Vehicle body structure performance simulation analysis method

Abstract

The invention discloses a vehicle body structure performance simulation analysis method. The method comprises the following steps: S1, carding a vehicle body skeleton architecture model; s2, segmenting a part formed by connecting a plurality of sections in the vehicle body skeleton architecture model, and determining a geometric model of a multi-section single section; s3, projecting the sections of the parts with the single section shape and the multi-section geometric model with the single section in the vehicle body skeleton architecture model to obtain the projected sections; s4, giving attributes to each section after projection; s5, performing central point marking on the section with the attribute, and determining a marked node; s6, generating a vehicle body skeleton model according to the marked nodes; s7, connecting a vehicle body structure according to the vehicle body skeleton model, and building a connected vehicle body skeleton model; s8, connecting the rear vehicle body skeleton model, and evaluating the performance of the vehicle body structure; according to the method, the vehicle body skeleton is segmented, the section projection is endowed with attributes, and node marking is performed on each shape center point of the section end face, so that the calculation efficiency is improved by 100-500%.

Description

Technical Field

[0001] The present invention relates to the field of vehicle body structure analysis, and particularly to a method for simulating and analyzing the performance of a vehicle body structure. Background Art

[0002] The forward development of an automobile is a rigorous and long process, and the R & D cycle of a vehicle may even take 5 to 6 years. In today's increasingly competitive global automotive market, the automotive industry needs to continuously compress the R & D cycle and accelerate the launch speed of new models in order to better occupy the automotive market share.

[0003] During the vehicle body R & D process, multiple rounds of modifications to the vehicle body structure and verification of vehicle body performance are required. The application of CAE finite element analysis technology can effectively assist the automotive R & D process and can replace tests to evaluate the performance of the vehicle body structure.

[0004] The traditional vehicle body modeling method is a combined modeling method of shell elements and solid elements, and according to different connection methods, the connection is made in a pairwise combination of solid elements, shell elements or 1D elements; in the CAE analysis and verification stage, due to the large size of the whole vehicle model and the large number of grids, this modeling method takes a long time and the calculation process is quite slow, with high requirements for computer performance, which slows down the vehicle body optimization and iteration process.

[0005] Existing methods for simulating and analyzing the performance of a vehicle body structure, such as CN104573174A, disclose a method for analyzing the stiffness of a vehicle body based on CAE; used to analyze the bending stiffness and torsional stiffness of the front longitudinal beam, sill and rear longitudinal beam of the vehicle body, including: establishing a finite element mesh model and coordinate system of the vehicle body, performing simulation tests by applying loads and constraints, obtaining the processing results, and generating curves, and then determining whether the processing results meet the requirements. If they meet the requirements, the processing results are saved; otherwise, a finite element mesh model of the vehicle body is re-established for re-simulation tests; the calculation efficiency of vehicle body performance in the prior art is low and it takes a long time.

[0006] Therefore, those skilled in the art urgently need to provide a method for simulating and analyzing the performance of a vehicle body structure with high calculation efficiency and short time consumption. Summary of the Invention

[0007] The object of the present invention is to provide a method for simulating and analyzing the performance of a vehicle body structure to solve the problems existing in the above prior art.

[0008] A method for simulating and analyzing the performance of a vehicle body structure includes the following steps:

[0009] S1: Sort out the vehicle body skeleton architecture model;

[0010] S2: Divide the parts formed by connecting multiple cross-sections in the body skeletal framework model to determine the geometric models of multiple single cross-sections;

[0011] S3: Perform cross-section projection on the cross-sections of the parts with single cross-section shapes and the geometric models of multiple single cross-sections in the body skeletal framework model to obtain the projected cross-sections;

[0012] S4: Assign attributes to each of the projected cross-sections;

[0013] S5: Mark the center points of the cross-sections after attribute assignment to determine the marked nodes;

[0014] S6: Generate a body skeleton model based on the marked nodes;

[0015] S7: Connect the body structures according to the body skeleton model to construct the connected body skeleton model;

[0016] S8: Evaluate the body structure performance based on the connected body skeleton model.

[0017] Preferably, comb the body skeletal framework model, specifically including: Import the 3D model established in CAD software into the analysis software, and split the 3D model into the body skeletal framework model and the remaining parts in the analysis software; The body skeletal framework model includes multiple geometric models; Convert the multiple geometric models into multiple grayscale models, and set the remaining parts to be hidden; Distinguish the multiple grayscale models, and divide the multiple grayscale models into parts with single cross-section shapes and parts formed by connecting multiple cross-sections; Create a new group one, change the color of the parts with single cross-section shapes to a unified color, and at the same time move the parts with single cross-section shapes to group one; Create a new group two, change the color of the parts formed by connecting multiple cross-sections to another unified color different from the color of the parts with single cross-section shapes, and at the same time move the parts formed by connecting multiple cross-sections to group two; Comb the body skeletal framework model according to group one and group two.

[0018] Preferably, divide the parts formed by connecting multiple cross-sections in the body skeletal framework model to determine the geometric models of multiple single cross-sections, specifically including: At the connection position of each cross-section of the parts formed by connecting multiple cross-sections in group two, establish a plane perpendicular to the side line of the parts formed by connecting multiple cross-sections; Divide and split the parts formed by connecting multiple cross-sections along the direction of the perpendicular plane to determine the geometric models of multiple single cross-sections.

[0019] Preferably, perform cross-section projection on the parts with a single cross-section shape and the geometric models with multiple single cross-sections in the vehicle body skeleton architecture model to obtain the projected cross-sections, specifically including: comparing the shapes of each cross-section in the parts with a single cross-section shape and the geometric models with multiple single cross-sections with the shapes in the cross-section library of the analysis software to determine the comparison result; the comparison result includes that the cross-section shape is in the cross-section library of the analysis software and that the cross-section shape is not in the cross-section library of the analysis software; based on the comparison result, project the cross-section shapes not in the cross-section library of the analysis software to obtain the projected cross-sections.

[0020] Preferably, assign attributes to each projected cross-section, specifically including: creating cross-section attributes for the parts with a single cross-section shape and the cross-sections of the geometric models with multiple single cross-sections in the cross-section library of the analysis software, and the projected cross-sections; the cross-section attributes include the shape of the cross-section and the corresponding material model.

[0021] Preferably, mark the center points of the cross-sections after attribute assignment to determine the marked nodes, specifically including: geometrically marking the center points of each shape of the cross-sections after attribute assignment; converting the marked geometric points into node marks to determine the marked nodes.

[0022] Preferably, generate a vehicle body skeleton model according to the marked nodes, specifically including: for the straight parts after marking the nodes, select two marked nodes as the two end points to generate a 1D part model; for the parts with a bent shape after marking the nodes, select two marked nodes as the two end points and select the side line on the part with a bent shape as the path to generate a 1D part model; generate a vehicle body skeleton model according to the 1D part model.

[0023] Preferably, connect the vehicle body structures according to the vehicle body skeleton model to construct the connected vehicle body skeleton model, specifically including: connecting different cross-sections in the 1D part model by using the co-node connection method; connecting the beam units between different shapes belonging to the same cross-section in the 1D part model by using spring-damper units; the number of the spring-damper units is the total number of nodes of the beam units; connecting different 1D part models by using the spring-damper units.

[0024] Preferably, evaluate the performance of the vehicle body structure according to the connected vehicle body skeleton model, specifically including: calculating the weight and mode of the connected vehicle body skeleton model; performing finite element analysis on the bending stiffness and torsional stiffness of the connected vehicle body skeleton model according to the weight and the mode to evaluate the performance of the vehicle body structure.

[0025] Compared with the prior art, the present invention provides a method for simulating and analyzing the performance of a vehicle body structure, having the following beneficial effects:

[0026] In the present invention, a 1D unit is used for vehicle body modeling, and a bush unit with a spring and a damper is used as the connection. The modeling method is simple, omitting the time for conventional mesh generation and mesh quality query and modification; by segmenting the vehicle body skeleton, projecting the cross-section after segmentation and assigning attributes, and marking nodes for each shape center point of the cross-section end face after attribute assignment; thus, the calculation efficiency is increased by 100 - 500%. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1 It is a schematic diagram of the analysis process of the present invention;

[0029] Figure 2 It is a schematic diagram of the vehicle body in a state without skin of the present invention;

[0030] Figure 3 It is a schematic diagram of the vehicle body in a state with skin of the present invention;

[0031] Figure 4 It is a schematic diagram of the vehicle body in a state with skin of the comparative example of the present invention;

[0032] Figure 5 It is a displacement nephogram of the vehicle body in a state with skin of the present invention;

[0033] Figure 6 It is a displacement nephogram of the vehicle body in a state with skin of the comparative example of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0035] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0036] As Figures 1-3 shown, a vehicle body model is established using the CBEAM unit in the 1D unit. As Figure 2 is the vehicle body in a state without skin, Figure 3The body with skin; only the front and rear two castings are in the form of shell elements, and the rest of the body model is established by connecting CBEAM elements and BUSH elements.

[0037] Example 1: Take the body with skin as an example;

[0038] S1: Before sorting out the body bone structure model, establish a 3D body model in CAD software;

[0039] Import the 3D model established in CAD software into the analysis software, and split the model into the body bone structure model and the remaining parts;

[0040] Change the color of the appearance of the body bone structure model to gray uniformly, and hide the remaining parts;

[0041] Divide the gray body bone structure model into parts with a single cross-sectional shape and parts composed of multiple connected cross-sections; the parts with a single cross-sectional shape are profile parts; the parts composed of multiple connected cross-sections are parts composed of thin plates;

[0042] Establish Group 1: Create a new Group 1, change the color of the parts with a single cross-sectional shape to a unified color, and at the same time move the parts with a single cross-sectional shape to Group 1; create a new Group 2, change the color of the parts composed of multiple connected cross-sections to another unified color different from the color of the parts with a single cross-sectional shape, and at the same time move the parts composed of multiple connected cross-sections to Group 2.

[0043] S2: For the parts composed of multiple connected cross-sections in Group 2, perform segmentation and splitting to obtain a geometric model of multiple single cross-sections.

[0044] S3: Compare the shape of each cross-section in the parts with a single cross-sectional shape and the geometric model of multiple single cross-sections with the shapes in the cross-section library of the analysis software to determine the comparison result; the comparison result is the cross-sectional shape in the cross-section library of the analysis software and the cross-sectional shape not in the cross-section library of the analysis software;

[0045] Based on the comparison result, project the cross-sectional shape not in the cross-section library of the analysis software to obtain the projected cross-section; the projected cross-section has the same shape and thickness as the geometric model.

[0046] S4: The cross-sectional shape in the cross-section library of the analysis software, the shape attributes of the projected cross-section, and the corresponding material attributes.

[0047] S5: Mark the center points of each shape of the cross-section after assigning attributes with geometric points; convert the marked geometric points into node marks to determine the marked nodes.

[0048] S6: For the straight parts after node marking, select two marked nodes as the two endpoints to generate a 1D part model; for the parts with a bent shape after node marking, select two marked nodes as the two endpoints and select the side line on the part with a bent shape as the path to generate a 1D part model.

[0049] Check whether the cross-section generation direction is consistent with that of the parts with a single cross-section shape and the parts formed by connecting multiple cross-sections. If it is consistent, it passes; if it is inconsistent, the selected model can be adjusted to a unit, the problematic unit can be selected, and the coordinate values in its attributes can be modified for change and adjustment.

[0050] S7: Connect different cross-sections in the 1D part model by using the co-node connection method; connect the beam elements between different shapes belonging to the same cross-section in the 1D part model by using spring-damper elements; the number of the spring-damper elements is the total number of nodes of the beam elements; connect different 1D part models by using the spring-damper elements.

[0051] Connect different parts by using spring-damper elements, and sort out 5-10 spring-damper elements at the connection points; input the respective six-directional stiffnesses at different connection positions according to different materials.

[0052] S8: Calculate the weight and mode of the connected vehicle body frame model; perform finite element analysis on the connected vehicle body frame model for bending stiffness and torsional stiffness according to the weight and the mode to evaluate the vehicle body structure performance.

[0053] According to the cross-section shape attributes in the S4 software cross-section library, the cross-section shape attributes after projection, and their corresponding material attributes, that is, according to the shape size attributes and material attributes, calculate the weight and mode of the connected vehicle body frame model through the analysis software.

[0054] The vehicle body mass and mode are key characteristics of the vehicle body, which can reflect the structural stability, dynamic response, reliability and other performances of the vehicle body. Measure the mass of the vehicle body, calculate its mode, and compare it with the conventional model, and the error difference is less than 5%; perform finite element analysis on the established vehicle body structure, evaluate its stiffness and strength results, and verify the feasibility of the model.

[0055] As Figures 3-4 shown, Figure 4To establish a vehicle body model by combining shell elements and solid elements; taking a certain vehicle body as an example, the vehicle body model is established by using the modeling method provided by the present invention. The results show that the mass of the vehicle body model established by the method of the present invention differs by 2.9% from that of the vehicle body model established by the conventional method. With the same boundary conditions, the bending stiffness, torsional stiffness and mode of the two models are calculated respectively. The difference in bending stiffness is 4.3%, the difference in torsional stiffness is 3.3%, and the difference in the natural frequency of the first-order mode is 3.9%; as Figures 5-6 shown, the distribution of the displacement nephograms of the two models is consistent. In the figure, Eigen Mode is interpreted as the eigenmode, Mag is the abbreviation of Magnitude, meaning amplitude, and Eigen Mode (Mag) is interpreted as the vibration amplitude corresponding to the eigenmode as a whole. Analysis system is interpreted as the analysis of the current visualization result, and No Result is interpreted as no valid data is calculated in the corresponding color area of the model; the calculation time is increased by 411%, greatly improving the calculation efficiency.

[0056] Table 1 Comparison table between the 1D model of the present application and the conventional model

[0057]

[0058] The present invention establishes a new method for establishing a vehicle body model, with very little difference in weight from the conventional model, and in terms of the calculation results, the vehicle body performance values differ by less than 5%, and the calculation efficiency is increased by 411%.

[0059] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0060] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for simulating and analyzing the performance of a vehicle body structure, characterized in that It includes the following steps: S1: Combing the body skeletal framework model; S2: Dividing the parts formed by connecting multiple cross-sections in the body skeletal framework model to determine the geometric models of multiple single cross-sections; S3: Performing cross-section projection on the cross-sections of the parts with a single cross-section shape and the geometric models of multiple single cross-sections in the body skeletal framework model to obtain the projected cross-sections; S4: Assigning attributes to each of the projected cross-sections; S5: Marking the center points of the cross-sections after attribute assignment to determine the marked nodes; S6: Generating the body skeleton model based on the marked nodes; S7: Connecting the body structure according to the body skeleton model to construct the connected body skeleton model; S8: Evaluating the body structure performance according to the connected body skeleton model.

2. The method for simulating and analyzing the performance of a vehicle body structure according to claim 1, wherein Combing the body skeletal framework model specifically includes: Importing the 3D model established in CAD software into the analysis software, and splitting the 3D model into the body skeletal framework model and the remaining components in the analysis software; the body skeletal framework model includes multiple geometric models; Converting the multiple geometric models into multiple grayscale models and setting the remaining components as hidden; Differentiating the multiple grayscale models and dividing the multiple grayscale models into parts with a single cross-section shape and parts formed by connecting multiple cross-sections; Creating a new group 1, changing the color of the parts with a single cross-section shape to a unified color, and at the same time moving the parts with a single cross-section shape to group 1; Creating a new group 2, changing the color of the parts formed by connecting multiple cross-sections to another unified color different from the color of the parts with a single cross-section shape, and at the same time moving the parts formed by connecting multiple cross-sections to group 2; Combing the body skeletal framework model according to group 1 and group 2.

3. A method for simulating and analyzing the performance of a vehicle body structure according to claim 2, characterized in that, Dividing the parts formed by connecting multiple cross-sections in the body skeletal framework model to determine the geometric models of multiple single cross-sections specifically includes: Establishing a plane perpendicular to the side line of the part formed by connecting multiple cross-sections at the connection position of each cross-section of the parts formed by connecting multiple cross-sections in group 2; Dividing and splitting the parts formed by connecting multiple cross-sections along the direction of the perpendicular plane to determine the geometric models of multiple single cross-sections.

4. A method for simulating and analyzing the performance of a vehicle body structure according to claim 3, characterized in that Performing cross-section projection on the parts with a single cross-section shape and the geometric models of multiple single cross-sections in the body skeletal framework model to obtain the projected cross-sections specifically includes: Comparing the shape of each cross-section of the parts with a single cross-section shape and the geometric models of multiple single cross-sections with the shapes in the cross-section library of the analysis software to determine the comparison result; the comparison result includes that the cross-section shape is in the cross-section library of the analysis software and that the cross-section shape is not in the cross-section library of the analysis software; Based on the comparison result, projecting the cross-section shapes not in the cross-section library of the analysis software to obtain the projected cross-sections.

5. A method for simulating and analyzing the performance of a vehicle body structure according to claim 4, characterized in that, Assigning attributes to each of the projected cross-sections specifically includes: Creating cross-section attributes for the cross-sections of the parts with a single cross-section shape and the geometric models of multiple single cross-sections in the cross-section library of the analysis software, as well as the projected cross-sections; The cross-section attributes include the shape of the cross-section and the corresponding material model.

6. The method for simulating and analyzing the body structure performance according to claim 5, wherein, Mark the center points of the cross-sections after attribute assignment, and determine the marked nodes, specifically including: Perform geometric point marking on the center points of each shape of the cross-section after attribute assignment; Convert the marked geometric points into node markings to determine the marked nodes.

7. A method for simulating and analyzing the performance of a vehicle body structure according to claim 6, characterized in that, Generate a vehicle body frame model based on the marked nodes, specifically including: For the straight parts after node marking, select two marked nodes as the two endpoints to generate a 1D part model; For the parts with a curved shape after node marking, select two marked nodes as the two endpoints, and select the side line on the part with a curved shape as the path to generate a 1D part model; Generate a vehicle body frame model based on the 1D part model.

8. A method for simulating and analyzing the performance of a vehicle body structure according to claim 7, characterized in that, Connect the vehicle body structures according to the vehicle body frame model to construct the connected vehicle body frame model, specifically including: Connect different cross-sections in the 1D part model by using the co-node connection method; Connect the beam elements between different shapes belonging to the same cross-section in the 1D part model by using spring-damper elements; the number of the spring-damper elements is the number of all nodes of the beam elements; Connect different 1D part models by using the spring-damper elements.

9. A method for simulating and analyzing the performance of a vehicle body structure according to claim 8, characterized in that Evaluate the performance of the vehicle body structure according to the connected vehicle body frame model, specifically including: Calculate the weight and mode of the connected vehicle body frame model; Perform finite element analysis on the bending stiffness and torsional stiffness of the connected vehicle body frame model according to the weight and the mode to evaluate the performance of the vehicle body structure.

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