Methods, equipment, and procedures for analyzing the thermal deformation of automotive rear hatch exterior panels

Abstract

This invention discloses a method, device, and program product for thermal deformation analysis of automotive rear cover exterior panels. The method includes: determining the analysis path based on instructions; if the path is determined to be a three-dimensional linear model analysis path, importing the three-dimensional model data of the upper outer panel, the exterior panel including the positioning components, and the connecting structure to obtain a three-dimensional dataset; if the path is determined to be a three-dimensional nonlinear model analysis path, importing the three-dimensional model data of the upper outer panel and the exterior panel excluding the positioning components to obtain a three-dimensional dataset; performing meshing operations on the components in the three-dimensional dataset; processing according to the three-dimensional linear model analysis path; processing according to the three-dimensional nonlinear model analysis path; and obtaining a temperature deformation cloud map. The method provided by this invention can significantly improve processing efficiency and the accuracy of analysis results.

Description

Technical Field

[0001] This invention relates to the field of sheet metal thermal deformation analysis technology, and in particular to a method, equipment and program product for thermal deformation analysis of automotive rear cover exterior panels. Background Technology

[0002] In the automotive manufacturing industry, the thermal deformation of the exterior trim panels of car rear covers has always been a key concern. Traditional automotive exterior trim panels experience rapid temperature increases under direct sunlight, and deformation under high-temperature conditions has been a primary focus of research and development. Currently used empirical formula analysis methods and traditional finite element analysis methods cannot analyze deformation values ​​at all locations of the component, and they also suffer from insufficient accuracy and time-consuming analysis of the thermal deformation of rear cover exterior trim panels. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies in analyzing the thermal deformation of automotive rear cover exterior panels, which are insufficient in accuracy and time-consuming. The invention provides a method, equipment, and program product for analyzing the thermal deformation of automotive rear cover exterior panels. The method can accurately and quickly obtain the analysis results of thermal deformation by distinguishing between three-dimensional linear model analysis paths and three-dimensional nonlinear model analysis paths.

[0004] The present invention provides a method for analyzing the thermal deformation of an automotive rear cover exterior panel, comprising: Determine and analyze the path based on the instructions; If the path is determined to be a three-dimensional linear model analysis path, then import the three-dimensional model data of the upper outer panel, the outer trim panel including the positioning parts, and the connecting structure to obtain a three-dimensional dataset. If the path is determined to be a three-dimensional nonlinear model analysis path, then import the three-dimensional model data of the upper outer panel and the outer trim panel excluding the positioning parts to obtain a three-dimensional dataset. Perform mesh generation on the components in the 3D dataset; If it is a three-dimensional linear model analysis path, first assign material properties to each component, then establish connections between each component and apply boundary conditions; If it is a three-dimensional nonlinear model analysis path, first establish the connection between each component, then set the contact relationship, then assign material properties to each component, and finally apply boundary conditions. A preset temperature load is applied to each component and analyzed to obtain a temperature deformation cloud map.

[0005] In one of the optional technical solutions, the import of three-dimensional model data of the upper outer panel, the outer trim panel including the positioning component, and the connecting structure is described. The positioning component includes a positioning pin and a connecting adhesive on the outer trim panel, and the connecting structure includes a connecting buckle provided on the upper outer panel.

[0006] In one of the alternative technical solutions, the meshing operation of the components in the three-dimensional dataset includes: For the three-dimensional linear model analysis path, all components are divided into tetrahedral three-dimensional meshes, with the mesh size of the upper outer panel and the outer trim panel being the first preset size, and the mesh size of the connecting buckle being the second preset size; For the three-dimensional nonlinear model analysis path, the middle surface of the upper outer panel and the outer trim panel is first extracted, and then the middle surface is divided into quadrilateral meshes with the mesh size being the third preset size. Local coordinate systems are established at the corresponding positions of the positioning pin, connecting buckle, and connecting adhesive, and spring elements are used to simulate the positioning pin, connecting buckle, and connecting adhesive.

[0007] In one of the alternative technical solutions, the step of first assigning material properties to each component, then establishing connections between the components and applying boundary conditions includes: Assign material properties, including elastic modulus, Poisson's ratio, density and coefficient of thermal expansion for the outer panel and connecting buckle, and elastic modulus, Poisson's ratio, density and coefficient of thermal expansion for the upper outer panel; The connection is established, with the connecting buckle and the upper outer panel connected by virtual bolts, and the connecting buckle and the outer trim panel connected by welding; the positioning pin and the upper outer panel are connected by flexible means, with the middle positioning pin only releasing the degree of freedom of movement in the Z-axis direction and the degree of freedom of rotation around the Z-axis, and restricting the other degrees of freedom; the positioning pins at both ends only releasing the degree of freedom of movement in the Y and Z-axis directions and the degree of freedom of rotation around the Z-axis, and restricting the other degrees of freedom; Apply boundary conditions to fix the connecting clip mounting surface at the center of the upper outer panel.

[0008] In one of the alternative technical solutions, the material properties of the exterior trim panel and the connecting buckle are specifically a modulus of elasticity of 3.7 × e. 9 Pa, Poisson's ratio 0.35, density 1230 kg / m³, coefficient of thermal expansion 5 × e -5 / K; The material properties of the upper outer panel are specifically the elastic modulus 2×e. 11 Pa, Poisson's ratio 0.266, density 7850 kg / m³, coefficient of thermal expansion 1.2 × e -5 / K.

[0009] In one of the alternative technical solutions, the steps of first establishing connections between the components, then setting contact relationships, then assigning material properties to each component, and finally applying boundary conditions include: Establish connections by simulating the corresponding positions of the model's locating pins, connecting clips, and connecting adhesive using spring units. Specifically, the locating pin units are set with stiffness in the X and Y directions, releasing the other four degrees of freedom; the connecting clip units are set with stiffness in the X, Y, and Z directions, releasing the other three degrees of freedom; and the connecting adhesive units are set with stiffness in all six directions based on the properties of the adhesive. Set the contact relationship, designate the upper outer panel contact surface as the primary contact surface, the outer trim panel contact surface as the secondary contact surface, and set the friction coefficient of the contact surfaces. Each component is assigned material properties. The material properties of the outer panel include component thickness, Poisson's ratio, density, as well as the elastic modulus curve, thermal expansion coefficient curve, and stress-strain curve as they change with temperature. The material properties of the upper outer panel include elastic modulus, Poisson's ratio, density, and thermal expansion coefficient. Apply boundary conditions to fix the connecting clip mounting surface at the center of the upper outer panel.

[0010] In one of the optional technical solutions, the preset temperature load is the Kelvin temperature of 353.15K corresponding to 80℃, and the objects applied are the upper outer panel and the outer trim panel.

[0011] The present invention provides a computer device, including a memory, a processor, and a computer program on the memory, wherein the processor executes the computer program to implement the steps of any of the aforementioned methods for analyzing the thermal deformation of an automotive rear cover exterior panel.

[0012] The present invention provides a computer-readable storage medium storing a computer program / instruction thereon, which, when executed by a processor, implements the steps of any of the aforementioned methods for analyzing the thermal deformation of an automotive rear cover exterior panel.

[0013] The present invention provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of any of the aforementioned methods for analyzing the thermal deformation of an automotive rear cover exterior panel.

[0014] The above technical solution has the following beneficial effects: The thermal deformation analysis method for automotive rear cover exterior panels provided by this invention determines the analysis path according to instructions and imports model data and modeling processes differently. Mesh generation, attribute assignment, connection establishment, and temperature load application are performed under two different paths, and finally, a temperature deformation cloud map is obtained. This method achieves the goal of taking into account both fast linear analysis and high-precision nonlinear analysis within the same framework, allowing users to flexibly choose according to engineering needs and quickly and efficiently analyze the thermal deformation of automotive rear cover exterior panels. Attached Figure Description

[0015] The disclosure of this invention will become more readily understood by referring to the accompanying drawings. It should be understood that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings: Figure 1 A flowchart illustrating a method for analyzing the thermal deformation of an automotive rear cover exterior panel according to an embodiment of the present invention; Figure 2 This is an exploded view of a car rear cover according to an embodiment of the present invention; Figure 3 This is a top view of the upper outer plate provided in an embodiment of the present invention; Figure 4 for Figure 2 A sectional view of section AA; Figure 5 for Figure 2 A sectional view of section BB; Figure 6 A schematic diagram of a three-dimensional model of the upper outer plate provided in an embodiment of the present invention; Figure 7 A schematic diagram of a three-dimensional model of an exterior trim panel provided in an embodiment of the present invention; Figure 8 A deformation cloud pattern of an exterior trim panel provided in an embodiment of the present invention; Figure 9 Another variational cloud diagram of the exterior trim panel provided in one embodiment of the present invention; Figure 10 A cross-sectional displacement diagram of the connecting buckle and positioning pin provided in an embodiment of the present invention; Figure 11 This is a curve showing the change of the elastic modulus of the exterior trim panel with temperature, provided in an embodiment of the present invention. Figure 12 A curve showing the change of the coefficient of thermal expansion of the exterior panel with temperature, provided in an embodiment of the present invention; Figure 13 This is a stress-strain curve diagram of an exterior panel at different temperatures provided in an embodiment of the present invention; Figure 14 This is a schematic diagram of the structure of a computer device provided in an embodiment of the present invention.

[0016] Figure reference numerals: 1. Upper outer panel; 2. Exterior trim panels; 3. Positioning pin; 4. Connecting buckle. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of one or more embodiments of this specification clearer, the technical solutions of one or more embodiments of this specification will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of them. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of one or more embodiments of this specification.

[0018] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another.

[0019] The technical solutions provided in the various embodiments of this specification are described in detail below with reference to the accompanying drawings.

[0020] In the existing technology, traditional analysis methods have the problems of insufficient accuracy in analyzing the thermal deformation of the rear cover exterior panel and long analysis time.

[0021] To address the shortcomings of existing technologies, this solution provides the following embodiments: like Figure 1 The figure shows a method for analyzing the thermal deformation of an automotive rear cover exterior panel 2 according to an embodiment of the present invention, comprising the following steps: Step S101: Determine and analyze the path based on the instructions; Step S102: If the path is determined to be a three-dimensional linear model analysis path, import the three-dimensional model data of the upper outer panel 1, the outer trim panel 2 including the positioning parts, and the connecting structure to obtain a three-dimensional dataset. Step S103: If it is determined to be a three-dimensional nonlinear model analysis path, then import the three-dimensional model data of the upper outer panel 1 and the outer trim panel 2 excluding the positioning parts to obtain a three-dimensional dataset. Step S104: Perform mesh generation on the components in the 3D dataset; Step S105: If it is a three-dimensional linear model analysis path, first assign material properties to each component, then establish connections between each component and apply boundary conditions. Step S106: If it is a three-dimensional nonlinear model analysis path, first establish connections for each component, then set contact relationships, then assign material properties to each component, and finally apply boundary conditions. Step S107: Apply the preset temperature load to each component and analyze it to obtain the temperature deformation cloud map.

[0022] In the actual execution process, the analyst or the system first issues a path selection instruction based on the analysis requirements or calculation accuracy requirements. When it is necessary to obtain the detailed deformation of the structure, the three-dimensional linear model analysis path is selected, and when it is necessary to improve the overall analysis accuracy, the three-dimensional nonlinear model analysis path is selected.

[0023] Under the three-dimensional linear model analysis path, the complete three-dimensional model including the outer trim panel 2 with positioning pin 3, the upper outer panel 1 and the buckle structure is imported into the analysis environment, so that the real geometric relationship of each structure can be directly reflected in the subsequent calculation process.

[0024] In the 3D nonlinear model analysis path, only the models of the upper outer panel 1 and the outer trim panel 2 are imported, while retaining the geometric information of the connection positions so that the connection relationship can be established later through an equivalent method. After the model is imported, all components are meshed. In the 3D linear model, the solids are discretized directly, and in the 3D nonlinear model, they are discretized after mid-surface extraction.

[0025] Subsequently, the modeling process is executed in different sequences according to the path differences. In the three-dimensional linear model, the material is defined first, then the connection relationship is established and the boundary constraints are applied. In the three-dimensional nonlinear model, the connection is established first, then the contact relationship is set and the material properties are further defined. Finally, the temperature load is applied uniformly for solution calculation to obtain the deformation distribution of each component under high temperature conditions.

[0026] This invention introduces two analysis paths and performs differentiated processing, enabling the acquisition of complete three-dimensional deformation results under different analysis requirements. Compared with empirical formula methods, it can cover deformation at all locations, while improving analysis accuracy and shortening the overall analysis cycle compared with traditional finite element methods.

[0027] In summary, this embodiment of the invention determines the analysis path according to the instructions and imports model data and modeling process differently. Mesh generation, attribute assignment, connection establishment and temperature load application are performed under two different paths, and finally a temperature deformation cloud map is obtained. This achieves the goal of taking into account both fast linear analysis and high-precision nonlinear analysis within the same method framework, allowing users to flexibly choose according to engineering needs and quickly and efficiently analyze the thermal deformation of the car rear cover exterior panel 2.

[0028] In one embodiment, in step S102, the three-dimensional model data of the upper outer panel 1, the outer trim panel 2 including the positioning component, and the connecting structure are imported. The positioning component includes the positioning pin 3 on the outer trim panel 2 and the connecting adhesive. The connecting structure includes the connecting buckle 4 provided on the upper outer panel 1.

[0029] In this embodiment, when importing the model into the three-dimensional linear model analysis path, the outer trim panel 2 model contains a positioning pin 3 structure, and at the same time retains the structural information of the connecting adhesive in the connection area. The upper outer panel 1 model contains a connecting buckle 4 structure. By importing the above complete structure, the assembly relationship can be directly established.

[0030] In the three-dimensional nonlinear model analysis path, although the locating pin 3 entity is not imported, the corresponding coordinate information is still recorded based on the location of the locating pin 3 and the connecting adhesive, providing a basis for subsequent equivalent modeling.

[0031] This embodiment ensures that the linear model has complete structural representation capabilities, while also ensuring that the nonlinear model can still accurately reflect the connection relationships even with a simplified structure, thus achieving a balance between computational efficiency and accuracy.

[0032] In one embodiment, step S104, which involves meshing the components in the 3D dataset, includes: For the three-dimensional linear model analysis path, all components are divided into tetrahedral three-dimensional meshes, with the mesh size of the upper outer plate 1 and the outer trim plate 2 being the first preset size, and the mesh size of the connecting buckle 4 being the second preset size; For the three-dimensional nonlinear model analysis path, the middle surface of the upper outer panel 1 and the outer trim panel 2 is first extracted, and then the middle surface is divided into quadrilateral meshes with the mesh size being the third preset size. Local coordinate systems are established at the corresponding positions of the positioning pin 3, connecting buckle 4 and connecting adhesive, and spring elements are used to simulate the positioning pin 3, connecting buckle 4 and connecting adhesive.

[0033] In this embodiment, under the three-dimensional linear model analysis path, the upper outer plate 1, the outer trim plate 2, and the connecting buckle 4 are directly divided into solid meshes. The upper outer plate 1 and the outer trim plate 2 adopt relatively consistent mesh scales to ensure overall calculation stability, while the connecting buckle 4, due to its smaller structural size, adopts a finer mesh for discretization, thereby improving the calculation accuracy of local areas.

[0034] In the three-dimensional nonlinear model analysis path, the middle surface of the upper outer panel 1 and the outer trim panel 2 is first extracted to reduce the model complexity. Then, the surface unit mesh is generated on the middle surface. Local coordinate system is established at the location of the positioning pin 3, connecting buckle 4 and connecting glue, so that the subsequent spring unit can be set according to the actual force direction. The model is then modeled by replacing the solid structure with spring unit.

[0035] In one embodiment, step S105, which involves first assigning material properties to each component, then establishing connections between the components and applying boundary conditions, includes: The material properties are assigned, including the elastic modulus, Poisson's ratio, density and coefficient of thermal expansion of the outer trim panel 2 and the connecting buckle 4, and the material properties of the upper outer panel 1 include the elastic modulus, Poisson's ratio, density and coefficient of thermal expansion. A connection is established, wherein the connecting buckle 4 is connected to the upper outer panel 1 by a virtual bolt, and the connecting buckle 4 is connected to the outer trim panel 2 by welding; the positioning pin 3 is connected to the upper outer panel 1 by a flexible connection, the middle positioning pin 3 only releases the degree of freedom of movement in the Z-axis direction and the degree of freedom of rotation around the Z-axis, and restricts the other degrees of freedom; the positioning pins 3 at both ends only release the degree of freedom of movement in the Y and Z-axis directions and the degree of freedom of rotation around the Z-axis, and restrict the other degrees of freedom; Apply boundary conditions to fix the mounting surface of the connecting buckle 4 at the center of the upper outer plate 1.

[0036] In this embodiment, under the three-dimensional linear model analysis path, material models are first established for each component and corresponding parameters are assigned so that each component has real physical properties during the calculation process. Then, the connection method is established according to the structural connection relationship. The buckle and the upper outer plate 1 are connected by virtual bolts, and the buckle and the outer trim plate 2 are connected by welding. Different degrees of freedom constraints are set at the positioning pin 3 to simulate the actual assembly state. The constraint methods at the middle position and the two ends are different, thereby reflecting the real structural stress characteristics. After the connection relationship is established, the central buckle mounting surface of the upper outer plate 1 is fixed as a boundary constraint.

[0037] Preferably, in the process of imparting material properties, the material properties of the outer trim panel 2 and the connecting buckle 4 are specifically an elastic modulus of 3.7 × e. 9 Pa, Poisson's ratio 0.35, density 1230 kg / m³, coefficient of thermal expansion 5 × e -5 / K; The material properties of the upper outer plate 1 are specifically the elastic modulus 2×e. 11 Pa, Poisson's ratio 0.266, density 7850 kg / m³, coefficient of thermal expansion 1.2 × e -5 / K.

[0038] In one embodiment, step S106, which involves first establishing connections between the components, then setting contact relationships, then assigning material properties to each component, and finally applying boundary conditions, includes: Establish connections by using spring units at the corresponding positions of the model positioning pin 3, connecting buckle 4, and connecting adhesive. Specifically, the positioning pin 3 unit is set with stiffness in the X and Y directions and the other four degrees of freedom are released; the connecting buckle 4 unit is set with stiffness in the X, Y, and Z directions and the other three degrees of freedom are released; and the connecting adhesive unit is set with stiffness in six directions according to the properties of the adhesive. Set the contact relationship, set the contact surface of the upper outer panel 1 as the main contact surface, set the contact surface of the outer trim panel 2 as the secondary contact surface, and set the friction coefficient of the contact surfaces; Each component is assigned material properties, including the component thickness, Poisson's ratio, density, and the elastic modulus curve, thermal expansion coefficient curve, and stress-strain curve as a function of temperature for the outer panel 2; the material properties of the upper outer panel 1 include the elastic modulus, Poisson's ratio, density, and thermal expansion coefficient. Apply boundary conditions to fix the mounting surface of the connecting buckle 4 at the center of the upper outer plate 1.

[0039] In this embodiment, under the three-dimensional nonlinear model analysis path, the positioning pin 3, the buckle and the connecting adhesive are simulated equivalently by the spring unit, so that the model can still reflect the connection characteristics without introducing complex solid structures. At the same time, the mechanical differences of different connection structures are reflected by setting stiffness parameters in different directions. After establishing the connection relationship, the contact behavior between the outer trim panel 2 and the upper outer panel 1 is simulated by setting the master-slave contact surface and friction parameters. Then, a material property curve that changes with temperature is introduced for the outer trim panel 2, so that the material properties can be dynamically adjusted with temperature changes, thereby more realistically reflecting the structural response under high temperature environment. Finally, boundary conditions are applied to complete the model construction.

[0040] In one embodiment, the preset temperature load is the Kelvin temperature of 353.15K corresponding to 80°C, and the objects applied are the upper outer panel 1 and the outer trim panel 2.

[0041] The structural diagram of the car rear cover in the above embodiment is shown below. Figure 2-5 As shown, the outer trim panel 2 covers the upper outer panel 1. The outer trim panel 2 and the upper outer panel 1, as well as the upper outer panel 1 and the vehicle body, are connected by positioning pins 3 and connecting clips 4. The three-dimensional model of the upper outer panel 1 is shown below. Figure 6 As shown, the 3D model of exterior panel 2 is as follows: Figure 7 As shown.

[0042] According to Figures 11-13 The curves were used to select the material properties of the outer panel 2 based on conditions such as temperature, in order to ensure the accuracy of the analysis results.

[0043] In one embodiment, a three-dimensional linear model analysis path is used to perform thermal deformation analysis on the outer trim panel 2 of the car rear cover under high temperature conditions of 80°C. The specific process is as follows: First, import the 3D model data of the upper outer panel 1, the outer trim panel 2 containing the locating pin 3, and the connecting buckle 4. The outer trim panel 2 model retains the complete geometric features of the locating pin 3, and the connecting buckle 4 model is modeled according to the actual parts. After importing, a 3D dataset containing all components is obtained.

[0044] Next, the components are divided into grids. All components are divided into tetrahedral three-dimensional grids. The grid size of the upper outer panel 1 and the outer trim panel 2 is 5mm, and the grid size of the connecting buckle 4 is 2mm. The grid Jacobian coefficient is greater than 0.3.

[0045] Then, material properties are assigned to each component, and material properties are established for the upper outer panel 1, outer trim panel 2, and connecting buckle 4. The material property assigned to the outer trim and connecting buckle 4 is: elastic modulus 3.7 × e. 9 Pa, Poisson's ratio 0.35, density 1230 kg / m³ 3 The coefficient of thermal expansion is 5×e -5 K / deg. The material properties of the upper outer panel 1 include: elastic modulus 2×e 11 Pa, Poisson's ratio 0.266, density 7850 kg / m³, coefficient of thermal expansion 1.2 × e -5 K / deg. Then assign the material properties to the corresponding parts.

[0046] Then, different connection methods are established based on the differences in the connection methods of the connecting clip 4 and the positioning pin 3. The connecting clip 4 is connected to the upper outer panel 1 using a virtual bolt connection with a tightening force of 0N. The connecting clip 4 is connected to the outer trim panel 2 using welding, with the weld material properties being the same as those of the outer trim panel 2. The positioning pin 3 is flexibly connected to the upper outer panel 1. The middle positioning pin 3 releases two degrees of freedom: Z-axis displacement and rotation around the Z-axis, while restricting the remaining degrees of freedom. The positioning pins 3 at both ends release three degrees of freedom: Y-axis and Z-axis displacement and rotation around the Z-axis, while restricting the remaining degrees of freedom.

[0047] Next, boundary conditions are applied to the component to fix the mounting surface of the center connecting buckle 4 of the upper outer plate 1.

[0048] Finally, a temperature load was applied to the component and analyzed. The 80℃ temperature was converted to Kelvin (353.15K). The temperature load was then applied to the upper outer panel 1 and the outer panel decorative parts. The deformation cloud diagram of the model under 80℃ was calculated as follows: Figure 8 As shown. In this embodiment, the entire analysis process takes 3 to 5 hours, and it can analyze the deformation value at any location of the 3D model, which is significantly shorter than the analysis time of existing technologies, and can also improve the accuracy of the analysis results.

[0049] In one embodiment, a three-dimensional nonlinear model analysis path is used to perform thermal deformation analysis on the automotive rear cover exterior panel 2 under high temperature conditions of 80°C. The specific process is as follows.

[0050] First, import the 3D model data of the two components, the upper outer panel 1 and the outer trim panel 2. The 3D model of the outer trim panel 2 does not include the geometric features of the locating pin 3. After importing, a 3D dataset is obtained.

[0051] Next, mesh generation is performed. The mid-surface of the upper outer panel 1 and the outer trim panel 2 is extracted, and then quadrilateral meshes are used to divide the sheet metal parts of the outer panel and the mid-surface of the outer trim panel 2, with a mesh size of 5mm. Mesh generation requirements: warpage less than 15, aspect ratio less than 5, Jacobian coefficient greater than 0.6, minimum quadrilateral angle greater than 45°, maximum quadrilateral angle less than 135°, maximum element length less than 10, minimum triangle angle greater than 20°, maximum triangle angle less than 120°, and triangle element ratio less than 5%. Local coordinate systems are established at the positions of locating pin 3 and connecting clip 4, with the Z-axis coinciding with the structural center axis. A series of local coordinate systems are established at the connecting adhesive positions, with the Z-axis direction being the normal to the position of the upper outer panel 1. The locating pin 3, connecting clip 4, and connecting adhesive are all simulated using 1d spring elements.

[0052] Next, the connection is established. The corresponding positions of the model's positioning pin 3, connecting buckle 4, and connecting adhesive are simulated using 1D spring elements. Specifically, the positioning pin 3 is set with a stiffness of 50 N / mm in the X and Y directions, releasing the remaining four degrees of freedom. The connecting buckle 4 is set with a stiffness of 50 N / mm in the X, Y, and Z directions, releasing the remaining three degrees of freedom. The connecting adhesive position is set with a stiffness of 2 N / mm in all six directions based on the adhesive properties.

[0053] Next, the contact settings are configured, with the upper outer panel 1 contact surface set as the primary contact surface and the outer trim panel 2 contact surface set as the secondary contact surface, and the contact surface friction coefficient set to 0.2.

[0054] Next, material properties were assigned to the components, and material properties were established for the upper outer panel 1 and the outer trim panel 2 respectively. The material parameters for the outer trim panel 2 include: component thickness 0.65mm, elastic modulus 3.7×e 9 Pa is given, along with a curve showing the elastic modulus as a function of temperature, a Poisson's ratio of 0.35, and a density of 1230 kg / m³. 3 The coefficient of thermal expansion is 5×e -5 K / deg and provides curves for the coefficient of thermal expansion versus temperature and stress-strain curves versus temperature. The material parameters of the upper outer plate 1 include: elastic modulus 2×e 11 Pa, Poisson's ratio 0.266, density 7850 kg / m³ 3 The coefficient of thermal expansion is 1.2 × e -5 K / deg. Then assign the attributes to the corresponding component.

[0055] Then, apply boundary conditions and fix the mounting surface of the center connecting buckle 4 of the outer panel 1 according to the actual situation.

[0056] Finally, a temperature load was applied to the component and analyzed. An 80°C temperature load was applied to the upper outer sheet metal part 1, and the temperature deformation contour map was obtained, as shown below. Figure 9As shown. In this embodiment, the entire analysis process takes 6 to 8 hours, which is significantly shorter than the analysis time of the prior art. It also comprehensively considers the effects of the adhesive, the contact friction between the outer trim panel 2 and the upper outer panel 1, the effects of the positioning pin 3 and the connecting buckle 4, and the influence of the material parameters of the outer trim panel 2 on the results with temperature changes, resulting in smaller errors in the analysis results.

[0057] In one embodiment, the three-dimensional linear model analysis path can be implemented using the CATIA software platform, and the accuracy of the analysis results can be verified by comparison with ANSYS and HYPERMESH software.

[0058] First, using the parts design and assembly design module of CATIA software, fully parametric 3D solid models of the rear cover upper outer panel 1, rear cover outer trim panel 2, and connecting buckle 4 were created according to the actual vehicle installation state. Among them, the flange features and reinforcing rib features of the upper outer panel 1 sheet metal part were fully preserved.

[0059] The geometric features of the positioning pins 3 are established on the exterior panel 2 model, including the middle positioning pin 3 and the two end positioning pins 3, whose diameter and height are based on the design values.

[0060] The elastic jaws and positioning shoulders of the connecting buckle 4 model are modeled according to the actual parts. After modeling, the above components are spatially positioned in the assembly environment to form the assembly dataset corresponding to the overall preview image, providing accurate geometric input for the subsequent generation of high-quality finite element meshes.

[0061] Then, the 3D mesh of the assembly was directly generated using CATIA's built-in finite element analysis module. The system set the upper outer panel 1 and the outer trim panel 2 as solid element objects, selected tetrahedral element type, and uniformly set the mesh size to 5mm. For the connecting buckle 4 with smaller geometric dimensions, the system automatically identified its features and refined its mesh size to 2mm.

[0062] After the mesh generation engine runs, it automatically checks the mesh quality, ensuring that the Jacobian coefficient of all tetrahedral elements is greater than 0.3 and that no distorted elements appear. The resulting 3D mesh model includes all shell thickness features of the upper outer plate 1, the curved shape of the outer trim 2, and the fine geometry of the connecting buckle 4, enabling the model's degrees of freedom to capture local deformation gradients.

[0063] Next, the material property assignment process begins. The system creates a dedicated material card for the sheet metal part of the upper outer panel 1, with its parameters fully set as follows: Young's modulus is 2 × e. 11 Pa, Poisson's ratio is taken as 0.266, and the coefficient of thermal expansion is taken as 1.2 × e -5 K / deg, yield strength is taken as 2.5×e 8 Pa, material density is taken as 27850 kg / m³ 3.

[0064] At the same time, another material card is established for the exterior decorative parts and connecting buckles 4, with the parameters set as follows: Young's modulus is 3.7 × e 9 Pa, Poisson's ratio is taken as 0.35, and density is taken as 1230 kg / m³ 3 The coefficient of thermal expansion is taken as 5×e -5 K / deg, yield strength is taken as 5.2×e 7 Pa.

[0065] Although the linear analysis path primarily utilizes the elastic modulus and coefficient of thermal expansion for thermal deformation calculations, explicitly loading the yield strength parameter facilitates rapid assessment in post-processing of whether the component has entered the plastic risk zone, providing additional reference for design decisions. The system assigns the aforementioned two material cards to the upper outer panel 1 and the outer trim panel 2, including the connecting clips 4, respectively, completing attribute binding.

[0066] During the connection establishment phase, the system creates differentiated connection forms one by one based on the structural characteristics of the actual connection buckle 4 and positioning pin 3.

[0067] First, the assembly constraints are automatically searched to identify all contact pairs between the base surface of the connecting clip 4 and the mounting surface of the upper outer panel 1. Then, virtual bolt connections are automatically added between each pair, with the bolt preload set to 0, to simulate the connection effect of the connecting clip 4 fastening the outer trim panel 2 assembly to the upper outer panel 1.

[0068] At the same time, the system identifies the mating relationship between the head of the connecting buckle 4 and the seat surface of the outer trim panel 2, and establishes a welding connection between the root of the connecting buckle 4 and the mounting plane of the outer trim panel 2. The mechanical properties of the weld material are directly specified to be the same as those of the outer trim panel 2, thereby realizing the integrated connection between the connecting buckle 4 and the outer trim panel 2.

[0069] For the locating pin 3, the system creates a flexible connection unit between the outer cylindrical surface of the pin and the inner wall of the corresponding pin hole on the upper outer plate 1. The connection properties of the intermediate locating pin 3 are set to retain only the translational degree of freedom along the Z-axis of the vehicle coordinate system and the rotational degree of freedom around the Z-axis, while all other four degrees of freedom are constrained.

[0070] The connection properties of the two end positioning pins 3 are set to release the translational degrees of freedom in the Y and Z axes and the rotational degrees of freedom around the Z axis, while restricting the translational degrees of freedom in the X axis and the rotational degrees of freedom around the X and Y axes.

[0071] By employing a differentiated assembly strategy that uses a simulated intermediate pin as the primary positioning reference and allows the pins at both ends to slide freely in the direction of thermal expansion, the problem of false thermal stress caused by over-constraint under temperature load is fundamentally avoided.

[0072] Next, the system automatically identifies the mounting surface of the connecting buckle 4 in the geometric center region on the upper outer panel 1, and applies a complete fixed constraint to all nodes on this surface, that is, restricts its translation in three directions and rotation in three directions, thereby establishing the unique reference of the entire model in space, so that the subsequent thermal deformation calculation results are all relative deformations with this fixed point as a reference, which is completely consistent with the scenario where the connecting buckle 4 is fixed to the body of the actual vehicle.

[0073] Then, the system creates a uniform temperature field load in the load condition definition module, with the temperature value set to 80℃. The solver automatically converts this temperature value to Kelvin (353.15K) internally and applies this uniform temperature field simultaneously to all nodes of the upper outer panel 1 and the exterior trim components, including the outer trim panel 2 and connecting clips 4, simulating the extreme condition where the entire rear cover assembly heats up to 80℃ under summer sun exposure. The solver then performs a linear elastic thermo-mechanical coupling calculation to obtain the displacement and stress field results of the model at the specified temperature.

[0074] Finally, after the solution is completed, the post-processing module outputs as follows: Figure 8 and Figure 9 The total displacement distribution cloud map shown and as follows Figure 10 The diagram shows the cross-sectional displacement of the connecting clip 4 and the locating pin 3. Analysts can visually read the total displacement value of the edge of the outer trim panel 2 from the contour plot.

[0075] In measurements of a specific rear cover assembly model, CATIA analysis showed a total displacement of 2.41 mm along the edge of the outer trim panel 2, with the deformation direction being inward bending. To verify the accuracy of the analysis results, the same 3D model and boundary conditions can be used to perform simulation analysis in both ANSYS and HYPERMESH software.

[0076] ANSYS uses solid elements with identical material properties and connection settings for calculation. HYPERMESH, in conjunction with its corresponding solver, uses shell elements and equivalent connections for modeling. The comparison results are shown in the table: ANSYS analysis shows that the total displacement along the edge of exterior panel 2 is 2.45 mm, with the bending direction inward.

[0077] The total displacement value of the second edge of the exterior panel analyzed by HYPERMESH is 2.01 mm, and the bending direction is also inward. The 2.41 mm obtained by this method, namely CATIA analysis, is exactly between the analysis results of the other two mainstream software programs, and all three are consistent in the bending direction.

[0078] The comparison results show that the three-dimensional linear model analysis path executed by CATIA in this embodiment can provide simulation accuracy comparable to industry benchmark software. The results are within a reasonable range acceptable to engineering, and have high accuracy and reliability. It can be fully used to guide the thermal deformation design optimization of the automotive rear cover exterior panel 2.

[0079] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0080] like Figure 14 The diagram shows a hardware structure of a computer device according to the present invention, including a memory 1402, a processor 1401, and a computer program on the memory 1402. The processor 1401 executes the computer program to implement the steps of the thermal deformation analysis method for the exterior trim panel of a car rear cover in any of the above embodiments.

[0081] Figure 14 Take a processor 1401 as an example.

[0082] The computer device may also include an input device 1403 and a display device 1404.

[0083] The processor 1401, memory 1402, input device 1403 and display device 1404 can be connected by a bus or other means. The figure shows an example of connection by bus.

[0084] The memory 1402, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as the program instructions / modules corresponding to the thermal deformation analysis method for the automotive rear cover exterior panel in the embodiments of this application. The processor 1401 executes various functional applications and data processing by running the non-volatile software programs, instructions, and modules stored in the memory 1402, thereby implementing the thermal deformation analysis method for the automotive rear cover exterior panel in the above embodiments.

[0085] Memory 1402 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and an application program required for at least one function; the data storage area may store data created based on the use of the thermal deformation analysis method for the automotive rear cover exterior panel. Furthermore, memory 1402 may include high-speed random access memory and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, memory 1402 may optionally include memory remotely located relative to processor 1401, and this remote memory may be connected via a network to means of performing the thermal deformation analysis method for the automotive rear cover exterior panel. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0086] The input device 1403 can receive user clicks and generate signal inputs related to user settings and function control for the thermal deformation analysis method of the vehicle's rear cover exterior panel. The display device 1404 may include a display screen or other display equipment.

[0087] When one or more modules are stored in the memory 1402 and are run by one or more processors 1401, the thermal deformation analysis method for the automotive rear cover exterior panel in any of the above method embodiments is executed.

[0088] When the computer device disclosed in this invention is running, it can execute all the steps of the above-mentioned method for analyzing the thermal deformation of the exterior trim panel of a car rear cover. By determining the analysis path according to the instructions and importing model data and modeling process differently, it performs mesh generation, attribute assignment, connection establishment and temperature load application under the two paths respectively, and finally obtains the temperature deformation cloud map. It achieves the goal of taking into account both fast linear analysis and high-precision nonlinear analysis within the same method framework, so that users can flexibly choose according to engineering needs and can quickly and efficiently analyze the thermal deformation of the exterior trim panel of the car rear cover.

[0089] One embodiment of the present invention provides a computer-readable storage medium storing a computer program / instructions that, when executed by a processor 1401, implement all the steps of the thermal deformation analysis method for the exterior trim panel of a car rear cover as described above.

[0090] In the context of this disclosure, a storage medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. The storage medium can be a machine-readable signal medium or a machine-readable storage medium. Optionally, the storage medium can be a non-transitory computer-readable storage medium, such as a ROM, random access memory (RAM), compact disc ROM (CD ROM), magnetic tape, floppy disk, and optical data storage device.

[0091] One embodiment of the present invention provides a computer program product, including a computer program / instructions, which, when executed by a processor, implement the steps of the thermal deformation analysis method for the exterior trim panel of a car rear cover as described above.

[0092] By running the aforementioned computer program, all steps of the thermal deformation analysis method for automotive rear cover exterior panels described above can be executed. By determining the analysis path according to the instructions and importing model data and modeling processes differently, mesh generation, attribute assignment, connection establishment, and temperature load application are performed under two different paths, ultimately obtaining a temperature deformation cloud map. This achieves the goal of balancing fast linear analysis and high-precision nonlinear analysis within the same methodological framework, allowing users to flexibly choose according to engineering needs and quickly and efficiently analyze the thermal deformation of automotive rear cover exterior panels.

[0093] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for analyzing the thermal deformation of an automotive rear cover exterior panel, characterized in that, include: Determine and analyze the path based on the instructions; If the path is determined to be a three-dimensional linear model analysis path, then import the three-dimensional model data of the upper outer panel, the outer trim panel including the positioning parts, and the connecting structure to obtain a three-dimensional dataset. If the path is determined to be a three-dimensional nonlinear model analysis path, then import the three-dimensional model data of the upper outer panel and the outer trim panel excluding the positioning parts to obtain a three-dimensional dataset. Perform mesh generation on the components in the 3D dataset; If it is a three-dimensional linear model analysis path, first assign material properties to each component, then establish connections between each component and apply boundary conditions; If it is a three-dimensional nonlinear model analysis path, first establish the connection between each component, then set the contact relationship, then assign material properties to each component, and finally apply boundary conditions. A preset temperature load is applied to each component and analyzed to obtain a temperature deformation cloud map.

2. The method for analyzing the thermal deformation of the automotive rear cover exterior panel according to claim 1, characterized in that, The process of importing the three-dimensional model data of the upper outer panel, the outer trim panel including the positioning component, and the connecting structure is described. The positioning component includes the positioning pin and the connecting adhesive on the outer trim panel, and the connecting structure includes the connecting buckle provided on the upper outer panel.

3. The method for analyzing the thermal deformation of the automotive rear cover exterior panel according to claim 2, characterized in that, The meshing operation for components in the 3D dataset includes: For the three-dimensional linear model analysis path, all components are divided into tetrahedral three-dimensional meshes, with the mesh size of the upper outer panel and the outer trim panel being the first preset size, and the mesh size of the connecting buckle being the second preset size; For the three-dimensional nonlinear model analysis path, the middle surface of the upper outer panel and the outer trim panel is first extracted, and then the middle surface is divided into quadrilateral meshes with the mesh size being the third preset size. Local coordinate systems are established at the corresponding positions of the positioning pin, connecting buckle, and connecting adhesive, and spring elements are used to simulate the positioning pin, connecting buckle, and connecting adhesive.

4. The method for analyzing the thermal deformation of the automotive rear cover exterior panel according to claim 2, characterized in that, The process of first assigning material properties to each component, then establishing connections between the components and applying boundary conditions includes: Assign material properties, including elastic modulus, Poisson's ratio, density and coefficient of thermal expansion for the outer panel and connecting buckle, and elastic modulus, Poisson's ratio, density and coefficient of thermal expansion for the upper outer panel; The connection is established, with the connecting buckle and the upper outer panel connected by virtual bolts, and the connecting buckle and the outer trim panel connected by welding; the positioning pin and the upper outer panel are connected by flexible means, with the middle positioning pin only releasing the degree of freedom of movement in the Z-axis direction and the degree of freedom of rotation around the Z-axis, and restricting the other degrees of freedom; the positioning pins at both ends only releasing the degree of freedom of movement in the Y and Z-axis directions and the degree of freedom of rotation around the Z-axis, and restricting the other degrees of freedom; Apply boundary conditions to fix the connecting clip mounting surface at the center of the upper outer panel.

5. The method for analyzing the thermal deformation of the exterior trim panel of a car rear cover according to claim 4, characterized in that, In the description of imparting material properties, the material properties of the exterior trim panel and connecting buckle are specifically an elastic modulus of 3.7 × e. 9 Pa, Poisson's ratio 0.35, density 1230 kg / m³, coefficient of thermal expansion 5 × e -5 / K; The material properties of the upper outer panel are specifically the elastic modulus 2×e. 11 Pa, Poisson's ratio 0.266, density 7850 kg / m³, coefficient of thermal expansion 1.2 × e -5 / K.

6. The method for analyzing the thermal deformation of the exterior trim panel of a car rear cover according to claim 2, characterized in that, The process of first establishing connections between components, then setting contact relationships, then assigning material properties to each component, and finally applying boundary conditions includes: Establish connections by simulating the corresponding positions of the model's locating pins, connecting clips, and connecting adhesive using spring units. Specifically, the locating pin units are set with stiffness in the X and Y directions, releasing the other four degrees of freedom; the connecting clip units are set with stiffness in the X, Y, and Z directions, releasing the other three degrees of freedom; and the connecting adhesive units are set with stiffness in all six directions based on the properties of the adhesive. Set the contact relationship, designate the upper outer panel contact surface as the primary contact surface, the outer trim panel contact surface as the secondary contact surface, and set the friction coefficient of the contact surfaces. Each component is assigned material properties. The material properties of the outer panel include component thickness, Poisson's ratio, density, as well as the elastic modulus curve, thermal expansion coefficient curve, and stress-strain curve as they change with temperature. The material properties of the upper outer panel include elastic modulus, Poisson's ratio, density, and thermal expansion coefficient. Apply boundary conditions to fix the connecting clip mounting surface at the center of the upper outer panel.

7. The method for analyzing the thermal deformation of the exterior trim panel of a car rear cover according to claim 1, characterized in that, The preset temperature load is the Kelvin temperature of 353.15K corresponding to 80℃, and it is applied to the upper outer panel and the outer trim panel.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method for analyzing the thermal deformation of the automotive rear cover exterior panel according to any one of claims 1-7.

9. A computer-readable storage medium having a computer program / instructions stored thereon, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method for analyzing the thermal deformation of the automotive rear cover exterior panel as described in any one of claims 1-7.

10. A computer program product, comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method for analyzing the thermal deformation of the automotive rear cover exterior panel as described in any one of claims 1-7.

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