Method and system for stiffness evaluation and optimization of automotive body joints

Abstract

The application provides a rigidity evaluation and optimization method and system for a vehicle body joint, and the method comprises the following steps: obtaining a vehicle type, obtaining a plurality of design input conditions corresponding to the vehicle type according to the vehicle type, and constructing a vehicle body finite element model corresponding to the vehicle type according to the plurality of design input conditions; a target joint model is cut from the vehicle body finite element model according to a first preset size, the target joint model comprises a plurality of joint branches, a target joint branch is locked from the target joint model, a preset load force is applied to the target joint branch, and other joint branches are constrained; a rigidity value of the target joint branch is obtained, and the target joint branch is optimized according to the rigidity value. The rigidity evaluation and optimization method for the vehicle body joint can identify problems of insufficient rigidity or stress concentration in the vehicle body structure in advance in the early design stage of the vehicle, so that the development cycle is shortened and the test cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile development, in particular to a rigidity evaluation and optimization method and system for a vehicle body joint. BACKGROUND

[0002] The connection part of a load-bearing rod beam piece in a vehicle body structure is referred to as a joint, and the joint is a connection part where load-bearing pieces intersect in the vehicle body structure, and the structure thereof is generally complex. The joint is a main force transmission component in the vehicle body structure, and the structure thereof directly determines the torsional stiffness, bending stiffness, vibration mode and safety performance of the vehicle body. Moreover, as a complex transition part in the vehicle body, the joint is prone to stress concentration and fatigue failure under the condition that the vehicle body often bears alternating stress, so whether the joint structure design is reasonable will directly affect the durability, NVH characteristics and safety performance of the vehicle body.

[0003] In the industry, the main machine manufacturers evaluate the strength, durability and safety performance in the project development process based on the following four aspects: 1. Multi-objective lightweight optimization method based on overall size optimization of the vehicle body; 2. Lightweight optimization design based on part shape optimization; 3. Multi-material—multi-part specification combination multi-objective lightweight optimization method; and 4. Multi-disciplinary optimization technology for lightweight process. The above traditional methods mainly analyze the overall size, part shape, material and process from four aspects to evaluate the modal, response, strength, durability and safety performance of the body-in-white.

[0004] However, there is less detailed and quantitative research on the rigidity of the joint part in the prior art, although the performance of the body-in-white meets the design requirements in the early evaluation, but cracking failure occurs in many body-in-whites during the vehicle durability test; through analysis of the body-in-white durability failure causes and fault rectification, it is found that the detailed and quantitative rigidity research on the joint part of the body-in-white is missing. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a rigidity evaluation and optimization method and system for a vehicle body joint, so as to provide a comprehensive and reliable structure optimization method for the key joint of the vehicle body, and thus the problems of insufficient rigidity or stress concentration in the vehicle body structure can be identified in advance in the early design stage of the vehicle, so as to shorten the development cycle and reduce the test cost.

[0006] According to the rigidity evaluation and optimization method for a vehicle body joint provided by the present application, the method comprises:

[0007] obtaining a vehicle type, and obtaining a plurality of design input conditions corresponding to the vehicle type according to the vehicle type, so as to construct a vehicle body finite element model corresponding to the vehicle type according to the plurality of design input conditions;

[0008] cutting a target joint model from the vehicle body finite element model according to a first preset size, the target joint model including a plurality of joint branches, locking a target joint branch from the target joint model and applying a preset load force to the target joint branch while other joint branches are constrained;

[0009] obtaining a stiffness value of the target joint branch and optimizing the target joint branch according to the stiffness value.

[0010] Further, the obtaining of the vehicle type and the obtaining of a plurality of design input conditions corresponding to the vehicle type to construct a vehicle body finite element model corresponding to the vehicle type according to the plurality of design input conditions comprises:

[0011] obtaining a vehicle design parameter and constructing a vehicle body three-dimensional model corresponding to the vehicle according to the vehicle design parameter;

[0012] extracting a middle surface from the vehicle body three-dimensional model and dividing the middle surface according to a preset grid size to obtain a vehicle body grid skeleton diagram.

[0013] Further, the step of extracting a middle surface from the vehicle body three-dimensional model and dividing the middle surface according to a preset grid size to obtain a vehicle body grid skeleton diagram further comprises:

[0014] obtaining material and size properties of each component part of the vehicle body and assigning each shell element in the vehicle body grid skeleton diagram according to the material and size properties of each component part;

[0015] assembling and welding each component part of the vehicle body according to a preset connection relationship of each component part to obtain a vehicle body finite element model, and performing modal analysis trial calculation on the vehicle body finite element model to verify the rationality of the vehicle body finite element model.

[0016] Further, the step of obtaining a stiffness value of the target joint branch and optimizing the target joint branch according to the stiffness value comprises:

[0017] determining whether the stiffness value of the target joint branch is greater than a preset stiffness threshold;

[0018] If the stiffness value is greater than the preset stiffness threshold, it is determined that the stiffness performance of the target joint branch is qualified, and another joint branch in the joint model is evaluated for stiffness performance.

[0019] Further, the step of determining whether the stiffness value of the target joint branch is greater than a preset stiffness threshold further comprises:

[0020] If the rigidity value is less than or equal to a preset rigidity threshold value, it is determined that the rigidity performance of the target joint branch is unqualified, and a DOE method is used to perform sensitivity analysis on the unqualified target joint branch to obtain contribution values corresponding to a plurality of influence parameters of the target joint branch respectively, the influence parameters including a plurality of size parameters and a plurality of thickness parameters.

[0021] Further, the step of obtaining the rigidity value of the target joint branch and optimizing the target joint branch according to the rigidity value further comprises:

[0022] According to the contribution value corresponding to each influence parameter, an influence parameter greater than a preset contribution threshold value is screened out, and the influence parameter greater than the preset contribution threshold value is marked as a target optimization parameter;

[0023] The target joint branch is optimized according to the target optimization parameter until the rigidity value of the target joint branch is greater than the preset rigidity threshold value.

[0024] Further, the step of performing modal analysis trial calculation on the body finite element model to verify the rationality of the body finite element model comprises:

[0025] The body finite element model after assembly welding is calculated by using a finite element program, and it is determined whether the calculation result exceeds the sixth order rigid body mode;

[0026] If the calculation result exceeds the sixth order rigid body mode, it is determined that the body finite element model after assembly welding is unreasonable.

[0027] Another aspect of the present application also provides a rigidity evaluation and optimization system for a vehicle body joint, the system comprising:

[0028] A body model construction module, and a plurality of design input conditions corresponding to the vehicle type are obtained according to the vehicle type, so as to construct a body finite element model corresponding to the vehicle type according to the plurality of design input conditions;

[0029] A rigidity test module for intercepting a target joint model from the body finite element model according to a first preset size, the target joint model including a plurality of joint branches, locking a target joint branch from the target joint model, and applying a preset load force to the target joint branch while constraining other joint branches;

[0030] A rigidity analysis and optimization module for obtaining a rigidity value of the target joint branch and optimizing the target joint branch according to the rigidity value.

[0031] Further, the body model construction module comprises:

[0032] A three-dimensional model construction unit is configured to acquire vehicle design parameters and construct a three-dimensional model of a vehicle body corresponding to the vehicle according to the vehicle design parameters.

[0033] An intermediate intercepting unit is configured to extract a median surface from the three-dimensional model of the vehicle body and divide the median surface according to a preset grid size to obtain a vehicle body grid skeleton diagram.

[0034] Further, the torque analysis module further comprises:

[0035] A vehicle body attribute defining unit is configured to acquire material and size attributes of each component of the vehicle body and assign each shell element in the vehicle body grid skeleton diagram according to the material and size attributes of each component.

[0036] A model analysis unit is configured to assemble and weld each component of the vehicle body according to a preset connection relationship of each component to obtain a vehicle body finite element model and perform modal analysis trial calculation on the vehicle body finite element model to verify the rationality of the vehicle body finite element model.

[0037] Compared with the prior art, the present application provides a brand-new vehicle body key joint structure optimization method, which can timely and effectively solve the problem of insufficient stiffness or stress concentration in the vehicle body structure in the early design stage. Specifically, first, a finite element model of the vehicle body is constructed according to a plurality of design conditions under the type of the vehicle, and a target joint model is intercepted from the vehicle body finite element model according to a preset size, and then a preset load force is applied to the target joint branch, and other joint branches are constrained to start the stiffness analysis test, so as to obtain the stiffness value of the target joint branch, and then the target joint branch is optimized according to the stiffness value, so as to identify the problem of insufficient stiffness or stress concentration in the vehicle body structure in advance in the early design stage of the vehicle, so as to shorten the development cycle and reduce the test cost.

[0038] Additional aspects and advantages of the application will be described in the following description, some of which will become apparent from the following description, some of which will be learned by practice of the embodiments of the application. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 A flowchart of the stiffness evaluation and optimization method of the automobile vehicle body joint for the first embodiment of the present application;

[0040] Figure 2 A flowchart of the stiffness evaluation and optimization method of the automobile vehicle body joint for the second embodiment of the present application;

[0041] Figure 3 A detailed diagram of step S106 in the second embodiment;

[0042] Figure 4 Fig. 2 is a schematic diagram illustrating the analysis of the influence parameters and the corresponding contribution amounts in the second embodiment;

[0043] Figure 5 Fig. 3 is a schematic diagram illustrating the structure of the stiffness evaluation and optimization system of the automobile body joint in the third embodiment of the present application.

[0044] The following detailed description will further describe the present application in combination with the above-mentioned drawings. DETAILED DESCRIPTION

[0045] In order to facilitate the understanding of the present application, the present application will be described more fully below in connection with the related drawings. The drawings show several embodiments of the present application. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0047] Referring to Fig. 1, which shows a flowchart of the stiffness evaluation and optimization method of the automobile body joint in the first embodiment of the present application, the method comprises steps S01 to S03, wherein: Figure 1

[0048] Step S01: Obtain the type of the whole vehicle, and obtain a plurality of design input conditions corresponding to the type of the whole vehicle according to the type of the whole vehicle, to construct a body finite element model corresponding to the type of the whole vehicle according to the plurality of design input conditions;

[0049] In the present embodiment, it should be noted that the input conditions generally include body size definition, man-machine hard point, arrangement scheme, system selection matching related to the body, attribute definition, and competitor vehicle model, etc. After the above input conditions are obtained, the construction of the body finite element model is completed.

[0050] Step S02: Cut a target joint model from the body finite element model according to a first preset size, the target joint model including a plurality of joint branches, lock a target joint branch from the target joint model, and apply a preset load force to the target joint branch while constraining other joint branches;

[0051] ​It should be noted that the first preset size generally refers to the sizes in X, Y and Z directions, and in this embodiment, the sizes in the three directions are 180mm, respectively, and the target joint model is contained in the finite element model of the vehicle body, and by adjusting the direction and size, the joint model of different parts can be obtained, and the preset load force is applied to the target joint branch, and the direction of the preset load force needs to be consistent with the test direction.

[0052] Step S03: obtaining the stiffness value of the target joint branch, and optimizing the target joint branch according to the stiffness value.

[0053] It should be noted that after the load force is applied, the torsion angle under the applied load force can be obtained, and the stiffness value can be obtained according to the ratio of the load force to the torsion angle, so as to complete the stiffness analysis and optimization of the target joint branch.

[0054] In summary, according to the stiffness evaluation and optimization method of the automobile body joint, the application provides a new vehicle body key joint structure optimization method, which can timely and effectively solve the problems of insufficient stiffness or stress concentration in the vehicle body structure in the early design stage. Specifically, first, a finite element model of the vehicle body is constructed according to a plurality of design conditions under the whole vehicle type, and a target joint model is obtained from the finite element model of the vehicle body according to a preset size, and then a preset load force is applied to the target joint branch, and other joint branches are constrained to start the stiffness analysis test, so as to obtain the stiffness value of the target joint branch, and then the target joint branch is optimized according to the stiffness value, so as to identify the problems of insufficient stiffness or stress concentration in the vehicle body structure in the early design stage of the automobile, so as to shorten the development cycle and reduce the test cost.

[0055] Please refer to Figure 2 , which is a flow chart of the stiffness evaluation and optimization method of the automobile body joint in the second embodiment of the application, and the method comprises steps S101 to S108, wherein:

[0056] Step S101: obtaining the whole vehicle design parameters, and constructing a three-dimensional model of the vehicle body corresponding to the whole vehicle according to the whole vehicle design parameters;

[0057] Specifically, in this step, a three-dimensional CAD model of the vehicle body is constructed according to the design input conditions, and after modeling, a file in *.step or *.igs format is exported.

[0058] Step S102: extracting the middle surface of the three-dimensional model of the vehicle body, and dividing the middle surface according to a preset grid size to obtain a vehicle grid skeleton diagram;

[0059] It should be noted that the established white body.step or.igs format geometry model file is imported into the nastran module of finite element pre-processing software Hypermesh, and the white body adopts sheet metal parts, so the method of extracting the middle surface is used instead of the entity, and then the thickness of each plate is defined according to the actual geometric size, which is better for the subsequent mesh division.

[0060] Further, since there may be gaps, overlaps or non-coincidence in the geometric vertex of the model, first, the geometry is cleaned, and then the middle surface is extracted.

[0061] Step S103: Obtain the material and size properties of each component of the vehicle body, and assign values to each shell element in the vehicle body mesh skeleton according to the material and size properties of each component;

[0062] Since the floor, ceiling, engine compartment, beam and other parts of the vehicle body are generally made of thin plate steel, the length is much larger than the thickness, so in this embodiment, plate shell elements are selected for modeling. In order to make the subsequent calculation file not too large, the specific assignment process is as follows: the 2D mesh of the white body is generally about 8mm in size. The aspect ratio is less than 5, the warping degree is less than 15 degrees, the minimum angle of the quadrilateral element is greater than 45 degrees, the maximum angle of the quadrilateral element is less than 135 degrees, the minimum angle of the triangular element is greater than 30 degrees, the maximum angle of the triangular element is less than 120 degrees, the skew degree is less than 60 degrees, and the Jacobian is greater than 0.7.

[0063] Then the assigned shell element is assigned with corresponding material and thickness properties. Material parameters include Young's modulus, Poisson's ratio and density, etc.

[0064] Step S104: Assemble and weld each component of the vehicle body according to the preset connection relationship of each component, obtain the vehicle body finite element model, and perform modal analysis trial calculation on the vehicle body finite element model to verify the rationality of the vehicle body finite element model;

[0065] It can be understood that after welding, the model needs to be checked, mainly to check the connectivity of the model and the quality of the model, and to perform modal analysis trial calculation and check the rationality of the modal analysis result, which is specifically:

[0066] Using a finite element program to calculate the vehicle body finite element model after assembly and welding, and determining whether the calculation result exceeds the sixth order rigid body mode;

[0067] If the calculation result exceeds the sixth order rigid body mode, it is determined that the vehicle body finite element model after assembly and welding is not reasonable, and if it is not reasonable, the welding points are checked and processed until the vehicle body finite element model after welding is reasonable.

[0068] Step S105: cutting a target joint model from the body finite element model according to a first preset size, the target joint model including a plurality of joint branches, locking a target joint branch from the target joint model, and applying a preset load force to the target joint branch while other joint branches are constrained;

[0069] Specifically, before the stiffness analysis, a cross section of all grid points connected by a rigid connecting element at the center points of each section (i.e., all inner plates on all cross sections are included) is created, all section units without load are fully constrained in all directions, and a unit load consistent with the tested direction is applied at the joint where the joint stiffness is to be tested.

[0070] Step S106: obtaining a stiffness value of the target joint branch, and optimizing the target joint branch according to the stiffness value;

[0071] Referring to Figure 3 , a detailed diagram of step S106 in the embodiment is shown, and the step S106 includes steps S1061 to S1065, wherein:

[0072] S1061: determining whether the stiffness value of the target joint branch is greater than a preset stiffness threshold;

[0073] S1062: if the stiffness value is greater than the preset stiffness threshold, determining that the stiffness performance of the target joint branch is qualified, and performing stiffness performance evaluation on another joint branch in the joint model;

[0074] S1063: if the stiffness value is less than or equal to the preset stiffness threshold, determining that the stiffness performance of the target joint branch is unqualified, and performing sensitivity analysis on the unqualified target joint branch by using a DOE method to obtain contribution values corresponding to a plurality of influence parameters of the target joint branch, the influence parameters including a plurality of size parameters and a plurality of thickness parameters;

[0075] S1064: screening an influence parameter greater than a preset contribution threshold according to the contribution value corresponding to each influence parameter, and marking the influence parameter greater than the preset contribution threshold as a target optimization parameter;

[0076] S1065: optimizing the target joint branch according to the target optimization parameter until the stiffness value of the target joint branch is greater than the preset stiffness threshold.

[0077] To ensure that joint stiffness meets specified requirements, it is necessary to perform a sensitivity analysis on the joints to identify the panels that play a decisive role in resolving joint stiffness and stress concentration issues. For key joints that do not meet design stiffness requirements, optimization is performed. A parametric SFE model of the body-in-white joint is created, and a joint stiffness sensitivity analysis is performed using the DOE method. Using the sensitivity analysis results, the panels that play a decisive role in joint stiffness and stress concentration are identified. Ultimately, these issues are resolved through joint structural optimization.

[0078] The DOE method is used to analyze the sensitivity of joint stiffness, which can effectively identify the main influencing parameters of joint stiffness. For example, but not limited to, the sensitivity study is conducted on the lower A-pillar joint of a certain car model. Figure 4 , which is a schematic diagram of the influencing parameters and the corresponding contribution. It is found that the section widths L1 and L2 have the largest contribution. A response surface is constructed based on the DOE analysis results. The genetic algorithm is used to find the optimal section parameters. See Table 1 below. The target joint branch is optimized according to the optimized target parameters, and then the stiffness analysis and optimization of a single joint branch are completed until all joint models and the joint models in each joint model have completed stiffness analysis and optimization.

[0079] Table 1

[0080] Design variable Initial value Lower limit Upper limit Optimized value Size variable L1 / mm 145 135 155 150 Size variable L2 / mm 131 121 146 145

[0081] In summary, according to the above-mentioned method for evaluating and optimizing the stiffness of automobile body joints, the stiffness analysis and optimization of key automobile body joints are carried out based on CAE technology and finite element method. First, the digital model of the vehicle body in white under the whole vehicle system is extracted; then the CAD model mesh is discretized into a finite element mesh model, and the thickness information and material properties of the material are actually defined; the joint is cut according to the preset size to analyze the finite element mesh model, and finally, according to the joint analysis specification requirements, the constraint boundary and the unit torque are applied to the cross-section center, and then the joint stiffness analysis and joint stiffness optimization analysis are performed, which provides a comprehensive and reliable structural optimization method for key joints of the vehicle body. In addition, the problem of insufficient stiffness or stress concentration in the vehicle body structure can be identified in advance in the early design stage of the vehicle, thereby shortening the development cycle and reducing the test cost.

[0082] See also Figure 5 , which is a schematic structural diagram of a vehicle body joint stiffness evaluation and optimization system according to a third embodiment of the present invention, the system comprises:

[0083] A vehicle body model building module 10 acquires a plurality of design input conditions corresponding to the vehicle type, so as to build a vehicle body finite element model corresponding to the vehicle type according to the plurality of design input conditions;

[0084] Further, the vehicle body model building module 10 comprises:

[0085] a three-dimensional model building unit configured to acquire vehicle design parameters and build a three-dimensional vehicle body model corresponding to the vehicle according to the vehicle design parameters;

[0086] an intermediate intercepting unit configured to extract a median surface from the three-dimensional vehicle body model and divide the median surface according to a preset grid size to obtain a vehicle body grid skeleton diagram;

[0087] a vehicle body attribute defining unit configured to acquire material and size attributes of each component part of the vehicle body and assign each shell element in the vehicle body grid skeleton diagram according to the material and size attributes of each component part;

[0088] a model analysis unit configured to assemble and weld each component part of the vehicle body according to a preset connection relationship of each component part to obtain a vehicle body finite element model and perform modal analysis trial calculation on the vehicle body finite element model to verify the rationality of the vehicle body finite element model;

[0089] Further, the model analysis unit further comprises:

[0090] a modal calculation sub-unit configured to calculate the vehicle body finite element model after assembly and welding using a finite element program and determine whether the calculation result exceeds the sixth order rigid body modal;

[0091] a modal analysis sub-unit configured to determine that the vehicle body finite element model after assembly and welding is not reasonable if the calculation result exceeds the sixth order rigid body modal.

[0092] a stiffness testing module 20 configured to intercept a target joint model from the vehicle body finite element model according to a first preset size, the target joint model comprising a plurality of joint branches, lock a target joint branch from the target joint model, and apply a preset load force to the target joint branch while constraining other joint branches;

[0093] a stiffness analysis and optimization module 30 configured to acquire a stiffness value of the target joint branch and optimize the target joint branch according to the stiffness value.

[0094] Further, the stiffness analysis and optimization module 30 further comprises:

[0095] a stiffness analysis unit configured to determine whether the stiffness value of the target joint branch is greater than a preset stiffness threshold;

[0096] a first stiffness performance determination unit configured to determine that the stiffness performance of the target joint branch is qualified if the stiffness value is greater than the preset stiffness threshold, and perform stiffness performance evaluation on another joint branch in the joint model.

[0097] The second rigidity performance determining unit is configured to determine that the rigidity performance of the target joint branch is unqualified if the rigidity value is less than or equal to the preset rigidity threshold value, and perform sensitivity analysis on the unqualified target joint branch by using a DOE method to obtain contribution values corresponding to a plurality of influence parameters of the target joint branch, wherein the influence parameters include a plurality of size parameters and a plurality of thickness parameters.

[0098] The target parameter obtaining unit is configured to filter out the influence parameters greater than the preset contribution threshold value according to the contribution values corresponding to each influence parameter, and mark the influence parameters greater than the preset contribution threshold value as target optimization parameters.

[0099] The rigidity performance optimizing unit is configured to optimize the target joint branch according to the target optimization parameters until the rigidity value of the target joint branch is greater than the preset rigidity threshold value.

[0100] In summary, according to the rigidity evaluation and optimization system of the automobile body joint described above, the CAE technology and the finite element method are used for the rigidity analysis and optimization of the key joint of the automobile body. First, the state number model of the body-in-white under the whole vehicle system is extracted. Then, the CAD model is discretized into a finite element grid model, the thickness information and material properties of the actual material are defined, and the joint is cut according to the preset size to analyze the finite element grid model. Finally, the constraint boundary and the unit torsion are loaded on the cross-section center according to the joint analysis specification, and the joint rigidity analysis and joint rigidity optimization analysis are performed. A comprehensive and reliable structure optimization method is provided for the key joint of the automobile body, which can identify the problems of insufficient rigidity or stress concentration in the automobile body structure in advance in the early design stage of the automobile, thereby shortening the development cycle and reducing the test cost.

[0101] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0102] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be noted that, for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. A method of assessing and optimizing the stiffness of a vehicle body joint, characterized in that, The method comprises: acquiring a whole vehicle type, and acquiring a plurality of corresponding design input conditions according to the whole vehicle type, to construct a body finite element model corresponding to the whole vehicle type according to the plurality of design input conditions, comprising: acquiring whole vehicle design parameters, and constructing a body three-dimensional model corresponding to the whole vehicle according to the whole vehicle design parameters, extracting a middle surface from the body three-dimensional model, and dividing the middle surface according to a preset grid size to obtain a body grid skeleton diagram, acquiring material and size attributes of each component part of the body, and assigning values to each shell element in the body grid skeleton diagram according to the material and size attributes of each component part, assembling and welding each component part of the body according to a preset connection relationship of each component part to obtain a body finite element model, and performing modal analysis trial calculation on the body finite element model to verify the rationality of the body finite element model, comprising: calculating the body finite element model after assembly and welding by using a finite element program, and determining whether the calculation result exceeds the sixth rigid body mode, if the calculation result exceeds the sixth rigid body mode, it is determined that the body finite element model after assembly and welding is not reasonable; cutting a target joint model from the body finite element model according to a first preset size, the target joint model including a plurality of joint branches, locking a target joint branch from the target joint model, and applying a preset load force to the target joint branch while constraining other joint branches; acquiring a stiffness value of the target joint branch, and optimizing the target joint branch according to the stiffness value.

2. The method of rigidity evaluation and optimization of automobile body joints according to claim 1, characterized in that, The step of acquiring the stiffness value of the target joint branch and optimizing the target joint branch according to the stiffness value comprises: determining whether the stiffness value of the target joint branch is greater than a preset stiffness threshold value; if the stiffness value is greater than the preset stiffness threshold value, it is determined that the stiffness performance of the target joint branch is qualified, and another joint branch in the joint model is evaluated for stiffness performance.

3. The method of rigidity evaluation and optimization of automobile body joints according to claim 2, characterized in that, The step of determining whether the stiffness value of the target joint branch is greater than a preset stiffness threshold value further comprises: if the stiffness value is less than or equal to the preset stiffness threshold value, it is determined that the stiffness performance of the target joint branch is unqualified, and a DOE method is used to perform sensitivity analysis on the unqualified target joint branch to obtain contribution values corresponding to a plurality of influence parameters of the target joint branch, the influence parameters including a plurality of size parameters and a plurality of thickness parameters.

4. The method of rigidity evaluation and optimization of automobile body joints according to claim 3, characterized in that, The step of acquiring the stiffness value of the target joint branch and optimizing the target joint branch according to the stiffness value further comprises: screening out influence parameters greater than a preset contribution threshold value according to the contribution value corresponding to each influence parameter, and marking the influence parameters greater than the preset contribution threshold value as target optimization parameters; optimizing the target joint branch according to the target optimization parameters until the stiffness value of the target joint branch is greater than the preset stiffness threshold value.

5. A system for the stiffness evaluation and optimization of a vehicle body joint, characterized by The system is used to implement the stiffness evaluation and optimization method of the automobile body joint according to any one of claims 1 to 4, and the system comprises: The body model construction module constructs a body finite element model corresponding to the vehicle type according to the design input conditions. The stiffness test module intercepts a target joint model from the body finite element model according to a first preset size, the target joint model including a plurality of joint branches, locks a target joint branch from the target joint model, and applies a preset load force to the target joint branch while constraining other joint branches. The stiffness analysis and optimization module obtains a stiffness value of the target joint branch and optimizes the target joint branch according to the stiffness value.

6. The system for the stiffness evaluation and optimization of automotive body joints according to claim 5, characterized in that, The body model construction module includes: A three-dimensional model construction unit that obtains vehicle design parameters and constructs a body three-dimensional model corresponding to the vehicle according to the vehicle design parameters. An intermediate interception unit that extracts a middle surface of the body three-dimensional model and divides the middle surface according to a preset grid size to obtain a body grid skeleton diagram.

7. The system for the stiffness evaluation and optimization of automotive body joints of claim 5, wherein, The body model construction module further includes: A body attribute definition unit that obtains material and size attributes of each component part of the body and assigns values to each shell element in the body grid skeleton diagram according to the material and size attributes of each component part. A model analysis unit that assembles and welds each component part of the body according to a preset connection relationship of each component part to obtain a body finite element model and performs modal analysis trial calculation on the body finite element model to verify the reasonableness of the body finite element model.

Images