Design method of self-repairing negative poisson ratio double-interlocking modular dot matrix energy absorption structure

Abstract

The invention discloses a design method of a self-repairing negative poisson ratio double-interlocking modular dot matrix energy absorption structure, and relates to the technical field of rail transit carriers, aerospace, new energy vehicles, special vehicles and armor protection. The energy absorption structure is based on a Priative TPMS thin-wall dot matrix, the energy absorption characteristic is adjusted by changing the cell opening size and the gradient change of the cell length in the Z-axis direction, and meanwhile, thin walls are additionally arranged at the cell openings around the dot matrix so that premature buckling of the openings can be avoided. In order to avoid external expansion deformation of the protection structure when the protection structure is pressed, the TPMS thin-wall dot matrix module is introduced into a macroscopic inward concave structure, and negative Poisson's ratio design is presented. The TPMS thin-wall dot matrix framework is made of a memory shape alloy material, through holes of a dot matrix are filled with a non-metal phase material to form a double-interlocking structure of the metal framework and the non-metal phase material, the inner surface layer of the metal framework is coated with a polyurea elastomer material, it is ensured that metal and non-metal materials are reliably combined, and the impact resistance is improved. The energy absorption structure is modularly designed, the three-dimensional cross-scale energy absorption structure can be assembled at will, and the energy absorption module can be conveniently replaced when the protection structure is locally damaged due to unmaintainability. Compared with a traditional energy absorption protection structure, the protection structure has the advantages of being higher in energy absorption efficiency, high in durability, low in maintenance cost, capable of being assembled and combined and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of plastic energy-absorbing protective structures, in particular to a design method for a double-interlocking modular lattice energy-absorbing protective structure that is self-repairing and has negative Poisson's ratio deformation characteristics. Background Art

[0002] In the fields of rail transit, aerospace, new energy vehicles, special vehicles, and armored protection, energy-absorbing protective structures are designed to mitigate impact and reduce the degree of structural deformation and extrusion during a collision. These structures can rapidly activate their crushing deformation mechanism, absorbing a certain amount of impact energy in a short period of time, thereby providing protection. Traditional simple tubular energy-absorbing structures experience severe load fluctuations during the crushing process. High peak impact forces create acceleration and deceleration shocks, and external expansion and deformation can compress surrounding structures, making them difficult to adapt to the protection requirements of new energy battery-powered vehicles. Furthermore, even in less severe collisions, protective structures that undergo plastic deformation often require replacement, which undoubtedly increases maintenance costs for large-area protection scenarios. Therefore, new plastic energy-absorbing protective structures with superior performance and more diverse functions are needed. These structures should achieve a stable crushing pattern, enhance energy absorption capacity, reduce load fluctuations during the crushing process, and feature features such as the ability to combine and easily replace energy-absorbing modules. Furthermore, after low-intensity collisions, the energy-absorbing structures can automatically repair themselves, meeting diverse protective safety requirements.

[0003] Based on the above requirements, the purpose of this patent is to design a lightweight energy-absorbing lattice structure with a negative Poisson's ratio, double interlocking, automatic repairability, and modular assembly. The negative Poisson's ratio structure has a lateral contraction characteristic when under pressure, which can reduce the squeeze on the surrounding structure. In the existing technology, the conventional negative Poisson's ratio structure has a single topological configuration, and there is severe shear failure in crushing, which reduces the energy absorption efficiency and has severe load fluctuations. Although the single metal thin-walled structure has the characteristics of lightweight, it is prone to buckling and stress concentration, and the material utilization rate is low. The conventional plastic energy-absorbing structure is a passive sacrificial protective structure. If plastic deformation occurs, it will face overall replacement, which increases maintenance costs.

[0004] In response to the problems existing in the above-mentioned traditional energy-absorbing protection structure, this patent is based on the TPMS lattice, and the innovative points of the designed lattice protection structure are as follows: 1. The smooth and continuous characteristics of TPMS are used to reduce stress concentration, improve the uniformity of the crush deformation of the energy-absorbing structure, avoid unnecessary shear failure, improve energy absorption efficiency, and reduce the crush peak load and fluctuation; 2. On this basis, the concave arc of the energy-absorbing structure filled with the TPMS lattice is controlled to achieve the negative Poisson's ratio characteristics of the crush process; 3. In order to avoid accidental buckling of thin-walled structures while maintaining lightweight characteristics, the thin-walled lattice structure is used as the skeleton and filled with lightweight energy-absorbing non-metallic phase materials to form a metal-non-metal double interlocking structure, thereby improving the stability and durability of the structure; 4. The material of the metal lattice used is shape memory alloy, which can automatically restore its original shape after a slight collision deformation, reducing maintenance costs; 5. The designed energy-absorbing structure is a modular unit. If irreparable damage occurs, only the local protection lattice structure module needs to be replaced. Summary of the Invention

[0005] The purpose of the present invention is to provide a self-repairing negative Poisson's ratio double-interlocking modular lattice energy-absorbing structure design method to solve the problems of low energy absorption efficiency, high peak force, significant load fluctuation and high maintenance cost of traditional energy-absorbing structures during collision. At the same time, it can replace damaged and irreparable local modules to meet diversified protection needs.

[0006] In order to achieve the above technical effects, the technical solutions adopted by the present invention are as follows:

[0007] A design method for a self-repairing negative Poisson's ratio double-interlocking modular lattice energy-absorbing structure includes a primitive-type TPMS thin-walled lattice made of shape memory alloy, a lightweight non-metallic energy-absorbing filler, and a modular assembly structure.

[0008] The primitive TPMS is a three-dimensional periodic structure with cubic symmetry, zero mean curvature, and smooth continuity. It can be expressed as follows using an implicit function:

[0009]

[0010] The crush energy absorption characteristics can be adjusted by structural parameters. The constant C regulates the size of the cell opening, and L regulates the cell length. The TPMS thin-walled lattice designed by the present invention reduces the cell opening by regulating the C value, thereby improving the energy absorption efficiency, and reduces the peak force and suppresses load fluctuations while improving the energy absorption efficiency by designing the gradient of L in the height Z direction. However, it is not realistic to achieve high energy absorption, stable crush deformation mode and low peak force of the TPMS structure by relying solely on implicit function regulation. Thin walls are added to the cell openings around the TPMS lattice to form a TPMS-like tubular lattice structure. The design of adding thin walls can suppress the premature buckling of the opening area during the TPMS cell crush process.

[0011] The Primitive TPMS's modular energy-absorbing box area is filled with thin-walled lattices. The outer surfaces of this modular energy-absorbing box are concave, with each concave surface being formed by stretching an arc. This modular energy-absorbing box structure with thin-walled lattices exhibits a negative Poisson's ratio, preventing damage to surrounding components caused by expansion and deformation of the protective structure when under pressure. This negative Poisson's ratio is controlled by the parameters of the concave arc.

[0012] The Primitive TPMS thin-walled modular lattice structure is used as the skeleton, and its good fluid permeability and interlaced voids are utilized to fill the skeleton with lightweight, energy-absorbing non-metallic phase materials. After the non-metallic phase materials are injected and shaped, a double-interlocking structure of a metal skeleton and a non-metallic filler is formed. The metal structure serves as the load-bearing force transmission path skeleton, and the non-metallic phase supports the structure to avoid local premature buckling. Taking into account factors such as energy absorption efficiency and lightweight, the non-metallic phase material can be natural fiber-reinforced PU foam, glass fiber-reinforced PU foam, etc. At the same time, a polyurea elastomer material is coated on the inner surface of the TPMS metal skeleton to form a functional interface layer with a thickness of 0.1 to 0.3 mm, which enhances the interfacial bonding strength between the metal and non-metallic materials while resisting impact and penetration.

[0013] The Primitive TPMS thin-walled lattice structure utilizes a shape-memory alloy. During mild collisions, the alloy absorbs energy through a stress-induced phase transition and automatically returns to its original shape after unloading, avoiding permanent deformation and reducing repair costs. To balance lightweight, protective, and cost requirements with additive manufacturing printability, the shape-memory alloy can utilize copper-based or iron-based alloys with specific compositions. The Primitive TPMS thin-walled metal lattice modular structure is integrally formed via 3D printing.

[0014] The modular assembly structure is integrally printed onto the upper and lower end surfaces of the TPMS lattice. T-shaped grooves and T-shaped protrusions are incorporated into the upper, lower, left, and right ends of the modular assembly structure. Adjacent modular energy-absorbing structures are assembled using these tenon-and-mortise structures. This allows for the three-dimensional assembly of modular energy-absorbing lattice structures using only 3D printing of standard modular energy-absorbing structures. This enables the construction of energy-absorbing structures across multiple scales and in various shapes. If a module in the protective structure becomes irreparably damaged, it can be readily replaced, eliminating the need for complete replacement and reducing maintenance costs.

[0015] Compared with the prior art, the advantages of the self-repairing negative Poisson's ratio double-interlocking modular lattice energy absorption structure design method of the present invention are: 1. Higher safety performance, using the Primitive type TPMS thin-walled lattice, through parameter adjustment and increasing the thin-wall design, significantly improving the energy absorption efficiency, reducing the peak force and suppressing load fluctuations; 2. Less damage to the surrounding components of the protective structure, the lattice structure has a concave arc design to avoid outward expansion deformation during the structural crushing process; 3. Higher durability, using a two-phase design, the metal skeleton bears the load and guides orderly deformation, and the non-metallic phase supports the thin-walled structure to avoid local premature buckling; 4. Low maintenance cost, the TPMS thin-walled lattice uses shape memory alloy, which can self-repair after a mild collision; 5. It can be assembled and replaced, and a modular assembly structure is installed in the energy absorption structure, which can be assembled into a complex three-dimensional energy absorption structure, and the irreparable local protection lattice module can be replaced at any time. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is an overall schematic diagram of the energy-absorbing protection structure.

[0017] Figure 2 This is a front view of the energy-absorbing protective structure.

[0018] Figure 3 This is an enlarged partial cross-section of the TPMS thin-walled lattice.

[0019] Figure 4 This is a partial enlarged view of the modular assembly structure.

[0020] Figure 5 This is the assembly diagram of the energy-absorbing protective structure.

[0021] The numbers in the figure are:

[0022] 1 Modular assembly structure 2 TPMS thin wall lattice 3 Thin wall 4 Non-metallic phase material 5 Polyurea elastomer material DETAILED DESCRIPTION

[0023] The technical solution of the present invention is described in detail below with reference to the accompanying drawings.

[0024] like Figure 1 、 2 As shown, the energy absorption protection modular structure described in this embodiment adopts a 4×4×4 array of Primitive type TPMS thin-walled dot matrix (2), the total height of which in the Z-axis direction is H (10mm≤H≤55mm), and the Primitive surface formula is:

[0025]

[0026] The C value is adjusted to reduce the opening size of the TPMS thin-walled lattice (2), and L is adjusted to allow the cell length to change gradiently in the height Z-axis direction. The initial cell length in the Z-axis direction is L1 = 0.2 ~ 0.25H, and the terminal cell length is L2. The gradient change ratio α = L2 / L1 (1.05≤α≤1.5). In order to suppress the premature buckling of the opening area during the cell crushing process, thin walls (3) are added to the cell openings around the TPMS thin-walled lattice (2). Figure 3 As shown, in order to ensure that the wall thickness of the TPMS thin-walled lattice (2) is t1=0.02~0.1L1 under low relative density conditions, the wall thickness of the added thin wall (3) is t2=0.7~0.8t1. The adjustment of parameters and the design of adding thin wall (3) can achieve a stable crushing deformation mode and low peak force of the TPMS thin-walled lattice (2), further improving the energy absorption efficiency of the energy absorption protection structure. The TPMS thin-walled lattice (2) is made of shape memory alloy. The protection structure can self-repair after a low-intensity collision. The shape memory alloy material can be a copper-based alloy or an iron-based alloy with a specific composition.

[0027] like Figure 2 As shown, the negative Poisson's ratio structure has the characteristic of lateral contraction when under pressure, and a macro-concave configuration is introduced around the TPMS thin-walled lattice (2). In order to balance the negative Poisson's ratio and energy absorption efficiency, the radius of the concave arc is R = 1.4 ~ 1.45H. The protective structure uses the negative Poisson's ratio characteristic to avoid damage to surrounding components due to external expansion deformation during the crushing process.

[0028] like Figure 3 As shown, the TPMS thin-walled lattice (2) serves as a skeleton, which has good fluid permeability and interlaced voids. This allows the non-metallic phase material (4) to be embedded within the metal skeleton during the foaming process, forming a double interlocking structure of the metal skeleton and the non-metallic filler. The non-metallic phase material (4) can be made of natural fiber reinforced PU foam, glass fiber reinforced PU foam, etc. The inner surface of the TPMS thin-walled lattice (2) is filled with a 0.1-0.3mm polyurea elastomer material (5), which allows the non-metallic phase material (4) to better adhere to the inner surface of the metal skeleton and has better impact and puncture resistance.

[0029] The energy absorbing and protective structure is modular in design, such as Figure 1 As shown, a modular assembly structure (1) is connected to the TPMS thin-walled lattice (2), and the total length and width of the modular assembly structure (1) are both W = 0.8 ~ 0.95H, and the thickness h = 0.06 ~ 0.1W. Figure 5 As shown, the T-shaped grooves and protrusions of the upper, lower, left and right end surface assembly structures of the modular energy absorbing lattice structure form a mortise and tenon structure, which is convenient for assembling the energy absorbing protective structure. Figure 4 As shown, the dimensions of the T-shaped structure are w1=2w2=0.2~0.25W, h1=h2=0.3~0.35h.

[0030] The above embodiments are only specific examples to further illustrate the purpose, technical solutions and beneficial effects of the present invention, and the present invention is not limited thereto. Any modifications, equivalent replacements, improvements, etc. made within the scope of the disclosure of the present invention are included in the scope of protection of the present invention.

Claims

1. A design method for a self-repairing negative Poisson's ratio double-interlocking modular lattice energy-absorbing structure, characterized by: The energy absorption structure is based on a primitive three-periodic minimal surface (TPMS) thin-walled lattice. The energy absorption characteristics are adjusted by changing the size of its cell openings and the gradient change of the cell length along the Z-axis. Thin walls are added at the cell openings around the lattice. The TPMS thin-walled lattice module introduces a macro-concave configuration, presenting a negative Poisson's ratio design; the TPMS thin-walled lattice frame is made of a shape memory alloy; The interior of the TPMS thin-walled lattice is filled with a lightweight, energy-absorbing non-metallic phase material, and the inner surface of the metal skeleton is coated with a polyurea elastomer material; The energy absorbing structure is modularly designed and can be assembled into a three-dimensional cross-scale energy absorbing structure at will.

2. The design method of a self-repairing negative Poisson's ratio double interlocking modular lattice energy absorption structure according to claim 1, characterized in that: The Primitive TPMS thin-walled lattice is constructed by the following implicit function expression: The constant C controls the size of the cell opening, and L controls the cell length. By adjusting the parameters, the cell opening is reduced and the cell length changes gradiently along the Z-axis. At the same time, thin walls are added to the cell openings around the lattice to avoid premature buckling of the openings, thereby improving the energy absorption efficiency and achieving a stable crush deformation mode.

3. The design method of a self-repairing negative Poisson's ratio double interlocking modular lattice energy absorption structure according to claim 1, characterized in that: The TPMS thin-walled lattice module introduces a macroscopic concave configuration and presents a negative Poisson's ratio design, which prevents the protective structure from expanding and deforming when it is under pressure, thereby preventing damage to other surrounding components.

4. The design method of a self-repairing negative Poisson's ratio double interlocking modular lattice energy absorption structure according to claim 1, characterized in that: The TPMS thin-walled lattice framework is made of a shape-memory alloy that can self-repair after minor collisions, reducing repair costs. The shape-memory alloy is also additively printable. The Primitive TPMS thin-walled metal lattice modular structure is integrally formed via 3D printing.

5. The design method of a self-repairing negative Poisson's ratio double interlocking modular lattice energy absorption structure according to claim 1, characterized in that: The interior of the TPMS thin-walled lattice is filled with a lightweight, energy-absorbing non-metallic phase material to form a double-interlocking configuration of a metal skeleton and non-metallic phase materials. The inner surface of the metal skeleton is coated with a polyurea elastomer material to ensure reliable bonding between the metal and non-metallic materials and improve impact resistance.

6. The design method of a self-repairing negative Poisson's ratio double interlocking modular lattice energy absorption structure according to claim 1, characterized in that: The energy absorbing structure is modularly designed, and adjacent modular energy absorbing structures are assembled through T-shaped grooves and T-protruding mortise and tenon structures, and can be arbitrarily assembled into a three-dimensional cross-scale energy absorbing structure. In case of irreparable damage, only the local protection lattice structure module needs to be replaced.

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