Functional gradient TPMS filled energy absorption box and design method thereof

Abstract

The invention belongs to the technical field of vehicle safety protection, and particularly relates to a functional gradient TPMS (Tire Pressure Monitor System) filled energy absorption box and a design method thereof, which are used for efficiently absorbing impact energy in a collision accident and reducing the injury risk of a passenger compartment. Through the multi-dimensional gradient design of the three-period minimal curved surface lattice structure and in combination with the 3D printing technology, efficient energy absorption and light weight are achieved. The TPMS structure filled in the energy absorption box is divided into a front gradient area, a middle gradient area and a rear gradient area in the longitudinal direction, the front portion is designed to be large in cell element and low in density so as to rapidly absorb initial impact energy, the rear portion stably dissipates residual energy through a small cell element and high-density structure, and smooth transition is achieved in the middle. According to the structure, the offset of a TPMS implicit function equation is controlled through parameterization, and the dynamic energy absorption efficiency is optimized. Through verification, the performance of the energy absorption box is obviously better than that of a traditional honeycomb filling structure, and the energy absorption box is suitable for the field of automobile collision protection.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of vehicle safety protection, and particularly relates to a functionally graded TPMS filled energy absorption box and a design method thereof, which is used for efficiently absorbing impact energy and reducing the risk of passenger cabin damage in a collision accident. BACKGROUND

[0002] In modern industry and daily life, various equipment and structures are often subjected to impact loads, such as automobile collisions, mechanical drops, etc. In order to protect the safety of equipment and personnel, effective energy absorption devices are needed to absorb and disperse impact energy, reducing the damage of impact to equipment and personnel. Traditional energy absorption boxes mostly use metal honeycomb structures or foam filling, which has the problems of low energy absorption efficiency, large weight, uncontrollable deformation, etc. Therefore, it is of great practical significance to develop a new type of energy absorption device with high energy absorption capacity and good impact resistance.

[0003] In recent years, lattice structures based on triply periodic minimal surfaces (TPMS) have attracted widespread attention in the field of structural lightweight design and impact resistance due to their lightweight high strength, good connectivity, controllable topological structure, etc. However, existing TPMS energy absorption structures are mostly uniformly designed, which cannot adapt to the multi-stage characteristics of energy transmission in the collision process, resulting in limited energy absorption efficiency. In addition, traditional manufacturing processes are difficult to realize the integrated forming of complex gradient structures. Therefore, there is an urgent need for an energy absorption box scheme combining gradient design and advanced manufacturing. SUMMARY

[0004] The application aims to provide a functionally graded TPMS filled energy absorption box and a design method thereof, which optimizes the energy absorption capacity and impact resistance of the structure by filling the TPMS structure with functional gradient changes inside the energy absorption box, solving the problems of low energy absorption efficiency and easy damage of existing energy absorption devices.

[0005] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0006] A functionally graded TPMS filled energy absorption box, comprising a box body and a TPMS structure filled inside the box body, the TPMS structure comprising a plurality of unit cells;

[0007] The TPMS structure adopts a Sheet-based Gyroid type TPMS structure;

[0008] The relative density of the unit cells in the TPMS structure filled inside the box body changes along the impact direction in a gradient manner;

[0009] The Sheet-based Gyroid type TPMS structure is modeled by an implicit function equation;

[0010] The implicit function equation is:

[0011] φ G (x,y,z)=cos(wx)sin(wy)+cos(wy)sin(wz)+cos(wz)sin(wx)=±C

[0012] wherein w is a period, (x,y,z) is a Cartesian coordinate system; φ G (x,y,z) is an isosurface; C is the offset of the minimal surface;

[0013] The function relationship between the relative density A of the unit cell in the Sheet-based Gyroid type TPMS structure and the offset C of the minimal surface is:

[0014] A=39.7C-0.84

[0015] By setting different C values, TPMS structures with different volume fractions can be obtained to control the relative density of the TPMS structure; by designing C, the change form of the relative density of the TPMS structure in three directions can be controlled;

[0016] The TPMS structure filled in the energy absorption box is divided into front, middle and rear gradient regions in the longitudinal direction, the front part adopts large unit cell and low density design to quickly absorb the initial impact energy, the rear part dissipates the remaining energy through small unit cell and high density structure, and the middle part realizes smooth transition.

[0017] The change range of the relative density y of the Sheet-based Gyroid type TPMS structure is 10% to 50%;

[0018] A design method of a functionally graded TPMS filled energy absorption box, comprising the following steps:

[0019] The implicit function equation is used as the input of the Ntopology software to establish a TPMS structure with a relative density gradient;

[0020] The TPMS structure with a relative density gradient is meshed and repaired by the Hypermesh software;

[0021] The TPMS structure with a relative density gradient after meshing and repairing is analyzed for mechanical properties by the Abaqus software;

[0022] The change form of the relative density gradient of the TPMS structure includes linear gradient change, double parabolic gradient change and double linear gradient change;

[0023] The box body of the energy absorption box is made of high-strength materials such as aluminum alloy, carbon fiber composite material, etc. to improve the overall strength and impact resistance of the energy absorption box.

[0024] The TPMS structure is connected with the box body by means of bonding or 3D printing integrated forming, and the stability of the TPMS structure in the box body is ensured.

[0025] The TPMS structure based on Sheet has the advantages of light weight, high strength, good connectivity and controllable topological structure, and can reduce the overall weight of the energy absorption box while ensuring the structural strength, and improve the lightweight performance

[0026] The relative density changes in the range of 10% to 50%, and can be adjusted according to different application requirements and impact conditions, so that the energy absorption box has good adaptability and versatility.

[0027] The shape and size of the energy absorption box can be designed and adjusted according to actual application requirements, and has good flexibility and customizability, and can meet the energy absorption requirements of different equipment and scenes.

[0028] The beneficial effects of the present application are:

[0029] The present application fills the TPMS structure with functional gradient change in the energy absorption box, optimizes the energy absorption capacity and impact resistance of the structure. The design of the relative density gradient can dynamically adjust the deformation form according to the size and position of the impact energy when the structure is impacted, so as to more effectively absorb and disperse the impact energy and improve the energy absorption efficiency.

[0030] The present application discloses a kind of functional gradient TPMS filled energy absorption box, by the multidimensional gradient design of Triply Periodic Minimal Surface (TPMS) lattice structure, in combination with 3D printing technology, realize high-efficiency energy absorption and light weight.Energy absorption box filled with TPMS structure is divided into front, middle and rear gradient region along longitudinal direction, front adopts large cell, low-density design to quickly absorb initial impact energy, rear is stabilized by small cell, high-density structure dissipates residual energy, middle realizes smooth transition.The structure optimizes dynamic energy absorption efficiency by parameterizing control TPMS implicit function equation offset (C value).It has been verified that the performance of the energy absorption box of the present application is significantly better than that of the conventional honeycomb filled structure, and is suitable for automobile crash protection field.

[0031] The implicit function equation of the TPMS structure is:

[0032] φ G (x,y,z)=cos(wx)sin(wy)+cos(wy)sin(wz)+cos(wz)sin(wx)=±C

[0033] Wherein, C is offset parameter.

[0034] The average relative density of all TPMS structures is 40%.

[0035] The gradient design is modeled by nTopology software, and meshed by Hypermesh (mesh type C3D10M) and analyzed by Abaqus.

[0036] Application of a functionally graded TPMS filled energy absorption box in the fields of vehicles, protective equipment, etc. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 Sheet-based Gyroid TPMS structure unit cell;

[0038] Figure 2 Relationship between relative density A and C values of Sheet-based Gyroid TPMS structure unit cell;

[0039] Figure 3 Traditional quadrilateral honeycomb unit cell;

[0040] Figure 4 TPMS structure with linearly varying density;

[0041] Figure 5 Traditional quadrilateral honeycomb filled energy absorption box;

[0042] Figure 6 Functionally graded TPMS structure filled energy absorption box;

[0043] Figure 7 Load-displacement curve of traditional quadrilateral honeycomb and functionally graded TPMS structure filled energy absorption box under compression load;

[0044] Figure 8 Stress distribution cloud map of traditional quadrilateral honeycomb and functionally graded TPMS structure filled energy absorption box under compression load. DETAILED DESCRIPTION

[0045] The present application will be described in detail below with specific embodiments. The following examples will help those skilled in the art to further understand the present application, but do not limit the present application in any form.

[0046] Example: Functionally graded TPMS filled energy absorption box

[0047] A functionally graded TPMS filled energy absorption box, comprising a box body and a TPMS structure filled in the box body, the TPMS structure comprising a plurality of unit cells, the structural schematic diagram of the unit cell being as shown in Figure 1 ;

[0048] (1) Structure design:

[0049] Sheet-based TPMS structure, high strength, large specific surface area. Gyriod as one of the typical TPMS structure, has excellent isotropy and energy absorption capacity. More importantly, compared with other structures, the forming quality of Gyriod structure is better. Therefore, Sheet-based G-type TPMS is selected as the filling structure.

[0050] Sheet-based G-type TPMS structure can be accurately expressed by implicit function, and the mechanical properties can be customized by changing the value of C. The formula is as follows:

[0051] φ G (x,y,z)=cos(wx)sin(wy)+cos(wy)sin(wz)+cos(wz)sin(wx)=±C

[0052] The relative density of TPMS structure changes in the range of 10%-50%, and the functional gradient of the structure is realized according to the following formula,

[0053]

[0054] Where ρ1 and ρ2 represent the density of the two ends of the specimen, x represents the position along the load direction, m is the correlation coefficient, ρ0 is the average relative density; Δρ is the density change of adjacent unit cell; ρ is the relative density of all unit cells;

[0055] The value of C affects the shape change and pore size of TPMS structure. By changing the value of C while keeping the size of TPMS lattice constant, the relative density of TPMS solid cell is changed, and finally the TPMS gradient structure is obtained. The relationship between the relative density A of Sheet-based Gyroid TPMS structure unit cell and the value of C is shown in Figure 2 The functional relationship between C value and relative density A is as follows:

[0056] A=39.7C-0.84

[0057] Where y is the relative density;

[0058] Based on the above method, by giving a gradient function to the value of C, the functional gradient of the structure is realized.

[0059] Modeling:

[0060] Traditional quadrilateral honeycomb structure is designed using nTopology commercial software (such as Figure 3The wall thickness of the honeycomb is given, a quadrilateral honeycomb unit cell is generated, the size of the unit cell is 1.2mmx1.2mmx1.2mm, and the size of the TPMS structure filled is 10mmx10mmx24mm. The energy absorption box shell is established, the wall thickness is 2mm, and the height is 24mm. The honeycomb structure and the square shell are subjected to Boolean operation to form a traditional quadrilateral honeycomb filled energy absorption box as shown in Figure 5 The STL file 1 is exported.

[0061] The TPMS lattice design is performed using the nTopology commercial software, a functionally graded Gyroid-based TPMS structure is generated by assigning a C value function relationship, as shown in Figure 4 The size of the unit cell is 3mmx3mmx3mm, and the size of the TPMS structure filled is 10mmx10mmx24mm. The energy absorption box shell is established, the wall thickness is 2mm, and the height is 24mm. The TPMS structure and the square shell are subjected to Boolean operation to form a functionally graded TPMS structure filled energy absorption box as shown in Figure 6 The STL file 2 is exported.

[0062] The STL file 1 and the STL file 2 are imported into Hypermesh, the model is meshed, and the mesh attribute is modified to C3D10M, the mesh size is 0.4mm, the mesh quality is checked, and the twisted elements are corrected, and the final file is exported as an INP file;

[0063] Performance analysis

[0064] The INP file is imported into the ABAQUS software for finite element analysis, the model is given a 316L stainless steel material, and a JC constitutive model is used. The upper and lower compression plates are added, the energy absorption box is placed in the middle of the upper and lower compression plates, the lower compression plate is fully fixed, and only the upper compression plate is allowed to move in the direction of the load. The energy absorption box and the compression plate are connected by a general contact, the tangential behavior is set as a penalty function, the friction coefficient is 0.3, and the normal behavior is defined as a hard contact. Then the upper compression plate is given a speed of 20m / s, and the energy absorption box is impacted, and key indicators such as reaction force and deformation are extracted.

[0065] The load-displacement curve of the traditional quadrilateral honeycomb and the functionally graded TPMS structure filled energy absorption box under compression load is as shown in Figure 7 ;

[0066] The honeycomb energy absorption box has high energy absorption efficiency in the initial displacement stage, but the energy absorption capacity decreases rapidly with the increase of displacement, indicating that its energy absorption capacity is limited, and it may be more suitable for low-intensity collision scenarios. The TMPS energy absorption box can maintain stable energy absorption in a larger displacement range, and has higher total energy absorption, which is suitable for medium and high intensity collisions. In summary, the energy absorption capacity and stability of the TMPS energy absorption box are better.

[0067] ComparisonFigure 8 The deformation shapes of the two models reveal significantly different Mises stress distributions. The honeycomb-filled energy-absorbing box exhibits a uniform stress distribution throughout the model from the onset of impact, leading to a global plastic deformation, including regions not in direct contact with the striker. This results in the honeycomb structure requiring a higher initial peak force to initiate collapse, followed by buckling in the central region, which continues until the end of the crash event. In contrast, the functionally graded TPS structure-filled energy-absorbing box shows a gradual spread of plastic strain in the impact zone and gradual deformation throughout the crash event without buckling. This behavior can be attributed to the graded thickness distribution along the length of the structure. Therefore, the functionally graded TPS structure has the advantage of reducing the initial peak force while preventing the energy-absorbing box from buckling.

[0068] The above describes specific embodiments of the present application. The above examples are only examples, and the core of the present application is to achieve dynamic energy management through the design of a functionally graded TPS. Any improvement scheme based on the principle of gradient control (such as asymmetric gradient, multi-dimensional gradient design) falls within the protection scope of the present application.

[0069] In summary, the above are only preferred embodiments of the present application and are not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A functionally graded TPMS-filled energy absorption box, characterized in that: the energy absorption box comprises a box body and a TPMS structure filled in the box body; the TPMS structure comprises a plurality of unit cells, and the relative density of all the unit cells changes along the impact direction in a gradient manner. 2.The functionally graded TPMS-filled energy absorption box according to claim 1, characterized in that: the TPMS structure adopts a Sheet-based Gyroid type TPMS structure. 3.The functionally graded TPMS-filled energy absorption box according to claim 1, characterized in that: the Sheet-based Gyroid type TPMS structure is modeled by an implicit function equation. 4.The functionally graded TPMS-filled energy absorption box according to claim 3, characterized in that: the implicit function equation is: φ G (x, y, z) = cos(w x) sin(w y) + cos(w y) sin(w z) + cos(w z) sin(w x) = ± C where w is a period, (x, y, z) is a Cartesian coordinate system; φ G (x, y, z) is an isosurface; C is an offset of the minimal surface. 5.The functionally graded TPMS-filled energy absorption box according to claim 1, characterized in that: the functional relationship between the relative density A of the unit cell in the Sheet-based Gyroid type TPMS structure and the offset C of the minimal surface is: A=39.7C-0.

84. 6.The functionally graded TPMS-filled energy absorption box according to claim 1, characterized in that: different C values are set to obtain TPMS structures with different volume fractions, so as to control the relative density of the TPMS structure; and the C is designed to control the change form of the relative density of the TPMS structure in three directions. 7.The functionally graded TPMS-filled energy absorption box according to claim 1, characterized in that: the TPMS structure filled in the energy absorption box is divided into front, middle and rear gradient regions along the longitudinal direction, the front region adopts a large cell and a low density design to quickly absorb the initial impact energy, the rear region adopts a small cell and a high density structure to stably dissipate the residual energy, and the middle region realizes a smooth transition. 8.The functionally graded TPMS-filled energy absorption box according to claim 1, characterized in that: the relative density y of the Sheet-based Gyroid type TPMS structure changes in a range of 10%to 50%.

9. A method of designing a functionally graded TPMS filled energy absorbing box, characterized by comprising the following steps: the implicit function equation is taken as an input of Ntopology software to establish a TPMS structure with a relative density gradient; a mesh division and repair are performed on the TPMS structure with the relative density gradient by using Hypermesh software; a mechanical property analysis is performed on the TPMS structure with the relative density gradient after the mesh division and repair by using Abaqus software. 10.A design method of the functionally graded TPMS-filled energy absorption box according to claim 1, characterized in that: the change form of the relative density gradient of the TPMS structure includes a linear gradient change, a double parabolic gradient change and a double linear gradient change; the box body of the energy absorption box is made of a high-strength material to improve the overall strength and impact resistance of the energy absorption box; the TPMS structure and the box body are connected by an adhesive or a 3D printing integral forming mode to ensure the stability of the TPMS structure in the box body.

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