alloy wires (202); The first shell (203) and the second shell (204) adopt a symmetrical layup angle design and form an integral laminated structure with the mesh alloy wire surface through hot pressing and curing. The horizontal NiTi shape memory alloy wire (201) is circumferentially positioned by a horizontal clamping mold (101), and the vertical NiTi shape memory alloy wire (202) is radially positioned by a vertical clamping mold (102). The circumferential spacing of the horizontal NiTi shape memory alloy wire (201) is 20-30 mm, the radial angle of the vertical NiTi shape memory alloy wire (202) is 30°, the diameter of the horizontal NiTi shape memory alloy wire (201) and the vertical NiTi shape memory alloy wire (202) is 0.1-0.4 mm, and the nickel-titanium mass ratio is 60:

40. The first shell portion (203) and the second shell portion (204) each contain 1-5 layers of fiber composite prepreg and the layup angle is selected from a combination of 0°, 90° or ±45°. The layup sequence of the first shell portion (203) and the second shell portion (204) is symmetrical about the mesh alloy wire face. The horizontal clamping mold (101) includes: a fixing strip (301) and a top strip (302) that fit together with a concave-convex shape, wherein the contact surfaces of the fixing strip (301) and the top strip (302) are provided with mutually cooperating U-shaped semi-cylindrical channels; the vertical clamping mold (102) is an annular concave-convex module composed of: a vertical upper fixing ring (303) and a vertical upper fixing block (304), and a vertical lower fixing ring (305) and a vertical lower fixing block (306), wherein the inner surface of the annular concave-convex module is provided with a V-shaped positioning channel.

2. A method for preparing a composite shell structure with embedded mesh NiTi shape memory alloy wires, wherein the method is used to prepare the composite shell structure with embedded mesh NiTi shape memory alloy wires as described in claim 1, characterized in that, Includes the following steps: Step 1: Lay the first layer of shell prepreg on the molding die; Step 2: Fix the mesh alloy wire surface with an embedded wire clamping mold, and achieve pre-positioning by epoxy resin bonding; Step 3: Symmetrically lay the second layer of shell prepreg on the surface of the mesh alloy wire, and apply a pre-pressure of 100-200N to form a preform; Step 4: Insert the conical cylinder mold and cure it in an autoclave at 4-5 atm and 100-150℃ for 4-6 hours; Step 5: After demolding, a vibration-resistant composite shell with a mesh-like NiTi shape memory alloy wire inlay structure is obtained.

3. The method for preparing a composite shell structure with embedded mesh NiTi shape memory alloy wires according to claim 2, characterized in that, In step 2, epoxy resin and curing agent are mixed at a mass ratio of 3.3:1, cured at room temperature for 4-6 hours, and excess alloy wire is cut off; the combined mold is a conical shell-cylindrical shell-conical shell type combined structure, with a conical groove inside.

4. The method for preparing a composite shell structure with embedded mesh NiTi shape memory alloy wires according to claim 2, characterized in that, The upper diameter of the conical cylindrical mold is 96mm, the lower diameter is 80mm, and the height is 230mm; the pre-pressure application time is not less than 30 minutes.

5. The method for preparing a composite shell structure with embedded mesh NiTi shape memory alloy wires according to claim 2, characterized in that, The fiber composite prepreg adopts a T700 grade carbon fiber / epoxy resin system, with a single layer thickness of 0.1 mm and an angle difference between adjacent layers ≥ 45°.

6. The method for preparing a composite shell structure with embedded mesh NiTi shape memory alloy wires according to claim 2, characterized in that, Before the high temperature and high pressure curing in step 4, the preform is subjected to a gradient temperature increase treatment: the temperature is increased to 80°C at a rate of 2°C / min and held for 30 minutes, and then increased to 120°C at a rate of 1.5°C / min to start curing. The gradient temperature increase treatment process is combined with a synchronous pressure increase operation of 0.5 atm / min.

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