Shock injury protection pad based on horse-shoe microstructure three-dimensional flexible metamaterial

Abstract

The application discloses a kind of based on horseshoe-shaped microstructure three-dimensional flexible metamaterial impact injury protective pad, purpose is to solve the problem of explosion impact injury and blunt injury behind bulletproof vest, avoid stress wave in acoustic impedance mismatch interface multiple reflection transmission to human body cause harm.The present application is by the lower hexahedron, the first upper end hexahedron, the middle hexahedron, the second upper end hexahedron Irregular cuboid consisting of.N hexahedral horseshoe-shaped microstructure unit is arranged by space array mode and is connected by the vertex connection of hexahedral horseshoe-shaped microstructure unit.It is composed of 12 solid curved rods by the end point connection of solid curved rod, and the solid curved rod is connected by two center-symmetrical bending cylinders;The present application can produce longitudinal tensile and transverse compression deformation simultaneously, effectively limit internal local damage collapse, meet wearable demand, while taking into account buffering and energy absorption characteristics, can effectively protect explosion impact injury and blunt injury behind bulletproof vest.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of explosion impact protection, and particularly relates to a battlefield personnel impact injury protection structure, and more particularly relates to an impact injury protection pad based on a horseshoe-shaped microstructure three-dimensional flexible metamaterial. BACKGROUND

[0002] In modern wars and anti-terrorism conflicts, explosion injury has become the main factor of combat casualties. The types of injury mainly include fragment penetration injury, explosion impact injury and behind armor blunt trauma. Explosion impact injury refers to various injuries caused by the direct action of blast overpressure on the body after explosion, which belongs to primary explosion injury. Explosion impact injury is usually multiple injuries, combined injuries, and the injury condition develops rapidly. Behind armor blunt trauma (BABT) refers to the local blunt contusion caused by the partial energy of a bullet or a fragment penetrating the body after being blocked by body armor. Behind armor blunt trauma usually causes bleeding and tissue laceration of local organs such as heart and lung at the bullet point, and may also cause brain tissue damage due to the far-reaching effect. Therefore, as an important equipment for effectively protecting combat personnel, further improving the protection performance of body armor has important significance in the field of dealing with modern wars and anti-terrorism conflicts.

[0003] At present, body armor mainly consists of a cover, a bulletproof layer, a buffer layer and a bulletproof insert plate. The cover is usually made of chemical fiber fabric or woolen fabric, which protects the bulletproof layer and makes the appearance beautiful. The bulletproof layer is usually made of single or composite materials such as metal, aramid fiber (kevlar fiber), high-strength high-modulus polyethylene and polyimide fiber (PI fiber), which can deflect or embed the penetrating bullets or explosive fragments. The bulletproof insert plate is a kind of insert plate for enhancing the protection ability of the bulletproof layer, mainly used for protecting against the penetration of rifle direct-fire bullets and high-speed small fragments. The buffer layer is used to absorb impact energy and reduce non-penetrating injury.

[0004] In order to protect against explosion impact injury and behind armor blunt trauma, a common method is to add a porous energy-absorbing material as a pad structure (i.e. a buffer layer) behind the bulletproof insert plate to absorb the non-penetration energy of the bullet. Common protective materials include PE, EVA or TPU foams, which usually achieve the effect of buffering and energy absorption through plastic deformation, fracture and other mechanical behaviors. However, for traditional materials, the structural impact characteristics depend on fewer structural degrees of freedom, and the mechanical properties are difficult to quantitatively control and design. In addition, the mechanical properties of traditional materials and human skin are not well matched, which will cause deformation incoordination between equipment and personnel, thereby affecting the freedom and sensitivity of single soldier's action, in addition, the reflection and transmission of stress waves at the acoustic impedance mismatch interface will also cause harm to the human body.

[0005] In recent years, with the rapid development of the fields of tissue engineering, soft robots, wearable devices, etc., flexible metamaterials have attracted extensive attention from researchers. Flexible metamaterials are new topological materials that can be equivalent to the mechanical properties of biological tissues based on unconventional mechanics design, and their inspiration comes from the reticular microstructure composed of curved and chain collagen fibers in soft biological tissues. Based on the inspiration from biological tissues, Jang et al. designed a three-dimensional flexible metamaterial with a horseshoe-shaped microstructure composed of two center-symmetric circular arc units. Due to the characteristics of the curved units, this type of metamaterial will undergo a transition from a bending-dominated mode to a tension-dominated mode when subjected to tension, thereby exhibiting a nonlinear J-shaped stress-strain response behavior (i.e., this type of metamaterial produces a low modulus response at a relatively small strain, and then sharply transitions to a high modulus response for a larger strain, see Jang K, Chung H U, Xu S, et al. Soft network composite materials with deterministic and bio-inspired designs [J]. Nature Communications, 2015, 6: 6566, i.e., the paper "Soft network composite materials with deterministic and bio-inspired designs" by Jang K, Chung H U, Xu S, et al. published in the journal Nature Communications in 2015) and higher ductility. By adjusting the parameters of the circular arc units, the mechanical properties can be controlled to accurately match the nonlinear characteristics of biological tissues. In the compression process, due to the influence of the Poisson's ratio effect, the three-dimensional flexible metamaterial with a horseshoe-shaped microstructure will produce a similar response along the in-plane vertical direction as the tension effect, and can play a good buffering and energy absorption role when subjected to impact. It has been widely used in the fields of soft biomedical devices and tissue engineering structures (see Jang K, Chung H U, Xu S, et al. Soft network composite materials with deterministic and bio-inspired designs [J]. Nature Communications, 2015, 6: 6566, i.e., the paper "Soft network composite materials with deterministic and bio-inspired designs" by Jang K, Chung H U, Xu S, et al. published in the journal Nature Communications in 2015). However, there is no public literature on the application of three-dimensional flexible metamaterials with a horseshoe-shaped microstructure in the field of impact injury protection structures.

[0006] Therefore, in order to meet the protection needs of modern war and anti-terrorism conflict, designing an effective protection pad structure for protecting explosion impact injury and blunt injury after wearing body armor is a technical problem that the person skilled in the art is extremely concerned about. SUMMARY

[0007] The technical problem to be solved by the present application is to provide an impact injury protection pad based on a horse-shoe-shaped microstructure three-dimensional flexible metamaterial, to solve the problems of explosion impact injury and blunt injury after wearing body armor caused by the development of high-energy weapons in modern war, to make up for the shortcomings of traditional materials and human skin mechanical properties mismatch, wearing discomfort, restricting the freedom and acuteness of single soldier action, and to avoid the harm to the human body caused by the multiple reflection and transmission of stress waves at the sound impedance mismatch interface.

[0008] The flexible metamaterial has the characteristics of double elastic stage because the horse-shoe-shaped microstructure configuration exists in the mode conversion behavior from bending dominant type to tensile dominant type in the stretching and compression process, that is, even in the case of low initial modulus, the energy absorption effect can be improved by increasing the modulus after mode conversion, and the load can be buffered and dissipated. In addition, the flexible metamaterial can adjust its mechanical properties by changing the unit parameters, so that it can match the stress and strain response of the skin. Therefore, reasonable design of the spatial topology configuration of the horse-shoe-shaped microstructure metamaterial can construct a protection pad structure with adjustable mechanical properties, excellent energy absorption characteristics, and impedance characteristics matching the human body.

[0009] The present application arranges the hexahedral horse-shoe-shaped microstructure unit configuration repeatedly to construct a body armor protection pad structure, which meets the wearing comfort demand on the basis of effectively protecting explosion impact injury and blunt injury after wearing body armor.

[0010] The technical solution of the present application is:

[0011] The application provides a shock injury protection pad based on a horseshoe-shaped microstructure three-dimensional flexible metamaterial, which is used in cooperation with a bulletproof insert plate. According to the standard document of NIJ 0101 06 "bulletproof performance of bulletproof clothes", the overall length L of the shock injury protection pad based on the horseshoe-shaped microstructure three-dimensional flexible metamaterial is not more than 254 mm, and the overall width W is not more than 305 mm. Let the side close to the head of the human tissue be the upper side, the side away from the head of the human tissue be the lower side, the side close to the heart of the human tissue be the left side, and the side away from the heart of the human tissue be the right side. The application is an irregular cube composed of a lower hexahedron, a first upper hexahedron, a middle hexahedron and a second upper hexahedron. The upper end surface of the lower hexahedron is connected with the lower end surfaces of the first upper hexahedron, the middle hexahedron and the second upper hexahedron; the first upper hexahedron and the second upper hexahedron are symmetrically located on the two sides of the middle hexahedron; the right end surface of the first upper hexahedron is connected with the left end surface of the middle hexahedron, and the lower end surface is connected with the upper end surface of the lower hexahedron; the left end surface of the second upper hexahedron is connected with the right end surface of the middle hexahedron, and the lower end surface is connected with the upper end surface of the lower hexahedron; the left end surface of the middle hexahedron is connected with the right end surface of the first upper hexahedron, the right end surface is connected with the left end surface of the second upper hexahedron, and the lower end surface is connected with the upper end surface of the lower hexahedron. The inner structure of the shock injury protection pad based on the horseshoe-shaped microstructure three-dimensional flexible metamaterial is composed of N hexahedron horseshoe-shaped microstructure unit cells arranged in a space array mode (i.e. the hexahedron horseshoe-shaped microstructure unit cells are arranged in a repeated translation mode) through the vertex connection of the hexahedron horseshoe-shaped microstructure unit cells, and N is determined by the overall length L and the overall width W of the application, and satisfies 3000 < N < 5000.

[0012] The overall length L of the application is not more than 254 mm, the overall width W is not more than 305 mm, and the overall thickness H satisfies 0 mm < H < 10 mm; the length of the lower hexahedron of the application is equal to L, and the width W1 satisfies 176 mm < W1 < 264 mm. The two hexahedrons on the left side and the right side of the upper end of the application are symmetrically the same, the length L1 satisfies L1 < L / 2, preferably 44.8 mm < L1 < 67.2 mm, the width W2 satisfies W2 < W / 2, preferably 64 mm < W2 < 96 mm, the length L2 of the hexahedron located at the middle position of the upper end of the application satisfies L2 < L / 2, preferably 48 mm < L2 < 72 mm, and the width W3 satisfies W3 < W / 2, preferably 38.4 mm < W3 < 57.6 mm. Let the side close to the human tissue be the inner side, and the application is installed on the inner side of the bulletproof insert plate of the bulletproof clothes.

[0013] The application is divided into inner and outer two-layer structures, and the two-layer structures are symmetrically the same and connected through the vertex connection of the hexahedron horseshoe-shaped microstructure unit cells.

[0014] The hexahedral horseshoe microstructure cell is composed of 12 solid curved rods (i.e., flexible metamaterial horseshoe structure) connected by the end points of the 12 solid curved rods, wherein the 8 common end points of the 12 solid curved rods collectively form the 8 vertices of the hexahedral horseshoe microstructure cell. The inner end face (i.e., the end face close to the human body) of the hexahedral horseshoe microstructure cell is connected with the outer end face (i.e., the end face away from the human body) of the hexahedral horseshoe microstructure cell by the ninth solid curved rod and the tenth solid curved rod located on the upper end face, and the eleventh solid curved rod and the twelfth solid curved rod located on the lower end face. The inner end face of the hexahedral horseshoe microstructure cell is parallel to the outer end face of the hexahedral horseshoe microstructure cell and has the same shape. The inner end face of the hexahedral horseshoe microstructure cell is a windmill-shaped structure composed of the first solid curved rod, the second solid curved rod, the third solid curved rod and the fourth solid curved rod connected end to end through the end points of the solid curved rods, wherein the vertex of the windmill-shaped structure coincides with the vertex of the hexahedral horseshoe structure cell. The outer end face of the hexahedral horseshoe microstructure cell is a windmill-shaped structure composed of the fifth solid curved rod, the sixth solid curved rod, the seventh solid curved rod and the eighth solid curved rod connected end to end through the end points of the solid curved rods, wherein the vertex of the windmill-shaped structure coincides with the vertex of the hexahedral horseshoe structure cell. The connection points of the ninth solid curved rod, the tenth solid curved rod, the eleventh solid curved rod and the twelfth solid curved rod coincide with the vertexes of the windmill-shaped structures of the inner and outer end faces of the hexahedral horseshoe microstructure cell. The ninth solid curved rod and the tenth solid curved rod have the same direction of the circular arc, and the eleventh solid curved rod and the twelfth solid curved rod have the same direction of the circular arc, but the direction of the circular arc of the ninth solid curved rod is opposite to that of the eleventh solid curved rod.

[0015] The solid curved rod (i.e., flexible metamaterial horseshoe structure) is composed of two first curved cylindrical bodies and a second curved cylindrical body connected along the center O. The first curved cylindrical body and the second curved cylindrical body have the same diameter t, and t is about 1 mm. The center axes of the first curved cylindrical body and the second curved cylindrical body are both a circular arc. The circular arcs of the first curved cylindrical body and the second curved cylindrical body are opposite in direction. Considering the buffering characteristics of the flexible metamaterial, the central angle θ of the circular arc is an obtuse angle, and satisfies The volume of the solid curved rod is mainly controlled by the radius R of the circular arc. If the volume of the solid curved rod is too large, the coordination and comfort of the body armor will be affected. If the volume of the solid curved rod is too small, it is difficult to meet the requirements of the 3D printing process. Therefore, the lower circular arc radius R satisfies 0.8mm<R<1.2mm.

[0016] To ensure the accuracy of the solid curved rod curved edge and the consistency of the hexahedral horseshoe-shaped microstructure cell shape, a 3D printing technology is used to prepare an impact injury protection pad based on a horseshoe-shaped microstructure three-dimensional flexible metamaterial. In order to consider the buffering and energy absorption effect, a polymer material with good plastic deformation ability and strong viscoelastic response (such as ZR680, TPU, Nylom12) is selected, the dynamic modulus E of the material along the printing direction satisfies E<2 GPa, the yield stress σ satisfies σ<50 MPa, and the elongation at break e satisfies e<50%. The mass M of the present application satisfies 45g<M<75g, which meets the lightweight requirement.

[0017] To explore the advantages of the present application in terms of deformation failure mode compared with traditional truss structure, static mechanical property test experiment is carried out, and quasi-static compression experiment is carried out with the help of universal testing machine, and camera is set up to record the deformation failure behavior of metamaterial in compression process. The experimental results are shown in Figure 6 When the strain ε is equal to 0, the traditional truss structure is in the initial state; when the strain ε is equal to 0.125, the traditional truss structure produces longitudinal displacement along the z-axis direction, but because of the initial defect and disturbance of the traditional truss structure, instability is observed in the second layer, so that the traditional truss structure produces transverse displacement along the y direction at the same time in the second layer, and instability occurs; when the strain ε is equal to 0.25, the traditional truss structure continues to produce longitudinal displacement along the z-axis direction, in addition to which local damage and collapse occur in the second layer, and the buffering and energy absorption effect decreases. On the contrary, as shown in Figure 7 When the strain ε is equal to 0, the present application is in the initial state; when the strain ε is equal to 0.125, the flexible metamaterial horseshoe-shaped structure of the present application can produce longitudinal tensile and transverse compression deformation at the same time because of its unique structure, effectively limiting the local damage and collapse in the interior, showing good stability, and the overall deformation is mainly longitudinal displacement along the z-axis direction; when the strain ε is equal to 0.25, the present application shows good stability, the overall deformation is still longitudinal displacement along the z-axis direction, and no local collapse and damage occur, the buffering and energy absorption effect is good, and the problems of explosion impact injury and blunt injury behind the bulletproof vest caused by the development of high-energy weapons can be effectively solved.

[0018] The specific process of protecting the battlefield personnel from impact injury by adopting the present application is as follows: firstly, the impact injury protection pad based on the three-dimensional flexible metamaterial of the horse-shoe-shaped microstructure is respectively placed in the inner side of the bulletproof insert plate of the bulletproof vest, then during the process of dynamic impact load, the present application produces longitudinal tensile and transverse compression deformation simultaneously when subjected to explosion impact and blunt impact, the bending dominant mode (hexahedral horse-shoe-shaped microstructure unit bending deformation dominant) is converted into the tensile dominant mode (hexahedral horse-shoe-shaped microstructure unit tensile deformation dominant), the nonlinear J stress-strain response behavior and higher ductility are presented, the local damage collapse in the present application is effectively limited, the deformation stability of the pad structure is improved, and the buffering and energy absorption capacity of the present application is effectively improved. Meanwhile, the present application has simple structure, light weight, high strength, and good coincidence with the biomechanical properties of human tissues, and meets the wearing comfort requirement, and improves the freedom and acuteness of individual combat.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] 1. When subjected to tensile action, the present application produces the conversion from the bending dominant mode to the tensile dominant mode, presents the nonlinear J stress-strain response behavior and higher ductility, takes into account the buffering and energy absorption characteristics, improves the protection performance of the present application, and avoids the damage to the human body caused by the multiple reflection and transmission of stress waves at the acoustic impedance mismatch interface.

[0021] 2. When subjected to blunt impact, the hexahedral horse-shoe-shaped microstructure unit can produce longitudinal tensile and transverse compression deformation simultaneously due to its unique structure, effectively limits the local damage collapse in the unit, improves the deformation stability of the present application, and effectively solves the problems of explosion impact injury and post-bulletproof vest blunt injury caused by the development of high-energy weapons.

[0022] 3. The present application has good mechanical stability and microstructure deformation capacity, simple structure, light weight, high strength, and strong designability, and has good coincidence with the biomechanical properties of human tissues, makes up for the problem that the mechanical properties of traditional materials and human skin do not match, meets the wearing comfort requirement, and improves the freedom and acuteness of individual combat.

[0023] The present application has simple structure, good coincidence with the biomechanical properties of human tissues, can not only meet the wearable requirement, but also take into account the buffering and energy absorption characteristics, can effectively protect against explosion impact injury and post-bulletproof vest blunt injury, and has important significance in the field of coping with modern war and anti-terrorism conflict. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a three-dimensional overall structure schematic diagram of the present application, and the right circle is an enlarged three-dimensional structure schematic diagram of a hexahedral horse-shoe-shaped microstructure unit 5;

[0025] Figure 2 This is a main view of the overall structure of the present invention. The circle on the left shows an enlarged main view of a hexahedral horseshoe-shaped microstructure unit cell 5.

[0026] Figure 3 This is a top view of the overall structure of the present invention. The circle on the right shows an enlarged top view of a hexahedral horseshoe-shaped microstructure unit cell 5.

[0027] Figure 4 This is a schematic diagram of a hexahedral horseshoe-shaped microstructure unit cell 5 of the present invention, wherein... Figure 4 (a) is a three-dimensional structural diagram of a hexahedral horseshoe-shaped microstructure unit cell 5. Figure 4 (b) is a front view of the front face of the hexahedral horseshoe-shaped microstructure unit cell 5. Figure 4 (c) is the front view of the rear end face of unit cell 5 of the hexahedral horseshoe-shaped microstructure. Figure 4 (d) is an enlarged structural schematic diagram of a solid curved rod 7;

[0028] Figure 5 This is a schematic diagram of the solid curved rod 7 (i.e., the horseshoe-shaped microstructure of flexible metamaterial) of the present invention;

[0029] Figure 6 This refers to the deformation failure behavior of traditional truss structures during static mechanical performance testing.

[0030] Figure 7 This invention describes the deformation failure behavior during static mechanical performance testing. Detailed Implementation

[0031] To facilitate understanding and implementation of the present invention by those skilled in the art, the following description, in conjunction with the accompanying drawings and specific examples, is provided.

[0032] The present invention will be clearly and completely described in this embodiment.

[0033] This invention provides an impact protection pad based on a horseshoe-shaped microstructure three-dimensional flexible metamaterial, used in conjunction with a ballistic insert. According to the NIJ 0101 06 standard document "Bulletproof Performance of Bulletproof Vests," the overall length L of the impact protection pad based on the horseshoe-shaped microstructure three-dimensional flexible metamaterial should not exceed 254 mm, and the overall width W should not exceed 305 mm. Let the side closer to the head be the upper side, the side farther from the head be the lower side, the side closer to the heart be the left side, and the side farther from the heart be the right side, as follows... Figure 1As shown, the present application is an irregular cuboid composed of a lower hexahedron 1, a first upper hexahedron 2, an intermediate hexahedron 3, and a second upper hexahedron 4. The upper end face of the lower hexahedron 1 is connected to the lower end faces of the first upper hexahedron 2, the intermediate hexahedron 3, and the second upper hexahedron 4. The first upper hexahedron 2 and the second upper hexahedron 4 are symmetrically located on the two sides of the intermediate hexahedron 3. The right end face of the first upper hexahedron 2 is connected to the left end face of the intermediate hexahedron 3, and the lower end face is connected to the upper end face of the lower hexahedron 1. The left end face of the second upper hexahedron 4 is connected to the right end face of the intermediate hexahedron 3, and the lower end face is connected to the upper end face of the lower hexahedron 1. The left end face of the intermediate hexahedron 3 is connected to the right end face of the first upper hexahedron 2, the right end face is connected to the left end face of the second upper hexahedron 4, and the lower end face is connected to the upper end face of the lower hexahedron 1. As shown in the enlarged three-dimensional structure diagram of the hexahedral horseshoe-shaped microstructure unit cell 5 in the right circle, the inner structure of the impact injury protection pad based on the horseshoe-shaped microstructure three-dimensional flexible metamaterial is composed of N hexahedral horseshoe-shaped microstructure unit cells 5 arranged in a spatial array (i.e., the hexahedral horseshoe-shaped microstructure unit cells 5 are arranged in a repeated translation manner) connected by the hexahedral horseshoe-shaped microstructure unit cell vertices 6. 3000<N<5000. Figure 1 As shown in the enlarged three-dimensional structure diagram of the hexahedral horseshoe-shaped microstructure unit cell 5 in the right circle, the inner structure of the impact injury protection pad based on the horseshoe-shaped microstructure three-dimensional flexible metamaterial is composed of N hexahedral horseshoe-shaped microstructure unit cells 5 arranged in a spatial array (i.e., the hexahedral horseshoe-shaped microstructure unit cells 5 are arranged in a repeated translation manner) connected by the hexahedral horseshoe-shaped microstructure unit cell vertices 6. 3000<N<5000.

[0034] As shown in the enlarged three-dimensional structure diagram of the hexahedral horseshoe-shaped microstructure unit cell 5 in the right circle, the inner structure of the impact injury protection pad based on the horseshoe-shaped microstructure three-dimensional flexible metamaterial is composed of N hexahedral horseshoe-shaped microstructure unit cells 5 arranged in a spatial array (i.e., the hexahedral horseshoe-shaped microstructure unit cells 5 are arranged in a repeated translation manner) connected by the hexahedral horseshoe-shaped microstructure unit cell vertices 6. 3000<N<5000. Figure 2 As shown, the overall length L of the present application is not more than 254 mm, the overall width W is not more than 305 mm, and the overall thickness H satisfies 0mm<H<10mm. The length of the lower hexahedron 1 is equal to L, and the width W1 satisfies 176mm<W1<264mm. The first upper hexahedron 2 and the second upper hexahedron 4 have the same shape and are symmetrically located on the two sides of the intermediate hexahedron 3. The length L1 of the first upper hexahedron 2 satisfies 44.8mm<L1<67.2mm, the width W2 satisfies 64mm<W2<96mm, the length L2 of the intermediate hexahedron 3 satisfies 48mm<L2<72mm, and the width W3 satisfies 38.4mm<W3<57.6mm. Let the side close to the human tissue be the inner side, and the present application is installed on the inner side of the bulletproof insert plate of the bulletproof vest. Figure 3 As shown, the present application is divided into inner and outer two-layer structures, and the two-layer structures are symmetrically the same and connected by the hexahedral horseshoe-shaped microstructure unit cell vertices 6.

[0035] As shown in the enlarged three-dimensional structure diagram of the hexahedral horseshoe-shaped microstructure unit cell 5 in the right circle, the inner structure of the impact injury protection pad based on the horseshoe-shaped microstructure three-dimensional flexible metamaterial is composed of N hexahedral horseshoe-shaped microstructure unit cells 5 arranged in a spatial array (i.e., the hexahedral horseshoe-shaped microstructure unit cells 5 are arranged in a repeated translation manner) connected by the hexahedral horseshoe-shaped microstructure unit cell vertices 6. 3000<N<5000. Figure 4(a) as shown, the hexahedral horse-shoe microstructure unit cell 5 is composed of 12 solid curved rods 7 (i.e. flexible metamaterial horse-shoe structure) connected by solid curved rod end points 8, wherein 8 common end points of the 12 solid curved rods 7 together form 8 vertices 6 of the hexahedral horse-shoe microstructure unit cell. The inner end face of the hexahedral horse-shoe microstructure unit cell 5 (i.e. the end face close to the human body) and the outer end face of the hexahedral horse-shoe microstructure unit cell 5 (i.e. the end face away from the human body) are connected by the ninth solid curved rod 79, the tenth solid curved rod 710 located on the upper end face, the eleventh solid curved rod 711, the twelfth solid curved rod 712 located on the lower end face, the inner end face of the hexahedral horse-shoe microstructure unit cell 5 is parallel to the outer end face of the hexahedral horse-shoe microstructure unit cell 5 and has the same shape. As Figure 4 (c) as shown, the inner end face of the hexahedral horse-shoe microstructure unit cell 5 is a windmill structure composed of the first solid curved rod 71, the second solid curved rod 72, the third solid curved rod 73, the fourth solid curved rod 74 connected end to end by the solid curved rod end points 8, wherein the windmill structure vertex 9 coincides with the hexahedral horse-shoe structure unit cell vertex 6; as Figure 4 (b) as shown, the outer end face of the hexahedral horse-shoe microstructure unit cell 5 is a windmill structure composed of the fifth solid curved rod 75, the sixth solid curved rod 76, the seventh solid curved rod 77, the eighth solid curved rod 78 connected end to end by the solid curved rod end points 8; the connection points of the ninth solid curved rod 79, the tenth solid curved rod 710, the eleventh solid curved rod 711, the twelfth solid curved rod 712 coincide with the windmill structure vertices 9 of the inner and outer end faces of the hexahedral horse-shoe microstructure unit cell 5. As Figure 4 (a) as shown, the ninth solid curved rod 79 and the tenth solid curved rod 710 have the same direction of circular arc, the eleventh solid curved rod 711 and the twelfth solid curved rod 712 have the same direction of circular arc, but the direction of circular arc of the ninth solid curved rod 79 is opposite to that of the eleventh solid curved rod 711.

[0036] As Figure 5 shown, the solid curved rod (i.e. flexible metamaterial horse-shoe structure) is composed of two first curved cylindrical bodies 10 and second curved cylindrical bodies 11 connected along the center O symmetry; the first curved cylindrical body 10 and the second curved cylindrical body 11 have the same diameter t, which is about 1mm; the center axes of the first curved cylindrical body 10 and the second curved cylindrical body 11 are both a circular arc, the circular arcs of the first curved cylindrical body 10 and the second curved cylindrical body 11 are opposite, considering the buffering characteristics of the flexible metamaterial, the circular arc central angle θ satisfies , the volume of the solid curved rod 7 is mainly controlled by the circular arc radius R, if the volume of the solid curved rod 7 is too large, it will affect the coordination and comfort of the body armor, if the volume is too small, it is difficult to meet the requirements of 3D printing process, therefore, the lower circular arc radius R satisfies 0.8mm<R<1.2mm.

[0037] To ensure the accuracy of the curved edge of the solid curved rod 7 and the consistency of the hexahedral horseshoe-shaped microstructure unit cell 5, a 3D printing technology is used to prepare the impact injury protection pad based on the horseshoe-shaped microstructure three-dimensional flexible metamaterial. In order to consider the buffering and energy absorption effect, a high-molecular polymer material with good plastic deformation ability and strong viscoelastic response (such as ZR680, TPU, Nylom12) is selected. The dynamic modulus E of the material along the printing direction satisfies E<2 GPa, the yield stress σ satisfies σ<50 MPa, and the elongation at break e satisfies e<50%. The mass M of the present application satisfies 45g<M<75g, which meets the requirement of lightness.

[0038] To verify the effect of the present application, the embodiment 1 of the present application is prepared by using the 3D printing technology, the high-molecular polymer material is Nylom12, N=4205, W=300mm, L=252mm, H=8mm, W1=220mm, L1=56mm, W2=80mm, L2=60mm, W3=48mm, t=1mm, θ=180°, R=1mm. The mass M of the embodiment 1 is 63.075g.

[0039] To explore the advantage of the present application in the deformation failure mode compared with the traditional truss structure, a static mechanical property test experiment is carried out, and a quasi-static compression experiment is carried out with the help of a universal testing machine, and a camera is set up to record the deformation failure behavior of the metamaterial in the compression process. The experimental results are shown in Figure 6 As shown in the figure, when the strain ε is equal to 0, the traditional truss structure is in the initial state; when the strain ε is equal to 0.125, the traditional truss structure produces longitudinal displacement along the z-axis direction as a whole, but because of the initial defects and disturbances of the traditional truss structure, instability is observed in the second layer, which causes the traditional truss structure to produce transverse displacement along the y direction at the same time, and instability occurs; when the strain ε is equal to 0.25, the traditional truss structure continues to produce longitudinal displacement along the z-axis direction as a whole, in addition to this, local damage and collapse occur in the second layer, and the buffering and energy absorption effect decreases. On the contrary, as shown in Figure 7 As shown in the figure, when the strain ε is equal to 0, the present application is in the initial state; when the strain ε is equal to 0.125, the flexible metamaterial horseshoe-shaped structure of the present application can produce longitudinal tensile and transverse compression deformation at the same time because of its unique structure, which effectively limits the local damage and collapse in the interior, and shows good stability, and the overall deformation is mainly longitudinal displacement along the z-axis direction; when the strain ε is equal to 0.25, the present application shows good stability, and the overall deformation is still longitudinal displacement along the z-axis direction, and no local collapse and damage occur, and the buffering and energy absorption effect is good, which can effectively solve the problems of explosion impact injury and blunt injury behind the bulletproof vest caused by the development of high-energy weapons.

[0040] The above is only one research idea and implementation mode of the present application. The specific structure and size can be adjusted according to actual needs. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the protection scope of the present application patent.

Claims

1. A shock injury protection pad based on a three-dimensional flexible metamaterial of horse-shoe shaped microstructures, characterized in that The overall length of the impact injury protection pad based on the horse-shoe-shaped microstructure three-dimensional flexible metamaterial is L, the overall width is W, and the overall thickness is H; the side close to the head of the human tissue is the upper side, the side away from the head of the human tissue is the lower side, the side close to the heart of the human tissue is the left side, and the side away from the heart of the human tissue is the right side; the impact injury protection pad based on the horse-shoe-shaped microstructure three-dimensional flexible metamaterial is an irregular cube composed of a lower hexahedron (1), a first upper hexahedron (2), a middle hexahedron (3), and a second upper hexahedron (4); the upper end surface of the lower hexahedron (1) is connected with the lower end surfaces of the first upper hexahedron (2), the middle hexahedron (3), and the second upper hexahedron (4); the first upper hexahedron (2) and the second upper hexahedron (4) are symmetrically located on the two sides of the middle hexahedron (3); the right end surface of the first upper hexahedron (2) is connected with the left end surface of the middle hexahedron (3); the left end surface of the second upper hexahedron (4) is connected with the right end surface of the middle hexahedron (3); the inner side structure of the impact injury protection pad based on the horse-shoe-shaped microstructure three-dimensional flexible metamaterial is composed of N hexahedron horse-shoe-shaped microstructure unit cells (5) connected through the hexahedron horse-shoe-shaped microstructure unit cell vertexes (6) in a spatial array arrangement manner, and N is a positive integer; The length of the lower hexahedron (1) is equal to L, and the width is W1 < W; the first upper hexahedron (2) and the second upper hexahedron (4) have the same shape structure; the length of the first upper hexahedron (2) is L1 < L / 2, and the width W2 satisfies W2 < W / 2; the length of the middle hexahedron (3) is L2 < L / 2, and the width W3 < W / 2; the side close to the human tissue is the inner side, and the impact injury protection pad based on the horse-shoe-shaped microstructure three-dimensional flexible metamaterial is installed on the inner side of the bulletproof plugboard of the bulletproof vest; The impact injury protection pad based on the horse-shoe-shaped microstructure three-dimensional flexible metamaterial is divided into inner and outer two-layer structures, and the two-layer structures are symmetrical and the same and are connected through the hexahedron horse-shoe-shaped microstructure unit cell vertexes (6). The hexahedral horse-shoe microstructure unit cell (5) is composed of 12 solid curved rods (7) connected by solid curved rod end points (8), the solid curved rods (7) are flexible metamaterial horse-shoe microstructures; 8 common end points of the 12 solid curved rods (7) jointly form 8 vertices (6) of the hexahedral horse-shoe microstructure unit cell; the inner end face of the hexahedral horse-shoe microstructure unit cell (5) and the outer end face of the hexahedral horse-shoe microstructure unit cell (5) are connected by the ninth solid curved rod (79) and the tenth solid curved rod (710) located on the upper end face, the eleventh solid curved rod (711) and the twelfth solid curved rod (712) located on the lower end face, the inner end face of the hexahedral horse-shoe microstructure unit cell (5) is parallel to the outer end face of the hexahedral horse-shoe microstructure unit cell (5) and has the same shape; the inner end face of the hexahedral horse-shoe microstructure unit cell (5) is a windmill-shaped structure composed of the first solid curved rod (71), the second solid curved rod (72), the third solid curved rod (73) and the fourth solid curved rod (74) connected head to tail through the solid curved rod end points (8), wherein the windmill-shaped structure vertex (9) coincides with the hexahedral horse-shoe microstructure vertex (6); the outer end face of the hexahedral horse-shoe microstructure unit cell (5) is a windmill-shaped structure composed of the fifth solid curved rod (75), the sixth solid curved rod (76), the seventh solid curved rod (77) and the eighth solid curved rod (78) connected head to tail through the solid curved rod end points (8); the connecting points of the ninth solid curved rod (79), the tenth solid curved rod (710), the eleventh solid curved rod (711) and the twelfth solid curved rod (712) coincide with the windmill-shaped structure vertices (9) of the inner and outer end faces of the hexahedral horse-shoe microstructure unit cell (5); the circular arc directions of the ninth solid curved rod (79) and the tenth solid curved rod (710) are the same, the circular arc directions of the eleventh solid curved rod (711) and the twelfth solid curved rod (712) are the same, but the circular arc direction of the ninth solid curved rod (79) is opposite to that of the eleventh solid curved rod (711); The solid curved rod (7) is composed of two first curved cylindrical bodies (10) and second curved cylindrical bodies (11) connected along the center O; the first curved cylindrical body (10) and the second curved cylindrical body (11) have equal diameters, both being t; the center axes of the first curved cylindrical body (10) and the second curved cylindrical body (11) are both circular arcs, the circular arcs of the first curved cylindrical body (10) and the second curved cylindrical body (11) are opposite, the circular arc central angle θ is an obtuse angle, and the volume of the solid curved rod (7) is regulated by the circular arc radius R.

2. The impact injury protection pad based on three-dimensional flexible metamaterial of horse-shoe microstructure of claim 1, wherein The L is not more than 254 mm, the W is not more than 305 mm, the H satisfies 0 mm < H < 10 mm, and the N satisfies 3000 < N < 5000.

3. The impact injury protection pad based on three-dimensional flexible metamaterials of horse-shoe microstructure according to claim 1, characterized in that The width W1 of the lower hexahedron (1) satisfies 176mm < W1 < 264mm; the length L1 of the first upper hexahedron (2) satisfies 44.8mm < L1 < 67.2mm, the width W2 satisfies 64mm < W2 < 96mm, the length L2 of the middle hexahedron (3) satisfies 48mm < L2 < 72mm, and the width W3 satisfies 38.4mm < W3 < 57.6mm.

4. The impact injury protection pad based on three-dimensional flexible metamaterials of horse-shoe microstructure according to claim 1, characterized in that t of the solid curved rod (7) is 1 mm, θ satisfies R satisfies 0.8 mm < R < 1.2 mm.

5. The impact injury protection pad based on three-dimensional flexible metamaterials of horse-shoe microstructure according to claim 1, characterized in that The impact injury protection pad based on the horseshoe-shaped microstructure three-dimensional flexible metamaterial is prepared by using a 3D printing technology of a polymer polymer material.

6. The impact injury protection pad based on three-dimensional flexible metamaterials of horse-shoe microstructure according to claim 5, characterized in that The polymer polymer material requires that a dynamic modulus E along a printing direction satisfies E < 2 GPa, a yield stress sigma satisfies sigma < 50 MPa, and a breaking elongation e satisfies e < 50%.

7. The impact injury protection pad based on three-dimensional flexible metamaterials of horse-shoe microstructure according to claim 6, characterized in that The polymer polymer material is any one of ZR680, TPU and Nylom12.

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