Method and device for simulating buckling instability of vehicle outer cover

Abstract

This application relates to the field of vehicle simulation technology, and particularly to a method and apparatus for simulating the compressive instability of vehicle exterior panels. The method includes: performing finite element modeling of the body-in-white to obtain a body-in-white model; dividing the exterior panel into multiple regions and assigning different thickness attributes to each region to obtain a target body-in-white model; applying constraints to the target body-in-white model to obtain a first target body-in-white model, and setting a pressure head on the exterior panel in the first target body-in-white model; establishing a surface-to-surface contact pair between the pressure head in the first target body-in-white model and the exterior panel to obtain a second target body-in-white model; and controlling the displacement of the pressure head based on the second target body-in-white model to perform compressive instability analysis on the exterior panel to generate compressive instability analysis results. This method can quickly and accurately assess the compressive instability of passenger vehicle exterior panels through preliminary simulation, reducing the risk of compressive instability on the sheet metal surface of passenger vehicle exterior panels.

Description

Technical Field

[0001] This application relates to the field of vehicle simulation technology, and in particular to a method and apparatus for simulating the pressure instability of vehicle exterior panels. Background Technology

[0002] For passenger car exterior panels, during use or when purchasing a car, there may be situations where the palm is pressed on the exterior panel. Because the sheet metal is relatively thin, it is easy for buckling instability to occur. When buckling instability occurs, it will make a "crackling" sound, which will affect the user's experience.

[0003] In related technologies, there is currently limited research on buckling instability of passenger car bodies. Only the snow-load buckling of the roof has been studied. For example, the paper "Analysis and Optimization Study of Snow-Load Buckling Performance of a Certain SUV (Sport Utility Vehicle) Roof" uses nonlinear buckling to calibrate snow-load buckling instability through simulation and experiments, and optimizes the vehicle body structure. However, in related technologies, the load of the above method is a uniformly distributed load of snow pressure, which is directly applied to the model nodes. It is relatively easy to implement, but the application scenarios are also relatively limited. Summary of the Invention

[0004] This application provides a method and apparatus for simulating the pressure instability of vehicle exterior panels. It can quickly and accurately assess the pressure instability of passenger vehicle panels by setting pre-simulation conditions such as contact relationships and constraints, thereby reducing the risk of pressure instability on the sheet metal surface of passenger vehicle exterior panels and improving the success rate of subsequent real vehicle pressure instability tests.

[0005] The first aspect of this application provides a simulation method for the pressure instability of a vehicle exterior panel, comprising the following steps: performing finite element modeling of the vehicle body-in-white to obtain a body-in-white model; based on preset stamping simulation results of the exterior panel, dividing the exterior panel in the body-in-white model into multiple regions, and assigning different thickness attributes to each region to obtain a target body-in-white model; applying constraints to the target body-in-white model to obtain a first target body-in-white model, and setting a pressure head on the exterior panel in the first target body-in-white model; establishing a surface-to-surface contact pair between the pressure head and the exterior panel in the first target body-in-white model to obtain a second target body-in-white model; and performing displacement control on the pressure head based on the second target body-in-white model to perform pressure instability analysis on the exterior panel to generate pressure instability analysis results.

[0006] Optionally, in one embodiment of this application, the step of performing finite element modeling of the vehicle's body-in-white to obtain a body-in-white model includes: acquiring the sheet metal geometric data of the vehicle's body-in-white; acquiring the neutral surface of the body-in-white based on the sheet metal geometric data, and meshing the neutral surface to obtain an initial body-in-white model; assigning attributes to the initial body-in-white model and performing modal analysis; and truncating the initial body-in-white model according to the results of the modal analysis to obtain the body-in-white model.

[0007] Optionally, in one embodiment of this application, the initial body-in-white model includes a weld point model and an adhesive model, wherein the weld point model is modeled using ACM solid element simulation, and the adhesive model is modeled using hexahedral elements.

[0008] Optionally, in one embodiment of this application, applying constraints to the target body-in-white model includes: constraining the degrees of freedom of rigid elements at multiple hard points of the subframe and cross-section of the target body-in-white model, wherein the cross-section is connected by rigid elements, and the multiple hard points of the subframe are connected to the body by rigid elements. A nonlinear stress-strain curve is applied to the surface of the outer body panels in the target body-in-white model, wherein the nonlinear stress-strain curve is obtained through relevant experimental testing.

[0009] Optionally, in one embodiment of this application, establishing a surface-to-surface contact pair between the pressure head and the outer cover in the first target body-in-white model includes: establishing a local coordinate system along the normal at the center point of the pressure head, and establishing a surface-to-surface contact pair between the pressure head and the outer cover based on the local coordinate system, wherein the pressure head is the master surface and the outer cover is the slave surface.

[0010] Optionally, in one embodiment of this application, the displacement control of the indenter based on the second target body-in-white model includes: gradually applying a load to the indenter based on a preset load application strategy to cause the indenter to displace, wherein the load is a forced displacement along the normal direction of the indenter in the local coordinate system.

[0011] Optionally, in one embodiment of this application, the method further includes: solving the pressure instability analysis results to obtain the displacement and load curves of the outer covering, and differentiating the displacement and load curves to obtain the derivative curves; in response to the minimum value of the derivative curve being less than or equal to a preset derivative curve threshold, performing structural optimization on the body-in-white corresponding to the target body-in-white model based on the pressure instability analysis results.

[0012] A second aspect of this application provides a simulation device for the pressure instability of a vehicle exterior panel, comprising: a modeling module for performing finite element modeling of the vehicle body-in-white to obtain a body-in-white model; a partitioning module for dividing the exterior panel in the body-in-white model into multiple regions based on preset stamping simulation results, and assigning different thickness attributes to each region to obtain a target body-in-white model; a constraint module for applying constraint conditions to the target body-in-white model to obtain a first target body-in-white model, and setting a pressure head on the exterior panel in the first target body-in-white model; a processing module for establishing a surface-to-surface contact pair between the pressure head and the exterior panel in the first target body-in-white model to obtain a second target body-in-white model; and an analysis module for performing displacement control of the pressure head based on the second target body-in-white model to perform pressure instability analysis on the exterior panel to generate pressure instability analysis results.

[0013] Optionally, in one embodiment of this application, the modeling module includes: an acquisition unit for acquiring the geometric data of the body-in-white sheet metal of the vehicle; a partitioning unit for acquiring the neutral surface of the body-in-white based on the geometric data of the body-in-white sheet metal, and performing mesh partitioning on the neutral surface to obtain an initial body-in-white model; and an analysis unit for assigning attributes to the initial body-in-white model and performing modal analysis, and for truncating the initial body-in-white model according to the results of the modal analysis to obtain the body-in-white model.

[0014] Optionally, in one embodiment of this application, the initial body-in-white model includes a weld point model and an adhesive model, wherein the weld point model is modeled using ACM solid element simulation, and the adhesive model is modeled using hexahedral elements.

[0015] Optionally, in one embodiment of this application, the constraint module includes: a constraint unit for constraining the degrees of freedom of rigid elements at multiple hard points of the cross-section and subframe in the target body-in-white model, wherein the cross-section is connected by rigid elements, and the multiple hard points of the subframe are connected to the body by rigid elements; and an assignment unit for assigning a nonlinear stress-strain curve to the surface of the outer covering in the target body-in-white model, wherein the nonlinear stress-strain curve is obtained through relevant experimental testing.

[0016] Optionally, in one embodiment of this application, the processing module includes: a construction unit, configured to establish a local coordinate system along the normal direction at the center point of the pressure head, and establish a surface-to-surface contact pair between the pressure head and the outer cover based on the local coordinate system, wherein the pressure head is the master surface and the outer cover is the slave surface.

[0017] Optionally, in one embodiment of this application, the analysis module includes: an application unit, configured to gradually apply a load to the indenter using a preset load application strategy to cause displacement of the indenter, wherein the load is a forced displacement along the normal direction of the indenter in the local coordinate system.

[0018] Optionally, in one embodiment of this application, the device further includes: a solution module, configured to solve the compression instability analysis results to obtain the displacement and load curves of the outer cover, and to differentiate the displacement and load curves to obtain a derivative curve; and an optimization module, configured to perform structural optimization on the body-in-white corresponding to the target body-in-white model based on the compression instability analysis results, in response to the minimum value of the derivative curve being less than or equal to a preset derivative curve threshold.

[0019] A third aspect of this application provides an electronic 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 pressure instability simulation method for vehicle exterior panels as described in the above embodiments.

[0020] A fourth aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for simulating the pressure instability of a vehicle exterior panel.

[0021] Additional aspects and advantages of this application 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 this application. Attached Figure Description

[0022] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a flowchart of a simulation method for pressure instability of a vehicle exterior panel according to an embodiment of this application; Figure 2 This is a schematic diagram of partition modeling based on stamping simulation results according to a specific embodiment of this application; Figure 3 This is a schematic diagram of the surface stiffness of the outer cover and the simulation constraint position of the pressure instability according to a specific embodiment of this application; Figure 4 This is a schematic diagram of surface stiffness loading according to a specific embodiment of this application; Figure 5 This is a schematic diagram of the automated dot distribution of surface stiffness of a passenger vehicle exterior panel according to a specific embodiment of this application; Figure 6This is a schematic diagram illustrating the post-processing of simulation results for evaluating the compressive instability of a passenger vehicle exterior panel according to a specific embodiment of this application; Figure 7 This is a flowchart of a simulation and evaluation method for surface pressure instability of passenger vehicle exterior panels according to a specific embodiment of this application; Figure 8 This is a schematic diagram of the structure of a simulation device for pressure instability of a vehicle exterior covering according to an embodiment of this application; Figure 9 This is a schematic diagram of the structure of an electronic device provided according to an embodiment of this application. Detailed Implementation

[0023] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0024] The following description, with reference to the accompanying drawings, describes a method and apparatus for simulating the compressive instability of vehicle exterior panels according to embodiments of this application. Addressing the problem that current studies on buckling instability of passenger vehicle bodies directly apply to model nodes without considering contact relationships, making them difficult to effectively apply to the surface compressive instability analysis of vehicle exterior panels, this application provides a method for simulating the compressive instability of vehicle exterior panels. This method allows for rapid and accurate assessment of compressive instability of passenger vehicle panels through preliminary simulation, reducing the risk of compressive instability on the sheet metal surface of passenger vehicle exterior panels and improving the success rate of subsequent real-vehicle compressive instability tests. By identifying high-risk areas for compressive instability in passenger vehicles through preliminary simulation, these key areas serve as input for subsequent tests, significantly reducing the number of test points and tests, and lowering the test cycle and cost.

[0025] Figure 1 This is a flowchart illustrating a simulation method for pressure instability of a vehicle exterior panel provided in an embodiment of this application.

[0026] like Figure 1 As shown, the simulation method for the pressure instability of the vehicle's outer body panel includes the following steps: In step S101, finite element modeling of the vehicle's body-in-white is performed to obtain the body-in-white model.

[0027] It should be noted that the body-in-white described in this embodiment is a technical term in automobile manufacturing, referring to the body structure that has been welded but not yet painted (unpainted) and without any accessories installed. In simpler terms, it refers to the overall structure of a car after removing all removable parts: a "metal frame + shell".

[0028] Optionally, in one embodiment of this application, finite element modeling of the vehicle's body-in-white is performed to obtain a body-in-white model, including: acquiring the sheet metal geometric data of the vehicle's body-in-white; acquiring the neutral surface of the body-in-white based on the sheet metal geometric data, and meshing the neutral surface to obtain an initial body-in-white model; assigning attributes to the initial body-in-white model and performing modal analysis; and truncating the initial body-in-white model according to the results of the modal analysis to obtain a body-in-white model.

[0029] It is understandable that body-in-white sheet metal refers to all the metal sheet stampings that make up the body-in-white, and is the basic component that makes up the load-bearing structure and shape of the body; the neutral surface of the body-in-white refers to the intermediate curved surface located in the middle of the thickness of the sheet metal part, with a geometric shape that is completely consistent with the sheet metal surface.

[0030] In actual implementation, the embodiments of this application can extract the neutral surface based on the geometric data of the body-in-white sheet metal, use shell elements for meshing, the mesh reference size is 8mm, the weld points are simulated using ACM (Area Contact Model) volume elements, the adhesive is used using hexahedral elements, after meshing, material properties are assigned, the correctness of the model connection is checked, and after the model is checked and found to be correct, a part of the body-in-white is cut out.

[0031] The specific process can be set as follows: 1. Raw data acquisition: Collect geometric data of the body-in-white sheet metal of the target vehicle, which can cover the three-dimensional shape, size and assembly relationship of all body-in-white sheet metal parts such as floor, longitudinal beams, A / B / C pillars, side panels, and roof.

[0032] 2. Neutral surface extraction and mesh generation: Based on the above body-in-white sheet metal geometry data, neutral surfaces are extracted from each sheet metal part (the position of the neutral surface is consistent with the center of the sheet metal part thickness). Shell elements are used to mesh the neutral surfaces. The mesh reference size can be set to 8mm (the mesh can be appropriately densified in key stress areas) to form an initial body-in-white model containing the main structure of the sheet metal parts.

[0033] 3. Connection modeling and attribute assignment: In the initial body-in-white model, ACM solid elements are used to simulate weld point connections, and hexahedral elements are used to simulate structural adhesive connections; based on the actual materials used in the body-in-white (low carbon steel, high strength steel, hot-formed steel, etc.), corresponding material properties (such as elastic modulus, Poisson's ratio, density, etc.) and sheet metal thickness parameters are assigned to each component.

[0034] In the finite element modeling of the body-in-white, the ACM solid element is equivalent to a virtual weld point.

[0035] 4. Modal Analysis and Model Extraction: Free modal analysis is performed on the initial body-in-white model after attribute assignment and connection modeling to verify the structural rationality of the model; based on the requirements of subsequent simulation analysis (such as local structural strength, NVH performance of specific areas, etc.), and combined with the modal analysis results, the target area of ​​the initial body-in-white model is extracted, and finally the body-in-white finite element model that meets the analysis requirements is obtained.

[0036] Optionally, in one embodiment of this application, the initial body-in-white model includes a weld point model and an adhesive model, wherein the weld point model is modeled using ACM solid element simulation, and the adhesive model is modeled using hexahedral elements.

[0037] Based on the above technical solution, the embodiments of this application can extract neutral surfaces and divide meshes based on the geometric data of the body-in-white sheet metal to construct an initial body-in-white model, then assign material properties and conduct modal analysis, and finally reasonably truncate the model based on the analysis results. This can simplify the model size and improve the calculation efficiency while ensuring the simulation accuracy of the body structure. At the same time, it can ensure that the established body-in-white finite element model is more in line with the actual structural characteristics, providing an accurate and reliable simulation basis for subsequent vehicle stiffness, strength and NVH performance analysis.

[0038] In step S102, based on the preset outer body panel stamping simulation results, the outer body panel in the body-in-white model is divided into multiple regions, and each region is assigned a different thickness attribute to obtain the target body-in-white model.

[0039] Specifically, the thickness gradient of the divided regions can be set to 0.1mm. When the thickness difference exceeds 0.1mm, the outer body panels in the body-in-white model need to be partitioned. Assuming that a passenger car side panel has four thicknesses of 6.9mm, 6.8mm, 6.7mm, and 6.6mm after stamping, it is divided into four regions according to the thickness, and each region is assigned a corresponding thickness attribute. The schematic diagram of the partitioned modeling is shown below. Figure 2 As shown.

[0040] In step S103, constraints are applied to the target body-in-white model to obtain the first target body-in-white model, and pressure heads are set on the outer covering parts of the first target body-in-white model.

[0041] Optionally, in one embodiment of this application, constraints are applied to the target body-in-white model, including: constraining the degrees of freedom of rigid elements at multiple hard points of the cross-section and subframe in the target body-in-white model, wherein the cross-section is connected by rigid elements, and the multiple hard points of the subframe are connected to the body by rigid elements; and applying a nonlinear stress-strain curve to the surface of the outer covering in the target body-in-white model, wherein the nonlinear stress-strain curve is obtained by relevant experimental testing.

[0042] In the simulation analysis of vehicle body instability under pressure, the pressure head can be understood as a rigid loading head used to press the outer body panel. In a real-world scenario, an actual pressure bar can be used to press the car door to see if the door will dent and become unstable. However, in the simulation analysis, a pressure head model needs to be set up to press the outer body panel.

[0043] In this embodiment, the rigid elements at four hard points on the body-in-white cross-section and subframe, comprising 123456 degrees of freedom, can be constrained. A nonlinear stress-strain curve is applied to the surface of the outer body panel, obtained through tensile testing of the outer body panel material. The indenter can be a rigid indenter with a diameter of 80mm (the indenter is circular, and 80mm is the standard indenter size for testing surface stiffness in the automotive industry), a mesh size of 3mm (the indenter is divided into finite element meshes, each 3mm in size, to ensure a sufficiently smooth shape and stable calculation). The mesh corresponding to the area of ​​the outer body panel where the indenter is located is refined (i.e., the small panel that the indenter will press on; the mesh should be denser and finer to ensure more accurate and less coarse calculations in the pressing area). The refined area size is 120mm. The grid is m×120mm with a mesh size of 2mm. The initial distance between the indenter and the sheet metal cover is L (at the start of the simulation, the indenter and the sheet metal cannot be directly attached; a small gap must be left, which is L). L = Ta / 2 + Tb / 2 + 0.1mm, where Ta is the thickness of the indenter and Tb is the thickness of the outer sheet metal cover. For example, if the thickness of the outer sheet metal cover of a passenger car is 0.7mm and the thickness of the indenter is 1.0mm, then the initial distance L = 0.7 / 2 + 1.0 / 2 + 0.1 = 0.86mm. The boundary conditions after applying constraints are as follows: Figure 3 As shown.

[0044] In actual execution, to improve work efficiency, the loading of the rigid indenter can be automated. Operation is simple: just click the loading point. The specific algorithm is as follows: the indenter is imported as a sub-file, and the coordinates and normals of the indenter's center point, as well as the coordinates and normals of the pressing points on the outer cover surface, are read. By comparison, the required rotation and movement distance of the indenter is obtained, thus achieving automatic movement and rotation of the indenter. A sample program is shown below: set SystemId [hm_entitymaxid systems] *createmarkpanel nodes 1 "Select the Node:" set nodenum [hm_getmark nodes 1] *createmarkpanel comps 1 "Select the Component:" set surfaceid [hm_getmark comps 1] *createmark nodes 1 "by set" "BC" set fix [hm_getmark nodes 1] This application embodiment uses rigid units to connect the cross-section of the target body-in-white model and the hard points of the subframe, and fully constrains its degrees of freedom, which can ensure the stability of the model boundary support and clear force transmission; the external covering parts are given a nonlinear stress-strain curve of the material obtained by the experiment, which can accurately reflect the real mechanical response of the sheet metal under large deformation, and improve the simulation accuracy and reliability of the pressing instability and surface stiffness analysis.

[0045] In step S104, a surface-to-surface contact pair is established between the pressure head and the outer cover in the first target body-in-white model to obtain the second target body-in-white model.

[0046] Optionally, in one embodiment of this application, establishing a surface-to-surface contact pair between the pressure head and the outer cover in the first target body-in-white model includes: establishing a local coordinate system along the normal at the center point of the pressure head, and establishing a surface-to-surface contact pair between the pressure head and the outer cover based on the local coordinate system, wherein the pressure head is the master surface and the outer cover is the slave surface.

[0047] The purpose of setting up contact pairs in this embodiment is to configure the pressing simulation: how the pressure head and the vehicle body panel (outer covering) will contact and rub against each other. In other words, applying contact pairs tells the simulation software that the pressure head will touch the outer covering, and there will be contact, compression, and friction between them.

[0048] Specifically, applying the contact pair involves establishing a local coordinate system along the normal direction at the center point of the indenter. The node number of the indenter center point is set to 100, and the node number of the corresponding outer cover is set to 200. A surface-to-surface contact pair is established between the rigid body of the indenter and the outer cover, with the rigid body indenter being the master surface and the outer cover being the slave surface. Figure 4 As shown, the friction coefficient is set to 0.2, and the initial contact adjustment parameter adjust is 0.5.

[0049] Furthermore, the local coordinate system of the indenter center can be implemented through an automated program. The center point of the indenter is the reference point, the normal direction is the Z-axis, and the line connecting any point in the XY plane perpendicular to the normal direction and passing through the reference point to the reference point is the Y-axis. The local coordinate system is established as follows: catch { *collectorcreateonly systcols "SYSTEMKA" "" 3 *currentcollector systcols "SYSTEMKA"} *createmark nodes 1 $basenode *systemcreate 1 0 $basenode "z-axis" $nodez "yz plane" $nodey #*nodecleartempmark *clearmarkall 1 2 Based on the above technical solution, the embodiments of this application can establish a local coordinate system along the normal at the center point of the pressure head, and establish a surface-to-surface contact pair between the pressure head (main surface) and the outer cover (secondary surface) based on this system. This can ensure accurate contact direction and stable contact behavior, enabling reasonable force transmission and contact constraint between the pressure head and the outer cover during the pressing process, effectively improving the simulation accuracy and calculation reliability of surface stiffness and instability analysis.

[0050] In step S105, the displacement of the pressure head is controlled based on the second target body-in-white model to perform pressure instability analysis on the outer covering to generate pressure instability analysis results.

[0051] Optionally, in one embodiment of this application, displacement control of the pressure head based on the second target body-in-white model includes: gradually applying load to the pressure head based on a preset load application strategy to cause displacement of the pressure head, wherein the load is a forced displacement along the normal direction of the pressure head in the local coordinate system.

[0052] In the actual execution of the instability analysis simulation, the parameters are set as follows: Nigeom=yes, initial load step increment 0.01, maximum load step increment 0.05, minimum increment step 1e-05, the load is a forced displacement of 8mm along the head normal in the local coordinate system, nodes 100 and 200 are set to sets_w and set_r respectively, in the output results, the field data output displacement, stress, strain and support reaction force, the historical data output sets (note: the historical data output set here is the data set in the simulation process) set_w and set_r displacement and support reaction force, the parameter setting information of S103 and S104 is saved in the subfile *.inp format and called through the lnclude file.

[0053] Specifically, this embodiment describes the output setting process in simulation analysis. For example, in instability simulation analysis, Nigeom=yes means enabling set nonlinearity because the cover will be pressed and deformed, so this must be enabled for the simulation analysis results to be accurate. The initial load step increment of 0.01, the maximum load step increment of 0.05, and the minimum increment step of 1e-05 mean controlling the calculation to prevent it from crashing and to make the simulation calculation less prone to collapse and more stable. The load is a forced displacement of 8mm along the normal of the indenter in the local coordinate system, which means that the indenter is pressed down 8mm perpendicular to the panel. The forced displacement is the forced 8mm to observe whether the panel will dent and become unstable. Nodes 100 and 200 are the indenter numbers.

[0054] This embodiment can implement step-by-step displacement control of the second target body-in-white model by using forced displacement along the normal direction of the indenter in the local coordinate system. This ensures accurate loading direction and a smooth and controllable loading process, truly reflecting the deformation and instability characteristics of the outer covering under normal load, and effectively improving the accuracy of the pressing instability analysis and the stability of the simulation process.

[0055] Optionally, in one embodiment of this application, the method further includes: solving the compression instability analysis results to obtain the displacement and load curves of the outer cover, and differentiating the displacement and load curves to obtain the derivative curves; in response to the minimum value of the derivative curve being less than or equal to a preset derivative curve threshold, performing structural optimization on the body-in-white corresponding to the target body-in-white model based on the compression instability analysis results.

[0056] Specifically, after setting the simulation parameters as described above, the simulation program can be submitted for solving. If it does not converge, the model should be debugged until it converges. The surfaces of the external covering that may be pressed need to be evenly dotted. Taking the side panel of a passenger car body as an example, the dotting diagram is shown below. Figure 5 As shown. The simulation results are imported into the post-processing software. A displacement-load curve is plotted with the displacement at point set_w as the abscissa and the support reaction at point set_r as the ordinate. The derivative curve is obtained by differentiating the curve, as shown in the figure. Figure 6 As shown, when the minimum value of the derivative curve is ≤5, it is considered that there is a risk of instability when the surface of the outer cover is pressed. When the analysis results of the surface of the outer cover do not meet the requirements, the structure needs to be optimized. The optimization scheme may include adding reinforcing film locally, adding support at the pressing point, etc.

[0057] In this embodiment, by solving the compression instability analysis results, the displacement-load curve of the outer covering is obtained, and the derivative curve is obtained by taking its derivative. Based on the comparison between the minimum value of the derivative curve and the preset threshold, the structural instability state is judged. The weak link of the stiffness of the outer covering can be accurately identified, thereby providing a clear basis for the structural optimization of the target body-in-white model and effectively improving the optimization efficiency and structural reliability.

[0058] In summary, as Figure 7 As shown, the simulation method for pressure instability of vehicle outer covering parts proposed in this application embodiment can be roughly summarized as follows: Step 1: Mesh the white body, connect the models, and extract a portion of the body model.

[0059] Step 2: Perform stamping simulation and assign thickness attribute partitions based on the stamping simulation results of the cover parts.

[0060] Step 3: Apply boundary conditions and apply pressure to analyze the instability of the pressure head.

[0061] Step 4: Establish contact pairs and set contact parameters.

[0062] Step 5: Set key input and output parameters for load step.

[0063] Step Six: Post-processing of simulation results of pressure instability of outer cover.

[0064] Step 7: Optimize unqualified solutions.

[0065] The compression instability simulation method for vehicle exterior panels proposed in this application can quickly and accurately assess the compression instability of passenger vehicle exterior panels through early-stage simulation, reducing the risk of compression instability on the sheet metal surface of passenger vehicle exterior panels and improving the first-pass success rate of subsequent real-vehicle compression instability tests. Early-stage simulation identifies high-risk areas for passenger vehicle compression instability, using these key areas as input for later tests, significantly reducing the number of test points and tests, and lowering the test cycle and cost. Through early-stage compression simulation and optimization analysis of passenger vehicle exterior panel sheet metal, the method reduces or eliminates the risk of body design changes and installation impacts caused by unsuccessful compression instability tests. Simulation technology effectively shortens the vehicle body development cycle, reduces testing and design change costs, and enhances the digitalization of vehicle exterior panel development.

[0066] Next, refer to the appendix. Figure 8 This application describes a simulation device for pressure instability of vehicle exterior panels according to an embodiment of the present application.

[0067] Figure 8 This is a block diagram of a simulation device for pressure instability of a vehicle exterior covering according to an embodiment of this application.

[0068] like Figure 8 As shown, the simulation device 10 for the pressure instability of the vehicle's outer covering includes: a modeling module 100, a partitioning module 200, a constraint module 300, a processing module 400, and an analysis module 500.

[0069] The modeling module 100 is used to perform finite element modeling of the vehicle's body-in-white to obtain the body-in-white model.

[0070] The partitioning module 200 is used to divide the outer body panel in the body-in-white model into multiple regions based on the preset outer body panel stamping simulation results, and assign different thickness attributes to each region to obtain the target body-in-white model.

[0071] The constraint module 300 is used to apply constraints to the target body-in-white model to obtain the first target body-in-white model, and to set pressure heads on the outer covering parts of the first target body-in-white model.

[0072] The processing module 400 is used to establish a surface-to-surface contact pair between the pressure head and the outer cover in the first target body-in-white model to obtain the second target body-in-white model.

[0073] The analysis module 500 is used to control the displacement of the pressure head based on the second target body-in-white model, so as to perform pressure instability analysis on the outer covering to generate pressure instability analysis results.

[0074] Optionally, in one embodiment of this application, the modeling module 100 includes: an acquisition unit, a partitioning unit, and an analysis unit; wherein, the acquisition unit is used to acquire the geometric data of the body-in-white sheet metal of the vehicle; the partitioning unit is used to acquire the neutral surface of the body-in-white based on the geometric data of the body-in-white sheet metal, and to perform mesh partitioning on the neutral surface to obtain an initial body-in-white model; the analysis unit is used to assign attributes to the initial body-in-white model and perform modal analysis, and to truncate the initial body-in-white model according to the results of the modal analysis to obtain a body-in-white model.

[0075] Optionally, in one embodiment of this application, the initial body-in-white model includes a weld point model and an adhesive model, wherein the weld point model is modeled using ACM solid element simulation, and the adhesive model is modeled using hexahedral elements.

[0076] Optionally, in one embodiment of this application, the constraint module 300 includes: a constraint unit and an assignment unit; wherein, the constraint unit is used to constrain the degrees of freedom of the rigid elements at multiple hard points of the subframe and the cross-section in the target body-in-white model, wherein the cross-section is connected by rigid elements, and the multiple hard points of the subframe are connected to the body by rigid elements; the assignment unit is used to assign a nonlinear stress-strain curve to the surface of the outer covering in the target body-in-white model, wherein the nonlinear stress-strain curve is obtained by relevant experimental testing.

[0077] Optionally, in one embodiment of this application, the processing module 400 includes: a construction unit, which is used to establish a local coordinate system along the normal at the center point of the pressure head, and establish a surface contact pair between the pressure head and the outer cover based on the local coordinate system, wherein the pressure head is the master surface and the outer cover is the slave surface.

[0078] Optionally, in one embodiment of this application, the analysis module 500 includes: an application unit, which is used to gradually apply a load to the indenter based on a preset load application strategy to cause the indenter to displace, wherein the load is a forced displacement along the normal direction of the indenter in a local coordinate system.

[0079] Optionally, in one embodiment of this application, the compression instability simulation device for vehicle outer body panels further includes: a solution module and an optimization module; wherein, the solution module is used to solve the compression instability analysis results to obtain the displacement and load curves of the outer body panels, and to differentiate the displacement and load curves to obtain the derivative curves; the optimization module is used to optimize the structure of the body-in-white corresponding to the target body-in-white model based on the compression instability analysis results in response to the minimum value of the derivative curve being less than or equal to a preset derivative curve threshold.

[0080] It should be noted that the explanation of the aforementioned embodiment of the simulation method for pressure instability of vehicle exterior panels also applies to the simulation device for pressure instability of vehicle exterior panels in this embodiment, and will not be repeated here.

[0081] The vehicle exterior panel pressing instability simulation device proposed in this application can quickly and accurately assess the pressing instability of passenger vehicle panels through preliminary simulation, reducing the risk of pressing instability on the sheet metal surface of passenger vehicle exterior panels and improving the first-pass success rate of subsequent real-vehicle pressing instability tests. By identifying high-risk areas for pressing instability in passenger vehicles through preliminary simulation, key areas are used as inputs for subsequent tests, significantly reducing the number of test points and tests, and lowering the test cycle and cost. Through preliminary pressing simulation and optimization analysis of passenger vehicle exterior panel sheet metal, the device reduces or eliminates the risk of body design cycle changes and impact on vehicle installation caused by unqualified pressing instability tests. Through simulation technology, the device effectively shortens the vehicle body development cycle, reduces the cost of testing and design changes, and improves the digitalization technology of vehicle exterior panel development.

[0082] Figure 9 A schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device may include: The memory 901, the processor 902, and the computer program stored on the memory 901 and capable of running on the processor 902.

[0083] When the processor 902 executes the program, it implements the simulation method for pressure instability of vehicle outer covering parts provided in the above embodiments.

[0084] Furthermore, electronic devices also include: Communication interface 903 is used for communication between memory 901 and processor 902.

[0085] The memory 901 is used to store computer programs that can run on the processor 902.

[0086] The memory 901 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0087] If the memory 901, processor 902, and communication interface 903 are implemented independently, then the communication interface 903, memory 901, and processor 902 can be interconnected via a bus to complete communication between them. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of representation, Figure 9 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0088] Optionally, in a specific implementation, if the memory 901, processor 902, and communication interface 903 are integrated on a single chip, then the memory 901, processor 902, and communication interface 903 can communicate with each other through an internal interface.

[0089] The processor 902 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.

[0090] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for simulating the pressure instability of vehicle exterior panels.

[0091] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0092] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0093] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0094] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0095] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. If implemented in hardware, as in another embodiment, it can be implemented using any one or more of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0096] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0097] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0098] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A method of crush instability simulation of a vehicle outer covering, characterized by, include: Perform finite element modeling of the vehicle's body-in-white to obtain the body-in-white model; Based on the pre-set outer body panel stamping simulation results, the outer body panel in the body-in-white model is divided into multiple regions, and each region is assigned a different thickness attribute to obtain the target body-in-white model. Constraints are applied to the target body-in-white model to obtain a first target body-in-white model, and pressure heads are set on the outer coverings of the first target body-in-white model; A surface-to-surface contact pair is established between the pressure head and the outer cover in the first target body-in-white model to obtain the second target body-in-white model; The displacement of the pressure head is controlled based on the second target body-in-white model in order to perform pressure instability analysis on the outer covering to generate pressure instability analysis results.

2. The method of buckling emulation of a vehicle outer covering of claim 1, wherein, The process of performing finite element modeling of the vehicle's body-in-white to obtain a body-in-white model includes: Obtain the geometric data of the vehicle's body-in-white sheet metal; Based on the sheet metal geometry data of the white body, the neutral surface of the white body is obtained, and the neutral surface is meshed to obtain the initial white body model; The initial body-in-white model is assigned attributes and subjected to modal analysis. Based on the results of the modal analysis, the initial body-in-white model is truncated to obtain the body-in-white model.

3. The method of crush instability simulation of a vehicle outer covering of claim 2, wherein, The initial body-in-white model includes a weld point model and an adhesive model. The weld point model is modeled using ACM solid element simulation, and the adhesive model is modeled using hexahedral elements.

4. The method of crush instability simulation of a vehicle outer covering of claim 2, wherein, The constraints imposed on the target body-in-white model include: Constrain the degrees of freedom of rigid elements at multiple hard points of the subframe and the cross-section of the target body-in-white model, wherein the cross-section is connected by rigid elements, and the multiple hard points of the subframe are connected to the body by rigid elements. A nonlinear stress-strain curve is applied to the surface of the outer body panel in the target body-in-white model, wherein the nonlinear stress-strain curve is obtained through relevant experimental tests.

5. The method of buckling emulation of a vehicle outer covering of claim 1, wherein, Establishing a surface-to-surface contact pair between the pressure head and the outer covering in the first target body-in-white model includes: A local coordinate system is established along the normal direction at the center point of the pressure head, and a surface-to-surface contact pair between the pressure head and the outer cover is established based on the local coordinate system, wherein the pressure head is the master surface and the outer cover is the slave surface.

6. The method of buckling emulation of a vehicle outer covering of claim 5, wherein, The displacement control of the pressure head based on the second target body-in-white model includes: The pressure head is gradually loaded based on a preset load application strategy to cause displacement of the pressure head, wherein the load is a forced displacement along the normal direction of the pressure head in the local coordinate system.

7. The method of buckling emulation of a vehicle outer covering of claim 1, wherein, Also includes: The results of the pressure instability analysis are solved to obtain the displacement and load curves of the outer cover, and the derivative curves are differentiated to obtain the derivative curves. In response to the minimum value of the derivative curve being less than or equal to a preset derivative curve threshold, the structure of the body-in-white corresponding to the target body-in-white model is optimized based on the results of the pressure instability analysis.

8. A press-through instability simulation device for a vehicle outer covering, characterized by include: The modeling module is used to perform finite element modeling of the vehicle's body-in-white to obtain the body-in-white model. The partitioning module is used to partition the outer cover in the body-in-white model into multiple regions based on the preset outer cover stamping simulation results, and assign different thickness attributes to each region to obtain the target body-in-white model. The constraint module is used to apply constraint conditions to the target body-in-white model to obtain a first target body-in-white model, and to set pressure heads on the outer covering parts of the first target body-in-white model; The processing module is used to establish a surface-to-surface contact pair between the pressure head and the outer cover in the first target body-in-white model to obtain a second target body-in-white model. The analysis module is used to control the displacement of the pressure head based on the second target body-in-white model in order to perform pressure instability analysis on the outer covering to generate pressure instability analysis results.

9. An electronic device, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the pressure instability simulation method for vehicle exterior panels as described in any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to implement the pressure instability simulation method for vehicle exterior panels as described in any one of claims 1-7.

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