Gradient dot matrix filling force transfer ring structure topological optimization method based on finite element analysis

Abstract

The invention discloses a finite element analysis-based gradient dot matrix filling force transfer ring structure topological optimization method, which comprises the following steps of: performing optimization design under different topological optimization volume fractions on an initial force transfer ring three-dimensional model by using traditional SIMP topological optimization; the method comprises the following steps: based on a stress cloud chart of each node of an initial force transmission ring three-dimensional model under a working condition obtained by finite element analysis, performing gradient dot matrix filling of stress field driving control cell element wall thickness on each force transmission ring three-dimensional model after traditional SIMP topological optimization, and in the dot matrix filling process, performing gradient dot matrix filling on the cell element wall thickness by circularly optimizing the maximum gradient value of the cell element wall thickness; and performing finite element analysis, calculation and comparison on the three-dimensional models of the force transfer rings after gradient dot matrix filling until the volume fractions of the three-dimensional models of the force transfer rings after dot matrix filling are in a preset interval, and obtaining an optimal three-dimensional model of the force transfer rings. According to the method, the optimization design of the force transmission ring structure is realized by fusing macroscopic topological optimization and microcosmic gradient dot matrix filling optimization, and the rigidity and the strength of the force transmission ring structure are improved.

Description

Technical Field

[0001] This invention belongs to the field of lightweight structural design, specifically relating to a topology optimization method for gradient lattice-filled force transmission ring structures based on finite element analysis. Background Technology

[0002] Lightweight design is one of the core objectives of rocket engine force transmission ring structure design, directly affecting the engine's thrust-to-weight ratio and payload efficiency. Existing lightweight technologies mainly focus on the following directions: 1. Single-scale topology optimization: Achieving weight reduction through macroscopic material distribution optimization. Studies have shown that traditional topology optimization (such as the SIMP method) has significant advantages in stiffness performance; 2. Micro-lattice structure design: Based on the lightweight and high-strength characteristics of high-porosity lattices, cell-based filling optimization is used. Traditional topology optimization dominates stiffness optimization, but its single-scale characteristics limit material utilization and multi-functional integration potential. While micro-lattice optimization can improve local performance, global stiffness is constrained by the macroscopic layout, making it difficult to achieve cross-scale synergistic effects. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and propose a topology optimization method for gradient lattice-filled force transmission ring structures based on finite element analysis.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] This invention presents a topology optimization method for gradient lattice-filled force transmission ring structures based on finite element analysis, as detailed below:

[0006] S1. Establish an initial three-dimensional model of the force transmission ring based on the actual unoptimized force transmission ring structure.

[0007] S2. Import the initial three-dimensional model of the force transmission ring into ABAQUS software and perform finite element simulation analysis to obtain the stress cloud diagram and displacement cloud diagram of each node of the initial three-dimensional model of the force transmission ring under working conditions.

[0008] S3. Import the initial three-dimensional model of the force transmission ring into the Ntopology software, and use the traditional SIMP topology optimization method to optimize the initial three-dimensional model of the force transmission ring, so as to obtain a preliminary optimized three-dimensional model of the force transmission ring.

[0009] S4. Based on the stress cloud diagram of each node of the initial force transmission ring three-dimensional model obtained in step S2, the gradient lattice of the preliminarily optimized force transmission ring three-dimensional model is filled with stress field driven control to obtain the final optimized force transmission ring three-dimensional model.

[0010] S5. Import the final optimized force transmission ring 3D model into Ntopology, and perform mesh generation in sequence using four cards: implicit volume mesh generation, surface mesh reconstruction, robust mesh control, and finite element volume mesh generation, to generate finite element mesh files.

[0011] S6. Import the finite element mesh file generated in step S5 into ABAQUS software for finite element simulation analysis and calculation to obtain the stiffness-to-mass ratio and ultimate bearing capacity of the final optimized force transmission ring three-dimensional model.

[0012] S7. Repeat steps S3 to S6, and each time the initial topology optimization volume fraction of the optimization design using the traditional SIMP topology optimization method is increased by a preset step size compared to the initial topology optimization volume fraction of the previous optimization design using the traditional SIMP topology optimization method, until the initial topology optimization volume fraction of the optimization design using the traditional SIMP topology optimization method reaches the preset value; then, the Pareto Frontier analysis method is used to analyze the stiffness-to-mass ratio and ultimate bearing capacity data of the final optimized force transmission ring three-dimensional model under different initial topology optimization volume fractions, to obtain the initial topology optimization volume fraction corresponding to the optimal combination of stiffness-to-mass ratio and ultimate bearing capacity, and the corresponding final optimized force transmission ring three-dimensional model is the optimal final optimized force transmission ring three-dimensional model, thus completing the optimization of the force transmission ring structure.

[0013] Preferably, the specific process of step S2 is as follows: import the initial force transmission ring three-dimensional model into ABAQUS software, set the material of the initial force transmission ring three-dimensional model, mesh the initial force transmission ring three-dimensional model, set reference point RP1 on the upper surface of the loading hole wall of the initial force transmission ring three-dimensional model and realize constraint control through MPC coupling, set reference point RP2 on the lower surface of the fixed hole wall of the initial force transmission ring three-dimensional model and realize constraint control through MPC coupling, apply a vertically upward force load to reference point RP1, apply a fixed constraint to reference point RP2 to simulate fixed boundary conditions, and then perform finite element simulation to obtain the stress cloud diagram and displacement cloud diagram of each node of the initial force transmission ring three-dimensional model.

[0014] Preferably, the specific process of step S3 is as follows: (1) Model import and preprocessing: import the initial force transmission ring three-dimensional model into Ntopology software, divide the initial force transmission ring three-dimensional model into meshes, set the initial force transmission ring three-dimensional model material, and establish FE Model; (2) Topology optimization setting and solution: specify the loading surface and constraint surface by optimizing the target card, set the response constraint by designing the response constraint card, and set the response constraint, including freezing the undesignable area and setting the initial topology optimization volume fraction, and then perform topology optimization by the topology optimization card to obtain the topology-optimized force transmission ring three-dimensional model; wherein, the topology optimization volume fraction is defined as the volume ratio of the pre-optimized force transmission ring three-dimensional model to the initial force transmission ring three-dimensional model; (3) Post-processing of optimization results: perform surface smoothing on the topology-optimized force transmission ring three-dimensional model by the smooth body card, and then process the surface-smoothed force transmission ring three-dimensional model by Boolean operation to obtain the pre-optimized force transmission ring three-dimensional model, and generate the pre-optimized force transmission ring three-dimensional model shell.

[0015] Preferably, the traditional SIMP topology optimization method uses the finite element equilibrium equation K(X)U(X)=F to control the volume fraction V(X)<V of the initially optimized force transmission ring three-dimensional model, with the minimum structural compliance C(X) as the requirement; the mathematical expression of the traditional SIMP topology optimization method is:

[0016]

[0017] In the formula, C(X) represents the structural compliance, K(X)U(X)=F is the finite element equilibrium equation, K(X) is the global stiffness matrix, U(X) is the nodal displacement vector, F is the nodal load vector, and X={x0,x1,…,x e ,…,x n} T Let x be the relative density vector of all grid cells. e Let be the relative density of the e-th grid cell.

[0018] Preferably, the specific process of step S4 is as follows: ① Select cell type and quantity; ② Set cell wall thickness: Import the stress data of each node of the initial force transmission ring 3D model obtained in step S2 through the point cloud import function, convert the stress data of each node into a continuous stress field through the point cloud to field card, and set the maximum and minimum values ​​of cell wall thickness gradient through the linear mapping card to map the stress field to the cell wall thickness gradient, forming a cell wall thickness gradient field. Among them, the minimum value of cell wall thickness gradient is fixed, and the maximum value of cell wall thickness gradient is optimized by iterative optimization; ③ Input cell through rectangular lattice filling card. The wall thickness gradient field is used to fill the lattice, resulting in a three-dimensional model of the force transmission ring after gradient lattice filling. Boolean operations are then performed on the three-dimensional model of the force transmission ring after gradient lattice filling, the shell of the initially optimized three-dimensional model of the force transmission ring, and the undesignable region. ④ The volume fraction of the three-dimensional model of the force transmission ring after gradient lattice filling is calculated. If the volume fraction of the three-dimensional model of the force transmission ring after gradient lattice filling exceeds the preset range, the maximum value of the cell wall thickness gradient in this cycle is reduced by the preset gradient value, and the process returns to step ②. Otherwise, the gradient lattice filling optimization of the initially optimized three-dimensional model of the force transmission ring is completed, and the final optimized three-dimensional model of the force transmission ring is obtained.

[0019] Preferably, the specific process of step S6 is as follows:

[0020] S61. Import the finite element mesh file generated in step S5 into ABAQUS software. Replace the initial 3D model of the force transmission ring with the final optimized 3D model of the force transmission ring. Repeat step S2 to obtain the stress contour plots and displacement contour plots of each node in the final optimized 3D model of the force transmission ring. Analyze the maximum displacement of the reference point RP1 on the final optimized 3D model of the force transmission ring and calculate the stiffness-to-mass ratio A of the final optimized 3D model of the force transmission ring. i ,for

[0021]

[0022] In the formula, K i For equivalent linear stiffness, M i To ultimately optimize the quality of the three-dimensional model of the force transmission ring, ΔF represents the force load difference, F max For the maximum force load, F min The minimum force load is given, and δ is the maximum displacement of the reference point RP1.

[0023] S62. Perform finite element simulation analysis and calculation on the final optimized three-dimensional model of the force transmission ring to obtain the ultimate bearing capacity of the final optimized three-dimensional model of the force transmission ring.

[0024] More preferably, the specific process of step S62 is as follows:

[0025] i. Import the finite element mesh file generated in step S5 into the ABAQUS software;

[0026] ii. Damage model selection: An asymptotic damage model is introduced to simulate the damage evolution process, and a ductile damage criterion model is selected to determine the damage initiation of the force transmission ring;

[0027] iii. In the ductile damage criterion model, the equivalent plastic strain at the onset of damage is adopted as a simplified form of the Hooputra ductility criterion;

[0028] iv. Finite element model settings: Set the fracture extension strain to 0, that is, when the strain of the mesh element reaches the equivalent plastic strain at the onset of damage, according to the progressive damage principle of ABAQUS flexible damage, the material is deleted to simulate the fracture process.

[0029] v. Finite Element Analysis: Apply force loads to the final optimized 3D model of the force transmission ring and perform finite element simulation until the final optimized 3D model of the force transmission ring fractures. Obtain the equivalent plastic strain at the onset of damage and record the force load and displacement data during the loading process to generate a force-displacement curve. Observe the damage initiation position, the peak load position, and the fracture stage on the force-displacement curve. Take the force load corresponding to the fracture of the final optimized 3D model of the force transmission ring as the ultimate bearing capacity of the final optimized 3D model of the force transmission ring, and generate stress cloud diagrams at the damage initiation time, a certain moment in the intermediate process, and the fracture time.

[0030] The present invention has the following beneficial effects:

[0031] This invention integrates macroscopic topology optimization and microscopic gradient lattice filling optimization to achieve optimized design of force transmission ring structures. Specifically, this invention performs finite element analysis on an initial 3D model of the force transmission ring established from an unoptimized force transmission ring structure to obtain stress cloud maps of each node under working conditions. The traditional SIMP topology optimization method is then used to optimize the initial 3D model of the force transmission ring under different topology optimization volume fractions, resulting in preliminarily optimized 3D models of the force transmission ring under different topology optimization volume fractions. Based on the stress cloud maps of each node of the initial 3D model of the force transmission ring under working conditions, stress field-driven gradient lattice filling is performed on the preliminarily optimized 3D models of the force transmission ring under different initial topology optimization volume fractions. During the gradient lattice filling process, the minimum value of the cell wall thickness gradient is fixed, and the maximum value of the cell wall thickness gradient is optimized iteratively to ensure that the volume fraction of the force transmission ring 3D model optimized by gradient lattice filling is within a preset range, thus obtaining the final optimized 3D model of the force transmission ring under different initial topology optimization volume fractions. The model was developed, and finite element analysis and calculation were performed on the final optimized three-dimensional force transmission ring model under different initial topology optimization volume fractions. The stiffness-to-mass ratio and ultimate bearing capacity of the final optimized three-dimensional force transmission ring model under different initial topology optimization volume fractions were obtained. The initial topology optimization volume fraction corresponding to the optimal combination of stiffness-to-mass ratio and ultimate bearing capacity was selected, and the corresponding final optimized three-dimensional force transmission ring model was the optimal final optimized three-dimensional force transmission ring model, thus completing the optimization of the force transmission ring structure. Among them, the method of integrating macroscopic topology optimization and micro-gradient lattice filling optimization was used to achieve lightweighting of the force transmission ring structure, while retaining the advantages of traditional topology optimization in maximizing global stiffness and achieving efficient material distribution. By controlling the thickness of the gradient lattice filling cell through stress field driving, dynamic matching between material distribution and local stress state was achieved, which can effectively reduce the phenomenon of high stress concentration, improve the material utilization rate in low stress areas, enhance local bearing capacity, and improve ultimate bearing capacity. Attached Figure Description

[0032] Figure 1 This is a flowchart of the present invention;

[0033] Figure 2 This is a schematic diagram of the three-dimensional model of the initial force transmission ring in this invention;

[0034] Figure 3 This is a schematic diagram showing the location of the reference point when setting loads and boundary conditions in this invention;

[0035] Figure 4 This is a schematic diagram of the iterative optimization of the traditional SIMP topology optimization method used in the intersection model of this invention when the volume fraction threshold is 0.5;

[0036] Figure 5This is a schematic diagram of the final optimized three-dimensional model structure of the force transmission ring in this invention;

[0037] Figure 6 A comparison of force-displacement curves from finite element simulations of topological, lattice, and intersecting models;

[0038] Figure 7 Stress cloud diagrams for damage initiation, intermediate process and fracture moment during finite element simulation of topological model, lattice model and intersection model;

[0039] Figure 8 This is a schematic diagram of a force transmission ring model optimized only by a uniform lattice filling optimization method. Detailed Implementation

[0040] The present invention will now be further described with reference to the accompanying drawings.

[0041] like Figure 1 As shown, the topology optimization method for gradient lattice-filled force transmission ring structures based on finite element analysis of this invention is as follows:

[0042] S1, such as Figure 2 As shown, an initial three-dimensional model of the force transmission ring is built using SolidWorks based on the unoptimized force transmission ring structure.

[0043] S2. Import the initial force transmission ring 3D model into the finite element software ABAQUS, set the material of the initial force transmission ring 3D model, mesh the initial force transmission ring 3D model, and set the loads and boundary conditions: set reference point RP1 on the upper surface of the loading hole wall of the initial force transmission ring 3D model and implement constraint control through MPC coupling; set reference point RP2 on the lower surface of the fixing hole wall of the initial force transmission ring 3D model and implement constraint control through MPC coupling, as follows. Figure 3 As shown, a vertically upward force load is applied to reference point RP1, and a fixed constraint is applied to reference point RP2 to simulate fixed boundary conditions; then, finite element simulation is performed to simulate the working condition of the force transmission ring, and stress cloud diagrams and displacement cloud diagrams of each node of the initial three-dimensional model of the force transmission ring are obtained.

[0044] S3. The initial force transmission ring three-dimensional model is optimized using the traditional SIMP (Solid Isotropic Material with Penalization) topology optimization method: (1) Model import and preprocessing: The initial force transmission ring three-dimensional model is imported into Ntopology software, the initial force transmission ring three-dimensional model is meshed, the initial force transmission ring three-dimensional model material is set, and FE Model is established; (2) Topology optimization setting and solution: The loading surface and constraint surface are specified by the Optimization Objective card to ensure that the load transmission path is clear. The response constraint is set by the Design Response Constraint card. The response constraint includes freezing the undesignable region and setting the initial topology optimization volume fraction V (the V value is set to 0.4 for the first time in this embodiment, and the iteration step size is 0.1). Then, the topology optimization is performed by the Topology Optimization card to obtain the topology-optimized force transmission ring three-dimensional model; (3) Post-processing of optimization results: The smooth body (Smoothen) is used to optimize the topology of the three-dimensional model of the force transmission ring. The Body card performs surface smoothing on the optimized force transmission ring 3D model to eliminate jagged edges and improve geometric continuity. Then, relevant Boolean operations are used to process the surface-smoothed force transmission ring 3D model to obtain a preliminary optimized force transmission ring 3D model, and a shell for this preliminary optimized model is generated. The topology optimization volume fraction is defined as the volume ratio of the preliminary optimized force transmission ring 3D model to the initial force transmission ring 3D model.

[0045] The traditional SIMP topology optimization method uses the finite element equilibrium equation K(X)U(X)=F to control the volume fraction V(X)<V of the initial optimized force transmission ring three-dimensional model, with the minimum structural compliance C(X) as the requirement. Figure 4 The figure shows the iterative optimization process of the traditional SIMP topology optimization method when V is 0.5. The mathematical expression of the traditional SIMP topology optimization method is:

[0046]

[0047] In the formula, C(X) represents the structural compliance, K(X)U(X)=F is the finite element equilibrium equation, K(X) is the global stiffness matrix, U(X) is the nodal displacement vector, F is the nodal load vector, and X={x0,x1,…,x e ,…,x n} T Let x be the relative density vector of all grid cells. e Let be the relative density of the e-th grid cell.

[0048] S4. Gradient lattice filling driven by stress field control on the initially optimized force transmission ring 3D model: ① Select cell type and quantity. In the intersecting model, since the model volume is easier to constrain, plate-type cells with stronger load-bearing capacity but larger volume ratio are selected; ② Set cell wall thickness: Import the stress data of each node of the initial force transmission ring 3D model obtained in step S2 using the Import Scalar Point Map function. Convert the stress data of each node into a continuous stress field using the Field from Point Map card. Set the maximum and minimum values ​​of the cell wall thickness gradient using the Linear Map card to map the stress field to the cell wall thickness gradient, forming a cell wall thickness gradient field. Considering the processing technology, the minimum value of the cell wall thickness gradient is fixed at 0.45 mm. The maximum value of the cell wall thickness gradient is optimized by iterative optimization; ③ Fill the rectangular lattice with rectangular... The cell wall thickness gradient field is input into the VolumeLattice card to perform lattice filling, resulting in a three-dimensional model of the force transmission ring after gradient lattice filling. Boolean operations are then performed on the shell (an outer shell of the initially optimized force transmission ring model to prevent the lattice from being exposed) and undesignable regions of the gradient lattice-filled three-dimensional model to ensure geometric compatibility and avoid interference. The volume fraction of the gradient lattice-filled three-dimensional model is calculated. If the volume fraction is not within the interval (V1, V2), the maximum cell wall thickness gradient value during this iteration is reduced by a preset gradient value, and the process returns to step ②. Otherwise, the gradient lattice filling optimization of the initially optimized force transmission ring model is completed, resulting in the final optimized force transmission ring three-dimensional model. Figure 5 As shown. In this embodiment, V1 is 0.315 and V2 is 0.348. The volume fraction of the force transmission ring 3D model after gradient lattice filling is defined as the ratio of the volume of the force transmission ring 3D model after gradient lattice filling to the volume of the initial force transmission ring 3D model.

[0049] S5. Import the final optimized 3D model of the force transmission ring into Ntopology. Then, use four cards in sequence to perform mesh generation: Mesh from Implicit Body, Remesh Surface, Robust Tetrahedral Mesh, and FE Volume Mesh to generate finite element mesh files (inp files). These files are used to convert the final optimized 3D model of the force transmission ring into high-quality, high-fidelity finite element mesh files, ensuring the accuracy, convergence, and computational efficiency of subsequent simulations (such as structural mechanics, fluid mechanics, or multiphysics analysis).

[0050] S6. Import the finite element mesh file generated in step S5 into ABAQUS software for finite element simulation analysis and calculation to obtain the stiffness-to-mass ratio and ultimate bearing capacity of the final optimized force transmission ring 3D model. The specific process is as follows:

[0051] S61. Import the finite element mesh file generated in step S5 into ABAQUS software. Replace the initial 3D model of the force transmission ring with the final optimized 3D model of the force transmission ring. Repeat step S2 to obtain the stress contour plots and displacement contour plots of each node in the final optimized 3D model of the force transmission ring. Analyze the maximum displacement of the reference point RP1 on the final optimized 3D model of the force transmission ring and calculate the stiffness-to-mass ratio A of the final optimized 3D model of the force transmission ring. i ,for

[0052]

[0053] In the formula, K i For equivalent linear stiffness, M i To ultimately optimize the quality of the three-dimensional model of the force transmission ring, ΔF represents the force load difference, F max For the maximum force load, F min The minimum force load is δ, and the maximum displacement of reference point RP1 is δ. In this embodiment, the applied force load ranges from 0 to 4200 N, and the maximum force load is F. max = 4200N, minimum force load F min =0.

[0054] S62. Perform finite element simulation analysis and calculation on the final optimized three-dimensional model of the force transmission ring to obtain the ultimate bearing capacity of the final optimized three-dimensional model of the force transmission ring:

[0055] i. Import the finite element mesh file generated in step S5 into the ABAQUS software;

[0056] ii. Damage Model Selection: When the load-transfer ring reaches its ultimate load capacity, damage will occur inside it. In order to effectively evaluate the ultimate load capacity of the optimized design structure, an asymptotic damage model is introduced to simulate the damage evolution process. In addition, the fracture behavior of the load-transfer ring material, photosensitive resin Imagine8000, is similar to that of brittle materials, but its damage initiation may be dominated by the nucleation and growth of microvoids (similar to the ductile mechanism). Therefore, the ductile damage criterion model (Ductile Failure Model), which is used to predict the damage initiation caused by void nucleation, growth and merging, is selected to determine the damage initiation of the load-transfer ring.

[0057] iii. The ductile damage criterion model assumes the equivalent plastic strain at the onset of damage. It is a function of stress triaxiality, and the simplified form of the Hooputra ductility criterion is given by...

[0058]

[0059] In the formula, η represents the triaxial stress, and η = -p / q, where p is the hydrostatic pressure and q is the Mises equivalent stress. The equivalent plastic strain for uniaxial tension-induced ductile damage. Let sinh be the equivalent plastic strain for ductile damage induced by uniaxial compressive deformation, sinh be a hyperbolic sine function, and k0 be a material parameter that depends on the material, strain rate, and temperature. Both k0 and η can be obtained through experiments or literature. + It is the stress triaxiality under uniaxial tensile deformation, and η + =1 / 3, η - The stress triaxiality is under uniaxial compressive deformation, and η - = -1 / 3;

[0060] Specifically, referring to the stress-strain curve of Imagine8000 material, the curve position corresponding to the tensile limit of Imagine8000 material at 47MPa is set as the damage initiation point. The equivalent plastic strain corresponding to the tensile limit of 47MPa in the stress-strain curve of Imagine8000 material is input into the ductility damage criterion, and the stress triaxiality η is derived by reverse formula based on the simplified formula of Hooputra ductility criterion.

[0061] iv. Finite element model settings: For conservative evaluation, the fracture extension strain is set to 0, i.e., when the strain of the mesh element reaches its maximum value. At that time, according to the progressive damage principle of ABAQUS flexible damage, the material was removed to simulate the fracture process;

[0062] v. Finite Element Analysis: Apply force loads to the final optimized 3D model of the force transmission ring and perform finite element simulation until the final optimized 3D model of the force transmission ring fractures. Obtain the equivalent plastic strain at the onset of damage and record the force load and displacement data during the loading process to generate a force-displacement curve. Observe the damage initiation position, the peak load position, and the fracture stage on the force-displacement curve. Take the force load corresponding to the fracture of the final optimized 3D model of the force transmission ring as the ultimate bearing capacity of the final optimized 3D model of the force transmission ring, and generate stress cloud diagrams at the damage initiation time, a certain moment in the intermediate process, and the fracture time.

[0063] S7. Repeat steps S3 to S6, and each time the initial topology optimization volume fraction for optimization using the traditional SIMP topology optimization method is increased by 0.1 compared to the previous initial topology optimization volume fraction for optimization using the traditional SIMP topology optimization method, until the initial topology optimization volume fraction for optimization using the traditional SIMP topology optimization method reaches 0.8; then, the Pareto Frontier analysis method is used to analyze the stiffness-to-mass ratio and ultimate bearing capacity data of the final optimized force transmission ring 3D model under different initial topology optimization volume fractions, to obtain the initial topology optimization volume fraction corresponding to the optimal combination of stiffness-to-mass ratio and ultimate bearing capacity, and the corresponding final optimized force transmission ring 3D model is the optimal final optimized force transmission ring 3D model, thus completing the optimization of the force transmission ring structure; in this embodiment, the optimal initial topology optimization volume fraction is obtained by comparison as 0.5, and the volume fraction of the final optimized force transmission ring 3D model obtained through step S4 after meshing in step S5 is 0.342. This volume fraction is defined as the ratio of the model volume after meshing to the volume of the initial force transmission ring 3D model.

[0064] The force transmission ring model optimized by this invention (denoted as the intersecting model) is compared with the force transmission ring model optimized only by the traditional SIMP topology optimization method (denoted as the topology model) and the force transmission ring model optimized only by the uniform lattice filling optimization method (denoted as the lattice model). It is found that the stiffness-to-mass ratio of the intersecting model of this invention is improved by 4.5% and 32.4% compared to the stiffness-to-mass ratio of the topology model and the lattice model, respectively. Figure 6 and Figure 7 As shown, Figure 6 The force-displacement curves of finite element simulations for the topological model, lattice model, and intersecting model are shown. The ultimate bearing capacity of the intersecting model is improved by 7.5% and 19.7% compared to the ultimate bearing capacity of the topological model and the lattice model, respectively. Figure 7 The paper presents stress cloud diagrams of damage initiation, intermediate process, and fracture time during finite element simulations of the topological model, lattice model, and intersecting model. It shows that the damage initiation of all three models is at the tensile strength of the material, which is 47 MPa. The fracture locations of the three models are also shown, and the fracture points are relatively weak, which can provide ideas for further optimization of subsequent models.

[0065] like Figure 8As shown, in the lattice model, the process of optimizing the force transmission ring model using only the uniform lattice filling optimization method is as follows: The initial force transmission ring 3D model is imported into Ntopology software, the cell type is selected, and the cell wall thickness and cell number are set so that the cell number of the lattice model is consistent with the cell number of the intersecting model. Lattice filling is achieved through the Rectangular Volume Lattice card. After filling, Boolean processing is performed on the outer shell of the initial force transmission ring 3D model (a shell outside the initial force transmission ring 3D model, the purpose of which is to prevent the lattice from being exposed) and the undesignable region. Then, the volume fraction of the force transmission ring 3D model after uniform lattice filling optimization is calculated. If the volume fraction of the force transmission ring 3D model after uniform lattice filling optimization is not within the interval (V1, V2), the maximum value of the cell wall thickness gradient is adjusted to make the volume fraction of the force transmission ring 3D model after uniform lattice filling optimization within the interval (V1, V2). The difference between optimizing the force transmission ring model using the traditional SIMP topology optimization method and step S3 is that the topology optimization volume fraction in the response constraint is directly set to the target value of 0.326.

Claims

1. A topology optimization method for gradient lattice-filled force transmission ring structures based on finite element analysis, characterized in that: Specifically as follows: S1. Establish an initial three-dimensional model of the force transmission ring based on the unoptimized force transmission ring structure; S2. Perform finite element simulation analysis on the initial three-dimensional model of the force transmission ring to obtain the stress cloud diagram and displacement cloud diagram of each node of the initial three-dimensional model of the force transmission ring under working conditions. S3. Import the initial three-dimensional model of the force transmission ring into Ntopology software, and use the traditional SIMP topology optimization method to optimize the initial three-dimensional model of the force transmission ring to obtain a preliminary optimized three-dimensional model of the force transmission ring. S4. Based on the stress cloud diagram of each node of the initial force transmission ring three-dimensional model obtained in step S2, the gradient lattice of the preliminarily optimized force transmission ring three-dimensional model is filled with stress field driven control to obtain the final optimized force transmission ring three-dimensional model. S5. Generate a finite element mesh file from the final optimized 3D model of the force transmission ring; S6. Import the finite element mesh file generated in step S5 into ABAQUS software, perform finite element simulation analysis and calculation, and obtain the stiffness-to-mass ratio and ultimate bearing capacity of the final optimized force transmission ring three-dimensional model. S7. Repeat steps S3 to S6, and each time the initial topology optimization volume fraction of the optimization design using the traditional SIMP topology optimization method is increased by a preset step size compared to the initial topology optimization volume fraction of the previous optimization design using the traditional SIMP topology optimization method, until the initial topology optimization volume fraction of the optimization design using the traditional SIMP topology optimization method reaches the preset value. Then, the Pareto front analysis method was used to analyze the stiffness-to-mass ratio and ultimate bearing capacity data of the final optimized force transmission ring 3D model under different initial topology optimization volume fractions. The initial topology optimization volume fraction corresponding to the optimal combination of stiffness-to-mass ratio and ultimate bearing capacity was obtained, and the corresponding final optimized force transmission ring 3D model was the optimal final optimized force transmission ring 3D model.

2. The topology optimization method for gradient lattice-filled force transmission ring structure based on finite element analysis according to claim 1, characterized in that: The specific process of step S2 is as follows: import the initial force transmission ring three-dimensional model into ABAQUS software, set the material of the initial force transmission ring three-dimensional model, mesh the initial force transmission ring three-dimensional model, set reference point RP1 on the upper surface of the loading hole wall of the initial force transmission ring three-dimensional model and achieve constraint control through MPC coupling, set reference point RP2 on the lower surface of the fixed hole wall of the initial force transmission ring three-dimensional model and achieve constraint control through MPC coupling, apply a vertically upward force load to reference point RP1, apply a fixed constraint to reference point RP2 to simulate fixed boundary conditions, and then perform finite element simulation to obtain the stress cloud map and displacement cloud map of each node of the initial force transmission ring three-dimensional model.

3. The topology optimization method for gradient lattice-filled force transmission ring structure based on finite element analysis according to claim 1, characterized in that: The specific process of step S3 is as follows: (1) Model import and preprocessing: Import the initial force transmission ring three-dimensional model into Ntopology software, divide the initial force transmission ring three-dimensional model into meshes, set the initial force transmission ring three-dimensional model material, and establish FE Model; (2) Topology optimization setting and solution: Specify the loading surface and constraint surface through the optimization target card, set the response constraint through the design response constraint card, and set the response constraint, including freezing the undesignable area and setting the initial topology optimization volume fraction, and then perform topology optimization through the topology optimization card to obtain the topology-optimized force transmission ring three-dimensional model; where the topology optimization volume fraction is defined as the volume ratio of the pre-optimized force transmission ring three-dimensional model to the initial force transmission ring three-dimensional model; (3) Post-processing of optimization results: Perform surface smoothing on the topology-optimized force transmission ring three-dimensional model through the smooth body card, and then process the surface-smoothed force transmission ring three-dimensional model through Boolean operation to obtain the pre-optimized force transmission ring three-dimensional model, and generate the shell of the pre-optimized force transmission ring three-dimensional model.

4. The topology optimization method for gradient lattice-filled force transmission ring structure based on finite element analysis according to claim 1, characterized in that: The traditional SIMP topology optimization method uses the finite element equilibrium equation K(X)U(X)=F to control the volume fraction V(X)<V of the initially optimized force transmission ring three-dimensional model, with a minimum structural compliance requirement C(X). The mathematical expression of the traditional SIMP topology optimization method is: In the formula, C(X) represents the structural compliance, K(X)U(X)=F is the finite element equilibrium equation, K(X) is the global stiffness matrix, U(X) is the nodal displacement vector, F is the nodal load vector, and X={x0,x1,…,x e ,…,x n } T Let x be the relative density vector of all grid cells. e Let be the relative density of the e-th grid cell.

5. The topology optimization method for gradient lattice-filled force transmission ring structure based on finite element analysis according to claim 1, characterized in that: The specific process of step S4 is as follows: ① Select cell type and quantity; ② Set cell wall thickness: Import the stress data of each node of the initial force transmission ring 3D model obtained in step S2 through the point cloud import function, convert the stress data of each node into a continuous stress field through the point cloud to field card, and set the maximum and minimum values ​​of cell wall thickness gradient through the linear mapping card to map the stress field to the cell wall thickness gradient to form a cell wall thickness gradient field; ③ Input the cell wall thickness gradient field through the rectangular lattice filling card, perform lattice filling, and obtain the force transmission ring 3D model after gradient lattice filling. Perform Boolean operations on the force transmission ring 3D model after gradient lattice filling and the shell and undesignable areas of the preliminarily optimized force transmission ring 3D model. ④ Calculate the volume fraction of the force transmission ring 3D model after gradient lattice filling. If the volume fraction of the force transmission ring 3D model after gradient lattice filling exceeds the preset range, reduce the maximum value of the cell wall thickness gradient in this loop to the preset gradient value and return to step ②. Otherwise, the gradient lattice filling optimization of the initial optimization of the force transmission ring 3D model is completed, and the final optimized force transmission ring 3D model is obtained.

6. The topology optimization method for gradient lattice-filled force transmission ring structure based on finite element analysis according to any one of claims 1 to 5, characterized in that: The specific process of step S6 is as follows: S61. Import the finite element mesh file generated in step S5 into ABAQUS software. Replace the initial 3D model of the force transmission ring with the final optimized 3D model of the force transmission ring. Repeat step S2 to obtain the stress contour plots and displacement contour plots of each node in the final optimized 3D model of the force transmission ring. Analyze the maximum displacement of the reference point RP1 on the final optimized 3D model of the force transmission ring and calculate the stiffness-to-mass ratio A of the final optimized 3D model of the force transmission ring. i ,for In the formula, K i For equivalent linear stiffness, M i To ultimately optimize the quality of the three-dimensional model of the force transmission ring, ΔF represents the force load difference, F max For the maximum force load, F min The minimum force load is given, and δ is the maximum displacement of the reference point RP1. S62. Perform finite element simulation analysis and calculation on the final optimized three-dimensional model of the force transmission ring to obtain the ultimate bearing capacity of the final optimized three-dimensional model of the force transmission ring.

7. The topology optimization method for gradient lattice-filled force transmission ring structure based on finite element analysis according to claim 6, characterized in that: The specific process of step S62 is as follows: i. Import the finite element mesh file generated in step S5 into the ABAQUS software; ii. Damage model selection: An asymptotic damage model is introduced to simulate the damage evolution process, and a ductile damage criterion model is selected to determine the damage initiation of the force transmission ring; iii. In the ductile damage criterion model, the equivalent plastic strain at the onset of damage is adopted as a simplified form of the Hooputra ductility criterion; iv. Finite element model settings: Set the fracture extension strain to 0, that is, when the strain of the mesh element reaches the equivalent plastic strain at the onset of damage, according to the progressive damage principle of ABAQUS flexible damage, the material is deleted to simulate the fracture process. v. Finite Element Analysis: Apply force loads to the final optimized 3D model of the force transmission ring and perform finite element simulation until the final optimized 3D model of the force transmission ring fractures. Obtain the equivalent plastic strain at the onset of damage and record the force load and displacement data during the loading process to generate a force-displacement curve. Observe the damage initiation position, the peak load position, and the fracture stage on the force-displacement curve. Take the force load corresponding to the fracture of the final optimized 3D model of the force transmission ring as the ultimate bearing capacity of the final optimized 3D model of the force transmission ring, and generate stress cloud diagrams at the damage initiation time, a certain moment in the intermediate process, and the fracture time.

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