Porous metamaterial energy absorption device based on paper folding and cutting forming process and design method thereof

Abstract

The invention discloses a porous metamaterial energy absorption device based on a paper folding and cutting forming process, which is prepared by adopting the paper folding and cutting forming process and comprises tetrakaidecahedron units which are arranged in a staggered manner, each tetrakaidecahedron unit comprises two square surfaces, four upper regular hexagonal surfaces and four lower regular hexagonal surfaces, wherein the two square surfaces are oppositely arranged up and down; the four upper regular hexagonal surfaces share the same edge with the upper square surfaces and are obliquely arranged downwards; the four lower regular hexagonal surfaces share the same edge with the lower square surfaces and are obliquely arranged upwards; and the four square hollow surfaces are formed after the upper regular hexagonal surfaces and the lower regular hexagonal surfaces are in butt joint. By utilizing the characteristic of flexible design of a paper folding and cutting technology, the preparation of converting a three-dimensional structure into a two-dimensional plane structure is more beneficial to precision control, the cost is greatly reduced, and meanwhile, the precision control is improved; by analyzing a deformation mechanism and deducing a function relational expression between structural energy absorption efficiency and structural parameters, structural optimization design with a controllable energy absorption effect is achieved, and the porous metamaterial energy absorption device meeting different requirements is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of impact-resistant porous materials, and in particular to a porous metamaterial energy absorption device based on a paper folding and cutting molding process and a design method thereof. Background Art

[0002] The porous structure has efficient energy absorption characteristics. When subjected to impact or compression loads, it can effectively absorb and disperse energy. It can maintain the integrity of the structure during the compression process, helping to protect the structure from damage. In addition, studies have shown that the honeycomb porous structure, as a typical metamaterial, has the characteristics of light weight and strong structure, and is widely used in aerospace and automotive transportation.

[0003] Traditional methods for preparing honeycomb porous structures include foam manufacturing, metal casting, and 3D printing. Among them, the foam manufacturing method includes physical foaming and chemical foaming. The physical foaming method uses gas to dissolve in the resin, and then reduces the pressure or heats to release the gas to form a porous structure; the chemical foaming method uses special chemical additives to form a porous structure in the material through the gas generated by the decomposition of the additives. Although the foam manufacturing method is easy to prepare and has low cost, the control accuracy of temperature and pressure conditions during the material preparation process is demanding, the structure preparation accuracy is unstable, and chemical additives may cause health risks to the environment and operators. The metal casting method is to pour molten metal into a specific mold to form a porous structure. The metal casting method can achieve stable structure preparation accuracy control, but it requires the preparation of a specific mold in advance, which limits the flexibility of the structural form and is costly when producing non-standard structures. The 3D printing method builds a porous structure by depositing materials layer by layer and following the design model. The 3D printing method is also limited by printing speed, material selection and cost.

[0004] In summary, the existing porous metamaterial energy absorption device preparation methods have the problem of not being able to take into account both easy preparation and structural preparation precision control. Easy preparation methods (such as foam manufacturing methods) cannot meet the requirements of structural precision control, while precision controllable methods (such as metal casting and 3D printing methods) are expensive and difficult to meet the optimization control under different requirements, which affects the promotion and application of porous metamaterial energy absorption devices. Summary of the invention

[0005] The main purpose of the present invention is to propose a porous metamaterial energy absorption device based on the origami forming process and a design method thereof, which utilizes the flexible design characteristics of origami and paper cutting technology, and converts the three-dimensional structure into a two-dimensional planar structure in reverse, which is more conducive to precision control, greatly reduces costs, and improves precision control; at the same time, by analyzing the deformation mechanism of the structure, the functional relationship between the structural energy absorption efficiency and the structural parameters is derived, and the structural optimization design with controllable energy absorption effect is achieved, so that a porous metamaterial energy absorption device with low initial peak stress and high specific energy absorption that meets different needs can be obtained, which has good practicality and economic benefits.

[0006] The technical solution adopted by the present invention is:

[0007] A porous metamaterial energy absorption device based on a paper-folding and cutting forming process, the porous metamaterial energy absorption device comprises a plurality of staggered tetradecahedral units, the tetradecahedral units comprise two square faces arranged opposite to each other in the upper and lower directions, four upper regular hexagonal faces co-edge-jointed with the upper square face and arranged obliquely downward, four lower regular hexagonal faces co-edge-jointed with the lower square face and arranged obliquely upward, and four square hollow faces formed by butting the upper regular hexagonal faces with the lower regular hexagonal faces, the side lengths of all square faces and regular hexagonal faces being equal; one and only one face of two adjacent tetradecahedral units being completely coplanar, wherein two coaxial tetradecahedral units in the upper and lower directions share a square face, and respectively share a regular hexagonal face with the tetradecahedral units on the left and right; the porous metamaterial energy absorption device is prepared by a paper-folding and cutting forming process.

[0008] In the above scheme, the included angle between the upper regular hexagonal face and the upper square face is 54.7°; the included angle between the lower regular hexagonal face and the lower square face is 54.7°.

[0009] In the above scheme, the porous metamaterial energy absorption device is a flat plate with a rectangular outer contour after being fully unfolded, and the flat plate is composed of square faces and regular hexagonal faces; it is divided into several periodic structures along the length direction of the flat plate, each periodic structure includes n×n square faces, n is the number of square faces along the width of the flat plate, which is an odd number, and the four sides of each square face are respectively shared with a regular hexagonal face, and the periphery of the periodic structure is all regular hexagonal faces, the outer regular hexagonal faces are only connected to the same side with one square face, and the inner regular hexagonal faces are connected to the same side with two square faces; two circumferentially adjacent regular hexagonal faces form an acute angle, thereby forming multiple X-shaped hollows inside the flat plate.

[0010] In the above scheme, the common edges of the regular hexagonal faces of adjacent periodic structures are folds.

[0011] In the above scheme, the preparation process of the porous metamaterial energy absorbing device comprises the following steps:

[0012] S11, establishing a two-dimensional geometric model of the porous metamaterial energy absorption device after unfolding, extracting the structural parameters of the tetradecahedron unit, including the side length a of the square face and the hexagonal face, the number n of square faces on the short side of the two-dimensional geometric model, the number m of folding layers, and the material wall thickness t;

[0013] S12. Select a plate of suitable material according to application requirements;

[0014] S13, cutting the plate in S12 according to the two-dimensional geometric model and structural parameters developed in S11, and removing excess material after cutting to obtain a plate having the same shape as the two-dimensional geometric model;

[0015] S14, bend the four regular hexagonal faces connected to the square face by 54.7° along the common edge toward the same side, so that one edge of two circumferentially adjacent regular hexagonal faces overlaps, thereby forming half of a tetradecahedral unit; complete the bending of all regular hexagonal faces in sequence according to the above method, and form a wavy semi-finished product structure with alternating concave and convex shapes;

[0016] S15. Fold the wavy semi-finished structure 180 degrees in a clockwise and counterclockwise order along the creases between the periodic structures to form a honeycomb porous metamaterial energy absorption device with tetradecahedral units.

[0017] In the above scheme, the common edge generated after the flat plate is folded is in a free state and does not need to be connected.

[0018] In the above scheme, the flat plate material is made of metal material.

[0019] Accordingly, the present invention also proposes a design method for the porous metamaterial energy absorbing device based on the origami forming process, comprising the following steps:

[0020] S21. Establish a three-dimensional geometric model of the porous metamaterial energy absorption device before and after unfolding, and extract structural parameters of the tetradecahedron unit, including the side length a of the square face and the hexagonal face, the number n of square faces on the short side of the two-dimensional geometric model, the number m of folded layers, and the material wall thickness t;

[0021] S22, material selection, determine the material parameters of the plate, including the material's stress-strain curve, density ρ, and Young's modulus E;

[0022] S23, cutting the flat material according to the two-dimensional geometric model and structural parameters after the expansion in S21, removing excess material after cutting to obtain a cut piece consistent with the two-dimensional geometric model, and then folding the cut piece to form a three-dimensional porous metamaterial energy absorbing device consistent with the three-dimensional geometric model in S21;

[0023] S24, perform compression and impact tests on the three-dimensional porous metamaterial energy absorbing device prepared in S23, and perform compression and impact simulation on the three-dimensional geometric model of S21, and verify the experimental results with the numerical simulation results to ensure the accuracy of the experimental and simulation results; then further analyze the compression mechanism of the material based on the energy dissipation analysis method according to the experimental and simulation results, and form a platform stress prediction formula for the porous metamaterial energy absorbing device under compression;

[0024] S25. According to the platform stress prediction formula of the porous metamaterial energy absorption device under compression in S24, the platform stress of the porous metamaterial energy absorption device under different structural parameters is calculated to provide a solution for designing a structure that matches the actual energy absorption efficiency requirements.

[0025] In the above method, in step S23, the folding method of the cut piece is: bend the four regular hexagonal faces connected to the square face along the common edge toward the same side by 54.7°, so that one edge of two circumferentially adjacent regular hexagonal faces overlaps, thereby forming half of a tetradecahedral unit; complete the bending of all regular hexagonal faces in sequence according to the above method to form a wavy semi-finished structure with alternating concave and convex shapes; fold the wavy semi-finished structure 180° in sequence along the creases between the periodic structures in a clockwise and counterclockwise order to form a honeycomb porous metamaterial energy absorption device with tetradecahedral units.

[0026] In the above method, in step S24, the platform stress prediction formula of the porous metamaterial energy absorbing device under compression is obtained as follows:

[0027]

[0028] In the formula, σ p is the platform stress; γ represents the aspect ratio, γ = a / t; a is the side length of the square face and the hexagonal face; t is the material wall thickness; γ c is a constant; y is the material yield stress; σ u is the material limit stress; n is the number of square faces on the short side of the two-dimensional geometric model; m is the number of folding layers; θ is the folding angle of the regular hexagonal face that shares the same edge with the square face, and θ = 54.7°; β is the rotation angle of the hinge line connecting the two regular hexagonal faces; h is the height of the porous metamaterial energy absorption device.

[0029] The beneficial effects produced by the present invention are:

[0030] The present invention provides a porous metamaterial energy absorbing device based on the origami forming process and a design method thereof. The flexible design characteristics of origami and paper cutting techniques are utilized to transform a complex three-dimensional porous metamaterial energy absorbing device into a simple two-dimensional flat plate structure by shearing and folding operations. The two-dimensional flat plate cut in a specific form is then folded to form a three-dimensional porous metamaterial energy absorbing device. This method solves the problem of difficult control of preparation accuracy in the traditional porous material preparation process and achieves the effect of simple preparation.

[0031] The porous metamaterial energy absorption device based on the origami forming process provided by the present invention has a stable deformation mode. Furthermore, through experimental research and numerical simulation analysis of the structure, a high-precision prediction formula for the platform force is proposed. Under limited constraints, the unknown variables of the prediction formula can be directly calculated quickly using computer software, thus solving the problem of difficult optimization of traditional Kevin foam structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 It is a three-dimensional geometric model diagram of the porous metamaterial energy absorption device of the present invention;

[0034] Figure 2 It is a characteristic model diagram of the tetradecahedron unit of the porous metamaterial energy absorption device;

[0035] Figure 3 It is a diagram of the tetradecahedron unit arrangement model of the porous metamaterial energy absorption device;

[0036] Figure 4 is a plan view of a cut rectangular plate of a porous metamaterial energy absorbing device;

[0037] Figure 5 This is a model diagram of the wavy semi-finished product structure after the regular hexagonal surface is bent;

[0038] Figure 6 It is a design flow chart of the porous metamaterial energy absorption device of the present invention;

[0039] Figure 7 This is a numerical simulation model diagram of a porous metamaterial energy absorption device;

[0040] Figure 8 This is a model diagram of the axial loading deformation process of the porous metamaterial energy absorption device;

[0041] Fig. 9 It is a comparison chart of stress-strain curves of the loading test of the porous metamaterial energy absorption device and the numerical simulation platform.

[0042] In the figure: 10, tetradecahedron unit; 11, upper square face; 12, lower square face; 13, upper regular hexagonal face; 14, lower regular hexagonal face; 15, square hollow face. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0044] It should be noted that the illustrations provided in the embodiments of the present invention are only used to illustrate the basic concept of the present invention in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout type may also be more complicated.

[0045] In the present invention, it is also necessary to explain that, if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, if the terms "first" and "second" appear, they are only used for description and distinction purposes, and cannot be understood as indicating or implying relative importance.

[0046] like Figure 1 As shown, the present invention proposes a porous metamaterial energy absorption device based on the origami forming process, and the porous metamaterial energy absorption device includes a plurality of staggered tetradecahedral units. Figure 2 As shown, the tetradecahedron unit includes two square faces arranged opposite to each other in the upper and lower parts, four upper regular hexagonal faces 13 that share the same edge with the upper square face 11 and are arranged obliquely downward, four lower regular hexagonal faces 14 that share the same edge with the lower square face 12 and are arranged obliquely upward, and four square hollow faces 15 formed by the upper regular hexagonal faces 13 and the lower regular hexagonal faces 14 being connected; the side lengths of all square faces and regular hexagonal faces are equal; the angle between the upper regular hexagonal face 13 and the upper square face 11 is 54.7°; the angle between the lower regular hexagonal face 14 and the lower square face 12 is 54.7°. Figure 3As shown, two adjacent tetradecahedral units have one and only one face that is completely coplanar, wherein the two coaxial tetradecahedral units share a square face and share a regular hexagonal face with the tetradecahedral units on the left and right, respectively.

[0047] like Figure 4 As shown, when the porous metamaterial energy absorption device is fully unfolded, it is a flat plate with a rectangular outer contour, which is composed of square faces and regular hexagonal faces; it is divided into several periodic structures along the length direction of the flat plate, each periodic structure includes n×n square faces, n is the number of square faces along the width of the flat plate, which is an odd number, and the four sides of each square face are co-edges with a regular hexagonal face respectively, and the periphery of the periodic structure is all regular hexagonal faces, and the outer regular hexagonal faces are only connected to the same side with one square face, and the inner regular hexagonal faces are connected to the same side with two square faces; two regular hexagonal faces adjacent to each other in the circumferential direction form an acute angle, thereby forming multiple X-shaped hollows inside the flat plate. The co-edges of the regular hexagonal faces of adjacent periodic structures are folds, and the fold direction is perpendicular to the long side of the rectangular flat plate. In this embodiment, it is divided into 5 periodic structures along the length direction of the flat plate, and each periodic structure includes 3×3 (a total of 9) square faces, with a total of 4 folds.

[0048] The porous metamaterial energy absorbing device of the present invention is prepared by using a paper folding and cutting molding process, and the preparation process includes the following steps:

[0049] S11. Establish a two-dimensional geometric model of the porous metamaterial energy absorption device after unfolding, and extract the structural parameters of the tetradecahedron unit, including the side length a of the square face and the hexagonal face, the number n of square faces on the short side (i.e., along the width of the plate) in the two-dimensional geometric model, the number m of folded layers, and the material wall thickness t;

[0050] S12. Select a plate of suitable material according to application requirements;

[0051] S13, according to the two-dimensional geometric model and structural parameters developed in S11, cutting the plate in S12 by using a laser cutting machine, and removing excess material after cutting to obtain a plate consistent with the geometric model;

[0052] S14, bend the four regular hexagonal faces connected to the square face along the common edge toward the same side by 54.7°, so that one edge of two circumferentially adjacent regular hexagonal faces overlaps, thereby forming half of a tetradecahedral unit; complete the bending of all regular hexagonal faces in sequence according to the above method to form a wavy semi-finished product structure with alternating concave and convex shapes, such as Figure 5 As shown;

[0053] S15, folding the wavy semi-finished product structure 180 degrees along the creases between the periodic structures in sequence to form a honeycomb porous metamaterial energy absorption device with tetradecahedral units. For details, see Figure 5First, fold the periodic structure 1 180° clockwise along crease 1, and then fold the periodic structures 1 and 2 180° counterclockwise along crease 2. Similarly, fold the periodic structures 1, 2, and 3 180° clockwise along crease 3, and fold the periodic structures 1, 2, 3, and 4 180° counterclockwise along crease 4. The common edges generated after the flat plate is folded are in a free state and do not need to be connected. Therefore, when the tetradecahedron unit is axially loaded, the four edges of the square form plastic hinges to achieve energy absorption effect.

[0054] The present invention utilizes the flexible design characteristics of origami and paper cutting techniques, and the preparation of the three-dimensional structure into a two-dimensional planar structure is more conducive to precision control, greatly reduces costs, and improves precision control.

[0055] Correspondingly, the present invention also proposes a design method for the porous metamaterial energy absorption device based on the origami forming process, which achieves the effect of predicting the structural energy absorption efficiency by establishing a functional relationship between the platform stress and the structural geometric parameters, such as Figure 6 As shown, the following steps are included:

[0056] S21. Use CAD-assisted design to establish a three-dimensional geometric model of the porous metamaterial energy absorption device before and after unfolding, and extract the structural parameters of the tetradecahedron unit, including the side length a of the square face and the hexagonal face, the number n of square faces on the short side of the two-dimensional geometric model, the number of folding layers m, and the material wall thickness t.

[0057] S22. Material selection, confirm material parameters, including material stress-strain curve, density ρ, and Young's modulus E. Specifically, according to application requirements, such as strength, weight, corrosion resistance, and cost, select appropriate materials. Commonly used materials include aluminum alloys, steel and other metals. Taking commonly used aluminum alloy materials as an example, a universal testing machine is used to complete the tensile test to obtain the measured engineering stress-strain curve of the material.

[0058] S23. According to the two-dimensional geometric model and structural parameters after the expansion of S21, the flat plate material is cut by a laser cutting machine, and the excess material is removed after cutting to obtain a cut piece consistent with the two-dimensional geometric model, and then the cut piece is folded to form a three-dimensional porous metamaterial energy absorption device consistent with the three-dimensional geometric model in S21. The folding method of the cut piece is as follows: the four regular hexagonal faces connected to the square face are bent 54.7° along the common edge toward the same side, so that one edge of the two regular hexagonal faces adjacent to each other in the circumferential direction overlaps, thereby forming half of a tetradecahedral unit; all the regular hexagonal faces are bent in sequence according to the above method to form a wavy semi-finished structure with alternating concave and convex shapes; the wavy semi-finished structure is folded 180° in sequence along the creases between the periodic structures to form a honeycomb porous metamaterial energy absorption device with tetradecahedral units.

[0059] S24, perform compression and impact tests on the three-dimensional porous metamaterial energy absorption device prepared in S23, and perform compression and impact simulation on the three-dimensional geometric model of S21, and verify the experimental results with the numerical simulation results to ensure the accuracy of the experimental and simulation results; then further analyze the compression mechanism of the material based on the energy dissipation analysis method according to the experimental and simulation results, and form a platform stress prediction formula for the porous metamaterial energy absorption device under compression. The specific steps are as follows:

[0060] The MTS universal testing machine was used to conduct axial quasi-static compression tests on the prepared three-dimensional porous metamaterial energy absorption device sample. The loading speed was set to 1 mm / s, and the compression force-time curve was collected through a computer control system. The side lengths of the square and the regular hexagon in the sample are equal, and the cross-sectional length and width can be calculated. Because the structure has variable cross-sections above and below, the minimum cross-sectional length and width are used as the calculation cross-sectional length. The minimum cross-sectional length and width are L = 2na, and the height is Sample cross-sectional area A = (2na) 2 . Wherein, θ is the folding angle of the regular hexagonal face sharing the same edge with the square face, and θ=54.7°.

[0061] Platform stress σ p and the average extrusion force F m The relationships are:

[0062]

[0063] The relationship between strain ε and deformation Δh is:

[0064]

[0065] The relationship between deformation Δh and time Δt is:

[0066] Δh=v×Δt (3)

[0067] Where v is the loading speed.

[0068] According to formulas (1), (2), and (3), the collected force-time curve can be converted into a stress-strain curve.

[0069] For the convenience of analysis, the ratio of the sample density to the matrix material density is defined as the relative density ρ r , the calculation formula is:

[0070]

[0071] Using platform stress σ p The formula for expressing the average load-bearing capacity of a material is:

[0072]

[0073] In the formula, ε is the variable strain, ε d is the strain range value, and σ(ε) is the function of stress with respect to strain.

[0074] Specific energy absorption SAE is the energy absorption per unit mass, representing the energy absorption efficiency of the structure. The calculation formula is as follows:

[0075]

[0076] In the formula, m s is the mass of the sample and ρ is the material density.

[0077] The commercial software ABAQUS / Explicit was used for numerical simulation. The material was meshed using conventional shell elements (S4R). Discrete rigid elements (R3D4) were used for the top and bottom platforms. The aluminum alloy AA6063O was used as the material. The contact form was defined as general contact with the porous metamaterial device itself. When the friction coefficient was 0.3, the mesh size was 1.5 mm to achieve the convergence condition. The deformation process was shown in Fig. Figure 7-8 The numerical results are compared with the experimental results, such as Fig. 9 As shown, the numerical simulation results (Simulation curve in the figure) are basically consistent with the experimental results (KC-1, KC-2, and KC-3 curves in the figure).

[0078] By analyzing the experimental results and numerical simulation results, it is found that the most critical deformation mechanism of the porous metamaterial energy absorbing device based on folding and paper-cutting technology under compressive load is the bending of the regular hexagonal surface along the crease. The stiffness of the regular hexagonal surface and the square surface is relatively large, and the energy consumed by the deformation of the thin plate can be ignored. Therefore, by calculating the energy consumed by the bending of the plastic hinge line at the crease, the overall energy absorption of the porous metamaterial energy absorbing device based on folding and paper-cutting technology can be roughly predicted.

[0079] Based on the assumption of ideal rigid-plastic material, the full plastic bending moment M per unit length of plastic hinge is p for:

[0080]

[0081] Among them, σ0 is the flow stress of the base material, and t is the wall thickness of the material. The linear relationship between flow stress and width-to-thickness ratio is used to calculate the flow stress formula:

[0082]

[0083] Where γ is the aspect ratio, and γ = a / t, γ c is a constant, set to 70, σ y is the material yield stress, σ uis the ultimate stress of the material.

[0084] Plastic hinges are generated at the folds. Assuming that the number of square faces on the short side of the metal plate is n and the number of folded layers is m, the number of hinges connecting the square face and the regular hexagonal face is 4n2m, with a corresponding rotation angle of θ, and the number of hinges connecting two regular hexagonal faces is n(m-1), and about half of these hinges have a rotation angle of β. According to the energy balance principle, the energy consumed by the bending of the hinge is equal to the work done by the external force, resulting in the following formula:

[0085]

[0086] In the formula, F m is the average extrusion pressure, h is the height of the specimen,

[0087] Substituting equations (1), (7) and (8) into equation (9), the platform stress prediction formula of the porous metamaterial energy absorption device under compression based on the kirigami process is obtained as follows:

[0088]

[0089] S25. According to the platform stress prediction formula of the porous metamaterial energy absorption device under compression in S24, the platform stress of the porous metamaterial energy absorption device under different structural parameters is calculated to provide a solution for designing a structure that matches the actual energy absorption efficiency requirements.

[0090] From step 4, we can know that according to the derived platform stress prediction formula of the porous metamaterial energy absorption device based on the origami process, it is very convenient to calculate the corresponding platform stress when different structural parameters (wall thickness t, number of single-sided square elements n, number of folded layers m, square side length a) change. The larger the platform stress, the higher the energy absorption efficiency. Or under limited conditions such as the overall size limit of the structure, it is easy to find the optimal solution of other structural parameters.

[0091] The present invention is more conducive to precision control by reversely unfolding the three-dimensional structure into a two-dimensional planar structure, which greatly reduces the cost and improves the precision control. Then, through the optimization design of structural parameters, a porous metamaterial energy absorption device with low initial peak stress and high specific energy absorption can be designed. This method has good practicality and economic benefits.

[0092] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0093] The order of execution of each step in the above embodiment does not mean the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

[0094] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A porous metamaterial energy absorption device based on folding and cutting paper forming process, characterized in that: The porous metamaterial energy absorption device includes a plurality of staggered tetradecahedral units, wherein the tetradecahedral units include two square faces arranged opposite to each other in the upper and lower directions, four upper regular hexagonal faces sharing the same edge with the upper square face and arranged obliquely downward, four lower regular hexagonal faces sharing the same edge with the lower square face and arranged obliquely upward, and four square hollow faces formed by connecting the upper regular hexagonal faces with the lower regular hexagonal faces, wherein the side lengths of all square faces and regular hexagonal faces are equal; one and only one face of two adjacent tetradecahedral units is completely coplanar, wherein two coaxial tetradecahedral units share a square face, and share a regular hexagonal face with the left and right tetradecahedral units respectively; the porous metamaterial energy absorption device is prepared by adopting a paper folding and cutting forming process.

2. The porous metamaterial energy absorption device based on the origami forming process according to claim 1 is characterized in that: The included angle between the upper regular hexagonal face and the upper square face is 54.7°; the included angle between the lower regular hexagonal face and the lower square face is 54.7°.

3. The porous metamaterial energy absorption device based on the origami forming process according to claim 1 is characterized in that: When the porous metamaterial energy absorption device is fully unfolded, it is a flat plate with a rectangular outer contour, and the flat plate is composed of square faces and regular hexagonal faces; it is divided into several periodic structures along the length direction of the flat plate, each periodic structure includes n×n square faces, n is the number of square faces along the width of the flat plate, which is an odd number, and the four sides of each square face are respectively shared with a regular hexagonal face, and the periphery of the periodic structure is all regular hexagonal faces, the outer regular hexagonal faces are only connected to the same side with one square face, and the inner regular hexagonal faces are connected to the same side with two square faces; two circumferentially adjacent regular hexagonal faces form an acute angle, thereby forming multiple X-shaped hollows inside the flat plate.

4. The porous metamaterial energy absorption device based on the origami forming process according to claim 3 is characterized in that: The common edges of the regular hexagonal faces of adjacent periodic structures are folds.

5. The porous metamaterial energy absorption device based on the origami forming process according to claim 1 is characterized in that: The preparation process of the porous metamaterial energy absorbing device comprises the following steps: S11, establishing a two-dimensional geometric model of the porous metamaterial energy absorption device after unfolding, extracting the structural parameters of the tetradecahedron unit, including the side length a of the square face and the hexagonal face, the number n of square faces on the short side of the two-dimensional geometric model, the number m of folding layers, and the material wall thickness t; S12. Select a plate of suitable material according to application requirements; S13, cutting the plate in S12 according to the two-dimensional geometric model and structural parameters developed in S11, and removing excess material after cutting to obtain a plate having the same shape as the two-dimensional geometric model; S14, bend the four regular hexagonal faces connected to the square face by 54.7° along the common edge toward the same side, so that one edge of two circumferentially adjacent regular hexagonal faces overlaps, thereby forming half of a tetradecahedral unit; complete the bending of all regular hexagonal faces in sequence according to the above method, and form a wavy semi-finished product structure with alternating concave and convex shapes; S15. Fold the wavy semi-finished structure 180 degrees in a clockwise and counterclockwise order along the creases between the periodic structures to form a honeycomb porous metamaterial energy absorption device with tetradecahedral units.

6. The porous metamaterial energy absorption device based on the origami forming process according to claim 5 is characterized in that: The common edges produced after the flat plate is folded are in a free state and do not need to be connected.

7. The porous metamaterial energy absorption device based on the origami forming process according to claim 5 is characterized in that: The plate material is made of metal.

8. The design method of the porous metamaterial energy absorbing device based on the origami forming process according to claim 1 is characterized in that: The following steps are involved: S21. Establish a three-dimensional geometric model of the porous metamaterial energy absorption device before and after unfolding, and extract structural parameters of the tetradecahedron unit, including the side length a of the square face and the hexagonal face, the number n of square faces on the short side of the two-dimensional geometric model, the number m of folded layers, and the material wall thickness t; S22, material selection, determine the material parameters of the plate, including the material's stress-strain curve, density ρ, and Young's modulus E; S23, cutting the flat material according to the two-dimensional geometric model and structural parameters after the expansion in S21, removing excess material after cutting to obtain a cut piece consistent with the two-dimensional geometric model, and then folding the cut piece to form a three-dimensional porous metamaterial energy absorbing device consistent with the three-dimensional geometric model in S21; S24, perform compression and impact tests on the three-dimensional porous metamaterial energy absorbing device prepared in S23, and perform compression and impact simulation on the three-dimensional geometric model of S21, and verify the experimental results with the numerical simulation results to ensure the accuracy of the experimental and simulation results; then further analyze the compression mechanism of the material based on the energy dissipation analysis method according to the experimental and simulation results, and form a platform stress prediction formula for the porous metamaterial energy absorbing device under compression; S25. According to the platform stress prediction formula of the porous metamaterial energy absorption device under compression in S24, the platform stress of the porous metamaterial energy absorption device under different structural parameters is calculated to provide a solution for designing a structure that matches the actual energy absorption efficiency requirements.

9. The design method of the porous metamaterial energy absorbing device based on the origami forming process according to claim 8 is characterized in that: In step S23, the folding method of the cut piece is as follows: the four regular hexagonal faces connected to the square face are bent 54.7° along the common edge toward the same side, so that one edge of two circumferentially adjacent regular hexagonal faces overlaps, thereby forming half of a tetradecahedral unit; all regular hexagonal faces are bent in sequence according to the above method to form a wavy semi-finished structure with alternating concave and convex shapes; the wavy semi-finished structure is folded 180° in sequence along the creases between the periodic structures in a clockwise and counterclockwise order to form a honeycomb porous metamaterial energy absorption device with tetradecahedral units.

10. The design method of the porous metamaterial energy absorption device based on the origami forming process according to claim 8 is characterized in that: In step S24, the obtained platform stress prediction formula of the porous metamaterial energy absorbing device under compression is: In the formula, σ p is the platform stress; γ represents the aspect ratio, γ = a / t; a is the side length of the square face and the hexagonal face; t is the material wall thickness; γ c is a constant; y is the material yield stress; σ u is the material limit stress; n is the number of square faces on the short side of the two-dimensional geometric model; m is the number of folding layers; θ is the folding angle of the regular hexagonal face that shares the same edge with the square face, and θ = 54.7°; β is the rotation angle of the hinge line connecting the two regular hexagonal faces; h is the height of the porous metamaterial energy absorption device.

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