A sudden elastic jump level hyperbolic beam multi-stable energy-absorbing structure

Abstract

The application discloses a sudden elastic jump hierarchical hyperbolic beam multi-stable metamaterial repeatable energy absorption structure, and belongs to the technical field of mechanical multi-stable metamaterials, which comprises m layers of multi-stable structure units, each layer of multi-stable structure unit is formed by sequentially connecting the same number of n hyperbolic beam single cells in a pipe-shaped structure, and each layer of multi-stable structure unit is sequentially stacked along the axis of the pipe-shaped structure; the hyperbolic beam single cell comprises a hyperbolic beam, an intermediate connecting rod and two side rods. The sudden elastic jump hierarchical hyperbolic beam multi-stable metamaterial repeatable energy absorption structure provided by the application is a layered metamaterial with a three-dimensional pipe-shaped geometric shape, which is designed based on the sudden elastic jump characteristics of the hyperbolic beam single cell, has multi-stable, multi-energy absorption platform and multi-step deformation capacity, and has higher strength and stability, higher efficiency and weight optimization, and greater manufacturing and installation convenience.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of sudden elastic jump level double curved beam multi-stable metamaterial repeat energy absorption structure, belong to mechanics multi-stable metamaterial technical field. BACKGROUND

[0002] Energy absorption structures and materials are widely used to protect humans and objects from impacts or collisions, such as spacecraft landing cushioning devices, automobile bumpers, bulletproof glass, helmets, and packaging of fragile objects, etc. Numerous methods have been proposed to improve the energy absorption characteristics of materials and structures. Previous research has mainly focused on the plastic large deformation energy absorption of metal materials and the fracture energy absorption of composite materials or ceramics during fragmentation. However, both of these energy absorption methods require high-quality materials, limiting their application range. Moreover, these materials undergo irreversible deformation or permanent damage during impact, which is not economical and environmentally friendly.

[0003] In dynamic systems, multi-stability is a state property, i.e., there are multiple stable equilibrium points in the vector space formed by the state of the system, and there are also some unstable equilibrium points between the stable equilibrium points. Multi-stable mechanical metamaterials are a new type of artificial material with special mechanical properties and stability, which can provide several different stable configurations through a microstructure. To meet the requirements of lightweight, impact-resistant, and shock-absorbing components in aerospace, transportation, and construction engineering, the repeatable elastic energy absorption characteristics of multi-stable phase transition structures are utilized to design reusable cushioning and energy absorption structures, and the development of lightweight metamaterials with high mechanical properties will provide more economical, convenient, and safe protection for future spacecraft landing cushions, engineering structure seismic resistance, and ship and bridge collision absorption.

[0004] Patent application CN115596799A discloses a "modular multi-stable metamaterial structure with adjustable mechanical properties," which includes adjustable mechanical properties of a single cell, a horizontal long connecting rod, and a vertical short connecting rod. It can be assembled into a modular multi-stable metamaterial according to needs, thereby achieving vibration isolation and noise reduction. In this structure, the number of single cell structures is adjusted, and the geometry of the curved beam single cell is changed to adjust the mechanical behavior of the multi-stable metamaterial. However, once the curved beam single cell structure with a groove is completed, its assembly direction is fixed, i.e., it can only be arrayed in the x and y directions, and the out-of-plane z direction array is not designed. In addition, the curved beam part of this structure, which is mainly used for vibration isolation, occupies a small proportion of the overall structure, which means that the additional support part of the structure is large, resulting in a large overall weight of the structure.

[0005] In the patent application with the publication number CN216241989U, a "multi-stage jump buckling energy absorption structure" is disclosed, which is composed of a plurality of clockwise spiral cone twisted curved beams and a same number of counterclockwise spiral cone twisted curved beams. These curved beams are interlaced and connected to form a mesh structure. The structure essentially uses the sudden elastic jump behavior of the inclined beam structure to realize the energy absorption of the multi-layer, mesh spiral cone structure. However, the force displacement curve of the structure shows that this deformation is only single-stable, which means that once the external force is removed, the structure will automatically return to the initial state. This automatic recovery of reverse displacement may cause a certain impact on the structure itself, which is fatal to fragile objects. In addition, the spiral cone structure has certain difficulties in manufacturing and assembly, and has high requirements for manufacturing conditions and equipment precision, as well as high requirements for the shape of the mounting hole.

[0006] It should be noted that the above content belongs to the technical cognition of the inventor and does not necessarily constitute prior art. SUMMARY

[0007] The present application provides a sudden elastic jump hierarchical hyperbolic beam multi-stable metamaterial repeatable energy absorption structure to solve the problems existing in the prior art. It has multi-stable, multi-energy absorption platform, multi-step deformation capability, higher strength and stability, higher efficiency and weight optimization, and greater manufacturing and installation convenience.

[0008] The present application achieves the above-mentioned purposes by adopting the following technical solutions:

[0009] A sudden elastic jump hierarchical hyperbolic beam multi-stable metamaterial repeatable energy absorption structure includes m layers of multi-stable structure units, each layer of multi-stable structure units is formed by n identical double hyperbolic beam cells connected in sequence, and each layer of multi-stable structure units is connected in sequence along the axis of the tubular structure; wherein n≥3.

[0010] The double hyperbolic beam cell includes a double hyperbolic beam, an intermediate connecting rod, and two side rods. The double hyperbolic beam is arranged between the two side rods, and the two ends of the double hyperbolic beam are connected to the upper parts of the two side rods. The intermediate connecting rod connects the midpoint of the double hyperbolic beam and extends beyond the top of the double hyperbolic beam.

[0011] In one embodiment, adjacent double hyperbolic beam cells in the same layer of multi-stable structure units share a side rod or are fixedly connected; in different layers of multi-stable structure units, the intermediate connecting rods and side rods of adjacent double hyperbolic beam cells are fixedly connected respectively.

[0012] In another embodiment, the double hyperbolic beam cell further includes an upper cross rod and a lower cross rod. The middle part of the upper cross rod is connected to the top of the intermediate connecting rod, and the two ends of the lower cross rod are connected to the lower parts of the two side rods.

[0013] In the same layer multi-stable structure unit, the upper crossbars and the lower crossbars of each hyperbolic beam cell are sequentially connected end to end; in the different layer multi-stable structure unit, adjacent hyperbolic beam cells share corresponding upper crossbars and lower crossbars or the upper crossbars and the lower crossbars of adjacent hyperbolic beam cells are fixedly connected.

[0014] Further, in the hyperbolic beam cell, the stiffness of the side bars and the lower crossbars is greater than the stiffness of the hyperbolic beam, the intermediate connecting rod and the upper crossbar.

[0015] Further, the hyperbolic beam has a span-to-depth ratio H, and as H increases, the effective crushing distance of the sudden elastic jump level hyperbolic beam multi-stable metamaterial repeatable energy absorption structure becomes longer.

[0016] Further, the hyperbolic beam is a sinusoidal hyperbolic beam or a trapezoidal hyperbolic beam, or a hyperbolic beam in a wave-shaped form formed by a plurality of curves in series. Generally, any hyperbolic beam with bistable characteristics can be used as the hyperbolic beam cell in the present application.

[0017] The beneficial effects of the present application include but are not limited to:

[0018] The sudden elastic jump level hyperbolic beam multi-stable metamaterial repeatable energy absorption structure provided by the present application is a layered metamaterial with a three-dimensional tubular geometric shape designed based on the sudden elastic jump characteristics of the hyperbolic beam cell, and is a mechanical metamaterial with multi-stable, multi-energy absorption platform and multi-step deformation capability. Specifically, the present application has the following advantages:

[0019] (1) The multi-stable metamaterial repeatable energy absorption structure can realize the change of stiffness from positive to negative in the range of large deformation and small deformation elasticity, and has the characteristics of multi-stability, programmability and repeatability.

[0020] (2) The multi-stable metamaterial repeatable energy absorption structure can be combined with a plastic large deformation metal element to realize the energy absorption of a elastic-plastic structure under different loads, and plays a certain complementary role in the development of current energy absorption devices.

[0021] (3) The multi-stable metamaterial repeatable energy absorption structure can be repeatedly used within the elastic limit, improving the utilization rate of materials and reducing engineering costs.

[0022] Further, compared with other array arrangements of single cells, the tubular structure in the multi-stable metamaterial repeatable energy absorption structure provided by the application can effectively disperse and bear stress, has higher strength and stability, and thus can effectively bear external load and maintain shape, so that the entire structure is more stable; secondly, the tubular structure can minimize the amount of material used while providing strength, has higher volume efficiency, and can reduce material waste, thereby achieving weight optimization; thirdly, the tubular structure has a simple geometric shape, is easy to manufacture, and the installation and disassembly process is relatively simple, and is easy to maintain and repair. Therefore, the tubular structure in the multi-stable metamaterial repeatable energy absorption structure provided by the application has higher strength and stability, higher efficiency and weight optimization, and greater manufacturing and installation convenience, and has wide application potential in various fields. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and serve to explain the principles of the application, and do not limit the application. In the drawings:

[0024] Figure 1 A structure diagram of one of the multi-stable metamaterial repeatable energy absorption structures provided by the application;

[0025] Figure 2 A structure diagram of one of the multi-stable metamaterial repeatable energy absorption structures provided by the application; Figure 1 A structure diagram of a double-curved beam single cell in the multi-stable metamaterial repeatable energy absorption structure;

[0026] Figure 3 A structure diagram of another multi-stable metamaterial repeatable energy absorption structure provided by the application;

[0027] Figure 4 A structure diagram of another multi-stable metamaterial repeatable energy absorption structure provided by the application; Figure 2 A structure diagram of a double-curved beam single cell in the multi-stable metamaterial repeatable energy absorption structure;

[0028] Figure 5 A structure diagram of a DCB-n-1-C multi-stable metamaterial repeatable energy absorption structure in Example 1 (n=3, 4, 5, 6; m=1);

[0029] Figure 6 A structure diagram of a DCB-3-m-C multi-stable metamaterial repeatable energy absorption structure in Example 1 (n=3; m=1, 2, …, 6);

[0030] Figure 7 A structure diagram of a DCB-5-m-C multi-stable metamaterial repeatable energy absorption structure in Example 1 (n=5; m=1, 2, …, 6);

[0031] Figure 8Figures of force-displacement curve and internal energy-displacement curve of the DCB-3-m-C multi-stable metamaterial repeatable energy-absorbing structure in Example 1;

[0032] Figure 9 Figures of force-displacement curve of the deformation mode and different curved beam span height of the DCB-6-2-C multi-stable metamaterial in Example 1;

[0033] Figure 10 Figures of force-displacement and internal energy-displacement curves of the DCB-6-4-C structure and its layered curved beam unit cell in Example 1 under different span heights: (a) force-displacement curve of the DCB-6-4-C; (b) force-displacement curve of the layered curved beam unit cell; (c) internal energy-displacement curve of the DCB-6-4-C structure; (d) internal energy-displacement curve of the layered curved beam unit cell;

[0034] Figure 11 Figures of the DCB-n-1-M multi-stable metamaterial repeatable energy-absorbing structure in Example 2 (n=3, 4, 5, 6; m=1)

[0035] Figure 12 Figures of the DCB-4-m-M multi-stable metamaterial repeatable energy-absorbing structure in Example 2 (n=4; m=1, 2, 3, 4, 5, 6);

[0036] Figure 13 Figures of the DCB-6-m-M multi-stable metamaterial repeatable energy-absorbing structure in Example 2 (n=6; m=1, 2, 3, 4, 5, 6);

[0037] Figure 14 Figures of the internal energy-displacement curve of the DCB-n-1-M multi-stable metamaterial in Example 2;

[0038] Figure 15 3D-printed hyperbolic beam unit cell and DCB-4-1, DCB-4-5-M test pieces;

[0039] Figure 16 Photos of the DCB-4-5-M test piece under different stable state conversions;

[0040] In the figure, 1, hyperbolic beam; 2, middle connecting rod; 3, side rod; 4, upper cross rod; 5, lower cross rod. DETAILED DESCRIPTION

[0041] In order to clearly illustrate the technical features of the present scheme, the present application will be described in detail below with reference to specific embodiments and its accompanying drawings.

[0042] It should be noted that in the following description, many specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in a variety of ways beyond the specific embodiments described herein. Accordingly, the present application is not limited to the specific embodiments disclosed.

[0043] As shown in Figure 1 or Figure 3 The present application provides a repeated energy-absorbing structure of a hyperbolic beam multi-stable metamaterial, which includes m layers of multi-stable structure units. Each layer of multi-stable structure units is formed by connecting n hyperbolic beam unit cells in sequence. The multi-stable structure units are stacked along the axis of the tubular structure. In different layers of multi-stable structure units, adjacent hyperbolic beam unit cells are placed vertically. Wherein, n≥3.

[0044] Specifically, as shown in Figure 2 , Figure 1 The hyperbolic beam unit cell in Figure 1 includes a hyperbolic beam 1, an intermediate connecting rod 2, and two side rods 3. The hyperbolic beam 1 is arranged between the two side rods 3, and the two ends of the hyperbolic beam 1 are connected to the upper parts of the two side rods 3. The intermediate connecting rod 2 connects the midpoint of the hyperbolic beam 1 and extends beyond the top of the hyperbolic beam 1. As shown in , in the same layer of multi-stable structure units, adjacent hyperbolic beam unit cells share a side rod or are fixedly connected to the side rods of adjacent hyperbolic beam unit cells; in different layers of multi-stable structure units, the intermediate connecting rods and side rods of adjacent hyperbolic beam unit cells are fixedly connected, respectively. Wherein, the hyperbolic beam serves to absorb and disperse energy from external loads and undergoes elastic deformation to maintain the stability of the structure. The hyperbolic beam has a bistable characteristic and can switch between different stable states. The side rods serve to transfer loads and provide rigid support, and usually have high strength and stiffness to withstand loads from the hyperbolic beam. The intermediate connecting rod is located in the middle of the hyperbolic beam and serves to transfer external loads, allowing the hyperbolic beam to switch uniformly between different stable states.

[0045] Figure 3 Alternatively, as shown in Figure 4 and Figure 3 , the hyperbolic beam unit cell further includes an upper cross rod 4 and a lower cross rod 5. The upper cross rod 4 is located above the side rod 3, and the middle part of the upper cross rod 4 is connected to the top of the intermediate connecting rod 2. The two ends of the lower cross rod 5 are connected to the lower parts of the two side rods 3.As shown in the drawings, in the same layer multi-stable structure unit, the upper cross bar and the lower cross bar of each hyperbolic beam cell are sequentially connected end to end; in the different layer multi-stable structure unit, adjacent hyperbolic beam cells share the corresponding upper cross bar and the lower cross bar or the upper cross bar and the lower cross bar of adjacent hyperbolic beam cells are fixedly connected. The side bar connects the cross bar and the hyperbolic beam, bears the load from the hyperbolic beam and transmits it to the lower cross bar. The side bar usually has high strength and rigidity to bear the load from the hyperbolic beam and transmit it to the cross bar. The upper cross bar and the lower cross bar are located on the upper and lower sides of the hyperbolic beam, and play a role in fixing and supporting the hyperbolic beam. The main function is to provide longitudinal stability and prevent the hyperbolic beam from excessive bending or twisting.

[0046] Further, the hyperbolic beam is a sinusoidal hyperbolic beam or a hyperbolic beam in a wave-shaped bending form formed by a plurality of curves in series. Generally, any hyperbolic beam having bistable characteristics can be used as the hyperbolic beam cell in the present application.

[0047] The span height of the hyperbolic beam is H. As H increases, the effective crushing distance of the repeated energy absorption structure of the sudden elastic jump hierarchical hyperbolic beam multi-stable metamaterial increases.

[0048] The sudden elastic jump hierarchical hyperbolic beam multi-stable metamaterial and the application effect thereof will be described in detail below through specific examples.

[0049] Example 1

[0050] In this embodiment, a multi-stable metamaterial repeated energy absorption structure without upper cross bar and lower cross bar in the hyperbolic beam cell is shown, which is marked as DCB-n-m-C metamaterial, n is the number of hyperbolic beam cells in each layer of multi-stable structure unit, and m is the number of layers of multi-stable structure unit. This structure is suitable for occasions with strict quality requirements.

[0051] Figures 5-7 Specifically, the structure diagrams of several typical multi-stable metamaterials, DCB-n-1-C, DCB-3-m-C and DCB-5-m-C, are shown. Specifically, Figure 5 In the drawings, the three-dimensional structure diagrams of the multi-stable metamaterial repeated energy absorption structure when n=3, 4, 5, 6 and m=1 are shown; Figure 6 The three-dimensional structure diagrams of the multi-stable metamaterial repeated energy absorption structure when n=3 and m=1, 2, 3, 4, 5, 6 are shown; Figure 7 In the drawings, the three-dimensional structure diagrams of the multi-stable metamaterial repeated energy absorption structure when n=5 and m=1, 2, 3, 4, 5, 6 are shown.

[0052] Figure 8 In the drawings, (a) and (b) show Figure 6The force-displacement curve and the internal energy-displacement curve of the DCB-3-m-C multi-stable metamaterial repeatable energy-absorbing structure shown in FIG. 6 are observed. Figure 8 (a) It can be seen that when the triangular multi-stable structure units of 1 layer, 2 layers and 3 layers are stacked, the force-displacement curve has a negative force value, and a bistable effect appears; and when the number of stacked layers is greater than or equal to 4 layers, a monostable effect appears. The bistable structure can recover to the initial state through the reverse external force after unloading, while the monostable structure can recover to the initial state without external force after unloading. In both cases, negative stiffness behavior occurs, that is, the slope of the force-displacement curve changes from "positive-zero-negative-zero-positive", which is due to the sudden elastic jump behavior of the hyperbolic beam structure during deformation.

[0053] Observation Figure 8 (b) It can be seen that for the energy-displacement curve, when the number of layers is greater than or equal to 4, the curve shows a continuous growth trend; when the number of layers is less than 4, the internal energy begins to decrease when the displacement reaches 9 mm, and the curve continues to rise until the displacement reaches about 12 mm, which is because the existence of multi-stable effect produces negative force value, resulting in a stage of internal energy reduction.

[0054] Further, the present embodiment is directed to the DCB-6-2-C multi-stable metamaterial repeatable energy-absorbing structure, and the influence of the hyperbolic beam span height H and the distance h g between the two curved beams on the structure is studied.

[0055] The hyperbolic beam span height H is nh (n = 1, 2, …, 8, h = 6 mm), and the distance between the two curved beams is h g When nh increases, h g value increases, which can make the structure look more coordinated as a whole.

[0056] Figure 9 The undeformed mode, deformation mode I, deformation mode II and recovered mode of the DCB-6-2-C metamaterial repeatable energy-absorbing structure under different span heights nh and different distances h g between the two curved beams are shown in (a)-(h), it can be seen that the hyperbolic beam structure has a sudden elastic jump behavior during deformation, and this deformation can completely recover to the initial state.

[0057] Figure 9 (i) shows the force-displacement curve of different hyperbolic beam span heights H at the same thickness, it can be seen that with the increase of the hyperbolic beam span height, the effective crushing distance of the structure becomes longer, and the effective crushing distance becomes n times of the original when the hyperbolic beam span height becomes n times of the original.

[0058] Figure 9 (j) shows the force-displacement curve of different h gBut the same H under several working conditions of the comparison results, the force-displacement curve of these working conditions is basically coincident, which shows that the distance h g has little effect on the results. Therefore, in practical applications, the value of h g can be determined arbitrarily according to the actual space size.

[0059] To further verify the double-curved beam unit cell structure and the tubular structure and the corresponding effect, the present application compares the force-displacement curve and the internal energy-displacement curve of the DCB-6-4-C structure and the corresponding hierarchical double-curved beam unit cell in the compression process, aiming to verify the relationship between the energy absorption characteristics of the polygonal hierarchical double-curved beam metamaterial and the hierarchical double-curved beam unit cell.

[0060] Figure 10 (a) is the force-displacement curve of the DCB-6-4-C tubular structure changing with the double-curved beam span height H, Figure 10 (b) is the force-displacement curve of the uniform hierarchical double-curved beam unit cell changing with the double-curved beam span height H. It can be seen that as the double-curved beam span height increases, the effective crushing distance of the structure becomes longer, and the peak crushing force of the DCB-6-4-C tubular structure is about 12 times that of the corresponding unit cell structure.

[0061] In addition, Figure 10 (c) shows that the internal energy of the DCB-6-4-C tubular structure increases with the increase of the span height, Figure 10 (d) gives the internal energy-displacement curve of the hierarchical curved beam unit cell structure. It can be seen that the internal energy increases with the increase of the span height, and the internal energy of the metamaterial and the unit cell differs by two orders of magnitude. Assembling the unit cell structure into a tubular metamaterial can make the overall structure more stable and greatly improve the energy absorption characteristics of the structure.

[0062] Example 2:

[0063] In this embodiment, a multi-stable metamaterial repeatable energy absorption structure with upper and lower horizontal rods in the double-curved beam unit cell is shown, which is marked as DCB-n-m-M metamaterial. Figures 11-13 Specifically, the structure diagrams of several typical multi-stable metamaterials, DCB-n-1-M, DCB-4-m-M and DCB-6-m-M, are shown.

[0064] Figure 14 For Figure 11 the internal energy-displacement curve of the DCB-n-m-M multi-stable metamaterial repeatable energy absorption structure shown in the above embodiment, the effect of the number of polygonal sides (m) on the energy absorption characteristics of the structure is compared.

[0065] It is observed Figure 14As can be seen from the left graph, with the increase of the number of polygon edges, the energy absorption characteristics of the multi-stable metamaterial repeatable energy absorption structure increase, which is due to the increase of the number of series-parallel hyperbolic beams. The internal energy curve of the bistable structure shows an obvious trend of first increasing and then decreasing, which is caused by the emergence of negative force value due to the bistable effect caused by the sudden elastic jump of the hyperbolic beam structure.

[0066] Observation Figure 14 As can be seen from the right graph, for the multi-stable metamaterial repeatable energy absorption structure DCB-4-6-M with more layers, the internal energy curve generally shows an upward trend, accompanied by the emergence of 6 rising platforms, corresponding to the occurrence of 6 times of layer-by-layer sudden elastic jump behavior. This layer-by-layer deformation multi-stable structure is suitable for various sizes of loads, and can adjust its deformation mode in real time according to the size of the external load.

[0067] It can be seen that the multi-stable metamaterial repeatable energy absorption structure provided in Example 2 has a number of times of sudden elastic jump behavior occurring in the deformation process, which is related to the number of layers of the multi-stable structure unit. This layer-by-layer deformation mechanism greatly enhances the energy absorption capacity of the tubular structure.

[0068] Further, by comparing Example 1 and Example 2, it can be seen that the monostable and bistable effects of DCB-n-m-C are related to the number of stacked layers of the structure. For the DCB-n-m-C structure, with the increase of the number of layers, the structure does not always remain in the bistable state, and it has a critical layer. When the number of layers is greater than the critical layer, the structure will change from bistable to monostable. For the DCB-n-m-C structure in actual engineering application, the multi-stable effect is the result of the synergistic effect of various factors.

[0069] However, the DCB-n-m-C structure has the advantages of lightweight, no excessive unnecessary mass, simple structure, and can be integrally formed without setting a cross bar. We construct the DCB-n-m-M structure by adding a cross bar constraint on the basis of the DCB-n-m-C structure, so as to ensure the multi-stable, multi-energy absorption platform, and multi-step deformation capacity of the structure. The two structures of DCB-n-m-C and DCB-n-m-M have a progressive relationship in logical construction, but each structure has its own advantages and disadvantages, and can be selected according to the actual application scene.

[0070] Further, in order to investigate the influence of materials on the performance of the multi-stable metamaterial repeatable energy absorption structure, the present inventors carried out the following experiment.

[0071] Experimental method:

[0072] Printed using Raise3D E2 printer, the technical principle is FFF fused filament fabrication technology, adopts IDEX independent double-nozzle extrusion system, supports double-material printing, and the diameters of left and right nozzles are 0.4mm.

[0073] The function expression of the printed curved beam is

[0074] The side wall of the side rod of each hyperbolic beam cell is a 45° chamfer, which aims to increase the connecting surface, four hyperbolic beam cells are bonded to form a single-layer three-dimensional structure, and five single-layer three-dimensional structures are bonded to form a five-layer structure as an experimental specimen, as shown in Figure 15 .

[0075] The manufacturing of the multi-stable metamaterial provided by the application is not limited to a single material, and the 3D printing technology can realize multi-material printing and preparation, the production cost is lower, and the manufacturing efficiency is higher.

[0076] The corresponding stable state conversion of the experimental specimen is shown in Figure 16 , and it can be seen that the structure can sequentially undergo five continuous sudden elastic buckling changes under the action of the axial load. In the multi-stable metamaterial repeat energy absorption structure provided by the application, the stiffness of the side rod and the lower cross rod in the hyperbolic beam cell is greater than the stiffness of the hyperbolic beam, the intermediate connecting rod and the upper cross rod.

[0077] In the description of the application, it should be understood that the terms "center", "upper", "lower", "vertical", "horizontal", "top", "bottom", etc. indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the application.

[0078] In the application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0079] The above specific embodiments cannot be regarded as a limitation on the protection scope of the application, and any alternative improvement or change made by those skilled in the art to the embodiments of the application falls within the protection scope of the application.

[0080] Any aspect of the application not otherwise specified is deemed to be within the skill of those in the art.

Claims

1. A reusable energy-absorbing structure of a hyperbolic beam multi-stable metamaterial with a sudden spring-loaded transition, characterized in that, It includes m layers of multistable structural units. Each layer of multistable structural units is formed by connecting the same number of n hyperbolic beam unit cells end to end to enclose a tubular structure. The multistable structural units of each layer are stacked and connected along the axis of the tubular structure, where n≥3. The hyperbolic beam unit cell includes a hyperbolic beam, a central connecting rod, and two side rods. The hyperbolic beam spans between the two side rods, and both ends of the hyperbolic beam are connected to the upper parts of the two side rods respectively. The central connecting rod connects the midpoint of the hyperbolic beam and extends beyond the top of the hyperbolic beam. In a multi-stable structural unit at the same level, adjacent hyperbolic beam units share side rods or the side rods of adjacent hyperbolic beam units are fixedly connected, and the side rods of each hyperbolic beam unit face the same direction; in a multi-stable structural unit at different levels, the bottom of the middle connecting rod of the upper hyperbolic beam unit is fixedly connected to the top of the middle connecting rod of the lower hyperbolic beam unit, and the bottom of the side rod of the upper hyperbolic beam unit is fixedly connected to the top of the side rod of the lower hyperbolic beam unit.

2. A reusable energy-absorbing structure of a hyperbolic beam multi-stable metamaterial with a sudden spring-loaded transition, characterized in that, It includes m layers of multistable structural units. Each layer of multistable structural units is formed by connecting the same number of n hyperbolic beam unit cells end to end to enclose a tubular structure. The multistable structural units of each layer are stacked and connected along the axis of the tubular structure, where n≥3. The hyperbolic beam unit cell includes a hyperbolic beam, a central connecting rod, and two side rods. The hyperbolic beam spans between the two side rods, and both ends of the hyperbolic beam are connected to the upper parts of the two side rods respectively. The central connecting rod connects the midpoint of the hyperbolic beam and extends beyond the top of the hyperbolic beam. The hyperbolic beam unit cell also includes an upper crossbar and a lower crossbar. The middle part of the upper crossbar is connected to the top of the intermediate connecting rod, and the two ends of the lower crossbar are respectively connected to the lower parts of the two side rods. In a multi-stable structural unit at the same level, the upper and lower crossbars of each hyperbolic beam unit cell are connected end to end in sequence, and the side bars of each hyperbolic beam unit cell face the same direction; in a multi-stable structural unit at different levels, the lower crossbar of the upper hyperbolic beam unit cell also serves as the upper crossbar of the lower hyperbolic beam unit cell, or the lower crossbar of the upper hyperbolic beam unit cell is fixedly connected to the upper crossbar of the lower hyperbolic beam unit cell.

3. The spring-loaded, layered hyperbolic beam multistable metamaterial reusable energy-absorbing structure according to claim 2, characterized in that, In the hyperbolic beam unit cell, the stiffness of the side bars and the lower crossbar is greater than that of the hyperbolic beam, the intermediate connecting bar, and the upper crossbar.

4. The spring-loaded, tiered hyperbolic beam multistable metamaterial reusable energy-absorbing structure according to claim 1 or 2, characterized in that, The span height of the hyperbolic beam is H. As H increases, the effective crushing distance of the hyperbolic beam multi-stable metamaterial repeatable energy-absorbing structure with sudden jump change level becomes longer.

5. The spring-loaded, tiered hyperbolic beam multistable metamaterial reusable energy-absorbing structure according to claim 1 or 2, characterized in that, The hyperbolic beam is a sinusoidal hyperbolic beam.

6. The spring-loaded, tiered hyperbolic beam multistable metamaterial reusable energy-absorbing structure according to claim 1 or 2, characterized in that, The hyperbolic beam is a trapezoidal hyperbolic beam.

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