Simulation analysis method for body-in-white strength

Abstract

The invention relates to a body-in-white strength simulation analysis method, which comprises the following steps of: establishing a finite element model of a body-in-white, performing automatic mesh generation by adopting a preset mesh generation standard, endowing a material thickness attribute, and endowing a linear elastic material attribute to parts in the finite element model of the body-in-white; the parts without the grids are subjected to weight balancing according to the mass and the mass center of the parts, and differential weight balancing processing is carried out on the passenger vehicle and the logistics vehicle to simulate the full-load state of the whole vehicle; and dynamic models of the front suspension and the rear suspension are established. According to the method, linear elastic material attributes are given to a body-in-white finite element model, and linear statics solution is performed based on the linear elastic material attributes, so that a complicated iterative calculation process of nonlinear simulation in the prior art is fundamentally avoided, and the calculation time of single-round simulation analysis is greatly shortened; therefore, rapid and multi-round iterative analysis in conceptual design and detailed design stages can be supported, and the development efficiency is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of body-in-white strength simulation analysis technology, and specifically to a body-in-white strength simulation analysis method. Background Technology

[0002] As the main load-bearing structure of the vehicle, the strength performance of the automotive body-in-white is directly related to the vehicle's safety, durability, and lightweight level. In the process of vehicle development, using computer-aided engineering simulation for body-in-white strength analysis and optimization has become an industry standard process. However, how to significantly improve simulation efficiency to support rapid, multi-round design iterations while ensuring simulation accuracy remains a huge challenge.

[0003] Chinese patent CN112699457B discloses an automatic simulation analysis method for the strength of automotive body-in-white. Its main steps include: importing the component geometric model and automatically generating a mesh; calculating and assigning material thickness attributes to the mesh through a complex mathematical model; reading the BOM table and automatically matching material parameters; converting and creating weld point information to complete model assembly; crucially, this method imports a nonlinear material library to replace linear materials in the model with nonlinear materials; finally, it imports multibody loads through hard points and sets parameters to perform nonlinear simulation calculations.

[0004] However, although the existing technology saves time by automating the preprocessing, it is essentially a nonlinear simulation with extremely high computational costs. The solution process itself is very time-consuming, making it difficult to meet the stringent efficiency requirements of modern vehicle platforms that require dozens of rapid iterations during the conceptual and detailed design stages. Furthermore, this approach loads the vehicle by creating hard points and directly importing multi-body loads. This method fails to consider the impact of flexible deformation of key structures such as the control arms and subframes in the suspension system on load transfer. The loads extracted based on the rigid body assumption deviate from the actual working conditions, thus affecting the accuracy of stress prediction. At the same time, this approach focuses on generalized model assembly and does not address the differentiated weight modeling for different vehicle types. For example, it fails to provide dedicated processing based on the different mechanisms of passenger vehicle occupant load transfer through seat supports and logistics vehicle cargo load distribution on the floor, resulting in the simulation model not matching the actual load-bearing state of a specific vehicle type. Therefore, there is an urgent need in the field for a body-in-white strength simulation analysis method that can significantly improve simulation efficiency while also ensuring the accuracy of simulation results by improving load input accuracy and enabling differentiated modeling for different vehicle types. Summary of the Invention

[0005] This application provides a method for simulating and analyzing the strength of a body-in-white to solve the above-mentioned problems.

[0006] In a first aspect, embodiments of this application provide a method for simulating and analyzing the strength of a white body, comprising the following steps: A finite element model of the body-in-white is established, and an automated mesh generation is performed using a preset mesh generation standard, and a material thickness attribute is assigned. The components in the finite element model of the body-in-white are then assigned linear elastic material properties. For components without a grid, counterweights are applied based on their mass and center of gravity, and passenger vehicles and logistics vehicles are treated differently to simulate a fully loaded vehicle. Establish dynamic models for the front and rear suspensions, replace the rigid bodies and subframes in the dynamic models with flexible bodies, and extract the forces and moments at preset points connecting the front and rear suspensions to the vehicle body according to the set working conditions to generate load files. The load file is loaded into the finite element model of the body-in-white, and the inertia release method is used to simulate the equilibrium state of the body-in-white without fixed constraints. Based on the linear elastic material properties, linear statics are solved to obtain the maximum equivalent stress of the body-in-white. Based on the obtained maximum equivalent stress and the corresponding material yield strength, the regions where the strength does not meet the requirements are identified and structural optimization is performed. Iterative analysis is conducted until the strength meets the requirements.

[0007] In conjunction with the first aspect, in one implementation, the step of balancing the ungrid-established components according to their mass and center of gravity, and the differentiated balancing treatment for passenger vehicles and logistics vehicles, specifically includes: For opening and closing components, a mass point is used for counterweighting, and the mass point is connected to the finite element model through an RBE3 element; For passenger vehicles, a finite element model of the seat support is established on the finite element model of the body-in-white, and mass points representing the occupant mass are applied on the finite element model of the seat support using RBE3 elements. For logistics vehicles, a set area is selected on the cargo box floor of the finite element model of the body-in-white, and mass points representing the mass of the goods are loaded through RBE3 elements.

[0008] In conjunction with the first aspect, in one implementation, after balancing the components without a mesh, the step further includes a centroid calibration step: Obtain the centroid height of the finite element model of the body-in-white after counterweighting; The obtained center of gravity height is compared with the preset full-load center of gravity height; Based on the comparison results, adjust the centroid coordinates of the mass points until they match.

[0009] In conjunction with the first aspect, in one implementation, replacing the swing arm and subframe in the dynamic model from rigid bodies to flexible bodies specifically includes: A finite element model of the swing arm and subframe is established, and the mesh is generated using a preset mesh standard. Material thickness attributes and linear elastic material properties adapted to the swing arm and subframe itself are assigned. Modal neutral files for the swing arm and subframe are generated based on the finite element model of the swing arm and subframe. In the dynamic model, the original rigid body model is replaced by the modal neutral file.

[0010] In conjunction with the first aspect, in one implementation method, the set operating conditions specifically include: At least one or more of the following conditions: stationary condition, braking condition, steady-state turning condition, driving condition, body torsion condition, and parallel upward jump condition.

[0011] In conjunction with the first aspect, in one implementation method, the preset point specifically includes: The connection points between the front / rear subframe and the body, the mounting points on the shock absorbers, and the upper supports of the springs.

[0012] In conjunction with the first aspect, in one implementation, the specific criteria for the region where the recognition intensity does not meet the requirements are as follows: If the maximum equivalent stress in a certain region is greater than or equal to the preset yield strength corresponding to that region, then the strength of that region is determined to be unsatisfactory.

[0013] In conjunction with the first aspect, in one embodiment, the structural optimization includes adjusting at least one of the following: geometry, local structure, or material properties, for areas where the strength requirement is not met.

[0014] In conjunction with the first aspect, in one embodiment, the adjustment of the geometry includes eliminating process gaps and increasing transition fillets; The adjustments to the local structure include adding reinforcing plates or ribs, or optimizing open-section beams into closed-section beams; The adjustment of the material properties includes changing the material grade or increasing the material thickness.

[0015] In conjunction with the first aspect, in one embodiment, the linear elastic material properties include elastic modulus, density, and Poisson's ratio.

[0016] The beneficial effects of the technical solutions provided in this application include: 1. This method assigns linear elastic material properties to the finite element model of the body-in-white and performs linear statics solution based on this, fundamentally avoiding the complex iterative calculation process of nonlinear simulation in the prior art. This significantly shortens the calculation time of single-round simulation analysis, thereby enabling rapid, multi-round iterative analysis in the conceptual design and detailed design stages, greatly improving development efficiency.

[0017] 2. This method extracts loads by replacing the rigid body and subframe in the dynamic model with a flexible body. This method can accurately simulate the deformation effect of these key components when they are actually subjected to force, thereby obtaining a more realistic and accurate load file than that based on the rigid body assumption. This high-precision load is loaded onto the body-in-white model, providing reliable boundary conditions for subsequent strength verification and significantly improving the accuracy of stress prediction results.

[0018] 3. This method uses differentiated counterweight processing based on the load-bearing characteristics of different vehicle models, enabling the finite element model to accurately reflect the actual load distribution and force transmission path of different vehicle models. This effectively avoids the risks of over-design or under-design brought about by the generalized model, and makes the simulation results highly consistent with the actual state of various vehicle models. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram illustrating the main steps of the present invention; Figure 2 This is a schematic diagram of the geometric model of the body-in-white assembly according to an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the assignment of material thickness properties in an embodiment of the present invention; Figure 4 This is a schematic diagram of the passenger vehicle counterweight processing according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the counterweight processing of a logistics vehicle according to an embodiment of the present invention; Figure 6 A working condition table diagram set for an embodiment of the present invention; Figure 7 This is a schematic diagram of the maximum equivalent stress obtained in an embodiment of the present invention; Figure 8 This is a schematic diagram of geometric shape adjustment according to an embodiment of the present invention. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0022] Please see Figure 1 This application provides a method for simulating and analyzing the strength of a white body, including the following steps: S1. Establish the finite element model of the body-in-white, use the preset mesh generation standard to automatically generate the mesh and assign the material thickness attribute, and assign the linear elastic material property to the parts in the finite element model of the body-in-white. S101: Modeling and Meshing; The geometric model of the body-in-white assembly completed in 3D CAD software (such as CATIA) is imported into finite element processing software (such as HyperMesh, ANSA, etc.) to construct the finite element model of the body-in-white. The finite element model of the body-in-white includes the body-in-white, glass, subframe, and CCB tube beam. Specifically, please refer to Figure 2 This embodiment completes automated mesh generation through the following process: In the finite element processing software, the automatic mesh generation function is invoked, and a mesh generation standard suitable for strength and durability analysis is selected from the preset mesh standard library. For example, a shell mesh standard with a size of 5mm (which can be represented as "durability 5mm") will be selected. The finite element processing software will automatically clean and generate the imported body-in-white assembly geometry model according to this selected standard, and finally generate a high-quality shell mesh suitable for simulation calculation. In addition, to improve mesh generation efficiency, meshing of fine geometric features such as bolts, weld points and weld seams can be canceled during batch processing. This can significantly reduce the number of unnecessary meshes and computational units, while avoiding mesh quality degradation caused by these complex geometries.

[0023] S102: Material thickness attribute assignment; like Figure 3 As shown, during or after the mesh generation process in step S101, the thickness information of all sheet metal parts is automatically identified and extracted from the imported body-in-white assembly geometric model by a programming script, and the corresponding part names are recorded at the same time. The script outputs these extracted material thickness values ​​and their corresponding component names and saves them to an intermediate data file (e.g., a CSV file); In the finite element processing software, the corresponding automated script is run to read and parse the intermediate data file generated above. The script will automatically match the corresponding part in the model according to the part name recorded in the file, and batch assign the material thickness value defined for the part in the file to all shell mesh elements under the part.

[0024] S103: Linear elastic material properties; To achieve rapid linear analysis, this step uses a pre-defined automated process to assign uniform linear elastic material properties to all metal structural components in the finite element model of the body-in-white in a one-time, batch manner. Specifically: First, a reference material card named after the material grade is pre-created in the software material library, and its basic parameters such as elastic modulus, density and Poisson's ratio are clearly defined. Then, an automated script is executed, which traverses the metal parts in the model and automatically matches and associates them with the corresponding reference cards in the material library based on their names and other identifiers.

[0025] This operation efficiently and accurately endows all metal parts with uniform linear elastic material properties, simplifying their mechanical behavior into that of a linear elastic body following Hooke's Law, thus improving the efficiency of linear statics analysis.

[0026] S2. For components without a grid, weights are added based on their mass and center of mass, and passenger vehicles and logistics vehicles are treated differently to simulate the full load of the vehicle. S201: Counterweight; Specifically, the unmeshed parts are weighted according to their mass and center of mass based on the sprung model data of the whole vehicle. The sprung model data of the whole vehicle includes the mass and three-dimensional center of mass coordinates of all parts (such as interior parts, electrical appliances, seat foam, carpets, etc.) that are not meshed in the finite element model of the body-in-white. The basic principle of weighting is that all parts with a mass exceeding 1kg should be taken into account.

[0027] The counterweight method is as follows: Create a mass point at the three-dimensional coordinates corresponding to the centroid of the component; Set the value of this mass point to the mass of the component; The mass point is flexibly connected to its actual mounting point or connection area on the vehicle body structure through the RBE3 unit. Among them, the RBE3 element can reasonably distribute the load of the mass point to a set of connection nodes in a weighted average manner, thereby simulating the real path of force transmission and avoiding unrealistic stress concentration.

[0028] S202: Differentiated weighting treatment; For common opening and closing components (such as car doors, hoods, tailgates, etc.), mass points are used for counterweight, and the mass points are connected to the finite element model through RBE3 elements; Additionally, please see Figure 4 and Figure 5 The configuration for different car models is handled as follows: ① For passenger vehicles, the passenger load is transferred to the vehicle floor through the seat frame; therefore, the method used in this paper is as follows: In the finite element processing software, create a new independent component, import the geometric model of the seat bracket into the component, and mesh it according to the meshing standard of the body-in-white (such as 5mm shell mesh) to generate the finite element model of the seat bracket. The finite element model of the created seat bracket is assembled into the overall finite element model of the body-in-white through its actual connection relationship with the body-in-white floor. For bolted connections, RBE2 elements or CBAR / CBEAM elements are used to simulate bolts and rigidly or flexibly connect the mounting point of the bracket to the corresponding node on the body floor. For welded connections, CWELD elements or RBE2 elements are used to simulate weld points and connect the welded edge of the bracket to the body floor. Create a mass point representing the occupant's weight at the seating position; This mass point is connected to the finite element model of the seat support below it using the RBE3 element.

[0029] ② For logistics vehicles, the cargo load is evenly distributed on the cargo box floor, therefore the method used in this paper is as follows: On the cargo box floor of the finite element model of the body-in-white, select a set of nodes representing the cargo coverage area; At the geometric center of this area, create a mass point representing the total weight of the cargo; The mass point is connected to the entire set of nodes selected on the floor using the RBE3 element.

[0030] This can simulate the physical effect of a cargo's weight being evenly distributed on the floor.

[0031] S203: Centroid calibration; Specifically, to ensure that the overall mass distribution of the finite element model of the body-in-white is consistent with the design objectives, centroid calibration is required: In finite element processing software, the built-in mass attribute calculation function is used to obtain the overall centroid coordinates of the finite element model of the entire body-in-white after the counterweight is completed. Compare the overall centroid coordinates with the preset full-load centroid height; If the overall centroid coordinates are higher than the preset full-load centroid height, it indicates that the upper part of the finite element model of the body-in-white is too heavy. Therefore, the three-dimensional coordinates of the cargo mass point of the logistics vehicle or the passenger mass point of the passenger vehicle should be lowered. If the overall centroid coordinates are lower than the preset full-load centroid height, then the three-dimensional coordinates of the cargo mass point of the logistics vehicle or the passenger mass point of the passenger vehicle will be adjusted upwards. After adjusting the three-dimensional coordinates of the mass point, the height of the centroid of the overall model needs to be recalculated and compared with the design datum again until it is the same or the deviation is within the preset deviation standard. In this embodiment, the preset deviation standard is 2mm.

[0032] The preset full-load center of gravity height is a theoretical value of the body-in-white under full-load design conditions, determined by the general layout department during the vehicle design phase through theoretical calculations and a comprehensive analysis of 3D digital models. It originates from design data from the early stages of vehicle development. It is typically released by the company's general layout department or weight management department and is one of the core target parameters for vehicle design.

[0033] S3. Establish dynamic models of the front and rear suspensions, replace the rigid bodies of the control arms and subframes in the dynamic models with flexible bodies, and extract the forces and moments at preset points connecting the front and rear suspensions to the vehicle body according to the set working conditions to generate load files. S301: Establish a multibody dynamics model; Specifically, in multibody dynamics software (such as Adams / Car, SIMPACK, etc.), a whole vehicle dynamics model including the front suspension, rear suspension, and steering system is established. In this embodiment, Adams / Car is used as an example. The structural components in the initial model include control arms (control arms, trailing arms, etc.), subframes, steering knuckles, etc. S302: Replace with a flexible body; To improve load extraction accuracy, key load-bearing components are replaced with flexible ones to account for the impact of their deformation on load distribution. The specific steps are as follows: In the finite element analysis software, open the three-dimensional geometric model of the swing arm and subframe; Mesh it using a mesh standard compatible with the finite element model of the body-in-white (such as a 5mm shell mesh), and assign it material thickness properties as well as linear elastic material properties that are compatible with the swing arm and subframe itself. Create interface nodes at locations where connections to other components are required (such as hinge points and bushing mounting points); Submit the calculation using the solver interface (e.g., generate MNF file for Adams, generate PNF file for SIMPACK) to generate a modal neutral file (mnf file) containing component mass, modal frequencies and mode shapes, and stiffness information. In the dynamic model, locate the corresponding rigid body component, and use the replacement function in the software (such as using the Flexible Body tool) to select the modal neutral file generated above and replace the original rigid body model accordingly. Ensure that the interface nodes on the replaced flexible body are correctly associated with the original connection points (such as bushings and hinges) in the finite element model of the body-in-white to ensure the correct transmission of force flow.

[0034] S303: Define Analysis Conditions and Extract Loads In dynamics software, extreme or fatigue load conditions that vehicles may encounter during real-world driving are simulated, such as... Figure 6As shown, these operating conditions include at least: Static condition: Simulates the state of a vehicle stationary on a horizontal road surface, serving as the reference load; Braking condition: Simulate emergency braking and apply corresponding deceleration; Steady-state cornering condition: Simulates steady-state cornering of the vehicle, applying corresponding centripetal acceleration; Driving conditions: Simulate rapid acceleration and apply corresponding acceleration; Vehicle body torsion condition: Simulates the torsional load on the vehicle body caused by wheel suspension, etc. Parallel upward jump condition: Simulates a vehicle driving over a road bump, with wheels in the same direction being impacted simultaneously; Setting Output Requests: In the simulation analysis settings, explicitly specify the preset loads to be extracted. These preset points are the connection points between the suspension and the body-in-white, specifically including: Mounting points of the front / rear subframe to the body, mounting points on the shock absorbers, and upper supports of the springs.

[0035] S304: Perform simulation and generate load files; Perform dynamic solutions using predefined operating conditions.

[0036] In the post-processing module, the force and torque of the six components (Fx, Fy, Fz, Mx, My, Mz) at all simulation time steps of the above preset point are output. The output load data is converted into a load file (such as a bdf file) according to the format required by the target finite element solver (such as Nastran). This file usually contains FORCE and MOMENT cards for defining loads, as well as commands to apply them to the corresponding nodes of the body-in-white finite element model.

[0037] S4. Load the load file into the finite element model of the body-in-white, and use the inertia release method to simulate the equilibrium state of the body-in-white without fixed constraints. Based on the linear elastic material properties, perform linear statics solution to obtain the maximum equivalent stress of the body-in-white. Based on the obtained maximum equivalent stress and the corresponding material yield strength, identify the areas where the strength does not meet the requirements and perform structural optimization. Iterate until the strength meets the requirements.

[0038] S401: Acquisition and comparison of maximum equivalent stress; In the finite element processing software, the load file generated in step S3 is read, and the forces and torques in the load file are precisely applied to the preset points (i.e., subframe mounting points, shock absorber mounting points, and spring supports) corresponding to the finite element model of the body-in-white.

[0039] In the solver settings of the finite element analysis software, activate the inertia release function; Based on the linear elastic material properties assigned to all metal parts in step S103, linear statics calculations are performed, and the solver will quickly calculate the stress and deformation distribution of the entire body-in-white finite element model in equilibrium.

[0040] The solution results are read in the finite element processing software and the equivalent stress cloud map is visualized. The maximum equivalent stress value of the entire body-in-white and its location are obtained through the extreme value search function of the finite element processing software. The maximum equivalent stress identified above is compared with the preset yield strength corresponding to the component where the stress point is located; wherein, the preset yield strength is a standard value retrieved from the enterprise's material database based on the material grade of the part; If the maximum equivalent stress in a certain region is greater than or equal to the preset yield strength corresponding to that region, then the strength of that region is determined to be insufficient; this embodiment is an example. Figure 7 As shown, the maximum equivalent stress in this region is 193.8 MPa. The material grade used for this part is DC04, and the yield strength is 170 MPa. Therefore, the strength of this region does not meet the requirements.

[0041] S402: Optimization and adjustment; Based on the regions that do not meet the requirements obtained in step S401, implement one or more of the following structural optimization measures: Local structural adjustments, such as adding reinforcing plates or ribs in this area; Geometric adjustments, such as eliminating process gaps or increasing the radius of transition fillets, can reduce stress concentration, or open section beams can be optimized into closed section beams to improve torsional stiffness. Adjusting material properties, such as replacing with higher strength materials or appropriately increasing the thickness of the sheet metal; like Figure 8 As shown, the method used in this embodiment is to eliminate process gaps; Update the optimized structure to the body-in-white assembly geometry model, then return to step S1. Based on the new body-in-white assembly geometry model, perform finite element modeling, counterweighting, load loading, and solution analysis again until the maximum equivalent stress of the body-in-white under all test conditions is lower than the preset yield strength of its corresponding region.

[0042] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0043] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0044] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A body-in-white strength simulation analysis method, characterized by, The method comprises the following steps: A finite element model of the body-in-white is established, automatic meshing is performed according to a preset meshing standard, and a material thickness attribute is assigned, and a linear elastic material attribute is assigned to a part in the finite element model of the body-in-white; After the parts without meshing are counterweighted according to their mass and center of mass, the passenger vehicle and the logistics vehicle are subjected to differential counterweight processing to simulate a full load state of the vehicle; A dynamics model of the front and rear suspensions is established, the swing arm and auxiliary frame in the dynamics model are replaced from a rigid body to a flexible body, and a preset point force and torque of the front and rear suspensions and the vehicle body are extracted according to a set working condition to generate a load file; The load file is loaded to the finite element model of the body-in-white, an inertia release method is used to simulate a balance state of the body-in-white without fixed constraints, linear statics is solved based on the linear elastic material attribute to obtain a maximum equivalent stress of the body-in-white, and a region with an unsatisfied strength requirement is identified based on the obtained maximum equivalent stress and a corresponding material yield strength, and structure optimization is performed, and iterative analysis is performed until the strength meets the requirement.

2. The body-in-white strength simulation analysis method according to claim 1, characterized by, The counterweighting of the parts without meshing according to their mass and center of mass, and the differential counterweight processing of the passenger vehicle and the logistics vehicle specifically comprises: For open and closed parts, mass points are used for counterweighting, and the mass points are connected to the finite element model through RBE3 units; For the passenger vehicle, a finite element model of a seat support is established on the finite element model of the body-in-white, and mass points representing the mass of passengers are applied to the finite element model of the seat support through RBE3 units; For the logistics vehicle, a set region is selected on the cargo box floor of the finite element model of the body-in-white, and mass points representing the mass of goods are loaded through RBE3 units.

3. The body-in-white strength simulation analysis method according to claim 2, characterized by, After the counterweighting of the parts without meshing, a center of mass calibration step is further included: The center of mass height of the finite element model of the body-in-white after the counterweighting is obtained; The obtained center of mass height is compared with a preset full load center of mass height; According to the comparison result, the center of mass coordinates of the mass points are adjusted until the two are consistent.

4. The body-in-white strength simulation analysis method according to claim 1, characterized by, The replacement of the swing arm and auxiliary frame in the dynamics model from a rigid body to a flexible body specifically comprises: A finite element model of the swing arm and auxiliary frame is established, meshing is performed according to a preset meshing standard, and a material thickness attribute and a linear elastic material attribute adapted to the swing arm and auxiliary frame are assigned; A modal neutral file of the swing arm and auxiliary frame is generated based on the finite element model of the swing arm and auxiliary frame; In the dynamics model, the modal neutral file is used to replace the original rigid body model.

5. The body-in-white strength simulation analysis method according to claim 1, characterized by, The set working condition specifically comprises: At least one or more of a static working condition, a braking working condition, a steady-state turning working condition, a driving working condition, a vehicle body torsion working condition, and a parallel upward jump working condition.

6. The body-in-white strength simulation analysis method according to claim 1, characterized by, The preset point specifically comprises: A connection point of the front / rear auxiliary frame and the vehicle body, an upper mounting point of a shock absorber, and a spring upper support.

7. The body-in-white strength simulation analysis method according to claim 1, characterized by, The specific standard for identifying the region with an unsatisfied strength requirement is: If the maximum equivalent stress of a region is greater than or equal to a preset yield strength corresponding to the region, it is determined that the strength of the region does not meet the requirement.

8. The body-in-white strength simulation analysis method according to claim 1, characterized by, The structure optimization includes at least one of geometry adjustment, local structure adjustment or material attribute adjustment for the region not meeting the strength requirement.

9. The body-in-white strength simulation analysis method according to claim 8, characterized by, The geometry adjustment includes eliminating process gaps or increasing transition fillets. The local structure adjustment includes adding reinforcing plates, reinforcing ribs or optimizing open cross-section beams to closed cross-section beams. The material attribute adjustment includes changing material grades or increasing material thickness.

10. The body-in-white strength simulation analysis method according to claim 1, characterized by, The linear elastic material attributes include elastic modulus, density and Poisson's ratio.

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