Concave angle asymmetric double-layer negative Poisson's ratio superstructure and application thereof

Abstract

The invention relates to a concave angle asymmetric double-layer negative Poisson's ratio superstructure and application thereof. A concave angle asymmetric double-layer negative Poisson's ratio superstructure comprises bearing pressing plates symmetrically arranged at the upper end and the lower end and a plurality of unit cell elements arranged between the two pressing plates, and is characterized in that the unit cell elements are arranged at equal intervals in the transverse direction and the vertical direction respectively to form an m * n array, each unit cell unit comprises a double-layer concave corner body, transverse connecting rods on the two sides and a vertical connecting rod on the upper portion, the lower portion of each double-layer concave corner body is an outer flat plate cell wall, and the ends of the transverse connecting rods between every two transversely adjacent unit cell units are connected into a whole. And the end parts of the vertical connecting rods between the vertically adjacent unit cell elements are connected with the outer flat plate cell walls into a whole. The deformation mode of the superstructure is influenced by the impact speed, when the speed is increased, the deformation mode transits from overall deformation to local deformation, different local deformation zones are generated, the superstructure has different horizontal contraction processes at different impact speeds, the negative Poisson's ratio effect is reduced along with the increase of the speed, and the local deformation zones are reduced. The superstructure can be applied to anti-impact protection parts of automobiles, airplanes and unmanned aerial vehicles and anti-impact protection parts of wearable protection devices.

Description

Technical Field

[0001] This invention relates to the field of lightweight porous materials and impact protection technology, and in particular to a concave-angle asymmetric double-layer negative Poisson's ratio superstructure and its applications. Background Technology

[0002] The closest existing technologies mainly fall into three categories: The first category is a single-layer concave hexagonal or star-shaped honeycomb structure, which is generally achieved by using a combination of diagonal and horizontal bars to achieve lateral contraction, and the mechanical properties are adjusted by changing the cell wall thickness or the included angle; The second category is a simple stacked multi-layer isomorphic honeycomb, in which each layer is fixed only by adhesive bonding or spot welding to form a protective plate with doubled thickness; The third category is to add longitudinal or transverse reinforcing ribs inside a single-layer honeycomb to form a "diabolo-shaped" or "star-arrow-shaped" variant to improve stiffness and energy absorption capacity.

[0003] However, the above scheme has limitations in in-plane impact (5-100 ms) -1 All of these approaches reveal irreconcilable contradictions under various operating conditions. In single-layer structures, due to thickness limitations, shear bands easily initiate at the acute angle where the diagonal and horizontal members intersect and penetrate the wall thickness, causing instantaneous breakage of the load-bearing path. The negative Poisson's ratio effect fails within the strain range of 0.15-0.20. In simple, multi-layered honeycomb structures, the lack of interlayer coordination mechanisms leads to multiple reflections of shock waves at the interface, causing debonding or warping. The actual energy absorption is actually lower than that of the single-layer thickened scheme, and the alternating positive and negative Poisson's ratios severely weaken the macroscopic auxetic effect. While ribbed reinforced honeycomb structures delay buckling, the ribs prematurely enter axial tension, drastically reducing lateral shrinkage. The negative Poisson's ratio drops from -0.7 to -0.2, essentially losing its auxetic characteristics.

[0004] Furthermore, existing technologies have not established an integrated design method for geometry-materials-processes for in-plane impacts of 5-100 m / s, resulting in a mismatch between experiments and simulations and making it difficult to directly apply optimization results to 3D printing or stamping mass production. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing single-layer or simply stacked negative Poisson's ratio honeycomb structures, such as shear band penetration, interlayer debonding, and rapid decay of negative Poisson's ratio under in-plane impact. This invention proposes a concave-angle asymmetric double-layer negative Poisson's ratio superstructure, which significantly reduces the initial peak impact force and increases specific energy absorption while maintaining lightweight design. It also ensures that the negative Poisson's ratio effect can be sustained to an engineering strain of 0.5 or higher, so that the structure can be used in impact-resistant protective parts of automobiles, aircraft, and drones, as well as in impact-resistant protective parts of wearable protective devices.

[0006] The technical solution of this invention is: an inward-angled asymmetric double-layer negative Poisson's ratio superstructure, comprising symmetrically arranged bearing plates at the upper and lower ends and a plurality of unit cells arranged in the middle of the two plates. The unit cells are equidistantly arranged along the horizontal and vertical directions, forming an m×n array, where m and n are at least 5, and m can be equal to n. Each unit cell includes a double-layered inward-angled main body, horizontal connecting rods on both sides, and a vertical connecting rod at the top. The lower part of the double-layered inward-angled main body is an outer flat cell wall. The ends of the horizontal connecting rods between horizontally adjacent unit cells are connected as one unit, and the ends of the vertical connecting rods between vertically adjacent unit cells are connected as one unit to the outer flat cell wall. The stress and specific energy absorption of this inward-angled asymmetric double-layer negative Poisson's ratio superstructure increase with increasing velocity. The deformation mode of this superstructure is affected by the impact velocity; as the velocity increases, the deformation mode transitions from overall deformation to local deformation, generating different local deformation zones.

[0007] Preferably, the upper, left, and right sides of the double-layer concave angle main body are all outer concave angle structures formed by outwardly inclined cell walls. The inner ends of the horizontal connecting rods and vertical connecting rods are respectively connected to the corresponding concave angle vertices. The outer flat cell wall and the outwardly inclined cell wall together form the outer layer of a single cell. Inside the outer layer, there are inner flat cell walls and innerly inclined cell walls arranged parallel to the outer flat cell wall and the outwardly inclined cell wall. The innerly inclined cell walls form the upper, left, and right inner concave angle structures. The inner flat cell walls and the innerly inclined cell walls together form the inner layer of a single cell. Connecting cell walls connect the corresponding concave angle vertices of the outer and inner layers of the single cell. Such a superstructure has significantly improved stability: through the interconnection design of the double-layer concave angle units, this metamaterial forms a cooperative deformation mechanism, resulting in more uniform and stable deformation under impact loads. Compared with traditional concave hexagonal or star-shaped single-layer negative Poisson's ratio structures, it has higher resistance to instability and overall deformation coordination. The inner and outer concave corner structures are interlocked. Due to the presence of interlayer constraint connecting the cell walls, the transverse contraction deformation is continuously guided, forcing the shear bands to migrate between layers rather than break through, thus significantly extending the negative Poisson's ratio maintenance interval.

[0008] Preferably, the moment of inertia of the transverse and vertical connecting rods is much smaller than that of the outwardly inclined cell wall and the outer flat cell wall. This allows for initial elastic buckling during the initial impact phase, reducing overall stiffness to suppress peak force; subsequently, it guides the orderly formation of plastic hinges, achieving gradual energy dissipation.

[0009] Preferably, the ends of the vertical connecting rods of the horizontally arranged unit cells in the top row are integrated with the upper bearing plate, which serves to support and uniformly load the structure during loading; the outer flat plate cell walls of the horizontally arranged unit cells in the bottom row are integrated with the lower bearing plate, which serves to fix the overall structure and prevent slippage when the upper end is subjected to structural loading.

[0010] An application of the aforementioned concave-angle asymmetric double-layer negative Poisson's ratio superstructure is characterized in that: the concave-angle asymmetric double-layer negative Poisson's ratio superstructure is used in the impact protection parts of automobiles, airplanes, and drones, as well as in the impact protection parts of wearable protective devices, and when applied, the bearing pressure plate on it faces outward to withstand the impact.

[0011] Preferably, the following design parameters are set for parameter adjustment during the design and fabrication of the superstructure: L0 is the length of the outwardly inclined cell wall, L1 is the length of the inwardly inclined cell wall; L2 is the length of the transverse and vertical connecting rods, c is the length of the connecting cell wall, θ is the angle between the outwardly inclined cell wall and the transverse and vertical connecting rods respectively, t is the thickness of each cell wall, and the overall out-of-plane thickness of the concave-angle asymmetric double-layer negative Poisson's ratio superstructure is b; the following dimensionless parameters are determined: aspect ratio α0 = L0 / L2, wall thickness ratio β0 = t / L0, and inner-outer side length ratio γ = L0 / L1. The determination of these parameters allows for programmed adjustment of the Poisson's ratio during the design process: by adjusting geometric parameters such as the connecting rod length ratio and the concave angle, the Poisson's ratio can be controllably adjusted within a large range, thereby enabling customized design for different buffering and load-bearing requirements and improving the adaptability and predictability of the structure under various impact conditions.

[0012] The working principle of this concave-angle asymmetric double-layer negative Poisson's ratio superstructure:

[0013] This superstructure has an asymmetrical structure in its unit cells. When compressed at a certain impact velocity, the bending deformation of the vertical connecting rods is rapidly transmitted to the root of the main cell wall, causing a controllable plastic hinge to form at the intersection of the inclined cell wall and the transverse connecting rods. At this point, the material enters the yielding stage, and a large amount of energy is dissipated through the bending-torsional coupling mechanism. Subsequently, the inner and outer layers of the unit cells interlock, and due to the constraint between the inner and outer layers, the transverse shrinkage deformation is continuously guided, and the negative Poisson's ratio effect is maintained over a larger strain range.

[0014] As the superstructure approaches the compaction stage, the inner and outer layers of the unit cell are completely interlocked, forming a secondary load-bearing platform. At this point, the unit cell shifts from being dominated by bending and shear to being dominated by axial compression, and the stiffness increases again. However, the peak force is significantly flattened, exhibiting a "double-platform" characteristic. Throughout the process, the impact energy is dissipated step by step through a triple mechanism of elastic buckling, plastic hinges, and interlayer interlocking, ultimately transforming into controllable plastic deformation heat and a small amount of elastic rebound. This avoids the brittle fracture of traditional superstructure honeycomb structures while ensuring that the superstructure can absorb a large amount of energy within an extremely short stroke, thereby achieving synergistic optimization of low peak force, high specific energy absorption, and stable negative Poisson's ratio effect.

[0015] The beneficial effects of this invention are:

[0016] 1. The stress and specific energy absorption of the proposed concave-angle asymmetric double-layer negative Poisson's ratio superstructure increase with increasing velocity. The deformation mode of this structure is affected by the impact velocity; as the velocity increases, the deformation mode transitions from overall deformation to local deformation, generating different local deformation zones.

[0017] 2. The superstructure exhibits different horizontal contraction processes under different impact velocities, with the negative Poisson's ratio effect decreasing as the velocity increases. The structure exhibits a better negative Poisson's ratio effect in the initial stage of medium-speed impacts, which weakens as the impact progresses. Under high-speed impacts, the structure displays a weak negative Poisson's ratio effect throughout the entire process.

[0018] 3. Integrated lightweight manufacturing: This superstructure can be integrally formed using additive manufacturing technology, with no connecting interfaces, effectively avoiding stress concentration and improving fatigue life; its semi-hollow configuration significantly reduces the overall weight while ensuring mechanical properties, making it suitable for protective components in aircraft, automobiles and other applications with strict requirements for lightweighting and impact resistance. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the main view of the concave-angle asymmetric double-layer negative Poisson's ratio superstructure;

[0020] Figure 2 yes Figure 1 A magnified view of part I - a schematic diagram of the main structure of a single cell (red represents the outer layer and blue represents the inner layer).

[0021] Figure 3 yes Figure 2 A schematic diagram of its three-dimensional structure;

[0022] Figure 4 To simulate the deformation mode of this negative Poisson's ratio superstructure under low-speed impact using computer simulation;

[0023] Figure 5 To simulate the deformation mode of this negative Poisson's ratio superstructure under medium-speed impact using computer simulation;

[0024] Figure 6 To simulate the deformation mode of this negative Poisson's ratio superstructure under medium-to-high-speed impact using computer simulation;

[0025] Figure 7 To simulate the deformation mode of this negative Poisson's ratio superstructure under high-speed impact using computer simulation;

[0026] Figure 8 To simulate the stress-strain curves of this negative Poisson's ratio superstructure under different impact velocities using computer simulation;

[0027] Figure 9To simulate the specific energy absorption curves of this negative Poisson's ratio superstructure under different impact velocities using computer simulation;

[0028] Figure 10 The computer simulation is used to measure the lateral displacement of this negative Poisson's ratio superstructure.

[0029] Figure 11 To simulate the dynamic Poisson's ratio of this negative Poisson's ratio superstructure at different velocities using computer simulation;

[0030] Figure 1-3 In the middle: 1. Outer plate cell wall, 2. Vertical connecting rod, 3. Horizontal connecting rod, 4. Outer inclined cell wall, 5. Connecting cell wall, 6. Inner inclined cell wall, 7. Inner plate cell wall, 8. Upper bearing pressure plate, 9. Lower bearing pressure plate. Detailed Implementation

[0031] Example 1: See Figure 1-11 ,in Figure 1-3 The diagram illustrates an asymmetric double-layer negative Poisson's ratio superstructure with concave angles, comprising symmetrically arranged load-bearing plates at the upper and lower ends and a plurality of unit cells arranged between the two plates. The unit cells are equidistantly arranged along the horizontal and vertical directions, forming an m×n array. In this embodiment, m=n=7. Each unit cell includes a double-layer concave angle main body, horizontal connecting rods 3 on both sides, and a vertical connecting rod 2 at the top. The lower part of the double-layer concave angle main body is an outer flat cell wall 1. The ends of the horizontal connecting rods 3 between horizontally adjacent unit cells are connected as one unit, and the ends of the vertical connecting rods 2 between vertically adjacent unit cells are connected as one unit to the outer flat cell wall 1. The ends of the vertical connecting rods 2 of the top row of horizontally arranged unit cells are connected as one unit to the upper load-bearing plate 8, serving to support and uniformly load the structure during loading. The outer flat cell wall 1 of the bottom row of horizontally arranged unit cells is connected as one unit to the lower load-bearing plate 9, serving to fix the overall structure and prevent slippage when the upper end is loaded.

[0032] The deformation mode of this structure is affected by the impact velocity. As the velocity increases, the deformation mode transitions from overall deformation to local deformation, generating different local deformation zones, such as... Figure 4-7 As shown.

[0033] The upper, left, and right sides of the double-layer concave angle main body are all outer concave angle structures formed by outwardly inclined cell walls. The inner ends of the horizontal and vertical connecting rods are respectively connected to the corresponding concave angle vertices. The outer flat cell wall and the outwardly inclined cell wall together form the outer layer of a single cell. Inside the outer layer, there are inner flat cell walls and inner inclined cell walls arranged parallel to the outer flat cell wall and the outwardly inclined cell wall. The inner inclined cell walls form the upper, left, and right inner concave angle structures. The inner flat cell walls and the inner inclined cell walls together form the inner layer of a single cell. Connecting cell walls connect the corresponding concave angle vertices of the outer and inner layers of the single cell. This metamaterial, through the interconnection design of the double-layer concave angle units, forms a synergistic deformation mechanism, resulting in more uniform and stable deformation under impact loads. Compared with traditional concave hexagonal or star-shaped single-layer negative Poisson's ratio structures, it has higher resistance to instability and overall deformation coordination. Figure 1 In the single cell unit, red represents the outer layer and blue represents the inner layer.

[0034] The inner and outer concave corner structures are interlocked. Due to the presence of interlayer constraint connecting the cell walls, the transverse contraction deformation is continuously guided, forcing the shear bands to migrate between layers rather than break through, thus significantly extending the negative Poisson's ratio maintenance interval.

[0035] The moment of inertia of the cross sections of the transverse and vertical connecting rods is much smaller than that of the outwardly inclined cell wall and the outer flat cell wall. This allows for elastic buckling in the initial stage of impact, reducing the overall stiffness to suppress the peak force. Subsequently, it guides the orderly formation of plastic hinges, achieving energy dissipation in stages.

[0036] In this embodiment, the finite element analysis software Abaqus was used to simulate the impact of the superstructure. The software uses T6061 aluminum alloy material to integrally mold the superstructure.

[0037] Then, low-speed impact, medium-speed impact, medium-high speed impact, and high-speed impact simulations were performed on the superstructure in the software, see [link / reference]. Figure 4-7 It demonstrates the deformation modes under various velocity impacts. As the velocity increases, the deformation mode transitions from overall deformation to local deformation, and different local deformation zones are generated.

[0038] To analyze the performance indicators of this superstructure, the following parameters were determined in the superstructure: L0 is the length of the outwardly inclined cell wall, L1 is the length of the inwardly inclined cell wall; L2 is the length of the transverse and vertical connecting rods, c is the length of the connecting cell wall, θ is the angle between the outwardly inclined cell wall and the transverse and vertical connecting rods respectively, t is the thickness of each cell wall, and the overall out-of-plane thickness of this concave-angle asymmetric double-layer negative Poisson's ratio superstructure is b; the following dimensionless parameters were determined: aspect ratio α0 = L0 / L2, wall thickness ratio β0 = t / L0, and inner-outer side length ratio γ = L0 / L1.

[0039] In the study of negative Poisson's ratio structures, the relative density of the structure refers to the ratio of the density of the negative Poisson's ratio structure to the density of the matrix material. Relative density is an important performance indicator describing the characteristics of negative Poisson's ratio structures. Due to the honeycomb structure characteristics of negative Poisson's ratio structures, according to the definition of relative density, its value ranges between 0 and 1. When the gaps between the unit cells of the structure are small and the cell walls are filled with matrix material, the density of the negative Poisson's ratio structure will tend to be the density of the matrix material, approaching 1. When the gaps between the unit cells of the negative Poisson's ratio structure are large and there is essentially no filling material between the structures, the relative density of the negative Poisson's ratio structure will approach 0. The size of the unit cells in the material is not directly related to the relative density; the relative density mainly depends on the structural shape of the unit cells. Therefore, establishing a mechanical model of the shape parameters and relative density of the unit cells of negative Poisson's ratio structures is of great significance.

[0040] Assuming the core material is homogeneous, the relative density of the concave-corner bilayer structure cell is:

[0041] (1)

[0042] In equation (1) ρ * ρ is the equivalent density of metamaterial cells. s For metamaterial cell material density, A * A represents the actual load-bearing area of ​​the metamaterial cell in the xy plane. s This represents the equivalent area of ​​a metamaterial cell.

[0043] Since the concave-angle polygonal negative Poisson's ratio honeycomb structure is a Y-axis symmetric structure, the actual load-bearing area of ​​its cell in the xy plane is:

[0044] A * =[t(6L0+3L2+2L0sinθ+6L1+3c+2L1sinθ]b (2)

[0045] Ignoring losses at the connections of the wall rods in the cell structure, the equivalent area of ​​its metamaterial is

[0046] A s =b[(2L0sinθ+2L2−2L0)(2L0sinθ+L2−L0cosθ)] (3)

[0047] The relative density of the structure can be calculated from the cell density and the density of the structural material. Therefore, the relative density of the concave polygonal negative Poisson's ratio honeycomb structure is:

[0048] (4)

[0049] Furthermore, to obtain the impact resistance performance of the concave-angled double-layer negative Poisson's ratio structure, a quantitative analysis was conducted on this superstructure. The plateau stress (σ) was selected. p The mechanical properties of a structure are evaluated using energy absorption (EA) and specific energy absorption (SEA). For negative Poisson's ratio structures, there are plateau stresses and plateau stress enhancement zones, with plateau stress σ... p The average of the two is used to represent:

[0050] (5)

[0051] In equation (5): σ(ℇ) — nominal stress due to nominal strain change;

[0052] ℇ y1 —The yield strain of the structure, that is, the nominal strain when the nominal compressive stress reaches the first stress peak;

[0053] ℇ d —Structural compaction strain.

[0054] To evaluate the energy absorption capacity of a structure in terms of lightweight materials, the performance of each structure is assessed using the energy dissipation per unit mass parameter. The total energy absorbed during plastic deformation of the structure can be expressed as:

[0055] (6)

[0056] In equation (6): RF(x) — the reaction force at the impact end;

[0057] x — compressive displacement;

[0058] S—Total displacement under compression.

[0059] Therefore, the energy absorbed per unit mass, SEA, is:

[0060] (7)

[0061] In equation (7), m represents the total mass of the entire honeycomb structure.

[0062] Figure 8 The image shows the stress-strain curves of the superstructure under different impact velocities. Figure 9 The curves shown in the image are the specific energy absorption curves of the superstructure at different impact velocities.

[0063] Table 1: Platform stress and specific energy absorption of the superstructure under different impact velocities

[0064]

[0065] Figure 9-10Table 1 shows that the stress and specific energy absorption of the superstructure increase with increasing velocity.

[0066] Figure 11 To simulate the dynamic Poisson's ratio of this negative Poisson's ratio superstructure at different velocities, the superstructure exhibits different horizontal contraction processes under different impact velocities, with the negative Poisson's ratio effect decreasing as the velocity increases. The superstructure demonstrates a better negative Poisson's ratio effect in the initial stage of medium-speed impacts, which weakens as the impact progresses. Under high-speed impacts, the superstructure exhibits a weak negative Poisson's ratio effect throughout the entire process.

[0067] Example 2: An application of the concave angle asymmetric double-layer negative Poisson's ratio superstructure in Example 1 above. This concave angle asymmetric double-layer negative Poisson's ratio superstructure is used in the impact protection parts of automobiles, airplanes, and drones, as well as in the impact protection parts of wearable protective devices. When applied, the bearing pressure plate on it faces outward to withstand the impact.

[0068] The following design parameters are set for parameter adjustments during the design and fabrication of this superstructure: L0 is the length of the outwardly inclined cell wall, L1 is the length of the inwardly inclined cell wall; L2 is the length of the transverse and vertical connecting rods, c is the length of the connecting cell wall, θ is the angle between the outwardly inclined cell wall and the transverse and vertical connecting rods respectively, t is the thickness of each cell wall, and the overall out-of-plane thickness of this concave-angle asymmetric double-layer negative Poisson's ratio superstructure is b; the following dimensionless parameters are determined: aspect ratio α0 = L0 / L2, wall thickness ratio β0 = t / L0, and inner / outer side length ratio γ = L0 / L1. The determination of these parameters allows for programmed adjustment of the Poisson's ratio during the design process: by adjusting geometric parameters such as the connecting rod length ratio and the concave angle, the Poisson's ratio can be controllably adjusted within a large range, thereby enabling customized design for different buffering and load-bearing requirements, improving the adaptability and predictability of the structure under various impact conditions. For example, as the angle θ decreases and the cell wall thickness t increases, the stress and specific energy absorption of the structure increase.

Claims

1. A concave corner asymmetric double-layer negative Poisson's ratio superstructure, comprising upper and lower ends of symmetrically arranged load-bearing plates and a plurality of unit cells arranged in the middle of the two plates, characterized in that: The single cell elements are arranged equidistantly along horizontal and vertical directions to form an m*n array, the single cell element comprises a double-layer inner recessed corner body, horizontal connecting rods on two sides and vertical connecting rods on the upper part, and the lower part of the double-layer inner recessed corner body is an outer flat cell wall, Ends of the horizontal connecting rods between horizontally adjacent single cell elements are connected integrally, Ends of the vertical connecting rods between vertically adjacent single cell elements are connected integrally with the outer flat cell wall.

2. The concave corner asymmetric double-layer negative Poisson's ratio superstructure of claim 1, wherein: The upper part, left side and right side of the double-layer inner recessed corner body are outer inclined cell walls forming an outer layer inner recessed corner structure, inner ends of the horizontal connecting rods and the vertical connecting rods are connected at corresponding inner recessed corner vertex positions respectively, the outer flat cell wall and the outer inclined cell wall jointly form an outer layer of the single cell element, inner flat cell walls and inner inclined cell walls arranged parallel to the outer flat cell wall and the outer inclined cell wall are arranged in the outer layer respectively, the inner inclined cell walls form upper, left and right inner layer inner recessed corner structures, the inner flat cell walls and the inner inclined cell walls jointly form an inner layer of the single cell element, and connecting cell walls are connected between corresponding inner recessed corner vertices of the outer layer and the inner layer of the single cell element.

3. The concave corner asymmetric double-layer negative Poisson's ratio superstructure of claim 2, wherein: The cross-sectional moment of inertia of the horizontal connecting rods and the vertical connecting rods is much smaller than that of the outer inclined cell wall and the outer flat cell wall.

4. The concave corner asymmetric dual-layer negative Poisson's ratio superstructure of claim 1, wherein: Ends of the vertical connecting rods of the single cell elements arranged horizontally in the uppermost row are connected with an upper bearing plate, and the outer flat cell walls of the single cell elements arranged horizontally in the lowermost row are connected with a lower bearing plate.

5. The use of the above-mentioned recessed corner asymmetric double-layer negative Poisson's ratio superstructure according to any one of claims 1-4, characterized in that: The inner recessed corner asymmetric double-layer negative Poisson's ratio superstructure is applied in impact-resistant protection parts of automobiles, airplanes and unmanned aerial vehicles, and in impact-resistant protection parts of wearable protection devices, and the upper bearing plate faces outward to bear impact when applied.

6. The use of a concave corner asymmetric dual-layer negative Poisson's ratio superstructure according to claim 5, characterized in that: The following design parameters are set for parameter adjustment during design and production of the superstructure: L0 is the length of the outer inclined cell wall, L1 is the length of the inner inclined cell wall, L2 is the length of the horizontal connecting rods and the vertical connecting rods, c is the length of the connecting cell walls, θ is the included angle between the outer inclined cell wall and the horizontal connecting rods and the vertical connecting rods respectively, t is the thickness of each cell wall, and the overall out-of-plane thickness of the inner recessed corner asymmetric double-layer negative Poisson's ratio superstructure is b; The following dimensionless parameters are determined: aspect ratio α0=L0 / L2, wall thickness ratio β0=t / L0, and inner-outer side length ratio γ=L0 / L1.

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