Energy Absorption Device of Porous Metamaterial Based on Origami Forming Process and Its Design Method

Abstract

The present invention discloses a porous metamaterial energy absorption device based on a paper folding and cutting forming process. The device is prepared by the paper folding and cutting forming process and includes staggered tetradecahedron units. The tetradecahedron 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. The present invention utilizes the flexible design characteristics of the paper folding and cutting technology. By converting the three-dimensional structure into a two-dimensional planar structure, the preparation is more conducive to precision control, greatly reducing costs and improving precision control. By analyzing the deformation mechanism and deducing the functional relationship between the structural energy absorption efficiency and the structural parameters, a structural optimization design with controllable energy absorption effect is achieved, thereby obtaining a porous metamaterial energy absorption device that meets different needs.

Description

Technical Field

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

[0002] Porous structures have efficient energy absorption characteristics. When subjected to impact or compressive loads, they can effectively absorb and disperse energy, and can maintain the integrity of the structure during compression, which helps to protect the structure from damage. In addition, research shows that honeycomb-like porous structures, as a typical type of metamaterial, have the characteristics of light weight and strong structure, and are widely used in aerospace and automotive transportation.

[0003] Traditional preparation methods for honeycomb-like porous structures include foam manufacturing methods, metal casting methods, 3D printing methods, etc. Among them, foam manufacturing methods include physical foaming methods and chemical foaming methods. The physical foaming method dissolves gas in resin and then reduces pressure or heats to release the gas to form a porous structure. The chemical foaming method uses special chemical additives, and the gas generated by the decomposition of the additives forms a porous structure in the material. Although foam manufacturing methods are easy to prepare and have low costs, the control accuracy requirements for temperature and pressure conditions during the material preparation process are harsh, the structure preparation accuracy is unstable, and chemical additives may pose health risks to the environment and operators. The metal casting method pours molten metal into a specific mold to form a porous structure. The metal casting method can achieve stable control of structure preparation accuracy, but specific molds need to be prepared in advance, which limits the flexibility of the structure form and is costly when producing non-standard structures. The 3D printing method constructs a porous structure by layer-by-layer deposition of materials and according to a design model. The 3D printing method is also limited by printing speed, material selection, and cost.

[0004] In summary, there is a problem in the existing preparation methods for porous metamaterial energy absorption devices that it is impossible to balance easy preparation and control of structure preparation accuracy. Easy preparation methods (such as foam manufacturing methods) cannot meet the requirements of structure accuracy control, while accuracy controllable methods (such as metal casting methods and 3D printing methods) are costly and difficult to meet the optimization control under different requirements, which affects the popularization 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. By utilizing the flexible design characteristics of origami and paper cutting technology, the preparation of the three-dimensional structure into a two-dimensional planar structure is more conducive to precision control, greatly reducing costs, and improving 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. 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 in the present invention is:

[0007] A porous metamaterial energy absorption device based on a paper folding and cutting process, the porous metamaterial energy absorption device comprising a plurality of staggered tetradecahedral units, the tetradecahedral units comprising two square faces arranged opposite each other in an upper and lower direction, four upper regular hexagonal faces sharing edges with the upper square face and arranged obliquely downward, four lower regular hexagonal faces sharing edges 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, 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 tetradecahedral units on the left and right respectively; the porous metamaterial energy absorption device is prepared using a paper folding and cutting process.

[0008] In the above solution, 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 when 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 co-edge-bound with a regular hexagonal face respectively. The periphery of the periodic structure is all regular hexagonal faces, and the outer regular hexagonal faces are only co-edge-bound with one square face, and the inner regular hexagonal faces are co-edge-bound 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 solution, the preparation process of the porous metamaterial energy absorbing device includes the following steps:

[0012] S11. Establish a two-dimensional geometric model of the expanded porous metamaterial energy absorption device, and extract the structural parameters of the tetrakaidecahedron unit, including the side lengths a of the square and hexagonal faces, the number n of square faces on the short side of the two-dimensional geometric model, the folding layer number m, and the material wall thickness t;

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

[0014] S13. Cut the flat plate in S12 according to the expanded two-dimensional geometric model and structural parameters in S11, and remove the redundant materials after cutting to obtain a flat plate with 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 to the same side, so that one edge coincides between two circumferentially adjacent regular hexagonal faces, thereby forming half of the tetrakaidecahedron unit; complete the bending of all regular hexagonal faces in the above method in turn to form a wavy semi-finished structure with alternating concave and convex;

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

[0017] In the above solution, the common edges generated after folding the flat plate are in a free state and do not need to be connected.

[0018] In the above solution, the flat plate material is a metal material.

[0019] Correspondingly, the present invention also proposes a design method for the porous metamaterial energy absorption device based on the origami cutting process, including the following steps:

[0020] S21. Establish a three-dimensional geometric model before the expansion and a two-dimensional geometric model after the expansion of the porous metamaterial energy absorption device, and extract the structural parameters of the tetrakaidecahedron unit, including the side lengths a of the square and hexagonal faces, the number n of square faces on the short side of the two-dimensional geometric model, the folding layer number m, and the material wall thickness t;

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

[0022] S23. Cut the flat plate material according to the expanded two-dimensional geometric model and structural parameters in S21, remove the redundant materials after cutting to obtain a cut piece consistent with the two-dimensional geometric model, and then form a three-dimensional porous metamaterial energy absorption device consistent with the three-dimensional geometric model in S21 by folding the cut piece;

[0023] S24. Conduct compression and impact tests on the three-dimensional porous metamaterial energy absorption device prepared in S23, and simultaneously conduct compression and impact simulations on the three-dimensional geometric model of S21. Mutually verify the experimental results and the numerical simulation results to ensure the accuracy of the experimental and simulation results. Then, further based on the energy dissipation analysis method according to the experimental results and the simulation results, analyze the compression mechanism of the material, and form a prediction formula for the plateau stress of the porous metamaterial energy absorption device under compression;

[0024] S25. According to the prediction formula for the plateau stress of the porous metamaterial energy absorption device under compression in S24, calculate the plateau stress of the porous metamaterial energy absorption device under different structural parameters, and 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 cutting piece is as follows: Bend the four regular hexagon faces connected to the square face by 54.7° along the common edge towards the same side, so that one edge coincides between two circumferentially adjacent regular hexagon faces, thereby forming half of the tetrakaidecahedron unit; Complete the bending of all regular hexagon faces in the above method in sequence to form a wavy semi-finished structure with alternating concave and convex; Fold the wavy semi-finished structure 180° in sequence along the creases between the periodic structures in a clockwise and counterclockwise alternating order to form a honeycomb-like porous metamaterial energy absorption device with tetrakaidecahedron units.

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

[0027]

[0028] In the formula, σ p is the plateau stress; γ represents the aspect ratio, γ = a / t; a is the side length of the square face and the hexagon face; t is the wall thickness of the material; γ c is a constant; σ y is the material yield stress; σ u is the material ultimate 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 hexagon face sharing the common edge with the square face, and θ = 54.7°; β is the rotation angle of the hinge line connecting two regular hexagon 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 absorption device based on a folding and cutting paper forming process and a design method thereof. By utilizing the flexible design characteristics of origami and paper cutting techniques, the complex three-dimensional porous metamaterial energy absorption device is transformed into a simple two-dimensional flat plate structure for shearing and folding operations. Then, the two-dimensional flat plate cut according to a specific form is folded to form a three-dimensional porous metamaterial energy absorption device. This method not only solves the problem of difficult preparation precision control in the traditional preparation process of porous materials, but also achieves the effect of simple preparation.

[0031] The porous metamaterial energy absorption device based on the folding and cutting paper forming process provided by the present invention has a stable deformation mode. Further, through experimental research and numerical simulation analysis of this structure, a prediction formula for high-precision platform force is proposed. Under limited constraint conditions, the unknowns of the prediction formula can be quickly calculated directly using computer software, solving the problem of difficult optimization of the traditional Kelvin foam structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[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 tetrakaidecahedron unit of the porous metamaterial energy absorption device;

[0035] Figure 3 It is a layout model diagram of the tetrakaidecahedron units of the porous metamaterial energy absorption device;

[0036] Figure 4 It is a plan view of the rectangular plate after cutting of the porous metamaterial energy absorption device;

[0037] Figure 5 It is a model diagram of the wavy semi-finished product structure after the regular hexagonal face 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 It is a numerical simulation model diagram of the porous metamaterial energy absorption device;

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

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

[0042] In the figure: 10, tetrakaidecahedron unit; 11, upper square face; 12, lower square face; 13, upper regular hexagon face; 14, lower regular hexagon face; 15, square hollow face. Specific embodiments

[0043] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to 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 only schematically illustrate the basic concept of the present invention. Therefore, only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape and size of the components in actual implementation. The types, quantities and proportions of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0045] In the present invention, it should also be noted that when terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying 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 to the present application. In addition, when terms such as "first" and "second" appear, they are only used for descriptive and distinguishing purposes and cannot be understood as indicating or implying relative importance.

[0046] As Figure 1 shown, the present invention proposes a porous metamaterial energy absorption device based on the origami cutting process. The porous metamaterial energy absorption device includes a plurality of tetrakaidecahedron units arranged in an interleaved manner. As Figure 2 shown, the tetrakaidecahedron unit includes two square faces arranged opposite to each other up and down, four upper regular hexagon faces 13 that share a side with the upper square face 11 and are arranged obliquely downward, four lower regular hexagon faces 14 that share a side with the lower square face 12 and are arranged obliquely upward, and four square hollow faces 15 formed after the upper regular hexagon faces 13 and the lower regular hexagon faces 14 are butted; the side lengths of all the square faces and regular hexagon faces are equal; the included angle between the upper regular hexagon face 13 and the upper square face 11 is 54.7°; the included angle between the lower regular hexagon face 14 and the lower square face 12 is 54.7°. As Figure 3As shown, there is exactly one completely coplanar face between two adjacent tetrakaidecahedron units. Among them, two tetrakaidecahedron units on the same axis share a square face, and share a regular hexagon face with the tetrakaidecahedron units on the left and right respectively.

[0047] As Figure 4 shown, after the porous metamaterial energy absorption device is fully deployed, it is a flat plate with a rectangular outer contour. The flat plate is composed of square faces and regular hexagon faces; it is divided into several periodic structures along the length direction of the flat plate. Each periodic structure includes n×n square faces, where n is the number of square faces along the width of the flat plate and is an odd number. Each side of each square face shares an edge with a regular hexagon face. The periphery of the periodic structure is all regular hexagon faces, and the peripheral regular hexagon faces are only connected by sharing an edge with one square face, and the internal regular hexagon faces are connected by sharing an edge with two square faces; two circumferentially adjacent regular hexagon faces form an acute angle, thus forming multiple X-shaped hollowings inside the flat plate. The common edge of the regular hexagon faces of adjacent periodic structures is a crease, and the direction of the crease 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. Each periodic structure includes 3×3 (a total of 9) square faces, and there are 4 creases in total.

[0048] The porous metamaterial energy absorption device of the present invention is prepared by a folding paper cutting process. The preparation process includes the following steps:

[0049] S11. Establish a two-dimensional geometric model of the porous metamaterial energy absorption device after deployment, and extract the structural parameters of the tetrakaidecahedron unit, including the side lengths a of the square face and the hexagon face, the number n of square faces on the short side (i.e., along the width of the flat plate) in the two-dimensional geometric model, the folding layer number m, and the material wall thickness t;

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

[0051] S13. According to the two-dimensional geometric model and structural parameters after deployment in S11, use a laser cutting machine to cut the flat plate in S12, and remove the excess material after cutting to obtain a flat plate consistent with the geometric model;

[0052] S14. Bend the four regular hexagon faces connected to the square face by 54.7° along the common edge to the same side, so that one edge of two circumferentially adjacent regular hexagon faces coincides, thus forming half of the tetrakaidecahedron unit; complete the bending of all regular hexagon faces in the above method in sequence to form a wavy semi-finished product structure with alternating convex and concave, as Figure 5 shown;

[0053] S15. Fold the wavy semi-finished product structure by 180° in sequence along the creases between the periodic structures to form a honeycomb-shaped porous metamaterial energy absorption device with tetrakaidecahedron units. Specifically, refer to Figure 5, first fold the periodic structure 1 by 180° clockwise along the crease 1, then fold the periodic structures 1 and 2 by 180° counterclockwise along the crease 2. Similarly, fold the periodic structures 1, 2, and 3 by 180° clockwise along the crease 3, and fold the periodic structures 1, 2, 3, and 4 by 180° counterclockwise along the 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 tetrakaidecahedron unit is axially loaded, plastic hinges are formed on the four sides of the square, achieving the energy absorption effect.

[0054] The present invention utilizes the flexible design characteristics of origami and paper-cutting techniques. The preparation of converting a three-dimensional structure into a two-dimensional plane structure in reverse is more conducive to precision control, greatly reducing costs while improving precision control.

[0055] Correspondingly, the present invention also proposes a design method for the porous metamaterial energy absorption device based on the origami and paper-cutting forming process. By establishing a functional relationship between the platform stress and the structural geometric parameters, the effect of predicting the structural energy absorption efficiency is achieved, as Figure 6 shown, including the following steps:

[0056] S21. Use CAD-assisted design to establish a three-dimensional geometric model before the porous metamaterial energy absorption device is unfolded and a two-dimensional geometric model after unfolding, and extract the structural parameters of the tetrakaidecahedron 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 folding layer number m, and the material wall thickness t.

[0057] S22. Select materials and confirm material parameters, including the stress-strain curve of the material, 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 metals such as aluminum alloys and steels. Taking the commonly used aluminum alloy material as an example, use a universal testing machine 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 unfolding in S21, use a laser cutting machine to cut the flat plate material. After cutting, remove the excess material to obtain a cut piece consistent with the two-dimensional geometric model, and then form a three-dimensional porous metamaterial energy absorption device consistent with the three-dimensional geometric model in S21 by folding the cut piece. The folding method of the cut piece is as follows: Fold the four regular hexagonal faces connected to the square face by 54.7° along the common edge towards the same side, so that one side of two circumferentially adjacent regular hexagonal faces coincides, thereby forming half of the tetrakaidecahedron unit; complete the folding of all regular hexagonal faces in the above method in sequence to form a wavy semi-finished structure with alternating convex and concave; fold the wavy semi-finished structure by 180° in sequence along the creases between the periodic structures to form a honeycomb-like porous metamaterial energy absorption device with tetrakaidecahedron units.

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

[0060] Use an MTS universal testing machine to conduct an axis quasi-static compression experiment on the prepared three-dimensional porous metamaterial energy absorption device specimen. Set the loading speed to 1 mm / s, and collect the compression force-time curve through a computer control system. The side lengths of the square and regular hexagon in the specimen are equal, and the cross-sectional length and width can be calculated. Since the structure has variable cross-sections up and down, the smallest cross-section is used as the calculation cross-section, and the length and width of the smallest cross-section are L = 2na, and the height is The cross-sectional area A of the specimen = (2na) 2 . Where θ is the folding angle of the regular hexagon face sharing a side with the square face, and θ = 54.7°.

[0061] The plateau stress σ p has the following relationship with the average extrusion force F m :

[0062]

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

[0064]

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

[0066] Δh = v×Δt (3)

[0067] In the formula, 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 specimen density to the matrix material density is defined as the relative density ρ r , and the calculation formula is:

[0070]

[0071] The formula for representing the average bearing capacity of the material with the plateau stress σ p 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] The 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 specimen, and ρ is the material density.

[0077] The commercial software ABAQUS / Explicit is used for numerical simulation. The material is meshed using conventional shell elements (S4R), and the top and bottom platforms use discrete rigid body elements (R3D4). For the AA6063O aluminum alloy material, the contact form is defined as general contact and self-contact of the porous metamaterial device. When the friction coefficient is taken as 0.3, the mesh size is 1.5 mm, and the convergence condition is reached. The deformation process is shown in Figures 7 - 8 . The numerical results are compared with the experimental results. As Figure 9 shown, the numerical simulation results (the Simulation curve in the figure) are basically in agreement with the experimental results (the KC-1, KC-2, and KC-3 curves in the figure).

[0078] Analyzing the experimental results and the numerical simulation results, the most crucial deformation mechanism of the porous metamaterial energy absorption device based on the fold-cut paper process under compressive load lies in the bending of the regular hexagonal surface along the crease. Since the regular hexagonal surface and the square surface have relatively large stiffness, 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 absorption device based on the fold-cut paper process can be roughly predicted.

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

[0080]

[0081] Among them, σ0 is the flow stress of the matrix material, and t is the material wall thickness. Using the linear relationship between the flow stress and the width-thickness ratio, the formula for calculating the flow stress:

[0082]

[0083] In the formula, γ is the width-thickness 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 hinge lines are generated at the creases. Assuming the number of square faces on the short side of the metal plate is n and the number of folding layers is m, then the number of hinge lines connecting square faces and regular hexagon faces is 4n2m, with a corresponding rotation angle of θ, and the number of hinge lines connecting two regular hexagon faces is n(m - 1), and approximately half of this part of the hinge lines has a rotation angle of β. According to the principle of energy balance, the energy consumed by the bending of the hinge lines is equal to the work done by the external force, and the following formula is obtained:

[0085]

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

[0087] Substituting equations (1), (7), and (8) into equation (9), the prediction formula for the compressive lower platform stress of the porous metamaterial energy absorption device based on the fold-cut paper process is obtained as follows:

[0088]

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

[0090] As can be seen from step 4, according to the derived prediction formula for the platform stress of the porous metamaterial energy absorption device based on the fold-cut paper process, it is very convenient to calculate the magnitude of the corresponding platform stress when different structural parameters (wall thickness t, number of single-sided square elements n, number of folding layers m, square side length a) change. The greater the platform stress, the higher the energy absorption efficiency. Or under limited conditions such as the overall size limitation of the structure, it is easy to find the optimal solution of other structural parameters.

[0091] The preparation of this invention by reversely unfolding a three-dimensional structure into a two-dimensional planar structure is more conducive to precision control, greatly reduces costs, and at the same time improves precision control. Through the optimized design of structural parameters, a porous metamaterial energy absorption device with a low initial peak stress and high specific energy absorption can be designed. This method has good practicability and economic benefits.

[0092] It should be noted that according to the needs of implementation, each step / component described in this application can be split into more steps / components, or two or more steps / components or parts of the operations of steps / components can be combined into new steps / components to achieve the purpose of this invention.

[0093] The sequence numbers of the steps in the above embodiments do not indicate the order of execution, and the order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0094] It should be understood that those of ordinary skill in the art can make improvements or transformations according to the above description, and all such improvements and transformations should fall within the protection scope of the appended claims of the present invention.

Claims

1. A design method for a porous metamaterial energy absorption device based on the paper-cut folding forming process, characterized in that, The porous metamaterial energy absorption device includes a number of intersecting tetrakaidecahedron units. The tetrakaidecahedron unit includes two square faces arranged opposite to each other up and down, four upper regular hexagon faces sharing a side with the upper square face and arranged obliquely downward, four lower regular hexagon faces sharing a side with the lower square face and arranged obliquely upward, and four square hollow faces formed after the upper regular hexagon faces and the lower regular hexagon faces are butted. The side lengths of all square faces and regular hexagon faces are equal; there is exactly one face that is completely coplanar between two adjacent tetrakaidecahedron units. Among them, two coaxially arranged tetrakaidecahedron units up and down share a square face and share a regular hexagon face with the tetrakaidecahedron units on the left and right respectively; the porous metamaterial energy absorption device is prepared by a folding paper cutting process; the design method includes the following steps: S21. Establish a three-dimensional geometric model of the porous metamaterial energy absorption device before deployment and a two-dimensional geometric model after deployment, and extract the structural parameters of the tetrakaidecahedron unit, including the side lengths of the square faces and the hexagonal faces. a , the number of square faces on the short side of the two-dimensional geometric model n , the number of folding layers m , the wall thickness of the material t ; S22. Select materials and determine the parameters of the flat material, including the stress-strain curve, density ρ, and Young's modulus E of the material. S23. According to the two-dimensional geometric model and structure parameters expanded in S21, cut the flat material. After cutting, remove the redundant material to obtain a cut piece consistent with the two-dimensional geometric model. Then, form a three-dimensional porous metamaterial energy absorption device consistent with the three-dimensional geometric model in S21 by folding the cut piece. S24. Conduct compression and impact tests on the three-dimensional porous metamaterial energy absorption device prepared in S23, and at the same time conduct compression and impact simulations on the three-dimensional geometric model in S21. Verify the experimental results and the numerical simulation results with each other to ensure the accuracy of the experimental and simulation results; further analyze the compression mechanism of the material based on the energy dissipation analysis method according to the experimental results and simulation results, and form a platform stress prediction formula for the porous metamaterial energy absorption device under compression. S25. According to the platform stress prediction formula of the porous metamaterial energy absorption device under compression in S24, calculate the platform stress of the porous metamaterial energy absorption device under different structural parameters, and provide a solution for designing a structure that matches the actual energy absorption efficiency requirements.

2. The design method of the porous metamaterial energy absorption device based on the paper-cut folding forming process according to claim 1, characterized in that, The included angle between the upper regular hexagon face and the upper square face is 54.7°; the included angle between the lower regular hexagon face and the lower square face is 54.7°.

3. The design method of the porous metamaterial energy absorption device based on the folding and cutting paper forming process according to claim 1, characterized in that, After the porous metamaterial energy absorption device is fully deployed, 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, and each periodic structure includes n n square faces, n is the number of square faces along the width of the flat plate, taking an odd number. Each side of the four sides of each square face shares an edge with a regular hexagonal face. The periphery of the periodic structure is all regular hexagonal faces, and the peripheral regular hexagonal faces are only connected by sharing an edge with one square face, and the internal regular hexagonal faces are connected by sharing an edge with two square faces; two circumferentially adjacent regular hexagonal faces form an acute angle, thereby forming multiple X-shaped hollowings inside the flat plate.

4. The design method of the porous metamaterial energy absorption device based on the paper-cut folding forming process according to claim 3, characterized in that The common side of the regular hexagon faces of adjacent periodic structures is a crease.

5. The design method of the porous metamaterial energy absorption device based on the paper-cut folding forming process according to claim 1, characterized in that The common side generated after the flat plate is folded is in a free state and does not need to be connected.

6. The design method of the porous metamaterial energy absorption device based on the folded paper cutting forming process according to claim 1, characterized in that The flat material is made of a metal material.

7. The design method of the porous metamaterial energy absorption device based on the paper-cut folding forming process according to claim 1, characterized in that, In step S23, the folding method of the cut piece is as follows: Bend the four regular hexagon faces connected to the square face by 54.7° along the common side towards the same side, so that one side of two circumferentially adjacent regular hexagon faces coincides, thereby forming half of the tetrakaidecahedron unit; complete the bending of all regular hexagon faces in the above method in turn to form a wavy semi-finished structure with alternating convex and concave; fold the wavy semi-finished structure 180° in turn along the creases between the periodic structures in a clockwise and counterclockwise alternating order to form a honeycomb-like porous metamaterial energy absorption device with tetrakaidecahedron units.

8. The design method of the porous metamaterial energy absorption device based on the paper-cut folding forming process according to claim 1, characterized in that, In step S24, the obtained platform stress prediction formula for the porous metamaterial energy absorption device under compression is: In the formula, is the platform stress; ; are the side lengths of the square face and the hexagonal face; t is the wall thickness of the material; is a constant; is the yield stress of the material; is the ultimate stress of the material; n is the number of square faces on the short side of the two-dimensional geometric model; m is the number of folding layers; is the folding angle of the hexagonal face sharing a side with the square face, and ; is the rotation angle of the hinge line where two hexagonal faces are connected; h is the height of the porous metamaterial energy absorption device.

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