Topological optimization design of integrated traction beam made of carbon fiber composite material

Abstract

The invention discloses topological optimization design of an integrated traction beam made of a carbon fiber composite material, and relates to the technical field of vehicle body optimization design. Specifically, according to the method, a finite element model of the integrated traction beam made of the carbon fiber composite material is constructed, grid unit nodes are extracted to construct a displacement function and a flexibility matrix, and the stress concentration distribution condition is obtained. And constructing a mathematical optimization model of the integrated traction beam of the carbon fiber composite material under different objective functions and constraint conditions, carrying out geometric reconstruction on the traction beam based on an optimal optimization result, and removing irregular curves and dispersed units of a final result by adopting a smooth filtering algorithm. And statics analysis is carried out on the traction beam before and after geometric reconstruction under specific working conditions through finite element simulation analysis. The topological optimization design of the carbon fiber composite material integrated traction beam can be used for weight reduction and rigidity optimization design of a rail transit carbon fiber composite material vehicle body, material removal is achieved, and the purposes of light weight and manufacturing cost reduction are achieved.

Description

Technical Field

[0001] The invention relates to a topological optimization design of an integrated traction beam of a carbon fiber composite material, belonging to the technical field of optimization design of rail transit vehicle bodies. Background Art

[0002] The car body underframe traction beam is one of the most important parts of the rail transit car body underframe. Its characteristic is that it bears the traction and braking force between the car body and the car body. The traditional aluminum alloy underframe traction beam has many parts, complex connection methods and heavy weight. Compared with the traditional metal material traction beam, the carbon fiber composite material traction beam has the characteristics of light weight and excellent mechanical properties. Therefore, it has become a trend to use composite material traction beams instead of metal traction beams in rail transit car bodies. The composite material traction beam mounting seat is connected to the car hook and bears a large load. The bearing capacity of the underframe depends largely on the traction beam. At the same time, the production cost of composite material parts is high and the designability is strong. It has become a problem for car body manufacturers to strictly control weight and take into account cost. Therefore, through topological optimization, the distribution of materials can be optimized, so that the composite material traction beam can achieve the best material utilization effect while meeting the mechanical performance requirements such as strength and stiffness, further reducing the weight of the composite material traction beam and reducing costs. The optimized traction beam structure can better cope with complex alternating loads, reduce stress concentration and fatigue damage, thereby improving its service life and reliability. Therefore, the optimization design of carbon fiber composite traction beam is one of the difficulties in the design of composite vehicle body, and the topological optimization design of carbon fiber composite traction beam is an important topic.

[0003] At present, carbon fiber composite integrated traction beams have been widely used in rail transit. Some inventors have studied the topological optimization design of carbon fiber composite traction beams. The invention patent with Chinese patent application number 202410384819.6 proposes a composite traction rod consisting of a composite fiber rod body, a metal end and a wedge block. The metal end of the composite traction rod is assembled with the carbon fiber rod through a mixed connection form such as a wedge structure, which avoids the problem of peeling failure at the connection part and improves the connection strength, compressive resistance and tensile resistance; the document "Zeng Ziming. Optimization design of traction beam structure based on sub-model method [D]. Dalian Jiaotong University, 2022." The sub-model method is used to perform topological optimization on the rear cover of the traction beam. In the compression condition, the static strength of the whole vehicle is calculated by combining finite element software. Considering the manufacturing process and lightweight design, the optimal solution for the rear cover structure of the traction beam is determined.

[0004] According to the existing publicly available experimental data, there is a lack of unified standards and basis in the design and use of composite traction beams, which increases the risk and uncertainty of application. The manufacturing cost of composite traction beams is relatively high, which is due to factors such as raw materials, production processes and quality control. Moreover, the interlaminar shear strength and impact resistance of carbon fiber composite traction beams are technical problems that require further optimization and improvement. The present invention combines the characteristics of composite traction beams, based on the combination of topological optimization and geometric reconstruction, sets the optimal force transmission path of the structure, the optimal material distribution, reduces the mass fraction and volume fraction of composite materials, and proposes a topological optimization design of a carbon fiber composite integrated traction beam. Summary of the invention

[0005] Conventional composite traction beam design criteria imitate the design of metal traction beams, ignoring the difficulties in the manufacturing process and the stress concentration that cause the stiffness of the composite structure to be less than that of the ideal metal material. In order to solve this problem, the present invention proposes a topological optimization design of a carbon fiber composite integrated traction beam that combines a traction beam design area optimization model with geometric reconstruction.

[0006] A topological optimization design of an integrated carbon fiber composite traction beam, comprising:

[0007] A: In combination with the stress concentration at the coupler mounting seat of the carbon fiber composite material integrated traction beam, a finite element model of the carbon fiber composite material integrated traction beam is constructed through displacement function and flexibility matrix;

[0008] B: Construct a mathematical model for topological optimization of an integrated traction beam made of carbon fiber composite materials;

[0009] C: Taking minimum flexibility and maximum stiffness as the objective function and the volume fraction after topology optimization in the optimization area not exceeding 0.7 of the initial volume as the optimization constraint, the first topology optimization process of carbon fiber composite integrated traction beam is established;

[0010] D: Taking the minimization of mass as the objective function and the maximum displacement as the optimization constraint, the topology optimization process of the second carbon fiber composite integrated traction beam is established;

[0011] E: Compare the two topology optimization iteration results, select the optimal iteration structure, and use the smoothing filter algorithm to establish the geometric reconstruction model of the carbon fiber composite integrated traction beam;

[0012] F: Set boundary conditions, loads, and constraints to perform static analysis on the original carbon fiber composite integrated traction beam structure and the geometrically reconstructed traction beam structure under tension conditions.

[0013] in;

[0014] Step A: Based on the stress concentration at the coupler mounting seat of the carbon fiber composite material integrated traction beam, a finite element model of the carbon fiber composite material integrated traction beam is constructed through a displacement function and a flexibility matrix;

[0015] The specific design steps include:

[0016] A1 constructs the node displacement function and flexibility matrix of the carbon fiber composite integrated traction beam:

[0017] Extract grid cells and establish coordinate system;

[0018] Determine the four nodes k, m, n, and p of the unit;

[0019] Construct the displacement function {δ(x, y)}, shape function R(x, y), and node displacement a.

[0020] A2 establishes the finite element model of the carbon fiber composite integrated traction beam design area:

[0021] Divide the design area and non-design area;

[0022] The design area includes around the draw beam coupler mountings;

[0023] The non-design area includes the main part connected to the anti-climbing frame and the main part connected to the corbel;

[0024] Assign material properties and discretize;

[0025] The vehicle body tensile condition is set to be loaded on the carbon fiber composite integrated traction beam, and a finite element model of the design area is established.

[0026] After completing the design process of step A, proceed to the design of step B, where;

[0027] Step B: Constructing a mathematical model for topological optimization of the carbon fiber composite integrated traction beam;

[0028] The specific design steps include:

[0029] Construct a mathematical model for static topology optimization of a single structural condition:

[0030] Where X is the relative density of the elements in the design area; N is the total number of nodes in the design area; C is the overall flexibility of the structure; F, K, and U are the load matrix, stiffness matrix, and displacement matrix of the structure, respectively; u e , k e are the displacement vector and stiffness vector of the unit node respectively.

[0031] After completing the design process of step B, proceed to the design of step C, where;

[0032] Step C: Taking minimum flexibility and maximum stiffness as the objective function and taking the volume fraction after topology optimization in the optimization area not exceeding 0.7 of the initial volume as the optimization constraint, the topology optimization process of the first carbon fiber composite integrated traction beam is established;

[0033] The specific design steps include:

[0034] C1 builds an optimization model for carbon fiber composite integrated traction beam:

[0035] The optimization objective function is constructed as minimum flexibility (maximum stiffness) C min (ρ);

[0036] The optimization constraint is set to that the volume fraction after topology optimization in the optimization region does not exceed 0.7 of the initial volume: V(ρ)≤0.7·V 0

[0037] The optimization setting convergence tolerance is 0.5% and the maximum number of iterations is 100.

[0038] C2 solves the optimization model of carbon fiber composite integrated traction beam:

[0039] The finite element model of the traction beam is solved according to the topology optimization model of C1, and the iterative process of topology optimization is obtained until the calculation converges;

[0040] Construct the density cloud map of the carbon fiber composite integrated traction beam at each iteration step;

[0041] The density threshold v is selected, and the material is removed from the density cloud map of each iteration step, and the area where the material cannot be removed is retained to form an iterative structure.

[0042] C3 draws the topology optimization iteration curve of the integrated traction beam of carbon fiber composite materials:

[0043] A point-line relationship diagram between volume fraction and iteration number is established, which satisfies that the volume fraction decreases with the increase of iteration number, and the volume fraction V(ρ) of the final iterative structure is obtained;

[0044] A point-line relationship diagram between compliance and iteration number is established, which satisfies that compliance decreases with the increase of iteration number, and stiffness increases with the increase of iteration number, and the compliance C(ρ) of the final iterative structure is obtained;

[0045] Set the dual Y-axes of volume fraction and compliance, the number of iterations as the X-axis, integrate the data, and construct the final carbon fiber composite integrated traction beam topology optimization iteration curve.

[0046] After completing the design process of step C, proceed to the design of step D, where;

[0047] Step D: Taking minimizing mass as the objective function and taking maximum displacement as the optimization constraint, a topology optimization process of the second carbon fiber composite material integrated traction beam is established; and a topology optimization process of the second carbon fiber composite material integrated traction beam is established;

[0048] The specific design steps include:

[0049] D1 builds an optimization model for integrated carbon fiber composite traction beams:

[0050] The optimization objective function is constructed to minimize the mass: M min (ρ);

[0051] Set the optimization constraint to Maximum Displacement: U max ≤3mm

[0052] The optimization setting convergence tolerance is 0.5% and the maximum number of iterations is 100.

[0053] D2 solves the optimization model of carbon fiber composite integrated traction beam:

[0054] The finite element model of the traction beam is solved according to the topology optimization model of C1, and the iterative process of topology optimization is obtained until the calculation converges;

[0055] Construct the density cloud map of the carbon fiber composite integrated traction beam at each iteration step;

[0056] The density threshold v is selected, and the material is removed from the density cloud map of each iteration step, and the area where the material cannot be removed is retained to form an iterative structure.

[0057] D3 draws the topology optimization iteration curve of the integrated traction beam of carbon fiber composite materials:

[0058] A point-line relationship diagram between volume fraction and iteration number is established, which satisfies that the volume fraction decreases with the increase of iteration number, and the volume fraction V(ρ) of the final iterative structure is obtained;

[0059] A point-line relationship diagram between compliance and iteration number is established, which satisfies that compliance decreases with the increase of iteration number, and stiffness increases with the increase of iteration number, and the compliance C(ρ) of the final iterative structure is obtained;

[0060] Set the dual Y-axes of volume fraction and compliance, the number of iterations as the X-axis, integrate the data, and construct the final carbon fiber composite integrated traction beam topology optimization iteration curve.

[0061] After completing the design process of step D, proceed to the design of step E, where;

[0062] Step E: Compare the two topology optimization iteration results, select the optimal iteration structure, and use the smoothing filter algorithm to establish the geometric reconstruction model of the carbon fiber composite integrated traction beam;

[0063] The specific design steps include:

[0064] The smoothing filter algorithm is used, and the Gaussian function is used as the weight to perform weighted averaging on the grid points of the traction beam after topology optimization. The Gaussian distribution formula is: Where (x, y) is the coordinate of the point inside the mask, (ux, uy) is the coordinate of the center point, and (x, y) is the standard deviation.

[0065] Take the center position of the template as the coordinate origin for sampling, and substitute each point into the Gaussian function;

[0066] Construct a set of cells corresponding to 10 parts with cell density layered in steps of 0 to 1, and set the optimized density threshold;

[0067] Regions with sufficient density are extracted for geometric reconstruction.

[0068] After completing the design process of step E, proceed to the design of step F, where;

[0069] Step F: setting boundary conditions, loads, and constraints, and conducting static analysis on the original carbon fiber composite integrated traction beam structure and the geometrically reconstructed traction beam structure under tension conditions;

[0070] The specific design steps include:

[0071] Stress analysis of F1 original carbon fiber composite integrated traction beam:

[0072] Finite element software (such as Abaqus, Ansys) is used to establish boundary conditions according to the working condition of A2, and MPC constraints are set for the reference point and section at the center of the coupling seat connection hole of the traction beam;

[0073] The reference point is used as the action point for applying the load, and a load of 800KN is applied along the negative direction of the X axis at the reference point at the loading location;

[0074] Release the X-axis freedom of the flanging rivet hole;

[0075] The stress analysis of the original traction beam structure was carried out, and the density threshold was selected to obtain the Signed Mises stress and Mises stress of the complete structure after material removal in the design area.

[0076] Stress analysis of carbon fiber composite integrated traction beam with F2 geometry reconstruction:

[0077] Finite element software (such as Hypermesh) is used to extract the neutral surface of the geometrically reconstructed carbon fiber composite integrated traction beam, assign material properties, and divide the mesh;

[0078] Establish the same boundary conditions;

[0079] Finite element software (such as Abaqus, Ansys) is used to analyze the stress of the geometrically reconstructed traction beam structure, and the density threshold is selected to obtain the Signed Mises stress and Mises stress of the complete structure after material removal in the design area.

[0080] Compared with the existing traction beam optimization technology, the carbon fiber composite material integrated traction beam based on geometric reconstruction of the present invention has the following beneficial effects:

[0081] The present invention provides a topological optimization design of an integrated traction beam of carbon fiber composite materials. The design takes into account that the root of the composite traction beam has a higher load-bearing capacity when working, but may produce greater deformation than a metal traction beam under special stress conditions, affecting the stability and safety of the train. A mathematical model for the topological optimization of an integrated traction beam of carbon fiber composite materials is constructed, and the optimized area of ​​the traction beam under tensile conditions is optimized to obtain an optimized iterative structure. At the same time, a smoothing filter method is used to geometrically reconstruct the topological optimization design of the integrated traction beam of carbon fiber composite materials, and finite element simulation calculations are further used to optimize the stress of the traction beam before and after. The topological optimization design of the integrated traction beam of carbon fiber composite materials of the present invention can find the optimal force transmission path of the material of the design structure and realize the removal of material, thereby achieving the purpose of lightweighting, enhancing mechanical properties, and reducing manufacturing costs.

[0082] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 It is a topology optimization design flow chart of the carbon fiber composite material integrated traction beam of the present invention;

[0084] Figure 2 is a grid unit node diagram of a traction beam of the present invention;

[0085] Figure 3 It is a finite element model of a carbon fiber composite integrated traction beam; in the figure, 1 is a carbon fiber composite vehicle body structure for rail transit, 2 is a carbon fiber composite vehicle body chassis, 3 is a carbon fiber composite integrated traction beam, 4 and 5 are the design area divisions of the carbon fiber composite integrated traction beam; 6 is the grid division of the design area of ​​the carbon fiber composite integrated traction beam;

[0086] Figure 4 It is the density cloud map of the first topology optimization process of the carbon fiber composite integrated traction beam, including the 5th, 7th, 12th and 15th iterations;

[0087] Figure 5 It is the iterative structure after material removal in the first topology optimization process of the carbon fiber composite integrated traction beam, including the 5th, 7th, 12th and 15th rounds of iterations;

[0088] Figure 6 It is the iterative curve of the first topology optimization process of the carbon fiber composite integrated traction beam, including the volume fraction V 0 and data of suppleness C;

[0089] Figure 7 It is the density cloud map of the second topology optimization process of the carbon fiber composite integrated traction beam, including the 7th, 14th, 21st, 28th, 35th, 42nd, and 49th iterations;

[0090] Figure 8 It is the iterative structure after material removal in the second topology optimization process of the carbon fiber composite integrated traction beam, including the 7th, 14th, 21st, 28th, 35th, 42nd, and 49th rounds of iteration;

[0091] Fig. 9 is the iterative curve of the second topology optimization process of the carbon fiber composite integrated traction beam, including the volume fraction V 0 and data of suppleness C;

[0092] Fig.10 is the Gaussian function weight matrix graph;

[0093] Fig.11 It is a diagram of the geometric reconstruction process of the carbon fiber composite material integrated traction beam;

[0094] Fig.12 This is the structural diagram of the carbon fiber composite material integrated traction beam after geometric reconstruction;

[0095] Fig.13 This is the stress analysis diagram of the original carbon fiber composite material integrated traction beam structure;

[0096] Fig.14 It is the topological optimization structural stress analysis diagram of the carbon fiber composite integrated traction beam. DETAILED DESCRIPTION

[0097] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0098] Explanation of the embodiment:

[0099] This embodiment provides a topology optimization design of a carbon fiber composite integrated traction beam, such as Figure 1 As shown, including:

[0100] First, perform step A, wherein:

[0101] A: In combination with the stress concentration at the coupler mounting seat of the carbon fiber composite material integrated traction beam, a finite element model of the carbon fiber composite material integrated traction beam is constructed through displacement function and flexibility matrix;

[0102] The specific design steps include:

[0103] A1 constructs the node displacement function and flexibility matrix of the carbon fiber composite integrated traction beam:

[0104] like Figure 2 As shown in the figure, after the cross-sectional mesh around the hole of the carbon fiber composite material integrated traction beam coupler installation location is discretized, a mesh node is extracted, the coordinate axis is built, and the node displacement function and flexibility matrix are established. The node displacement function is:

[0105]

[0106] Among them, δ(x, y) is the displacement function, R(x, y) is the shape function, and a is the node degree of freedom.

[0107] A2 establishes the finite element model of the carbon fiber composite integrated traction beam design area:

[0108] According to step A1, the carbon fiber composite material integrated traction beam is divided into a design area and a non-design area;

[0109] The design area includes around the draw beam coupler mountings;

[0110] The non-design area includes the main part connected to the anti-climbing frame and the main part connected to the corbel;

[0111] The material properties of the integrated traction beam of carbon fiber composite materials are given as shown in Table 1, which are discretized, and the vehicle body tensile working condition is set as shown in Table 2. The finite element model of the design area is established, as shown in Figure 3 shown.

[0112] Table 1 Performance parameters of carbon fiber unidirectional and fabric prepreg EM135 / HFW200T / 42 single-layer board

[0113]

[0114] Table 2 Tensile working conditions of carbon fiber composite integrated traction beam

[0115]

[0116] After completing the design process of step A, proceed to the design of step B, where;

[0117] B: Construct a mathematical model for topological optimization of an integrated traction beam made of carbon fiber composite materials;

[0118] The specific design steps include:

[0119] Establish a single-condition static topology optimization mathematical model:

[0120]

[0121] Where X is the relative density of the elements in the design area; N is the total number of nodes in the design area; C is the overall flexibility of the structure; F, K, and U are the load matrix, stiffness matrix, and displacement matrix of the structure, respectively; u e , k e are the displacement vector and stiffness vector of the unit node respectively.

[0122] After completing the design process of step B, proceed to the design of step C, where;

[0123] C: Taking minimum flexibility and maximum stiffness as the objective function and the volume fraction after topology optimization in the optimization area not exceeding 0.7 of the initial volume as the optimization constraint, the first topology optimization process of carbon fiber composite integrated traction beam is established;

[0124] The specific design steps include:

[0125] C1 builds an optimization model for carbon fiber composite integrated traction beam:

[0126] according to Figure 3 The established finite element model sets the optimization objective function to maximum stiffness and minimum flexibility;

[0127] The optimization constraint is that the volume fraction after topology optimization in the optimization area does not exceed 0.7 of the initial volume;

[0128] The optimized responses are volume fraction and compliance;

[0129] When the difference between the target values ​​in two consecutive iterations is less than the allowable value, the optimization iteration is considered to have converged. The allowable value for convergence is 0.5%, and the maximum number of iterations allowed is 100;

[0130] Topology optimization mathematical model:

[0131]

[0132] Where: iis the unit density; C(ρ) is the structural flexibility; u is the node displacement; K is the overall stiffness matrix; P is the applied load vector; V(ρ) is the optimized volume, V 0 is the original volume, equilibrium equation is the structural equilibrium equation; 0<ρ min <ρ i <1 is the lower limit of density of each unit.

[0133] C2 solves and builds an optimization model for carbon fiber composite integrated traction beam:

[0134] like Figure 4 The figure shows the first topology optimization iteration process of the carbon fiber composite integrated traction beam. The final structure is finally calculated and converged after 15 rounds of iterations.

[0135] Select the typical iteration results of the 5th, 7th, 12th and 15th rounds respectively and obtain their corresponding density cloud maps;

[0136] Selecting the density threshold v = 0.3, we can obtain the structures after material removal corresponding to the density cloud maps of the 5th, 7th, 12th, and 15th rounds, as shown in the figure: Figure 5 shown.

[0137] C3 draws the topology optimization iteration curve of the integrated traction beam of carbon fiber composite materials:

[0138] like Figure 6 The first topology optimization iteration curve of the carbon fiber composite integrated traction beam is shown, and the distribution of the material on the structure is obtained;

[0139] Select the density threshold v = 0.3, establish a point-line graph of volume fraction and number of iterations, and satisfy the requirement that the volume fraction decreases as the number of iterations increases. The final iteration result V(ρ) = 0.7;

[0140] A point-line graph of compliance and iteration number is established, which satisfies that compliance decreases with the increase of iteration number, and stiffness increases with the increase of iteration number. The final iteration result C(ρ)=1.15×10 6 ;

[0141] The final iterative structure is obtained by combining the changes in compliance, volume fraction and number of iterations.

[0142] After completing the design process of step C, proceed to the design of step D, where;

[0143] D: Taking the minimization of mass as the objective function and the maximum displacement as the optimization constraint, the topology optimization process of the second carbon fiber composite integrated traction beam is established;

[0144] The specific design steps include:

[0145] D1 builds an optimization model for integrated carbon fiber composite traction beams:

[0146] according to Figure 3 The established finite element model sets the optimization objective function to the minimum mass;

[0147] The optimization constraint is that the maximum displacement does not exceed 3 mm;

[0148] The optimized responses are volume fraction, mass fraction, and displacement response;

[0149] When the difference between the target values ​​in two consecutive iterations is less than the allowable value, the optimization iteration is considered to have converged. The optimization setting convergence allowable value is 0.5%, and the maximum number of iterations allowed is 100.

[0150] Topology optimization mathematical model:

[0151]

[0152] Where: i is the unit density; M(ρ) is the structural mass; u is the node displacement; K is the overall stiffness matrix; P is the applied load vector; U max Maximum displacement; 0<ρ min <ρ i <1 is the lower limit of density of each unit.

[0153] D2 solves and constructs the optimization model of carbon fiber composite integrated traction beam:

[0154] like Figure 7 The figure shows the second topology optimization iteration process of the carbon fiber composite integrated traction beam. The final structure is finally calculated and converged after 49 rounds of iterations.

[0155] Select the typical iteration results of the 7th, 14th, 21st, 28th, 35th, 42nd and 49th rounds respectively, and obtain their corresponding density cloud maps;

[0156] Selecting the density threshold v = 0.3, we can obtain the structures after material removal corresponding to the density cloud maps of the 5th, 7th, 12th, and 15th rounds, as shown in the figure: Figure 8 shown.

[0157] D3 draws the topology optimization iteration curve of the integrated traction beam of carbon fiber composite materials:

[0158] like Fig. 9 The second topology optimization iteration curve of the carbon fiber composite integrated traction beam is shown, and the distribution of the material on the structure is obtained;

[0159] Select the density threshold v = 0.3, establish a point-line graph of volume fraction and number of iterations, and satisfy the requirement that the volume fraction decreases as the number of iterations increases. The final iteration result V(ρ) = 0.655;

[0160] A point-line graph of compliance and iteration number is established, which satisfies that compliance decreases with the increase of iteration number, and stiffness increases with the increase of iteration number. The final iteration result C(ρ)=1.10×10 6 ;

[0161] The final iterative structure is obtained by combining the changes in compliance, volume fraction and number of iterations.

[0162] After completing the design process of step D, proceed to the design of step E, where;

[0163] E: Compare the two topology optimization iteration results, select the optimal iteration structure, and use the smoothing filter algorithm to establish the geometric reconstruction model of the carbon fiber composite integrated traction beam;

[0164] The specific design steps include:

[0165] like Fig.10 The figure shows the weighted average of the grid points of the traction beam after topology optimization using the Gaussian function as the weight;

[0166] Gaussian distribution formula:

[0167]

[0168] Where (x, y) is the coordinate of the point inside the mask, (ux, uy) is the coordinate of the center point, and σ is the standard deviation. i，j is the value of each coordinate element; take the center position of the template as the coordinate origin for sampling, substitute each point into the Gaussian function, v = 0.3, and get the Gaussian template coefficient;

[0169] like Fig.11 The construction unit density is shown as 0 to 1, and the unit Set corresponding to 10 parts is layered. The optimization density threshold is set to 0.15, and the area with sufficient density is extracted for geometric reconstruction. The geometric reconstruction structure of the carbon fiber composite integrated traction beam is obtained, as shown in Fig.12 shown.

[0170] After completing the design process of step D, proceed to the design of step E, where;

[0171] F: Set boundary conditions, loads, and constraints to perform static analysis on the original carbon fiber composite integrated traction beam structure and the geometrically reconstructed traction beam structure under tension conditions;

[0172] The specific design steps include:

[0173] Stress analysis of F1 original carbon fiber composite integrated traction beam:

[0174] According to the working condition A2, the boundary conditions are established, and the reference point and the cross section at the center of the coupling hole of the traction beam are set with MPC constraints;

[0175] The reference point is used as the action point for applying the load, and a load of 800KN is applied along the negative direction of the X axis at the reference point at the loading location;

[0176] Release the X-axis freedom of the flanging rivet hole;

[0177] like Fig.10 As shown in the figure, the stress analysis of the original traction beam structure is carried out. The density threshold is selected to obtain the Signed Mises stress and Mises stress of the complete structure after the material in the design area is removed.

[0178] Stress analysis of carbon fiber composite integrated traction beam with F2 geometry reconstruction:

[0179] like Fig.11 As shown in the figure, for the stress analysis of the geometric traction beam structure, the density threshold is selected to obtain the Signed Mises stress and Mises stress of the complete structure after material removal in the design area.

Claims

1. A topological optimization design of an integrated carbon fiber composite traction beam, characterized in that: include: A: In combination with the stress concentration at the coupler mounting seat of the carbon fiber composite integrated traction beam, a finite element model of the carbon fiber composite integrated traction beam is constructed through displacement function and flexibility matrix. B: Construct a mathematical model for topological optimization of an integrated traction beam made of carbon fiber composite materials; C: Taking minimum flexibility and maximum stiffness as the objective function and the volume fraction after topology optimization in the optimization area not exceeding 0.7 of the initial volume as the optimization constraint, the first topology optimization process of carbon fiber composite integrated traction beam is established; D: Taking the minimization of mass as the objective function and the maximum displacement as the optimization constraint, the topology optimization process of the second carbon fiber composite integrated traction beam is established; E: Compare the two topology optimization iteration results, select the optimal iteration structure, and use the smoothing filter algorithm to establish the geometric reconstruction model of the carbon fiber composite integrated traction beam; F: Set boundary conditions, loads, and constraints to perform static analysis on the original carbon fiber composite integrated traction beam structure and the geometrically reconstructed traction beam structure under tension conditions.

2. The topological optimization design of a carbon fiber composite material integrated traction beam according to claim 1, characterized in that: In said A, the specific steps include: A1 constructs the grid node displacement function and flexibility matrix of carbon fiber composite integrated traction beam: According to the three-dimensional model of the integrated traction beam of carbon fiber composite materials, the neutral surface is extracted to divide the grid and obtain the discretized grid unit. The grid unit nodes are extracted to construct the displacement function and flexibility matrix. The function is expressed as: Among them, δ(x, y) is the displacement function, R(x, y) is the shape function, and a is the node degree of freedom. A2 establishes the finite element model of the carbon fiber composite integrated traction beam design area: According to the displacement function and flexibility matrix of A1, the design area and non-design area are divided. The design area includes the area around the traction beam coupler mounting seat, and the non-design area includes the main part connected to the anti-climber frame and the main part connected to the bolster. Material properties are assigned and discretized, and the vehicle body tensile condition is set to load the carbon fiber composite integrated traction beam to establish a finite element model of the design area.

3. The topology optimization design of a carbon fiber composite material integrated traction beam according to claim 1 is characterized in that: In B, the mathematical model of the structural single-condition static topology optimization based on the orthogonal penalty material density method is as follows: Where X is the relative density of the elements in the design area; N is the total number of nodes in the design area; C is the overall flexibility of the structure; F, K, and U are the load matrix, stiffness matrix, and displacement matrix of the structure, respectively; u e , k e are the displacement vector and stiffness vector of the unit node respectively.

4. The topology optimization design of a carbon fiber composite material integrated traction beam according to claim 1, characterized in that: In said C, the specific design steps include: C1 builds an optimization model for carbon fiber composite integrated traction beam: According to the established finite element model, the optimization objective function is set to maximum stiffness and minimum flexibility, and the optimization constraint is that the volume fraction after topology optimization in the optimization area does not exceed 0.7 of the initial volume. A maximum of 100 iterations is allowed. The mathematical model is as follows: C2 solves the optimization model of carbon fiber composite integrated traction beam: The optimization model of C1 is calculated using a finite element solver to obtain the first topology optimization process. After the calculation converges, the finite element post-processing software is used to obtain the density cloud map of the carbon fiber composite material integrated traction beam in each iteration and the iterative structure after material removal. C3 draws the topology optimization iteration curve of the integrated traction beam of carbon fiber composite materials: The iterative optimization results of the composite traction beam obtained by C2 are integrated to construct a topology optimization iteration curve, and the relationship between the volume fraction and compliance optimization response and the number of iterations in each round is established.

5. The topology optimization design of a carbon fiber composite material integrated traction beam according to claim 1, characterized in that: In the F, the specific design steps include: D1 builds an optimization model for integrated carbon fiber composite traction beams: According to the established finite element model, the optimization objective function is set to minimize the mass, the optimization constraint is set to the maximum displacement, and a maximum of 100 iterations are allowed. The mathematical model is as follows: D2 solves the optimization model of carbon fiber composite integrated traction beam: The optimization model of D1 is calculated using a finite element solver to obtain the first topology optimization process. After the calculation converges, the finite element post-processing software is used to obtain the density cloud map of the carbon fiber composite material integrated traction beam in each iteration and the iterative structure after material removal. D3 draws the topology optimization iteration curve of the integrated traction beam of carbon fiber composite materials: The iterative optimization results of the composite traction beam obtained in D2 are integrated to construct a topology optimization iterative curve, and the relationship between the volume fraction and the compliance optimization response and the number of iterations in each round is established.

6. The topology optimization design of a carbon fiber composite material integrated traction beam according to claim 1, characterized in that: In the E, the Gaussian filtering method is used to perform weighted averaging on the grid points using the Gaussian function as the weight, and the final iterative result of the topology optimization is used to extract the area with sufficient density for geometric reconstruction. The reconstructed grid is further smoothed or optimized to remove the noise and fluctuation of the grid during the calculation process.

7. The topology optimization design of a carbon fiber composite material integrated traction beam according to claim 1, characterized in that: In said F, the specific steps include: Stress analysis of F1 original carbon fiber composite integrated traction beam Boundary conditions are set, and MPC constraints are set for the reference point and cross section at the center of the coupling hole of the traction beam. The reference point is used as the point of action for applying the load, and a load of 800KN is applied along the negative direction of the X axis at the reference point at the loading point. Only the X-axis degree of freedom is released at the rivet hole of the bottom flange. The stress analysis of the original traction beam structure is carried out, and the density threshold is selected to obtain the Signed Mises stress and Mises stress of the complete structure after the material removal in the design area. Stress analysis of carbon fiber composite integrated traction beam with F2 geometry reconstruction: The stress analysis of the carbon fiber composite integrated traction beam after geometric reconstruction is carried out, and the density threshold is selected to obtain the Signed Mises and Mises stresses of the design area after material removal and the complete structure. The iterative optimization results obtained by D2, the E geometric reconstruction structure and the F1 and F2 stress analysis results are integrated to determine the topological optimization design of the carbon fiber composite integrated traction beam.

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