Automobile front longitudinal beam crushing performance analysis method

Abstract

The invention relates to the technical field of automobile optimization simulation methods, in particular to an automobile front longitudinal beam crushing performance analysis method. Arranging a rigid wall, and constraining and fixing the rigid wall; setting boundary conditions of the finite element analysis model, setting a rear end constraint point, and ensuring that the front longitudinal beam model can advance along a single direction; coupling a rigid unit with the constrained grid unit at the rear end of the front longitudinal beam, and carrying out displacement loading; a display dynamics module is applied to solving software for simulation calculation; the overall stress state of the front longitudinal beam is obtained through a loading point force-displacement curve, the total energy absorption state of the part is obtained through an energy change curve, and the actual deformation state of the part in the crushing process is obtained through a stress cloud picture. The optimization comparison analysis process is high in accuracy, and the crushing resistance of the front longitudinal beam can be quickly and effectively analyzed; a vehicle body design engineer can conveniently confirm performance indexes of self-designed part structures in the early stage of vehicle body development, so that the part development period and cost are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of automobile optimization simulation methods, and in particular to a method for analyzing the crushing performance of an automobile front longitudinal beam. Background Art

[0002] When a car collides head-on, the load-bearing capacity of the energy-absorbing structure composed of the front longitudinal beam and the anti-collision beam directly affects the safety performance of the entire vehicle. The front longitudinal beam is an important load-bearing component at the front end of the vehicle body and the main energy-absorbing component during a frontal collision. Its energy absorption characteristics and deformation mode determine the vehicle body acceleration response and force transmission path during a collision, and have a significant impact on the crashworthiness of the vehicle structure.

[0003] Domestic and foreign research shows that the energy absorbed by the front longitudinal beam in a head-on collision accounts for about 50% of the total energy absorbed by the vehicle, which has a very important impact on the collision safety performance of the entire vehicle. The main failure form of the front longitudinal beam in the normal energy absorption process is crushing failure, so the analysis and evaluation of the crushing performance of the front longitudinal beam is particularly important.

[0004] However, the most intuitive evaluation of vehicle collision safety is to conduct a whole vehicle collision analysis. However, when optimizing the structure of specific parts, this method is difficult to decompose the overall goal, and the verification calculation is too large. This results in a long development cycle and increased costs. At the same time, in the early stages of body development, it is difficult for body design engineers to intuitively confirm the evaluation indicators of the part structure they designed. Summary of the invention

[0005] In order to overcome the shortcomings of the existing technology, a method for analyzing the crushing performance of a front longitudinal beam of an automobile is provided. The optimization and comparative analysis process has high accuracy and can quickly and effectively analyze the crushing resistance of the front longitudinal beam itself; it is convenient for body design engineers to confirm the performance indicators of their own designed part structures in the early stage of body development, thereby reducing the part development cycle and cost.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for analyzing the crushing performance of a front longitudinal beam of an automobile, comprising the following steps:

[0008] S1: First, select the front longitudinal beam of the automobile to be analyzed, and use the finite element pre-processing model software to establish the front longitudinal beam crushing simulation analysis model; perform a center surface inspection on the front longitudinal beam crushing simulation analysis model, and if it is qualified, mesh the center surface to form mesh units;

[0009] S2: Perform quality check on grid cells;

[0010] S3: Set the welding point connection and set up the welding unit at the welding point position;

[0011] S4: Set a rigid wall and constrain the fixed rigid wall at the same time; set the boundary conditions of the finite element analysis model, set the rear end constraint point, constrain the 5 degrees of freedom of the grid, and ensure that the front longitudinal beam model can move in a single direction;

[0012] S5: Apply rigid units to couple the constrained grid units at the rear end of the front longitudinal beam to obtain the loading point and perform displacement loading;

[0013] S6: Set material properties;

[0014] S7: Set the contact properties of the entire model and set the mass scaling factor;

[0015] S8: Apply the display dynamics module in the solution software to perform simulation calculations;

[0016] S9: extract the force-displacement curve of the loading point and the energy change curve;

[0017] Confirm the hourglass change, if it is greater than the set value, return to step S7, otherwise output the stress cloud map;

[0018] S10: The overall stress state of the front longitudinal beam can be determined through the force-displacement curve at the loading point, the total energy absorption state of the part can be determined through the energy change curve, and the actual deformation state of the part during the crushing process can be determined through the stress cloud diagram.

[0019] Furthermore, in S1, the qualified condition is the condition without broken and chipped surface.

[0020] Furthermore, in S1, the size of the grid unit is 3-15 mm, and the types of the grid unit are rectangular shell unit and triangular shell unit.

[0021] Furthermore, in S2, the items for mesh unit quality inspection are: target size, minimum size, maximum size, aspect ratio warping, triangle unit percentage, maximum inner angle of quadrilateral, minimum inner angle of quadrilateral, maximum inner angle of triangle, minimum inner angle of triangle, inclination and Jacobian.

[0022] Furthermore, in S3, the welding point is set as a polygonal welding point, and the welding point unit is coupled with the surrounding grid using a flexible unit.

[0023] Furthermore, in S5, the displacement is set to 25-35 mm.

[0024] Furthermore, in S6, material stress-strain curve, elastic modulus, Poisson's ratio, and mass density are introduced.

[0025] Further, in S7, the friction coefficient is set to 0.15, and the target time increment is set to 5e-07.

[0026] Furthermore, in S9, the hourglass energy increment standard is set to 8-12%.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention arranges a rigid obstacle avoidance device at the front end of the front longitudinal beam and a constraint at the rear end, so that the front longitudinal beam is displaced in the obstacle avoidance direction, and collects the crushing force and internal energy data of the longitudinal beam; only the force and internal energy change curves during the crushing process are observed, and the main investigation indicators are the crushing force peak value and the internal energy rising effect. At the same time, the actual deformation state of the part during the crushing process is judged according to the stress cloud map.

[0029] 1. The method is simple to set up and easy to operate. The present invention obtains the force-displacement curve, energy change curve, and stress cloud diagram reflecting the deformation state during the crushing process of the front longitudinal beam. The crushing performance of the front longitudinal beam in the design process can be intuitively observed based on several data.

[0030] 2. The optimization comparison and analysis process is highly accurate, providing a theoretical basis for body design engineers, providing a change direction for subsequent design optimization, and facilitating body design engineers to confirm the performance indicators of their own designed parts structure in the early stage of body development, greatly reducing the parts development cycle and cost. The present invention can quickly and effectively analyze the anti-crushing ability of the front longitudinal beam itself.

[0031] 3. A regular working host can complete a round of analysis in 1.5 hours to achieve the purpose of rapid optimization and iteration. At the same time, it has the characteristics of simple steps, short time consumption, high accuracy, etc., and has a strong practical application foundation.

[0032] The present invention is different from the traditional method of decomposing the performance indicators downward after simulating the performance of the whole vehicle. Instead, it decouples the vehicle body structure and sets the working condition and performs performance analysis for individual small assembly-level parts. Since the stress state of individual small assembly parts is relatively simple, it is easier to set the working condition and the operation is more convenient. At the same time, because the coupling conditions are reduced, the simulation analysis accuracy will be significantly improved, the analysis time will be greatly reduced, and it can be completed by a conventional working host. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is the analysis flow chart of the present invention.

[0034] Figure 2 It is a schematic diagram of the crush analysis of the front longitudinal beam of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with examples of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the implementation case described is only one of the embodiments of the present invention, and those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It is particularly important to point out that all similar replacements and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0036] like Figure 1 , Figure 2 As shown in the figure, a method for analyzing the crushing performance of the front longitudinal beam of an automobile is provided. A rigid obstacle avoidance is set at the front end of the front longitudinal beam, and a constraint is set at the rear end, so that the front longitudinal beam is displaced in the obstacle avoidance direction, and the crushing force and internal energy data of the longitudinal beam are collected. At the same time, due to the force of a single system, in order to avoid the collapse of the components, the overall simulation effect is distorted, and the displacement distance cannot be too large. Only the force and internal energy change curves during the crushing process are observed. The main indicators for investigation are the crushing force peak value and the internal energy rise effect. At the same time, the actual deformation state of the parts during the crushing process is judged based on the stress cloud map.

[0037] The analysis method specifically includes the following steps:

[0038] Step 1: Use finite element pre-processing model software to establish a front longitudinal beam crush simulation analysis model, and perform a center surface inspection on the simulation model to confirm that there are no broken or chipped surfaces.

[0039] After passing the test, the processed center surface is meshed, the mesh unit size is 8 mm, and the mesh unit types are S4R (rectangular shell element) and S3 (triangular shell element).

[0040] Step 2: Perform quality inspection on the grid units. The specific inspection standards are as follows:

[0041] Table 1 Grid unit inspection standards

[0042]

[0043] Step 3. Set the solder joint connection. Use the theoretical design position for the solder joint position. Set up a welding unit at the solder joint position. Set the solder joint to Hexa (polygonal solder joint). Use Rbe3 (flexible unit) to couple the solder joint unit with the surrounding mesh.

[0044] Step 4: Set rigid walls and constrain fixed rigid walls. Set the boundary conditions of the finite element analysis model and set the rear end constraint surface, which is taken from the connection area between the front longitudinal beam part and the body cockpit. Constrain the grid with 5 degrees of freedom to ensure that the front longitudinal beam model can move in a single direction.

[0045] Step 5. In order to effectively simulate the actual state of the front longitudinal beam in the crush bench test and ensure that the front longitudinal beam moves perpendicular to the rigid wall, apply Rbe2 (rigid unit coupling) to the constrained grid unit at the rear end of the front longitudinal beam to obtain the loading point and perform displacement loading. The displacement is set to 30 mm.

[0046] Step 6. Then set the material properties and import the material stress-strain curve, elastic modulus, Poisson's ratio, and mass density.

[0047] Step 7: Set the contact properties of the entire model, where the friction coefficient is set to 0.15. At the same time, on the premise of ensuring the accuracy of the simulation analysis results, set the mass scaling factor to improve the calculation speed, and the target time increment is set to 5e-07.

[0048] Step 8: Use the display dynamics module in the solution software to perform simulation calculations.

[0049] Step 9, extract the force-displacement curve of the loading point, extract the energy change curve, confirm the hourglass change, set the hourglass energy increment standard to 10%, if it is too large, return to step 7, and output the stress cloud map if it is qualified. The stress cloud map represents the actual deformation state of the part during the crushing process.

[0050] Step 10: The force-displacement curve at the loading point represents the overall stress state of the front longitudinal beam, the energy change curve represents the total energy absorption state of the part, and the stress cloud diagram reflects the actual deformation state of the part during the crushing process. The analysis results can intuitively show the main stress deformation area of ​​the part and the main energy absorption location. Through this analysis, the performance of the front longitudinal beam can be further optimized effectively.

[0051] The present invention obtains the force-displacement curve, energy change curve, and stress cloud diagram reflecting the deformation state of the front longitudinal beam during the crushing process. Based on several data, the crushing performance of the front longitudinal beam during the design process can be intuitively observed, providing a design theoretical basis for body design engineers, providing a change direction for subsequent design optimization, and facilitating body design engineers to confirm the performance indicators of their own designed part structures in the early stage of body development, greatly reducing the part development cycle and cost. The present invention can quickly and effectively analyze the crushing resistance of the front longitudinal beam itself to achieve the purpose of rapid optimization and iteration. At the same time, it has the characteristics of simple steps, short time consumption, high accuracy, etc., and has a strong practical application foundation.

[0052] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for analyzing the crushing performance of a front longitudinal beam of an automobile, characterized in that: The specific steps include: S1: First, select the front longitudinal beam of the automobile to be analyzed, and use the finite element pre-processing model software to establish the front longitudinal beam crushing simulation analysis model; Perform a center plane inspection on the front longitudinal beam crush simulation analysis model, and if qualified, divide the center plane into meshes to form mesh units; S2: Perform quality check on grid cells; S3: Set the welding point connection and set up the welding unit at the welding point position; S4: Set a rigid wall and constrain the fixed rigid wall at the same time; set the boundary conditions of the finite element analysis model, set the rear end constraint point, constrain the 5 degrees of freedom of the grid, and ensure that the front longitudinal beam model can move in a single direction; S5: Apply rigid units to couple the constrained grid units at the rear end of the front longitudinal beam to obtain the loading point and perform displacement loading; S6: Set material properties; S7: Set the contact properties of the entire model and set the mass scaling factor; S8: Apply the display dynamics module in the solution software to perform simulation calculations; S9: extract the force-displacement curve of the loading point and the energy change curve; Confirm the hourglass change, if it is greater than the set value, return to step S7, otherwise output the stress cloud map; S10: The overall stress state of the front longitudinal beam is determined by the force-displacement curve at the loading point, the total energy absorption state of the parts is determined by the energy change curve, and the actual deformation state of the parts during the crushing process is determined by the stress cloud diagram.

2. The method for analyzing the crushing performance of a front longitudinal beam of an automobile according to claim 1, characterized in that: In S1, the acceptable condition is when there is no broken or chipped surface.

3. The method for analyzing the crushing performance of a front longitudinal beam of an automobile according to claim 1, characterized in that: In S1, the size of the grid unit is 3-15 mm, and the types of the grid unit are rectangular shell unit and triangular shell unit.

4. The method for analyzing the crushing performance of a front longitudinal beam of an automobile according to claim 1, characterized in that: In S2, the mesh unit quality inspection items are: target size, minimum size, maximum size, aspect ratio warping, triangle unit percentage, quadrilateral maximum inner angle, quadrilateral minimum inner angle, triangle maximum inner angle, triangle minimum inner angle, inclination and Jacobian.

5. The method for analyzing the crushing performance of a front longitudinal beam of an automobile according to claim 1, characterized in that: In S3, the welding point is set as a polygonal welding point, and the welding point unit is coupled with the surrounding grid using a flexible unit.

6. The method for analyzing the crushing performance of a front longitudinal beam of an automobile according to claim 1, characterized in that: In S5, the displacement is set to 25-35 mm.

7. The method for analyzing the crushing performance of a front longitudinal beam of an automobile according to claim 1, characterized in that: In the above S6, the material stress-strain curve, elastic modulus, Poisson's ratio, and mass density are introduced.

8. The method for analyzing the crushing performance of a front longitudinal beam of an automobile according to claim 1, characterized in that: In S7, the friction coefficient is set to 0.15 and the target time increment is set to 5e-07.

9. The method for analyzing the crushing performance of a front longitudinal beam of an automobile according to claim 1, characterized in that: In the above S9, the hourglass energy increment standard is set to 8-12%.

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