A method for analyzing crush performance of an automobile front longitudinal beam

Abstract

The present application relates to the technical field of optimization simulation method of automobile, in particular to a kind of automobile front longitudinal beam crush performance analysis method.Rigid wall is set, and rigid wall is fixedly constrained;Boundary conditions of finite element analysis model are set, rear end constraint point is set, to ensure that front longitudinal beam model can advance along single direction;Rigid unit is applied to couple the mesh element of rear end constrained of front longitudinal beam, and displacement loading is carried out;Simulation calculation is carried out in solving software by applying display dynamics module;The overall stress state of front longitudinal beam is obtained by loading point force-displacement curve, the total energy absorption state of part is obtained by energy change curve, and the actual deformation state of part in crush process is obtained by stress nephogram.Optimization comparison analysis process has high accuracy, can quickly and effectively analyze the compression crush resistance of front longitudinal beam itself;It is convenient for body design engineer to confirm the performance index of self-designed part structure in the early stage of body development, thereby reducing part development cycle and cost.

Description

Technical Field

[0001] This invention relates to the technical field of automotive optimization simulation methods, specifically a method for analyzing the crush performance of a front longitudinal beam in an automobile. Background Technology

[0002] When a car is involved in a frontal collision, 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 of the vehicle body and is the main energy-absorbing component during a frontal collision. Its energy absorption characteristics and deformation mode determine the vehicle body's acceleration response and force transmission path during the collision, which has a significant impact on the crashworthiness of the vehicle structure.

[0003] Domestic and international research indicates that the front longitudinal beam absorbs approximately 50% of the total energy absorbed by a vehicle in a frontal collision, significantly impacting the overall vehicle's crash safety performance. The primary failure mode of the front longitudinal beam during normal energy absorption is crushing failure; therefore, the analysis and evaluation of its crushing performance are of paramount importance.

[0004] However, the most intuitive way to evaluate vehicle collision safety is through whole-vehicle crash analysis. But this method struggles to break down the overall target when optimizing specific component structures, and the computational load for verification is excessive. This results in excessively long development cycles and increased costs. Furthermore, in the early stages of vehicle body development, body design engineers find it difficult to intuitively confirm the evaluation metrics for the structural components they design. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, a method for analyzing the crush performance of automotive front longitudinal beams is provided. The optimized comparative analysis process has high accuracy and can quickly and effectively analyze the crush resistance of the front longitudinal beams themselves. This allows body design engineers to confirm the performance indicators of their designed parts in the early stages of body development, thereby reducing the development cycle and cost of parts.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A method for analyzing the crush performance of a front longitudinal beam of an automobile includes the following steps:

[0008] S1: First, select the front longitudinal beam of the car to be analyzed, and use finite element preprocessing model software to establish a front longitudinal beam crushing simulation analysis model; check the center surface of the front longitudinal beam crushing simulation analysis model, and after it passes the test, mesh the center surface to form mesh elements.

[0009] S2: Perform quality checks on the mesh cells;

[0010] S3: Set up solder joint connection, and set up a welding unit at the solder joint location;

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

[0012] S5: Apply rigid elements to couple the constrained mesh elements at the rear end of the front longitudinal beam to obtain the loading point and apply displacement.

[0013] S6: Set material properties;

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

[0015] S8: Use the explicit dynamics module in the solver software to perform simulation calculations;

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

[0017] Confirm the hourglass change; if it exceeds the set value, return to step S7; otherwise, output the stress cloud diagram.

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

[0019] Furthermore, in S1, "qualified" means there are no broken or fragmented surfaces.

[0020] Furthermore, in S1, the size of the mesh unit is 3 to 15 mm, and the mesh unit type is a rectangular shell unit and a triangular shell unit.

[0021] Furthermore, in S2, the items for quality inspection of the grid cells are: target size, minimum size, maximum size, aspect ratio, warping, percentage of triangle cells, maximum interior angle of quadrilateral, minimum interior angle of quadrilateral, maximum interior angle of triangle, minimum interior angle of triangle, tilt and Jacobian.

[0022] Furthermore, in S3, the solder joints are set as polygonal solder joints, and the solder joint units are coupled to the surrounding mesh using flexible units.

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

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

[0025] Furthermore, 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 standard for the hourglass energy increment is set to 8-12%.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] This invention sets a rigid obstacle at the front end of the front longitudinal beam and a constraint at the rear end, causing the front longitudinal beam to move in the direction of the obstacle avoidance, 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 indicators are the peak crushing force and the effect of internal energy rise. At the same time, the actual deformation state of the part during the crushing process is judged based on the stress cloud diagram.

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

[0030] 2. The optimized comparative analysis process boasts high accuracy, providing body design engineers with a theoretical basis for design and directions for subsequent design optimization. It facilitates body design engineers in confirming the performance indicators of their designed parts in the early stages of body development, significantly reducing part development cycles and costs. This invention can quickly and effectively analyze the crush resistance of the front longitudinal beam itself.

[0031] 3. A standard working host can complete one round of analysis in 1.5 hours, achieving rapid optimization and iteration. It also features simple steps, short processing time, and high accuracy, providing a strong foundation for practical applications.

[0032] This invention differs from traditional vehicle performance simulations that decompose performance indicators downwards. Instead, it decouples the vehicle body structure and sets operating conditions and performs performance analysis on individual sub-assembly level parts. Since the stress state of individual sub-assembly parts is relatively simple, it is easier to set operating conditions and operate more conveniently. At the same time, because the coupling conditions are reduced, the accuracy of simulation analysis will be significantly improved, and the analysis time will be greatly reduced, which can be completed by a conventional host machine. Attached Figure Description

[0033] Figure 1 This is the analysis flowchart of the present invention.

[0034] Figure 2 This is a schematic diagram of the front longitudinal beam crushing analysis of the present invention. Detailed Implementation

[0035] The technical solution of the present invention will be clearly and completely described below with reference to examples. Obviously, the described embodiments are merely one example of the present invention, and those skilled in the art can refer to the content herein to appropriately improve the process parameters. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and those skilled in the art can obviously make modifications or appropriate changes and combinations to the methods and applications described herein without departing from the content, spirit, and scope of the present invention to realize and apply the technology of the present invention.

[0036] like Figure 1 , Figure 2 As shown, a method for analyzing the crushing performance of a front longitudinal beam in an automobile involves setting a rigid obstacle at the front end of the longitudinal beam and a constraint at the rear end, causing the longitudinal beam to displace in the direction of the obstacle. Data on the crushing force and internal energy of the longitudinal beam are collected. However, due to the single-system stress, to avoid component collapse and distortion of the overall simulation effect, the displacement distance cannot be too large; only the force and internal energy change curves during the crushing process are observed. The main indicators examined are the peak crushing force and the increase in internal energy. Simultaneously, the actual deformation state of the component during the crushing process is determined based on the stress cloud diagram.

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

[0038] Step 1: Use finite element preprocessing software to establish a simulation analysis model of the front longitudinal beam crushing, and check the center surface of the simulation model to confirm that there are no broken or fragmented surfaces.

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

[0040] Step 2: Perform quality checks on the mesh cells. The specific inspection standards are shown in the table below:

[0041] Table 1. Mesh Cell Inspection Standards

[0042]

[0043] Step 3: Set up the solder joint connection. Use the theoretical design position for the solder joint. Set up welding elements at the solder joint position. Set the solder joint as Hexa (polygonal solder joint). Couple the solder joint element with the surrounding mesh using Rbe3 (flexible element).

[0044] Step 4: Set up a rigid wall and constrain it. Set the boundary conditions for the finite element analysis model, and set the rear constraint surface. This constraint surface is taken from the connection area between the front longitudinal beam part and the vehicle body and cockpit. The constraint mesh has 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 test bench and ensure that the front longitudinal beam moves perpendicular to the rigid wall, apply Rbe2 (rigid element coupling) to the constrained mesh element at the rear end of the front longitudinal beam to obtain the loading point and apply displacement, with the displacement set to 30mm.

[0046] Step 6: Then set the material properties, 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, with the friction coefficient set to 0.15. At the same time, to improve the calculation speed while ensuring the accuracy of the simulation analysis results, the mass scaling factor is set, with the target time increment set to 5e-07.

[0048] Step 8: Perform simulation calculations using the explicit dynamics module in the solver software.

[0049] Step 9: Extract the force-displacement curve at the loading point, extract the energy change curve, confirm the hourglass change, and set the hourglass energy increment standard to 10%. If it is too large, return to step 7. If it is qualified, output the stress cloud diagram, which 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 component, and the stress cloud diagram reflects the actual deformation state of the component during the crushing process. The analysis results clearly show the main stress-deformation areas and main energy-absorbing parts of the component, allowing for effective further performance optimization of the front longitudinal beam.

[0051] This invention provides force-displacement curves, energy change curves, and stress cloud diagrams reflecting the deformation state during the crushing process of the front longitudinal beam. Based on these data, the crushing performance of the front longitudinal beam can be intuitively observed during the design process, providing theoretical basis for vehicle body design engineers and directions for subsequent design optimization. It facilitates vehicle body design engineers in confirming the performance indicators of their designed parts in the early stages of vehicle body development, significantly reducing the development cycle and cost. This invention can quickly and effectively analyze the crushing resistance of the front longitudinal beam itself, achieving rapid optimization and iteration. Furthermore, it features simple steps, short processing time, and high accuracy, possessing a strong foundation for practical application.

[0052] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method of analyzing crush performance of an automobile front rail, characterized by, Specifically comprising the following steps: S1: First select the car front longitudinal beam needs to be analyzed, the application of finite element pre-processing model software to establish the front longitudinal beam crush simulation analysis model; The center surface of the front longitudinal beam crush simulation analysis model is checked, and the center surface is meshed to form a grid element after passing the check; S2: Quality inspection of the grid element; S3: Set the welding point connection, and set the welding unit at the welding point position; S4: Set the rigid wall, and constrain the rigid wall; set the boundary conditions of the finite element analysis model, set the rear constraint point, constrain the grid 5 degrees of freedom, and ensure that the front longitudinal beam model can move in a single direction; S5: Apply the rigid element to couple the grid element of the constrained rear end of the front longitudinal beam to obtain the loading point and perform displacement loading; S6: Set the material properties; S7: Set the contact properties of the entire model, and set the mass scaling coefficient; S8: In the solving software, apply the display dynamics module to perform simulation calculation; S9: Extract the force-displacement curve of the loading point and the energy change curve; Confirm the hourglass change, if greater than the set value, return to step S7, otherwise output the stress cloud map; S10: Determine the overall stress state of the front longitudinal beam through the force-displacement curve of the loading point, determine the total energy absorption state of the part through the energy change curve, and determine the actual deformation state of the part in the crushing process through the stress cloud map.

2. The automobile front longitudinal beam crush performance analysis method according to claim 1, wherein in S1, the pass is a condition without broken surface and broken surface.

3. The automobile front longitudinal beam crush performance analysis method according to claim 1, wherein in S1, the grid element size is 3-15mm, and the grid element type is rectangular shell element and triangular shell element.

4. The automobile front longitudinal beam crush performance analysis method according to claim 1, wherein in S2, the grid element quality inspection items are: target size, minimum size, maximum size, aspect ratio warping, triangular element percentage, quadrilateral maximum internal angle, quadrilateral minimum internal angle, triangular maximum internal angle, triangular minimum internal angle, inclination and Jacobian.

5. The automobile front longitudinal beam crush performance analysis method according to claim 1, wherein in S3, the welding point is set as a polygon welding point, and the welding point unit is coupled with the surrounding grid by using a flexible unit.

6. The automobile front longitudinal beam crush performance analysis method according to claim 1, wherein in S5, the displacement is set to 25-35mm.

7. The automobile front longitudinal beam crush performance analysis method according to claim 1, wherein in S6, the material stress-strain curve, elastic modulus, Poisson's ratio and mass density are imported.

8. The automobile front longitudinal beam crush performance analysis method according to claim 1, wherein in S7, the friction coefficient is set to 0.15, and the target time increment is set to 5e-07.

9. The automobile front longitudinal beam crush performance analysis method according to claim 1, wherein in S9, the sandglass energy increment standard is set to 8-12%. ​ ​ ​ ​ ​ ​ ​ ​

Images