A heterochiral spliced variable-stiffness negative poisson's ratio metamaterial structure

Abstract

The application discloses a kind of heterochiral splicing variable stiffness negative Poisson's ratio metamaterial structures, belong to mechanical metamaterial technical field.The structure includes multiple right-handed chiral compression-torsion cells, multiple left-handed chiral compression-torsion cells and intermediate layer array connection system arranged between the two, and right-handed chiral compression-torsion cell and left-handed chiral compression-torsion cell are arranged in series along the axial direction.The application effectively offsets macroscopic torsion under axial load by longitudinal heterochiral splicing of reverse helical skeleton, realizes active adjustment to structural stiffness and negative Poisson's ratio characteristics by using internal integrated elastic cable pretension mechanism, and guarantees the cooperative deformation capability between multiple units based on intermediate layer array connection system.The structure eliminates the torsional instability of single chirality structure, overcomes the defects of traditional metamaterial mechanical performance solidification unadjustable, and is easy to modular array expansion, and can be mainly used in shock protection, variable aircraft and intelligent vibration isolation and other application scenarios.

Description

Technical Field

[0001] This invention relates to the field of mechanical metamaterials technology, and in particular to a heterochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure. Background Technology

[0002] Metamaterials are a new class of materials that achieve extraordinary mechanical properties through artificial structural design rather than relying on the material itself. Among them, dilatant metamaterials with negative Poisson ratio properties exhibit significant application potential in energy absorption, shear resistance, indentation resistance, and impact protection due to their unique deformation behavior of lateral expansion under tension and lateral contraction under compression. Among various negative Poisson ratio structures, chiral structures have attracted much attention due to their excellent deformation capacity and outstanding energy dissipation characteristics. Traditional chiral structures typically rely on the rotational and bending deformation of nodes or ligaments to achieve the dilatant effect, and are mostly composed of periodic arrangements of cells with a single chirality (fully left-handed or fully right-handed). However, such structures often exhibit significant macroscopic torsional deformation under axial loads. This strong tension-torsion or compression-torsion coupling effect often has adverse effects in practical engineering, easily leading to additional shear stress at the connection interface, causing structural instability or connection failure, thus making it difficult to effectively integrate with non-chiral structural components. Although some studies have attempted to use heterochiral stacking to counteract macroscopic torsion, maintaining the overall stability and isotropic response of the structure under large deformation conditions remains a current technical challenge.

[0003] Furthermore, most current negative Poisson's ratio metamaterials have their equivalent elastic modulus and Poisson's ratio fixed after manufacturing (e.g., through 3D printing or casting), making real-time adjustment impossible based on changes in external load conditions. However, applications such as aerospace variability vehicles, soft robots, or intelligent vibration isolation systems often require structures to switch between "flexible and deformable" and "rigid and load-bearing" operating modes, or to dynamically adjust their energy absorption characteristics based on the magnitude of impact energy. Existing variable stiffness technologies largely rely on smart materials (such as shape memory alloys, but their response speed is slow and temperature-limited) or fluid drive systems (requiring complex pumps and valves, resulting in large volumes), lacking a compact, fast-responding, and purely mechanical stiffness and Poisson's ratio adjustment scheme.

[0004] Meanwhile, existing chiral metamaterials are mostly fabricated as continuous monoliths, lacking modular assembly designs. When constructing large-area or complex curved surface protective structures, the rigid connections between units often restrict the free deformation of individual cells, leading to a weakening or even loss of the overall negative Poisson's ratio effect. Therefore, there is an urgent need for a heterochiral splicing variable stiffness negative Poisson's ratio metamaterial structure that can overcome the defects of single chiral torsion, possesses the ability to actively adjust stiffness and Poisson's ratio, and is easy to expand into modular arrays, in order to meet the urgent needs of modern engineering for high-performance intelligent structures. Summary of the Invention

[0005] To overcome the technical shortcomings of existing chiral metamaterial structures, such as macroscopic torsional coupling effects under axial loads, fixed and unadjustable mechanical properties (stiffness and Poisson's ratio) after molding, and limitations on unit deformation due to connection methods during array expansion, this invention provides a heterochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure. This structure effectively counteracts macroscopic torsion under axial loads through longitudinal heterochiral splicing of a reverse helical skeleton; it utilizes an internally integrated elastic cable pre-tensioning mechanism to actively adjust the structure's stiffness and negative Poisson's ratio; and based on a unique intermediate layer array connection system, it ensures the coordinated deformation capability among multiple units. Therefore, this invention meets the urgent needs for structural adaptability and modularity in scenarios such as impact protection, morphing aircraft, and intelligent vibration isolation.

[0006] It should be understood that, in this invention, all naming and definitions of terms involving components, orientations, etc., are used solely to describe this invention. Related terms may be equivalently replaced or directionally adjusted according to actual circumstances, and should not be construed as limiting the invention.

[0007] This invention proposes a heterochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure, which mainly comprises four sets of symmetrically arranged, axially connected right-handed and left-handed compression-torsion cells, and an intermediate layer array connection system between the two types of cells. The structure is fabricated using an integrated molding casting process, with embedded helical rigid rods arranged in a specific direction of rotation as a reinforcing skeleton. Specifically, the right-handed compression-torsion cells contain right-handed helical rigid rods arranged in a right-handed helix along the axial direction, and the left-handed compression-torsion cells contain left-handed helical rigid rods arranged in a left-handed helix along the axial direction. Specifically, the right-handed compression-torsion cells are located above, and the left-handed compression-torsion cells are located below. The two are tightly connected or integrally molded through an intermediate coupling connecting plate, together forming a basic structural unit that possesses both macroscopic zero torsional characteristics and a negative Poisson's ratio effect. The intermediate layer array connection system includes an intermediate coupling connection plate and an array interconnection hinge assembly. The upper and lower surfaces of the intermediate coupling connection plate have grooves for connecting cells, and the four corners of its sides have connecting slots for engaging with the array interconnection hinge assembly to achieve a detachable connection. Multiple basic structural units can be modularly spliced ​​together using the array interconnection hinge assembly to construct a large-area metamaterial array. The array interconnection hinge assembly is made of a flexible material, capable of accommodating the radial displacement generated by each unit during negative Poisson's ratio deformation, thus ensuring that the free deformation of individual cells is not hindered during array applications.

[0008] It should be noted that under axial load, the corresponding right-handed and left-handed compression-torsion cells tend to produce torsional deformations in opposite directions. At this time, the intermediate layer array connection system effectively restricts the relative rotation of the contact surfaces of the two types of cells, forcing the helical rigid rods inside the cells to move along a preset guide path, converting the obstructed torsional potential energy into radial expansion deformation. This "compression-torsion-tension" coupling mechanism causes the overall structure to produce significant lateral expansion under compression, thereby achieving a negative Poisson's ratio effect and eliminating the macroscopic torsional instability inherent in traditional single-chiral structures. Specifically, when a single right-handed compression-torsion cell is subjected to axial pressure, due to the guiding effect of its internal right-handed helical rigid rods, the structure undergoes clockwise torsion while undergoing compressive deformation. Similarly, when a single left-handed compression-torsion cell is subjected to axial pressure, the structure undergoes counterclockwise torsion while undergoing compressive deformation. It is important to note that, because the intermediate coupling plate effectively restricts the relative rotation between the contact surfaces of the two types of cells, when the overall structure is subjected to axial compression, the clockwise torsional tendency of the right-handed compressive-torsional cells cancels out the counterclockwise torsional tendency of the left-handed compressive-torsional cells. This hindered torsional deformation forces the internal right-handed and left-handed helical rigid rods to press outward against the flexible matrix, thus transforming into significant radial expansion deformation. In other words, the structure shortens axially while its lateral dimension increases, exhibiting a typical negative Poisson's ratio effect.

[0009] The right-handed compression-torsion unit includes a right-handed upper connecting plate, a right-handed bottom connecting plate, a right-handed top bearing end cap, three right-handed helical rigid rods, a right-handed variable stiffness adjustment and limiting assembly, and a right-handed elastic unit group. The right-handed helical rigid rods are arranged in a right-handed helix along the axial direction and are connected between the right-handed upper connecting plate and the right-handed bottom connecting plate.

[0010] It should be noted that the right-handed compression-torsion cell is filled with a right-handed elastic unit group. The right-handed elastic unit group is made of a flexible matrix material using an integrated casting process, and encapsulates a right-handed helical rigid rod. Specifically, the right-handed elastic unit group includes three right-handed elastic cables, a right-handed embedded rigid reinforcement, a right-handed embedded anchoring end, and a right-handed rigid-flexible coupling node. One end of the right-handed elastic cable is fixed inside the right-handed elastic unit group via the right-handed embedded anchoring end, and the other end passes upward through the right-handed top bearing end cap. A right-handed variable stiffness adjustment and limiting component is provided along the axial direction of the right-handed elastic cable. A right-handed stiffness adjustment knob is located above the right-handed top bearing end cap. By operating the right-handed stiffness adjustment knob or directly pulling the right-handed elastic cable, the tension state of the elastic cable can be changed, causing the right-handed variable stiffness adjustment and limiting component to engage with a pre-set locking structure on the end cap surface, thereby applying an axial preload to the cell. In addition, to enhance structural durability, right-handed embedded rigid reinforcements and right-handed rigid-flexible coupling nodes are also provided inside the flexible matrix to strengthen the interface bonding between the elastic cable, rigid frame and flexible matrix, and prevent delamination during large deformation.

[0011] The left-handed compression-torsion cell includes a left-handed upper connecting plate, a left-handed bottom connecting plate, a left-handed top bearing end cap, three left-handed helical rigid rods, a left-handed stiffness adjustment knob, a left-handed variable stiffness adjustment limiting assembly, and a left-handed elastic unit group. The structural composition of the left-handed compression-torsion cell is similar to that of the right-handed compression-torsion cell, but the chirality is reversed. Specifically, the left-handed helical rigid rods are arranged in a left-handed helix along the axial direction and connect between the left-handed upper connecting plate and the left-handed bottom connecting plate.

[0012] It should be noted that the left-handed compression-torsion cell is filled with a left-handed elastic unit group, which is also made of flexible matrix material through an integrated casting process, and encapsulates the left-handed helical rigid rod. The left-handed elastic unit group includes three left-handed elastic cables, a left-handed embedded rigid reinforcement, a left-handed embedded anchoring end, and a left-handed rigid-flexible coupling node. One end of the left-handed elastic cable is fixed inside the left-handed elastic unit group through the left-handed embedded anchoring end, and the other end passes upward through the left-handed top bearing end cap. A left-handed variable stiffness adjustment and limiting component is provided along the axial direction of the left-handed elastic cable. A left-handed stiffness adjustment knob is provided above the left-handed top bearing end cap. By operating the left-handed stiffness adjustment knob or directly pulling the left-handed elastic cable, the tension state of the elastic cable can be changed, causing the left-handed variable stiffness adjustment and limiting component to engage with the pre-set locking structure on the end cap surface, thereby applying an axial preload to the cell. In addition, the flexible matrix is ​​equipped with left-handed embedded rigid reinforcements and left-handed rigid-flexible coupling nodes to strengthen the interface bonding between the elastic cable, rigid frame and flexible matrix, and prevent peeling during large deformation.

[0013] It should be noted that, through the right-handed or left-handed elastic unit group, the right-handed or left-handed variable stiffness adjustment and limiting component installed on the right-handed or left-handed elastic cable, and the locking structure set on the right-handed or left-handed top bearing end cap, operating the right-handed or left-handed stiffness adjustment knob or performing a lifting action can change the effective tensile length of the right-handed or left-handed elastic cable, causing the right-handed or left-handed variable stiffness limiting components at different positions to engage in the locking structure, thereby achieving the application of graded axial preload to the cell. Specifically, by adjusting the right-handed and left-handed stiffness adjustment knobs, tightening the internal right-handed and left-handed elastic cables can effectively change the internal preload of the structure. Variations in preload can significantly adjust the equivalent axial stiffness of the structure, while simultaneously altering the initial helical angle and constraint state of the helical skeleton. This, in turn, modulates the deformation coupling relationship between axial compression and radial expansion, enabling active control of the negative Poisson's ratio effect. Furthermore, because the intermediate coupling connecting plate is located at the neutral plane of torsional deformation, and the array interconnected hinge group is designed with radial expansion margins, this connection method allows each unit to freely generate radial expansion under compression, thereby ensuring stable negative Poisson's ratio response and energy absorption performance through multi-unit collaboration.

[0014] Beneficial effects: This invention effectively counteracts macroscopic torsional deformation under axial load through the longitudinal splicing design of heterochiral compression-torsion cells, eliminating the inherent torsional instability of traditional single-chiral structures. Simultaneously, it achieves a stable negative Poisson's ratio effect using a "compression-torsion-tension" coupling mechanism. Through the cooperation of built-in elastic unit groups and variable stiffness adjustment limiting components, graded axial preload can be applied to the cells, enabling active adjustment of structural stiffness and negative Poisson's ratio, overcoming the inherent limitations of traditional metamaterials in terms of fixed and unadjustable mechanical properties. Furthermore, the use of an intermediate layer array connection system with flexible interconnected hinge groups allows for the detachable assembly of multiple units while effectively adapting to radial displacement during cell deformation, ensuring coordinated deformation capabilities in arrayed applications. This results in a structure with advantages such as compactness, rapid response, and ease of modular expansion. Attached Figure Description

[0015] To clearly illustrate the embodiments and related technical solutions of the present invention, the accompanying drawings involved in the embodiments will be briefly described below. It should be understood that the following drawings are only for illustrating some embodiments of the present invention. Those skilled in the art can also obtain other related technical solutions and drawings based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the overall structure of the heterochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure provided in an embodiment of the present invention.

[0017] Figure 2 This is a top view of the overall structure of the anisochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure provided in an embodiment of the present invention.

[0018] Figure 3 A schematic diagram of the basic structural unit of the heterochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure provided in an embodiment of the present invention.

[0019] Figure 4 This is a schematic diagram of the local explosion of the right-handed compressive-torsional cell in a heterochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure provided in an embodiment of the present invention.

[0020] Figure 5 This is a schematic diagram of a right-handed elastic unit group structure for a heterochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure provided in an embodiment of the present invention.

[0021] Figure 6 This is a schematic diagram of the local explosion of the left-handed compressive-torsional cell of the anisochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure provided in an embodiment of the present invention.

[0022] Figure 7 This is a schematic diagram of a left-handed elastic unit group structure for an anisochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure provided in an embodiment of the present invention.

[0023] Figure 8 This is a schematic diagram of the compressive and torsional deformation of the right-handed compressive-torsional cell of the heterochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure provided in an embodiment of the present invention.

[0024] Figure 9 This is a schematic diagram of the compression and torsional deformation of the left-handed compressive-torsional cell of the anisochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure provided in an embodiment of the present invention.

[0025] Figure 10 This is a schematic diagram of the compression and torsional deformation of the basic structural unit of the anisochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure provided in an embodiment of the present invention.

[0026] Figure 11 This is a schematic diagram of the overall structural compression deformation and transverse torsional deformation of the anisochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure provided in an embodiment of the present invention.

[0027] Labeling Explanation: 1. Right-handed compression-torsion cell; 101. Right-handed upper connecting plate; 102. Right-handed bottom connecting plate; 103. Right-handed top bearing end cap; 104. Right-handed helical rigid rod; 105. Right-handed stiffness adjustment knob; 106. Right-handed variable stiffness adjustment limit assembly; 107. Right-handed elastic unit group; 10701. Right-handed elastic cable; 10702. Right-handed embedded rigid reinforcement; 10703. Right-handed embedded anchor end; 10704. Right-handed rigid-flexible coupling node; 2. Left-handed compression-torsion cell; 201. Left 202. Left-handed upper connecting plate; 203. Left-handed bottom connecting plate; 204. Left-handed top bearing end cap; 205. Left-handed helical rigid rod; 206. Left-handed stiffness adjustment knob; 207. Left-handed variable stiffness adjustment limit assembly; 208. Left-handed elastic unit group; 20701. Left-handed elastic cable; 20702. Left-handed embedded rigid reinforcement; 20703. Left-handed embedded anchor end; 20704. Left-handed rigid-flexible coupling node; 3. Intermediate layer array connection system; 301. Intermediate coupling connection plate; 302. Array interconnection hinge group. Detailed Implementation

[0028] To clearly illustrate the embodiments of the present invention, a detailed description will be provided below in conjunction with the accompanying drawings. In the drawings, the same or similar reference numerals are used to refer to components with the same or similar functions. It should be understood that the following description in conjunction with the accompanying drawings is merely exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0029] It should be noted that the same reference numerals may be used repeatedly in different embodiments or figures. This repetition is only for simplification of description and illustration, and does not in itself indicate that there is a necessary relationship between the various embodiments or structures.

[0030] In the description of this invention, terms such as "upper," "lower," "left," "right," "longitudinal," "axial," "radial," "four corners," "clockwise," and "counterclockwise," which indicate orientation or positional relationships, are defined based on the orientation or position shown in the accompanying drawings. These definitions are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the components referred to must have a specific orientation, nor should they constitute a limitation on this invention. Furthermore, unless otherwise explicitly specified, "a plurality of" in this invention means two or more.

[0031] The following description illustrates different structures of the present invention through specific embodiments and accompanying drawings, with particular examples focusing on the components and their arrangement. It should be understood that these examples are merely illustrative and should not be construed as limiting the invention.

[0032] Please see Figures 1 to 3This invention provides a heterochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure, which mainly includes four sets of right-handed compressive-torsional cells 1 and left-handed compressive-torsional cells 2 arranged symmetrically along the axial direction and connected in series, as well as an intermediate layer array connection system 3 between the two types of cells. Specifically, the right-handed compressive-torsional cells 1 are located on top, and the left-handed compressive-torsional cells 2 are located on the bottom (this orientation is only for illustration and can be interchanged in actual applications). The two are tightly connected or integrally formed by an intermediate coupling connecting plate 301, together forming a basic structural unit with both macroscopic zero torsional characteristics and negative Poisson's ratio effect. The intermediate layer array connection system 3 includes an intermediate coupling connecting plate 301 and an array interconnection hinge group 302. The intermediate coupling connecting plate 301 has connection slots at the four corners of its side. Multiple basic structural units can be modularly spliced ​​together through the array interconnection hinge group 302 to construct a large-area metamaterial array. This structure not only effectively counteracts macroscopic torsion under axial load by utilizing heterochiral design, but also achieves infinite expansion and local maintainability of the structure through modularization.

[0033] See Figure 4 and Figure 5 The right-handed compression-torsion cell 1 includes a right-handed upper connecting plate 101, a right-handed bottom connecting plate 102, a right-handed top bearing end cap 103, three right-handed helical rigid rods 104, a right-handed variable stiffness adjustment and limiting assembly 106, and a right-handed elastic unit group 107. The right-handed helical rigid rods 104 are arranged in a right-handed helix along the axial direction and are connected between the right-handed upper connecting plate 101 and the right-handed bottom connecting plate 102.

[0034] It should be noted that, to achieve flexible deformation and stiffness adjustment, the right-handed compression-torsion cell 1 is filled with a right-handed elastic unit group 107. This right-handed elastic unit group 107 is made of a flexible matrix material using an integrated casting process, and encapsulates the right-handed helical rigid rod 104 within it. Specifically, the right-handed elastic unit group 107 includes three right-handed elastic cables 10701, a right-handed embedded rigid reinforcement 10702, a right-handed embedded anchoring end 10703, and a right-handed rigid-flexible coupling node 10704. One end of the right-handed elastic cable 10701 is fixed inside the right-handed elastic unit group 107 via the right-handed embedded anchoring end 10703, and the other end passes upward through the right-handed top bearing end cap 103. A right-handed variable stiffness adjustment limiting component 106 is provided along the axial direction of the right-handed elastic cable 10701. A right-handed stiffness adjustment knob 105 is located above the right-handed top bearing end cap 103. By operating the right-hand stiffness adjustment knob 105 or directly pulling the right-hand elastic cable 10701, the tension state of the elastic cable can be changed, causing the right-hand variable stiffness adjustment limiting component 106 to engage with the pre-set locking structure on the end cap surface, thereby applying axial preload to the cell. Furthermore, to enhance structural durability, the flexible matrix is ​​also equipped with a right-hand embedded rigid reinforcement 10702 and a right-hand rigid-flexible coupling node 10704 to strengthen the interface bonding between the elastic cable, the rigid frame, and the flexible matrix, preventing delamination during large deformations.

[0035] Please see Figure 6 and Figure 7 The left-handed compression-torsion cell 2 includes a left-handed upper connecting plate 201, a left-handed bottom connecting plate 202, a left-handed top bearing end cap 203, three left-handed helical rigid rods 204, a left-handed stiffness adjustment knob 205, a left-handed variable stiffness adjustment limiting component 206, and a left-handed elastic unit group 207. The structural composition of the left-handed compression-torsion cell 2 is similar to that of the right-handed compression-torsion cell 1, but the chirality is reversed. Specifically, the left-handed helical rigid rods 204 are arranged in a left-handed helix along the axial direction and are connected between the left-handed upper connecting plate 201 and the left-handed bottom connecting plate 202.

[0036] It should be noted that the left-handed compression-torsion cell 2 is filled with a left-handed elastic unit group 207, which is also made of flexible matrix material through an integrated casting process, and encapsulates the left-handed helical rigid rod 204 within it. The left-handed elastic unit group 207 includes three left-handed elastic cables 20701, a left-handed embedded rigid reinforcement 20702, a left-handed embedded anchoring end 20703, and a left-handed rigid-flexible coupling node 20704. One end of the left-handed elastic cable 20701 is fixed inside the left-handed elastic unit group 207 through the left-handed embedded anchoring end 20703, and the other end passes upward through the left-handed top bearing end cap 203. A left-handed variable stiffness adjustment limiting component 206 is provided along the axial direction of the left-handed elastic cable 20701. A left-handed stiffness adjustment knob 205 is provided above the left-handed top bearing end cap 203. By operating the left-handed stiffness adjustment knob 205 or directly pulling the left-handed elastic cable 20701, the tension state of the elastic cable can be changed, causing the left-handed variable stiffness adjustment limiting component 206 to engage with the pre-set locking structure on the end cap surface, thereby applying axial preload to the cell. Furthermore, the flexible matrix also contains a left-handed embedded rigid reinforcement 20702 and a left-handed rigid-flexible coupling node 20704 to strengthen the interface bonding between the elastic cable, the rigid frame, and the flexible matrix, preventing delamination during large deformations.

[0037] See Figures 4 to 10 Please refer to further information. Figures 8 to 10 When a single right-handed compressive-torsional cell 1 is subjected to axial pressure (i.e., compression along direction A), due to the guiding effect of its internal right-handed helical rigid rod 104, the structure undergoes compressive deformation while simultaneously exhibiting clockwise torsion (i.e., along direction B). Similarly, when a single left-handed compressive-torsional cell 2 is subjected to axial pressure, the structure undergoes compressive deformation while simultaneously exhibiting counterclockwise torsion (i.e., along direction C). It should be noted that, because the intermediate coupling connecting plate 301 effectively restricts the relative rotation between the contact surfaces of the two types of cells, when the overall structure is subjected to axial compression, the clockwise torsion tendency of the right-handed compressive-torsional cell 1 and the counterclockwise torsion tendency of the left-handed compressive-torsional cell 2 cancel each other out. This hindered torsional deformation forces the internal right-handed helical rigid rod 104 and left-handed helical rigid rod 204 to press outward against the flexible matrix, thereby transforming into significant radial expansion deformation. In other words, the structure shortens axially while its lateral dimension increases, exhibiting a typical negative Poisson's ratio effect.

[0038] See Figures 1 to 11 Please refer to further information. Figure 11By adjusting the right-hand stiffness adjustment knob 105 and the left-hand stiffness adjustment knob 205, the internal right-hand elastic cable 10701 and left-hand elastic cable 20701 are tightened, effectively changing the internal preload of the structure. Changes in preload can significantly adjust the equivalent axial stiffness of the structure, while simultaneously altering the initial helical angle and constraint state of the helical skeleton, thereby controlling the deformation coupling relationship between axial compression and radial expansion, achieving active control of the negative Poisson's ratio effect. The intermediate layer array connection system 3 is manufactured using an integrated molding process, including an intermediate coupling connection plate 301 and an array interconnection hinge group 302. The upper and lower surfaces of the intermediate coupling connection plate 301 are provided with grooves for connecting cells, and connection slots are provided at the four corners of the side, enabling detachable connection with the array interconnection hinge group 302. Since the intermediate coupling connecting plate 301 is located at the neutral plane of torsional deformation, and the array interconnection hinge group 302 is designed with radial expansion margin, this connection method allows each unit to freely generate radial expansion when under pressure, thereby ensuring that multiple units work together to achieve stable negative Poisson's ratio response and energy absorption performance.

[0039] In summary, although the present invention has been described in detail above with reference to specific embodiments, the scope of protection of the present invention is not limited to the specific embodiments described. Those skilled in the art can modify, alter, or adapt these embodiments without departing from the principles of the present invention. All such changes or substitutions based on the inventive concept should be covered within the scope of protection of the present invention.

Claims

1. A heterochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure, characterized in that, include: Multiple right-handed compression-torsion cells (1), multiple left-handed compression-torsion cells (2), and an intermediate layer array connection system (3) disposed between the right-handed compression-torsion cells (1) and the left-handed compression-torsion cells (2); the right-handed compression-torsion cells (1) and the left-handed compression-torsion cells (2) are arranged in series along the axial direction; wherein, the right-handed compression-torsion cell (1) includes a right-handed upper connecting plate (101), a right-handed bottom connecting plate (102), a right-handed top bearing end cap (103), three right-handed helical rigid rods (104), a right-handed variable stiffness adjustment and limiting assembly (106), and a right-handed elastic unit group (107); the right-handed helical rigid rods (104) are connected to the right-handed upper connecting plate (101) and the left-handed compression-torsion cells (2). Between the chiral bottom connecting discs (102); the right-handed elastic unit group (107) fills the inside of the right-handed compression-torsion cell (1), is made of flexible matrix material through an integrated casting process, and encapsulates the right-handed helical rigid rod (104); the right-handed elastic unit group (107) includes three right-handed elastic cables (10701), a right-handed embedded rigid reinforcement (10702), a right-handed embedded anchor end (10703), and a right-handed rigid-flexible coupling node (10704); the left-handed compression-torsion cell (2) includes a left-handed upper connecting disc (201), a left-handed bottom connecting disc (202), a left-handed top bearing end cap (203), and three left-handed helical rigid rods (204). The left-handed stiffness adjustment knob (205), the left-handed variable stiffness adjustment limit assembly (206), and the left-handed elastic unit group (207) are included. The left-handed helical rigid rod (204) is connected between the left-handed upper connecting plate (201) and the left-handed bottom connecting plate (202). The left-handed elastic unit group (207) is filled inside the left-handed compression-torsion cell (2), and is made of flexible matrix material through an integrated casting process, and covers the left-handed helical rigid rod (204) therein. The left-handed elastic unit group (207) includes three left-handed elastic cables (20701), a left-handed embedded rigid reinforcement (20702), a left-handed embedded anchor end (20703), and a left-handed rigid-flexible joint. Coupled node (20704); The intermediate layer array connection system (3) is used to restrict the relative rotation of the contact surfaces of the right-handed compression-torsion cell (1) and the left-handed compression-torsion cell (2), so that the opposite torsional tendencies generated by the two under axial load cancel each other out, and convert the obstructed torsional potential energy into radial expansion deformation, so that the overall structure exhibits a negative Poisson's ratio effect; One end of the right-handed elastic cable (10701) is fixed inside the right-handed elastic unit group (107) through the right-handed embedded anchor end (10703), and the other end passes upward through the right-handed top bearing end cap (103); The right-handed variable stiffness adjustment limit component (106) is provided along the axial direction of the right-handed elastic cable (10701).A right-hand stiffness adjustment knob (105) is provided above the right-hand top bearing end cap (103); by operating the right-hand stiffness adjustment knob (105) or directly pulling the right-hand elastic cable (10701), the tension state of the elastic cable can be changed, causing the right-hand variable stiffness adjustment limiting component (106) to engage in the pre-set locking structure on the end cap surface, thereby applying axial preload to the cell.

2. The anisochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure according to claim 1, characterized in that, One end of the left-handed elastic cable (20701) is fixed inside the left-handed elastic unit group (207) through the left-handed embedded anchor end (20703), and the other end passes upward through the left-handed top bearing end cap (203); the left-handed variable stiffness adjustment limiting component (206) is provided along the axial direction of the left-handed elastic cable (20701); a left-handed stiffness adjustment knob (205) is provided above the left-handed top bearing end cap (203); by operating the left-handed stiffness adjustment knob (205) or directly pulling the left-handed elastic cable (20701), the tension state of the elastic cable can be changed, so that the left-handed variable stiffness adjustment limiting component (206) is engaged in the pre-set mating locking structure on the end cap surface, thereby applying axial preload to the cell.

3. The anisochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure according to claim 1, characterized in that, The intermediate layer array connection system (3) includes an intermediate coupling connection plate (301) and an array interconnection hinge group (302); the upper and lower surfaces of the intermediate coupling connection plate (301) are provided with grooves for connecting cells, and the four corners of the side are provided with connection slots for cooperating with the array interconnection hinge group (302) to achieve detachable connection.

4. The anisochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure according to claim 3, characterized in that, The array interconnect hinge group (302) is made of flexible material and can adapt to the radial displacement generated by each unit during the negative Poisson's ratio deformation process, ensuring that it will not hinder the free deformation of the single cell when used in array applications.

5. The anisochiral spliced ​​variable stiffness negative Poisson's ratio metamaterial structure according to claim 3, characterized in that, Multiple basic structural units are modularly spliced ​​together through the intermediate layer array connection system (3) to form a large-area metamaterial array; the intermediate coupling connection plate (301) is located at the neutral plane position of torsional deformation, and the array interconnection hinge group (302) is provided with radial expansion margin, so that each unit can freely generate radial expansion when under pressure, realizing the negative Poisson's ratio response and energy absorption performance of multi-unit collaboration.

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