Pressure-torsion coupled metamaterial cell element and negative Poisson's ratio energy absorption structure composed of same

Abstract

The invention provides a compression-torsion coupled metamaterial cell element and a negative Poisson's ratio energy absorption structure composed of the compression-torsion coupled metamaterial cell element, and relates to the technical field of compression-torsion energy absorption metamaterials. The cell element comprises an upper connecting plate assembly and a lower connecting plate assembly, an upper-layer four-rod tensioning assembly and a lower-layer four-rod tensioning assembly are arranged between the upper connecting plate assembly and the lower connecting plate assembly, each of the upper-layer four-rod tensioning assembly and the lower-layer four-rod tensioning assembly comprises four compression rigid rod pieces and a plurality of tension elastic bodies, the compression rigid rod pieces are staggered in space to form a quadrangular prism-like frame, and the tail ends of the upper compression rigid rod piece and the lower compression rigid rod piece are hinged; adjacent hinge points and two corresponding corners of the surfaces of the upper connecting plate assembly and the lower connecting plate assembly are connected through tensile elastic bodies and apply pre-tightening force; the energy absorption structure is formed by combining a plurality of cell element arrays, and the negative Poisson's ratio effect is achieved by regulating and controlling the arrays. According to the cell element, a tensioning structure is integrated into a metamaterial configuration, the cell element has the compression-torsion coupling characteristic, the non-localized deformation response of the structure is achieved, and the energy absorption structure has the negative Poisson's ratio effect and provides excellent bearing and impact resistance through an efficient energy absorption mechanism.

Description

Technical Field

[0001] This invention relates to the field of compressive-torsional energy-absorbing metamaterials, and in particular to a compressive-torsional coupled metamaterial cell and its composition of a negative Poisson's ratio energy-absorbing structure. Background Technology

[0002] In the field of impact protection engineering, the development of energy-absorbing materials is crucial for protecting the human body and precision equipment from sudden impacts. Mechanical metamaterials, with their designable ultralight properties, negative Poisson's ratio effect, and compressive-torsional coupling behavior, significantly surpass the performance boundaries of traditional materials, showing revolutionary potential, especially in terms of energy absorption density.

[0003] Existing energy-absorbing metamaterials can be divided into two categories based on their failure mechanisms: 1. Single-use metamaterials (such as metal honeycomb and plastic truss lattice) achieve high specific energy absorption through irreversible plastic deformation or structural collapse. However, they have inherent defects such as easy failure after single use under impact load, chain collapse caused by node fracture (such as domino-like failure of eight-fold truss lattice at 30% strain), and increased brittleness in low temperature environment. These defects cause local instability or damage to the energy-absorbing structure, resulting in premature failure of the structure before it can fully realize its energy absorption potential. Furthermore, they are not reusable. 2. Reusable metamaterials (such as bistable curved beams and multistable origami structures) rely on elastic deformation or steady-state switching to consume energy. Although they have a cycle life of tens of thousands of cycles, they are limited by the strength of the material and the local deformation mode, resulting in generally lower energy absorption and significantly reduced energy absorption efficiency.

[0004] In view of the above reasons, this invention proposes a compression-torsion coupled negative Poisson's ratio metamaterial cell and energy-absorbing structure, which has compression-torsion coupling characteristics, can realize non-local deformation response of the structure, and through an efficient energy absorption mechanism, exhibits stable negative stiffness behavior after reaching the peak load, thereby producing a softer response to external impacts, effectively mitigating instantaneous impacts and improving energy dissipation efficiency, ultimately enabling the structure to have excellent load-bearing, impact resistance and vibration suppression performance. Summary of the Invention

[0005] The purpose of this invention is to provide a compression-torsion coupled negative Poisson's ratio metamaterial cell and energy-absorbing structure that can achieve spatial self-equilibrium, has compression-torsion coupling characteristics, can achieve non-localized deformation response of the structure, and exhibits stable negative stiffness behavior after reaching peak load through an efficient energy absorption mechanism, thereby producing a softer response to external impacts, effectively mitigating instantaneous impacts and improving energy dissipation efficiency, ultimately enabling the structure to have excellent load-bearing, impact resistance and vibration suppression performance.

[0006] On one hand, the present invention provides a negative Poisson's ratio metamaterial cell structure with compression-torsion coupling, comprising: an upper connecting plate assembly and a lower connecting plate assembly arranged opposite to each other, wherein an upper four-bar tensioning assembly and a lower four-bar tensioning assembly are disposed between the upper connecting plate assembly and the lower connecting plate assembly, each of the upper four-bar tensioning assembly and the lower four-bar tensioning assembly comprising four compression rigid members and multiple tension elastic bodies, wherein the starting end of each compression rigid member is connected sequentially to each corner of the upper connecting plate assembly or the lower connecting plate assembly via a ball-head connecting rod. The rotating connection allows each of the compression rigid members to form a quadrangular prism-like frame by interlacing in space. The ends of each compression rigid member extend diagonally and are located at the endpoints of the quadrangular prism-like frame. The ends of each compression rigid member of the upper four-bar tensioning assembly are hinged to the ends of the corresponding compression rigid members of the lower four-bar tensioning assembly via hinges. The two corners of each adjacent hinge and the two corners corresponding to the surfaces of the upper and lower connecting plate assemblies are connected by the tension elastic body and a preload is applied.

[0007] Preferably, both the upper connecting plate assembly and the lower connecting plate assembly include opposing base plates. A cover plate is provided on one opposite side surface of the two base plates and is detachably connected to it by bolts. Hinge holes are provided at the four corners of the base plates. The ball joint connecting rod is rotatably installed in cooperation with the hinge holes. Corresponding through holes are provided on the cover plate.

[0008] Preferably, the cover plate is provided with hooks at its four corner edges for hooking and pre-tensioning the tensioned elastomer.

[0009] Preferably, the hinge is a Y-type hinge, which is rotatably connected to the ends of the two compression rigid members arranged in a Y-shape in the upper four-bar tensioning assembly and the lower four-bar tensioning assembly.

[0010] Preferably, the Y-shaped hinge is made of flexible TPU material by 3D printing.

[0011] Preferably, the compression rigid rod is a carbon tube, the beginning of which is threaded to the straight end of the ball-head connecting rod, and the end of which is embedded in the rotating end of the Y-shaped hinge.

[0012] Preferably, the tension elastic body is a spring, one end of which is hung on the hook and the other end is anchored to the end of the hinge.

[0013] Preferably, each corner of the base plate is provided with an array connection end extending outward along its cross axis, and each array connection end is provided with a hinge hole, so that adjacent cell structures can be hinged by T-pins engaging with the hinge holes.

[0014] Preferably, the four compression rigid members in the upper four-bar tensioning assembly and the lower four-bar tensioning assembly are twisted clockwise or counterclockwise in the spatial torsion direction.

[0015] On the other hand, the present invention provides a pressure-torsion coupled negative Poisson's ratio metamaterial energy-absorbing structure composed of the above-mentioned cell structure, which is composed of a number of cells connected by T-shaped pins at the array connection end, and adjacent cells are arranged in a clockwise and counterclockwise alternating arrangement in the spatial torsion direction.

[0016] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: 1. Inspired by the principle of tension as a whole, this structure incorporates its core design concept into metamaterial configuration, realizing non-local deformation response of the structure. When subjected to load or impact, its elastic units stretch in concert, prompting the whole structure to participate in energy dissipation, thereby effectively avoiding the problem of energy absorption interruption caused by local instability or damage. 2. Compared to traditional reusable mechanical metamaterials, this structure achieves a more efficient energy absorption mechanism under load or impact through the synergistic effect of internal tension-compression units (including a significant torsional effect), exhibiting excellent load-bearing and impact resistance performance. When the compressive force reaches its peak, the metamaterial further exhibits a negative stiffness effect, making its response to external impacts more gradual and gentle. Thus, while maintaining efficient energy dissipation, it effectively mitigates collision or vibration transmission, significantly reducing impact damage to the protected object. 3. During the impact process, the unique deformation mode of this structure (the negative Poisson's ratio effect after the torsion of cell components and the regulation of energy-absorbing structure) can significantly attenuate the peak impact force and acceleration response, thereby providing excellent impact protection. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is an isometric view of type I cell in this invention; Figure 2 This is a front view of type I cell in this invention; Figure 3This is a top view of a portion of the Type I cell (with the upper connecting plate assembly removed) in this invention; Figure 4 This is an isometric view of the type II cell in this invention; Figure 5 This is a front view of the type II cell in this invention; Figure 6 This is a top view of a portion of the Type II cell (with the upper connecting plate assembly removed) in this invention; Figure 7 This is a structural diagram of the components of the cell structure of the present invention; Figure 8 This is a three-dimensional structural diagram of the energy-absorbing structure formed by cell-unit connection and combination in this invention; Figure 9 This is a top view of the energy-absorbing structure formed by the cell-cell connection and combination of the present invention; Explanation of reference numerals in the attached figures: 1: Array connection end; 2: Tension elastic body; 3: Cover plate; 4: Nut; 5: Base plate; 6: Ball head connecting rod; 7: Hinge; 8: Compression rigid rod; 9: Hook; 10: Center bolt; 11: T-pin. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0020] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] like Figure 1-7 As shown, this invention provides a compression-torsional coupling metamaterial cell, comprising: an upper connecting plate assembly and a lower connecting plate assembly arranged opposite each other, positioned at opposite ends of the cell's axial direction; an upper four-bar tensioning assembly and a lower four-bar tensioning assembly are disposed between the upper and lower connecting plate assemblies, serving as the core load-bearing unit; both assemblies include four compression rigid rods 8 and multiple tension elastic bodies 2, cooperating to form a spatial self-balancing system. Its configuration is as follows: the four compression rigid rods 8 are spatially staggered to form a quasi-quadrangular prism frame; the starting end of each compression rigid rod 8 is sequentially rotatably connected to the corners of the upper or lower connecting plate assembly via ball-head connecting rods 2; the end of each compression rigid rod 8 extends diagonally from its starting end and is located at the endpoints of the quasi-quadrangular prism. The ends of each compression rigid member 8 of the upper four-bar tensioning assembly are hinged to the ends of the corresponding compression rigid members 8 of the lower four-bar tensioning assembly through hinges 7. The adjacent hinges 7 and the two nearest corners corresponding to the surfaces of the upper and lower connecting plate assemblies are connected by tension elastic bodies 2 and preloaded.

[0023] Inspired by the principle of tension as a whole, the aforementioned cell unit incorporates its core design concept into the metamaterial configuration, achieving a non-localized deformation response. Under load or impact, its elastic units work together to stretch, prompting the entire structure to participate in energy dissipation, thus effectively avoiding energy absorption interruption caused by local instability or damage. Compared to traditional reusable mechanical metamaterials, this structure, under load or impact, achieves a more efficient energy absorption mechanism through the synergistic effect of internal tension-compression units (including a significant torsional effect), exhibiting excellent load-bearing and impact resistance. When the compressive force reaches its peak, the metamaterial further exhibits a negative stiffness effect, making its response to external impacts more gradual and gentle. This effectively mitigates collision or vibration transmission while maintaining efficient energy dissipation, significantly reducing impact damage to the protected object.

[0024] After the upper four-bar tensioning assembly and the lower four-bar tensioning assembly are connected, based on the different clockwise and counterclockwise torsional directions of the four rigid members 8 under compression in the spatial torsion direction after being compressed, the cell structure can be divided into Class I cells (such as...). Figure 1-3 (as shown) and type II cellular units (such as Figure 4-6 As shown in the figure, type I cells are twisted clockwise, and type II cells are twisted counterclockwise.

[0025] In this embodiment, both the upper connecting plate assembly and the lower connecting plate assembly include opposing base plates 5. Each base plate 5 has a cover plate 3 on its opposite side surface, which is detachably connected to it via four central bolts 10 and nuts 4. Hinge holes are provided at the four corners of the base plates 5. The ball-head connecting rod 6 has a configuration with a ball head at one end and a straight rod at the other. The ball head end forms a ball-and-spot hinge with the hinge holes at the four corners of the base plate 5, while the straight rod end is fixedly connected to the end of the compression rigid member 8 in the four-bar tensioning assembly, thus decoupling load transfer from rotational freedom. The ball head end of the ball-head connecting rod 6 is rotatably mounted in conjunction with the hinge hole. Corresponding through holes are provided on the cover plate 3 to avoid affecting the rotation of the ball-head connecting rod 6.

[0026] Specifically, hooks 9 are provided at the four corner edges of the cover plate 3 for hooking and pre-tensioning the tension elastic body 2. The tension elastic body 2 is a spring, one end of which is hung on the hook 9 and the other end is anchored to the end of the hinge 7. The four corners of the base plate 5 are provided with array connection ends 1 extending horizontally outward along its cross axis. Each array connection end 1 has a hinge hole, and adjacent cell structures can be hinged by T-pins 11 engaging with the hinge holes.

[0027] In this embodiment, the hinge 7 is a Y-shaped hinge, which is rotatably connected to the ends of the two compression rigid rods 8 arranged in a Y-shape in the upper and lower four-bar tensioning assemblies. The Y-shaped hinge is made of flexible TPU material by 3D printing, and its core functions are: 1) to connect the upper and lower four-bar tensioning assemblies stacked axially within the hinge cell; 2) to serve as the central anchor point of the tensioned elastic body 2, and its design can coordinate interlayer deformation through flexible hinge.

[0028] In this embodiment, the rigid compression member 8 is a carbon tube, the beginning of which is threaded to the straight end of the ball-head connecting rod 6, and the end of which is embedded in the rotating end of the Y-type hinge. Its configuration is as follows: four members are connected in a staggered manner in space to form a quadrangular prism-like frame - the tail end of each member is connected to a vertex of the base of the virtual quadrangular prism, and the beginning end is connected to the vertex of the base plate 5 that is diagonally opposite to it in space.

[0029] The present invention also provides a negative Poisson's ratio energy-absorbing structure composed of the above-mentioned compression-torsion coupled metamaterial cells. It is an array structure composed of several cells hinged together at the array connection end 1 by T-shaped pins 11. Adjacent cells are arranged in a staggered arrangement of clockwise and counterclockwise torsion in the spatial torsion direction, that is, adjacent cells rotate in opposite directions. Under compressive load, the structure is torsioned in coordination with the rod through the elastic tension transmission. By adjusting the array structure of the energy-absorbing structure, it can generate a negative Poisson's ratio effect. After entering the densification stage, the negative Poisson's ratio effect causes the structure to shrink radially, increase the relative density and improve the strength and stiffness.

[0030] Compared to traditional reusable mechanical metamaterials, this energy-absorbing structure achieves a more efficient energy absorption mechanism under load or impact through the synergistic effect of internal tension-compression units (including a significant torsional effect), exhibiting excellent load-bearing and impact resistance. When the compressive force reaches its peak, the metamaterial further exhibits a negative stiffness effect, making its response to external impacts more gradual and gentle. Thus, while maintaining efficient energy dissipation, it effectively mitigates the transmission of collisions or vibrations, significantly reducing impact damage to the protected object.

[0031] like Figure 8-9 As shown, in this embodiment, the energy-absorbing structure contains nine cells arranged in a 3×3 array. Each cell is located at a node of the grid. The array connection ends 1 between adjacent cells are hinged together by T-shaped pins 11, meaning that the middle cell structure is simultaneously hinged to the cells located in its upper left, lower left, upper right, and lower right directions. Furthermore, adjacent cells are arranged in a staggered clockwise and counterclockwise twisting pattern during spatial torsion. That is, during array assembly, type I and type II cells are arranged in a checkerboard pattern, causing the rods of adjacent cells to rotate in opposite directions. The energy-absorbing structure formed by arranging multiple cells in this manner exhibits a significant negative Poisson's ratio effect, which can significantly attenuate the peak impact force and acceleration response, thereby providing excellent impact protection.

[0032] Based on the above configuration and connection relationship—the tensioned elastic body 2 is tensioned to the Y-shaped hinge 7 via the hook 9, and the compression rigid rod 8 is hinged to the base plate 5 via the ball-head connecting rod 6, so that the upper and lower connecting plate assemblies are flexibly interconnected via the Y-shaped hinge 7, and the unit cells are hinged arrayed through the array connecting end 1 on the base plate 5. Under macroscopic compressive load, this metamaterial produces synergistic axial contraction and radial torsion, exhibiting significant compression-torsion coupled deformation behavior and negative Poisson's ratio effect, thereby producing a softer response to external impacts, effectively mitigating instantaneous impacts and improving energy dissipation efficiency, ultimately giving the structure excellent load-bearing, impact resistance and vibration suppression performance.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A metamaterial cell with compression-torsion coupling, characterized in that, include: An upper connecting plate assembly and a lower connecting plate assembly are arranged opposite each other. An upper four-bar tensioning assembly and a lower four-bar tensioning assembly are provided between the upper connecting plate assembly and the lower connecting plate assembly. Each of the upper four-bar tensioning assembly and the lower four-bar tensioning assembly includes four compression rigid rods and multiple tension elastic bodies. The starting end of each compression rigid rod is rotatably connected to each corner of the upper connecting plate assembly or the lower connecting plate assembly through a ball-head connecting rod. The compression rigid rods are staggered in space to form a quasi-quadrangular prism frame. The end of each compression rigid rod extends diagonally and is located at each end of the quasi-quadrangular prism. The end of each compression rigid rod of the upper four-bar tensioning assembly is hinged to the end of the corresponding compression rigid rod of the lower four-bar tensioning assembly through a hinge. The adjacent hinges and the two corners corresponding to the surfaces of the upper and lower connecting plate assemblies are connected through the tension elastic bodies and a preload is applied.

2. The metamaterial cell with compression-torsion coupling according to claim 1, characterized in that, Both the upper connecting plate assembly and the lower connecting plate assembly include opposing base plates. Each of the two base plates has a cover plate that is detachably connected to it by bolts on one side surface. The base plates have hinge holes at their four corners. The ball joint connecting rod is rotatably installed in cooperation with the hinge holes. The cover plate has corresponding through holes.

3. The metamaterial cell with compression-torsion coupling according to claim 2, characterized in that, The cover plate is provided with hooks at its four corner edges for hooking and pre-tensioning the tensioned elastic body.

4. The metamaterial cell with compression-torsion coupling according to claim 1, characterized in that, The hinge is a Y-type hinge, which is rotatably connected to the ends of the two compression rigid members arranged in a Y-shape in the upper four-bar tensioning assembly and the lower four-bar tensioning assembly.

5. The metamaterial cell with compression-torsion coupling according to claim 1, characterized in that, The Y-shaped hinge is made of flexible TPU material by 3D printing.

6. The metamaterial cell with compression-torsion coupling according to claim 1, characterized in that, The compression rigid member is a carbon tube, the beginning of which is threaded to the straight end of the ball-head connecting rod, and the end of which is embedded in the rotating end of the Y-type hinge.

7. The metamaterial cell with compression-torsion coupling according to claim 3, characterized in that, The tension elastic body is a spring, one end of which is hung on the hook and the other end is anchored to the end of the hinge.

8. The metamaterial cell with compression-torsion coupling according to claim 2, characterized in that, The base plate has array connection ends extending outward along its cross axis on the outer side of each corner. Each array connection end is provided with a hinge hole, and adjacent cell structures can be hinged by T-pins engaging with the hinge holes.

9. The metamaterial cell with compression-torsion coupling according to claim 2, characterized in that, The four compression rigid members in the upper four-bar tensioning assembly and the lower four-bar tensioning assembly are twisted clockwise or counterclockwise in the spatial torsional direction.

10. A negative Poisson's ratio energy-absorbing structure composed of metamaterial cells with compression-torsion coupling as described in any one of claims 1-9, characterized in that, It is composed of several cells connected by T-shaped pins at the array connection end, and adjacent cells are arranged in a clockwise and counterclockwise alternating pattern in the spatial torsion direction.

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