A method and system for rapid visual assessment of vehicle body weld fatigue

Abstract

The application provides a kind of vehicle body welding point fatigue rapid evaluation visualization method and system, comprising: establishing point welding structure finite element model, and carrying out pre-processing operation to the model;Finite element solution is carried out to the model after pre-processing operation, and result file is obtained;Each welding point data is extracted based on the result file and the simplified structure stress range calculation is carried out;Based on the calculated simplified structure stress range, material main S-N curve, load fatigue load spectrum, calculate fatigue life data, evaluate the fatigue degree of vehicle body welding point;The calculation result is output in visualized way.

Description

Technical Field

[0001] This invention belongs to the field of simulation analysis technology, specifically relating to a visualization method and system for rapid fatigue assessment of vehicle body weld points. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] During the design and development of a vehicle body, fatigue analysis of the spot welded structures on the body is required. A typical vehicle body usually has tens of thousands of weld points. Modeling them and accurately predicting their fatigue life using numerical simulation is difficult and time-consuming. At the same time, the large number and complex arrangement of the weld points also make post-processing of simulation visualization very challenging.

[0004] In addition, due to the special nature of spot welded structures, there is currently no unified fatigue evaluation standard for spot welded structures, either domestically or internationally. Each OEM can only conduct limited fatigue test data and apply it according to the test standards during the vehicle body design stage, based on the combination of materials, plate thickness, and weld diameter, and thus cannot form a standardized industry standard.

[0005] To address the aforementioned issues, existing technologies include fatigue analysis of the spot-welded structure of the vehicle body based on the equivalent structural stress method. However, this method has the following drawbacks: when using the equivalent structural stress method, the spot-welded structure is modeled as an umbrella-shaped structure, resulting in a highly complex model. If tens of thousands of weld points are modeled using this method, the entire vehicle model will become excessively large, significantly increasing computation and design time costs. Furthermore, the principle of the equivalent structural stress method is very complex, making it difficult to develop computational software based on this method.

[0006] Another approach involves fatigue analysis of the spot-welded structure of the vehicle body based on the load-life method. In the post-processing stage, secondary development technology is used to output a weld utilization cloud map, achieving the goal of visualizing the preliminary calculation results. However, this method has the following drawbacks: fatigue analysis using the load-life method heavily relies on fatigue test data, requiring a large amount of data support. Each fatigue test often involves millions or tens of millions of cycles, and the combinations of different plate thicknesses and weld nugget diameters are numerous. This limits the number of fatigue tests that OEMs can conduct, significantly impacting the accuracy of the fatigue analysis. Limited data also forces designers to passively optimize the structure based on existing fatigue test data, greatly restricting the scope of optimization. Furthermore, theoretically, the load-life method simply evaluates the fatigue strength of the weld by judging whether the minimum shear force of the weld is less than the minimum shear force obtained from the fatigue test. This is not rigorous enough, as the mechanical factors affecting the fatigue strength of spot-welded structures are far more numerous. Therefore, this method cannot form a convincing and unified standard for evaluating fatigue strength. Meanwhile, its visualization processing is relatively simple, only outputting a simple solder joint utilization cloud map, without directly calculating and outputting direct and key result data such as solder joint fatigue life and cumulative damage. Summary of the Invention

[0007] To address the aforementioned problems, this invention proposes a visual method for rapid fatigue assessment of vehicle body weld points, which can significantly shorten simulation calculation time.

[0008] According to some embodiments, the present invention adopts the following technical solution:

[0009] Firstly, a visual method for rapid fatigue assessment of vehicle body weld points is disclosed, including:

[0010] A finite element model of the spot weld structure is established, and preprocessing operations are performed on the model.

[0011] The model after preprocessing is solved using the finite element method to obtain the result file.

[0012] Data for each weld point is extracted from the results file, and a simplified structural stress range calculation is performed.

[0013] Based on the simplified structural stress range and material master SN curve calculated by calculation, fatigue load spectrum is applied, fatigue life data is calculated, and the fatigue degree of vehicle body weld points is evaluated.

[0014] The calculation results are output in a visual format.

[0015] As a further technical solution, a finite element model of the spot weld structure is established, and preprocessing operations are performed on this model, specifically:

[0016] The vehicle body model is subjected to mid-surface extraction and unnecessary chamfer removal to establish conditions for subsequent mesh generation;

[0017] The vehicle body in the model is automatically meshed, and weld points are automatically created according to the one-to-one correspondence principle of mesh nodes.

[0018] Then, by reading the geometric thickness and material information of the vehicle body structural components, the subsystem to which the component belongs is determined, and it is named according to the standard format;

[0019] Create weld points with different weld nugget diameters in batches and define dangerous weld points;

[0020] Finally, the vehicle body model is output as a finite element .cdb file and a .inp file recording weld point information, respectively, thus completing the preprocessing stage.

[0021] As a further technical solution, the model after preprocessing is solved using the finite element method to obtain the result file, including:

[0022] Import the CDB file of the vehicle body finite element model into the software for solution calculation. After the calculation is completed, the finite element result file will be automatically generated.

[0023] As a further technical solution, data for each weld point is extracted based on the result file: the node and unit number information corresponding to the spot weld structure is extracted, and then the nodal force and nodal moment of the spot weld structure of the vehicle body are extracted using a simplified structural stress calculation program. After that, the structural stress range value is calculated based on the simplified structural stress method.

[0024] As a further technical solution, a simplified calculation of the structural stress range is performed, specifically including:

[0025] Assuming that the force within the plate is uniformly applied to half of the weld edge, calculate the maximum membrane structure stress at the weld nugget edge;

[0026] To calculate bending stress, the maximum component of the bending moment can be used;

[0027] Calculate the maximum stress in a typical structure;

[0028] Calculate the membrane components of the in-plane and transverse shear stress at the edge of the weld nugget within the plate. The in-plane shear stress membrane component is obtained through torsional moment calculation; the transverse shear stress membrane component can be calculated using F. z Calculate with M;

[0029] Define the structural stress range, simplify the in-plane shear stress range, and simplify the transverse shear stress range;

[0030] The final simplified structural stress range is obtained based on the structural stress range, the simplified in-plane shear stress range, and the simplified transverse shear stress range.

[0031] As a further technical solution, the assessment of the fatigue level of the vehicle body weld points specifically includes:

[0032] After solving for the simplified stress range of the spot welded structure, fatigue life is predicted using the main SN curve of the steel. Finally, the cumulative fatigue damage ratio of the spot welded structure is calculated based on Miner's linear cumulative fatigue damage theory. If the cumulative damage ratio is less than 1, the fatigue life of the spot welded structure is considered to meet the design requirements.

[0033] As a further technical solution, the calculation results can be output in a visual manner, including:

[0034] Construct a finite element mesh model of the vehicle body from the results file and reproduce it in a graphics library;

[0035] Then, based on the mesh information in the inp and rst files, the original element numbers, node numbers, and coordinate information are mapped to the finite element mesh model.

[0036] Then, the vertices of the defined finite element mesh are colored according to the fatigue analysis data. Next, the color of each vertex is interpolated using the interpolation method to obtain the RGBA value of the color of any point in the mesh, so that the cell is smoothly colored. Finally, a color cloud map is output.

[0037] The simplified structural stress range, fatigue life cycles, and cumulative fatigue damage values ​​of the spot-welded structure are plotted on the visualized finite element model using cloud maps.

[0038] Using the "converting points into lines" method to visualize weld fatigue data, the stress-distance diagram along the starting weld point of the evaluated weld is output.

[0039] Secondly, a visual system for rapid fatigue assessment of vehicle body weld points is disclosed, including:

[0040] The model building module is configured to: build a finite element model of the spot weld structure and perform preprocessing operations on the model;

[0041] The solver module is configured to perform finite element analysis on the preprocessed model and obtain the result file.

[0042] The calculation module is configured to extract data from each weld point based on the result file and perform simplified structural stress range calculation.

[0043] The evaluation module is configured to: calculate the simplified structural stress range and material master SN curve based on calculations, apply fatigue load spectrum, calculate fatigue life data, and evaluate the fatigue degree of vehicle body weld points;

[0044] The output module is configured to output the calculation results in a visual manner.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] The spot welding model of this invention can be simulated using only Beam single beam elements, without the need to construct a complex umbrella-shaped structure, which greatly shortens the simulation calculation time from a modeling theory perspective.

[0047] This invention comprehensively considers the axial and tangential shear forces and bending moments acting on the weld joint, and decomposes these stress conditions into membrane stress and bending stress, resulting in more accurate, rigorous and convincing predictions.

[0048] This invention utilizes Python to perform secondary development on finite element software, significantly reducing preprocessing time.

[0049] This invention can fit limited fatigue data into an SN curve, and use this curve to predict the fatigue life of spot welded structures under all conditions. This is equivalent to having almost unlimited experimental data, so it has universality and can well form an industry standard. At the same time, it also removes the limitation that the lack of experimental data previously made subsequent optimization difficult.

[0050] The calculation process of this invention is easier to implement in a computer program than the complex equivalent structural stress method theory, which helps designers to program and develop it.

[0051] This invention, based on the Python language, can directly output a fatigue life cumulative damage (cumulative damage = fatigue life / number of cycles) cloud map during the post-processing stage, making the simulation report more convincing.

[0052] This invention proposes a "point-to-line" visualization method for solder joint data, which outputs a stress-distance diagram along the starting solder joint of the evaluated solder joint. This effectively reflects the stress concentration phenomenon and related mechanical properties in the solder joint area, which helps designers to focus on optimization in the future.

[0053] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

[0054] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0055] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0056] Figure 1 This is a flowchart of the overall subsystem of an embodiment of the present invention;

[0057] Figure 2 This is a schematic diagram of the finite element model of the sub-spot welding structure in an embodiment of the present invention;

[0058] Figure 3 This is a schematic diagram of the sub-rst file reading process according to an embodiment of the present invention;

[0059] Figure 4 This is a simplified structural stress principle model diagram of an embodiment of the present invention;

[0060] Figure 5 This is a flowchart illustrating the sub-calculation process of an embodiment of the present invention;

[0061] Figure 6 This is a visualization flowchart of the post-processing of an embodiment of the present invention;

[0062] Figure 7 This is a fatigue damage cloud diagram of the vehicle body in an embodiment of the present invention;

[0063] Figure 8 This is a schematic diagram of the solder joints evaluated in an embodiment of the present invention;

[0064] Figure 9 This is a line graph showing the stress range of the simplified structure of the sub-weld joint in an embodiment of the present invention. Detailed implementation method:

[0065] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0066] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0067] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0068] Example 1:

[0069] In this embodiment, a subway car body is used as an example, but this does not mean that the rapid fatigue assessment visualization method for car body weld points provided by this invention is only applicable to the assessment visualization of subway car bodies. It can also be applied to the assessment of other car bodies depending on the assessment object.

[0070] This embodiment discloses a method for rapid visual assessment of fatigue at vehicle body weld points, including:

[0071] Step 1: This step uses the Python programming language to perform secondary development on the Hypermesh software. The finite element model of the spot welding structure is simulated using Beam188 beam elements. The carrier for the spot welding is the vehicle body. Specific model diagrams are attached. Figure 2 As shown.

[0072] First, a secondary development program is used to extract mid-surfaces and clean up unnecessary chamfers on the vehicle body model, establishing the conditions for subsequent mesh generation. Then, the vehicle body model is automatically meshed, and weld points are automatically created according to the one-to-one correspondence principle of mesh nodes. Next, by reading the geometric thickness and material information of the vehicle body structural components, the subsystem to which the component belongs (such as end walls, side walls, etc.) is determined, and it is named according to the standard format of "subsystem_component number_thickness_material". Then, weld points with different weld nugget diameters are created in batches according to design requirements. When defining dangerous weld points, a specific naming method is used: weld_i_n and weld_i_e to define node positions and elements, and they are grouped into sets. Finally, the vehicle body model is output as a finite element .cdb file and a .inp file recording weld point information, concluding the preprocessing stage.

[0073] Step Two: This step involves fatigue analysis of the spot-welded structure of the vehicle body based on the simplified structural stress method combined with the master SN curve of stainless steel material, as detailed below:

[0074] 2.1: Import the vehicle body finite element model cdb file into Ansys software for solution calculation. After the calculation is completed, the finite element result rst file will be automatically generated.

[0075] 2.2: The overall attribute information of the finite element model under study, including the total number of nodes and elements, is obtained by reading the cdb file. The inp file is a character-based data file based on the Pythton programming language, and the solver is Abaqus software. The file can be opened as a text file with Notepad and stores the node element location information of the spot weld structure to be analyzed. By reading the inp file, the location information of the weld nodes and surrounding elements can be obtained. The calculation date, machine identifier, file length, and other attribute information of the file are obtained by reading the header of the rst file. The process of reading the rst file is shown in the attached figure. Figure 3 As shown.

[0076] Based on this, the node and unit number information corresponding to the spot welded structure can be extracted. Then, using a simplified structural stress calculation program (implementing a simplified structural stress method), the nodal forces Fx, Fy, Fz and nodal moments Mx, My, Mz of the vehicle body spot welded structure can be extracted. Afterwards, the structural stress range value is calculated based on the simplified structural stress method. The principle diagram of the simplified structural stress method is attached. Figure 4 As shown:

[0077] The entire finite element calculation process is specifically divided into the following contents:

[0078] 2.2.1: First, calculate the membrane stress. This invention assumes that the force within the plate acts uniformly on half of the weld edge. Therefore, the maximum membrane stress at the weld nugget edge is:

[0079]

[0080] Where t is the thickness of the plate and d is the diameter of the weld nugget.

[0081] 2.2.2: Next, calculate the bending stress; the maximum component of the bending moment can then be used:

[0082]

[0083] Since there is a force Fz perpendicular to the plate plane, the maximum bending component of the structural stress of the rigid support bending at the weld nugget edge in the plate can be calculated using the following formula:

[0084]

[0085] t is the plate thickness, which is directly equal to 1.744 times the value.

[0086] 2.2.3: The maximum normal structural stress can then be calculated using the following formula:

[0087]

[0088] σ b =σ bm +σ bF,max .

[0089] 2.2.4: Next, calculate the membrane components of the in-plane and transverse shear stresses at the edge of the weld nugget within the plate. The former can be calculated using the torsional moment M. z Conclusion:

[0090]

[0091] The membrane component resisting transverse shear stress can be represented by F. z Calculate with M:

[0092]

[0093] 2.2.5: Equivalent structural stress range (ΔS) s ) is defined as:

[0094]

[0095] Δσ s This refers to the range of structural stress.

[0096] Similarly, simplify the in-plane shear stress range (ΔT) s ) and simplified transverse shear stress range (ΔT) Z It can be defined as:

[0097]

[0098] and It is a dimensionless polynomial function of the bending ratio r (under load control conditions), thus ultimately simplifying the structural stress range (ΔS). e The definition of ) is:

[0099]

[0100] The above is a simplified calculation process for the structural stress method.

[0101] 2.3: Fatigue life of spot-welded structures obtained based on the main SN curve

[0102] After solving for the simplified stress range of the spot-welded structure, the obtained values ​​can be substituted into the SN curve to calculate the fatigue life. This involves using the main SN curve of the steel for fatigue life prediction. Finally, the cumulative fatigue damage ratio of the spot-welded structure is calculated based on Miner's linear cumulative fatigue damage theory. The calculation formula for this part is existing technology and will not be elaborated here. If the cumulative damage ratio is less than 1, the fatigue life of the spot-welded structure is considered to meet the design requirements and can withstand ten million cycles of fatigue load. This calculation process can be solved using a computer program written in Python. The specific flowchart is attached. Figure 5 As shown.

[0103] Step 3: This step uses Python and open-source computer graphics engines (such as OpenGL or DirectX) and graphical interface development libraries like QT for post-processing visualization development, as detailed below:

[0104] First, a finite element mesh model of the vehicle body is constructed from the results file and reproduced in a graphics library. Then, based on the mesh information in the .inp and .rst files, the original element numbers, node numbers, and coordinates are mapped to the finite element mesh model. Next, the vertices of the defined finite element mesh are colored according to the fatigue analysis data. Then, interpolation is used to calculate the color of each vertex, thereby obtaining the RGBA value of the color at any point within the mesh, resulting in smooth coloring within each cell. Finally, a color contour map is output. Detailed processing steps are attached. Figure 6 As shown.

[0105] The final result is that the simplified structural stress range, fatigue life cycles, and cumulative fatigue damage values ​​of the spot-welded structure are plotted as cloud maps on the visualized finite element model. The cumulative fatigue damage cloud map is attached. Figure 7 As shown:

[0106] Using the "converting points into lines" method to visualize weld fatigue data, the stress-distance graph along the starting weld point of the evaluated weld point is output. The vertical axis of the graph is the stress, and the horizontal axis is the distance along the starting weld point.

[0107] With attachment Figure 7 Taking the cloud diagram as an example, the maximum cumulative fatigue damage ratio of the spot-welded structure of the vehicle body under the third working condition is 0.106, which is less than 1 specified in Miner's linear fatigue cumulative damage theory. Therefore, it is believed that the fatigue strength of the stainless steel spot-welded vehicle body meets the service requirement of being able to withstand ten million cycles of load without fatigue failure.

[0108] This invention can also derive a simplified structural stress range of the evaluated weld joint—a distance diagram along the starting weld joint, as shown in the attached diagram. Figure 8 As shown in the attached graph, the output curve is as follows. Figure 9 As shown:

[0109] The stress curve at this weld point shows a sharp abrupt change around the middle, indicating a significant stress gradient at this location. This can be found in the model as a node, which corresponds to a base frame beam, causing the sudden change in stress. This perfectly matches the result and proves that the simplified stress visualization method of "converting points into lines" can effectively reflect the stress concentration phenomenon and related characteristics in the weld point area.

[0110] This data can also be exported to Excel and Word files, which makes it easier for designers to process the data further and write simulation analysis reports.

[0111] This embodiment uses Python to integrate and develop multiple finite element analysis software programs, significantly saving development time and reducing development difficulty. It comprehensively considers axial and tangential shear forces and bending moments acting on the weld joint, decomposing these stress conditions into membrane stress and bending stress, resulting in more accurate and rigorous predictions. Limited fatigue data can be fitted into a single SN curve, which has universal applicability in predicting the fatigue life of spot-welded structures under all conditions, and can well form an industry standard. In the post-processing stage, a cumulative damage cloud map of fatigue life can be directly output.

[0112] This embodiment proposes a "point-to-line" visualization method for solder joint data, which outputs a stress-distance diagram along the starting solder joint of the evaluated solder joint, effectively reflecting the stress concentration phenomenon and related mechanical properties in the solder joint area.

[0113] The fatigue assessment system for spot welded structures developed in this embodiment can be used not only in the design of rail transit vehicle bodies, but also in other engineering fields such as fatigue-resistant design of spot welds for automotive body-in-white.

[0114] Example 2:

[0115] Based on the method in Embodiment 1, a visual system for rapid fatigue assessment of vehicle body weld points is disclosed, comprising:

[0116] The model building module is configured to: build a finite element model of the spot weld structure and perform preprocessing operations on the model;

[0117] The solver module is configured to perform finite element analysis on the preprocessed model and obtain the result file.

[0118] The calculation module is configured to extract data from each weld point based on the result file and perform simplified structural stress range calculation.

[0119] The evaluation module is configured to: calculate the simplified structural stress range and material master SN curve based on calculations, apply fatigue load spectrum, calculate fatigue life data, and evaluate the fatigue degree of vehicle body weld points;

[0120] The output module is configured to output the calculation results in a visual manner.

[0121] This embodiment of the sub-technical solution can significantly reduce the time cost of finite element simulation in the vehicle body structure design process. Furthermore, the fatigue analysis method used is universal, easily forming industry analysis standards, and the calculation results are highly visualized, significantly improving the design efficiency of stainless steel spot-welded vehicle bodies. It effectively solves the problems of slow pre-processing modeling, complex calculation processes, cumbersome post-processing, and the inability to visualize calculation results for numerous weld points in the vehicle body product design process due to the presence of tens of thousands of weld points.

[0122] Example 3:

[0123] The purpose of this embodiment is to provide a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the above-described method.

[0124] Example 4

[0125] The purpose of this embodiment is to provide a computer-readable storage medium.

[0126] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the steps of the above method.

[0127] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0128] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0129] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0130] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0131] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0132] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A visual method for rapid fatigue assessment of vehicle body weld points, characterized in that, include: A finite element model of the spot weld structure is established, and preprocessing operations are performed on the model, specifically: The preprocessing stage involves extracting mid-surfaces and removing redundant chamfers from the vehicle model to prepare for subsequent mesh generation. Automatic mesh generation is then performed on the vehicle body, and weld points are automatically created based on a one-to-one correspondence between mesh nodes. Next, the geometric thickness and material information of the vehicle body structural components are read to determine the subsystem to which the component belongs, and it is named according to a standard format. Weld points with different weld nugget diameters are created in batches, and critical weld points are defined. Finally, the vehicle model is output as a finite element .cdb file and a .inp file recording weld point information, concluding the preprocessing stage. The model after preprocessing is solved using the finite element method to obtain the result file. Based on the results file, data for each weld point is extracted and simplified structural stress range calculations are performed. Specifically, this includes: assuming the force within the plate acts uniformly on half of the weld edge, calculating the maximum membrane stress at the weld nugget edge; calculating bending stress, which can be done using the maximum component of the bending moment; calculating the maximum general structural stress; calculating the membrane components of the in-plane and transverse shear stress at the weld nugget edge within the plate, where the in-plane shear stress membrane component is obtained through torsional moment calculation; and the transverse shear stress membrane component can be obtained using... and Perform calculations; define the structural stress range, the simplified in-plane shear stress range, and the simplified transverse shear stress range; based on the structural stress range, the simplified in-plane shear stress range, and the simplified transverse shear stress range, obtain the final simplified structural stress range; Based on the simplified structural stress range and material master SN curve calculated by calculation, fatigue load spectrum is applied, fatigue life data is calculated, and the fatigue degree of vehicle body weld points is evaluated. The calculation results are output in a visual format.

2. The visual method for rapid fatigue assessment of vehicle body weld points as described in claim 1, characterized in that, The model after preprocessing is solved using the finite element method to obtain the result file, which includes: Import the CDB file of the vehicle body finite element model into the software for solution calculation. After the calculation is completed, the finite element result file will be automatically generated.

3. The visual method for rapid fatigue assessment of vehicle body weld points as described in claim 1, characterized in that, Data for each weld point is extracted from the result file: the node and unit number information corresponding to the spot weld structure is extracted, and then the nodal force and nodal moment of the spot weld structure of the vehicle body are extracted using a simplified structural stress calculation program. After that, the structural stress range value is calculated based on the simplified structural stress method.

4. The visual method for rapid fatigue assessment of vehicle body weld points as described in claim 1, characterized in that, The assessment of fatigue level at vehicle body weld points specifically includes: After solving for the simplified stress range of the spot welded structure, fatigue life is predicted using the main SN curve of the steel. Finally, the cumulative fatigue damage ratio of the spot welded structure is calculated based on Miner's linear cumulative fatigue damage theory. If the cumulative damage ratio is less than 1, the fatigue life of the spot welded structure is considered to meet the design requirements.

5. The visual method for rapid fatigue assessment of vehicle body weld points as described in claim 1, characterized in that, The calculation results will be output in a visual format, including: Construct a finite element mesh model of the vehicle body from the results file and reproduce it in a graphics library; Then, based on the mesh information in the inp and rst files, the original element numbers, node numbers, and coordinate information are mapped to the finite element mesh model. Then, the vertices of the defined finite element mesh are colored according to the fatigue analysis data. Next, the color of each vertex is interpolated using the interpolation method to obtain the RGBA value of the color of any point in the mesh, so that the cell is smoothly colored. Finally, a color cloud map is output. The simplified structural stress range, fatigue life cycles, and cumulative fatigue damage values ​​of the spot-welded structure are plotted on the visualized finite element model using cloud maps. Using the "converting points into lines" method to visualize weld fatigue data, the stress-distance diagram along the starting weld point of the evaluated weld is output.

6. A visual system for rapid fatigue assessment of vehicle body weld points, characterized in that, include: The model building module is configured to: build a finite element model of the spot weld structure and perform preprocessing operations on the model, specifically: The preprocessing stage involves extracting mid-surfaces and removing redundant chamfers from the vehicle model to prepare for subsequent mesh generation. Automatic mesh generation is then performed on the vehicle body, and weld points are automatically created based on a one-to-one correspondence between mesh nodes. Next, the geometric thickness and material information of the vehicle body structural components are read to determine the subsystem to which the component belongs, and it is named according to a standard format. Weld points with different weld nugget diameters are created in batches, and critical weld points are defined. Finally, the vehicle model is output as a finite element .cdb file and a .inp file recording weld point information, concluding the preprocessing stage. The solver module is configured to perform finite element analysis on the preprocessed model and obtain the result file. The calculation module is configured to: extract data from each weld point based on the result file and perform simplified structural stress range calculations, specifically including: assuming the force within the plate acts uniformly on half of the weld edge, calculating the maximum membrane stress at the weld nugget edge; calculating bending stress, i.e., using the maximum component of the bending moment; calculating the maximum general structural stress; calculating the membrane components of the in-plane and transverse shear stress at the weld nugget edge within the plate, wherein the membrane component of the in-plane shear stress at the weld nugget edge within the plate is obtained through torsional moment calculation; the membrane component of the transverse shear stress can be obtained using... and Perform calculations; define the structural stress range, the simplified in-plane shear stress range, and the simplified transverse shear stress range; based on the structural stress range, the simplified in-plane shear stress range, and the simplified transverse shear stress range, obtain the final simplified structural stress range; The evaluation module is configured to: calculate the simplified structural stress range and material master SN curve based on calculations, apply fatigue load spectrum, calculate fatigue life data, and evaluate the fatigue degree of vehicle body weld points; The output module is configured to output the calculation results in a visual manner.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method described in any one of claims 1-5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it performs the steps of the method described in any one of claims 1-5 above.

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