Automobile side door anti-collision bar assembly and door inner panel welding strength analysis method and system

Abstract

The present invention provides a method and system for analyzing the welding strength of a side door anti-collision bar assembly and a door inner panel of an automobile, and belongs to the technical field of automobile component performance evaluation. The welding strength analysis method of the present invention comprises the following steps: selecting a vehicle model to be evaluated; obtaining the moment of inertia and the door rotation angular velocity ω, and then obtaining the energy E of the rotating particle system according to the moment of inertia and the door rotation angular velocity ω; obtaining the thickness ratio a of the rear bracket thickness to the inner panel thickness, and the number of welds b, and then calculating the threshold value K of cracking of all welds based on the thickness ratio a and the number of welds b; and evaluating the welding strength according to the value of E / K. The present invention also provides a system for implementing the welding strength analysis method. The beneficial effects of the present invention are: greatly improving the consistency between the early design analysis and the later test results, and improving the efficiency of design analysis.

Description

Technical Field

[0001] The invention relates to an automobile component performance evaluation technology, and in particular to an automobile side door anti-collision rod assembly and a door inner panel welding strength analysis method and system. Background Art

[0002] As an important component of the car door, the car side door anti-collision bar assembly plays a key role in improving side collision and offset collision, and is widely used in car door design and development. The existing car door anti-collision bar assembly consists of an anti-collision bar front bracket, an anti-collision bar and an anti-collision bar rear bracket, which are connected by carbon dioxide shielded welding; the assembly components are connected to the inner panel by spot welding through the rear bracket and the front bracket. After the design is completed, virtual analysis is required. The main defects of the existing virtual analysis are:

[0003] 1) Poor analysis consistency: The analysis results all meet the standard requirements, but after the actual vehicle test, the weld joints between the rear bracket and the inner panel often crack;

[0004] 2) Low analysis efficiency: The existing analysis requires complete door data for modeling, which is a large workload and requires dedicated personnel to perform the analysis. The analysis cycle is long, wasting a lot of manpower and material resources. Summary of the invention

[0005] In order to solve the problems in the prior art, the present invention provides a method and system for analyzing the welding strength of an automobile side door anti-collision bar assembly and an inner door panel.

[0006] The method for analyzing the welding strength of the automobile side door anti-collision bar assembly and the door inner panel of the present invention comprises the following steps:

[0007] Steps for selecting vehicle models: Select the vehicle model to be evaluated;

[0008] Steps to obtain rotational energy E: Obtain the moment of inertia And the door rotation angular velocity ω, then according to the moment of inertia The energy E of the anti-collision bar assembly is obtained by the door rotation angular velocity ω;

[0009] The step of obtaining the threshold value K of the cracking of the weld point is as follows: obtaining the thickness ratio a of the rear bracket thickness to the inner plate thickness and the number b of the weld points, and then calculating the threshold value K of the cracking of all weld points based on the thickness ratio a and the number b of the weld points;

[0010] Welding strength evaluation steps: Evaluate welding strength based on the E / K value.

[0011] The present invention is further improved, and the calculation formula of the rotational energy E is:

[0012]

[0013] Where, E is the energy of the anti-collision bar assembly rotation; is the moment of inertia of the anti-collision bar assembly; ω is the angular velocity of the door rotation, the moment of inertia The angular velocity can be directly obtained through the system software. Set to 1 rad / s.

[0014] The present invention is further improved, the moment of inertia The calculation method is:

[0015]

[0016] Among them, the m i is the mass of particle i, r i is the rotation radius of particle i around the hinge axis, i is a particle on the anti-collision bar assembly, and all particle systems constitute the anti-collision bar assembly.

[0017] The present invention is further improved, the threshold value K of the cracking of the solder joint is calculated based on the empirical formula of the cracking threshold value obtained by fitting a large amount of data, and the empirical formula is: .

[0018] The present invention is further improved. In the welding strength evaluation step, when the E / K≥1, the risk of cracking is high. By adjusting the thickness ratio a of the rear bracket thickness to the inner plate thickness and the value of the number of welds b, E / K<1 is made; when E / K<1, the risk of cracking is low and the design does not change.

[0019] The present invention also provides a system for implementing the above-mentioned automobile side door anti-collision bar assembly welding strength analysis method, comprising:

[0020] Model selection module: used to select the model to be evaluated;

[0021] Rotational energy E acquisition module: used to obtain rotational inertia And the door rotation angular velocity ω, then according to the moment of inertia The energy E of the anti-collision bar assembly is obtained by the door rotation angular velocity ω;

[0022] A module for obtaining a threshold value K for cracking of welding points: used to obtain a thickness ratio a between the thickness of the rear bracket and the thickness of the inner plate, and the number of welding points b, and then calculate the threshold value K for cracking of all welding points based on the thickness ratio a and the number of welding points b;

[0023] Welding strength evaluation module: used to evaluate welding strength according to the E / K value.

[0024] Compared with the prior art, the beneficial effects of the present invention are: greatly improving the efficiency of design analysis, without the need for dedicated modeling, and the welding strength can be evaluated by simply inputting the corresponding parameters. The present invention can provide data support for the design of part plate thickness and the number of welds, thereby improving the robustness of the design. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic structural diagram of the automobile side door anti-collision bar assembly of the present invention;

[0026] Figure 2 This is a schematic diagram of the installation of the automobile side door anti-collision bar assembly of the present invention;

[0027] Figure 3 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0029] like Figure 1 and Figure 2 As shown, the automobile side door anti-collision bar assembly 5 of this example includes an anti-collision bar 1, a front bracket 2 arranged at one end of the anti-collision bar 1, and a rear bracket 3 arranged at the other end of the anti-collision bar 1. The automobile side door anti-collision bar assembly 5 of this example is welded to the automobile side door inner panel 4 through welding points on the front bracket 2 and the rear bracket 3. The rear bracket of this example is easy to crack during the rotation of the car door. Therefore, this example mainly analyzes the welding strength between the rear bracket and the automobile side door inner panel 4 to evaluate the welding performance of the automobile side door anti-collision bar assembly 5.

[0030] like Figure 3 As shown, the method for analyzing the welding strength of the automobile side door anti-collision bar assembly and the door inner panel of the present invention comprises the following steps:

[0031] Step 1: Select the model to be evaluated;

[0032] Step 2: Get the moment of inertia Ic and the door rotation angular velocity ω, and then according to the moment of inertia The energy E of the anti-collision bar assembly is obtained by the door rotation angular velocity ω;

[0033] Step 3, obtaining the thickness ratio a of the rear bracket thickness to the inner plate thickness and the number of welds b, and then calculating the threshold value K of cracking of all welds based on the thickness ratio a and the number of welds b;

[0034] Step 4: Evaluate the welding strength according to the E / K value. When E / K≥1, the risk of cracking is high. By adjusting the thickness ratio a of the rear bracket to the inner plate thickness and the value of the number of welds b, make E / K<1; when E / K<1, the risk of cracking is low, and the design is not changed and ends.

[0035] In this example, there is no particular order for step 2 and step 3. The energy E of the rotating particle system can be calculated first, or the threshold value K of weld cracking can be calculated first. Alternatively, the calculations can be performed simultaneously after inputting the parameters.

[0036] The calculation process of the rotational energy E in this example is:

[0037]

[0038] Where, E is the energy of the anti-collision bar assembly rotation; is the moment of inertia of the anti-collision bar assembly; ω is the angular velocity of the door rotation, the moment of inertia The angular velocity can be directly obtained through the system software. Set to 1 rad / s.

[0039] Moment of inertia in this example The calculation method is:

[0040]

[0041] Among them, the m i is the mass of particle i, r i is the rotation radius of particle i around the hinge axis, i is a particle on the anti-collision bar assembly, and all particle systems constitute the anti-collision bar assembly.

[0042] The crack threshold K of the weld in this example is calculated based on the crack threshold empirical formula obtained by fitting a large amount of existing data in the selected vehicle model. The empirical formula is: .

[0043] The cracking of the weld at the connection between the rear bracket and the inner plate of the side door anti-collision bar of the present invention is essentially because the connection strength at the weld position has reached a threshold value, and the strength threshold value is related to the energy of the anti-collision bar assembly in the test. The greater the energy, the easier it is to break the threshold value. Therefore, analyzing the energy input of the anti-collision bar assembly and the energy absorption limit of the weld is the key to solving the problem. There is no such design method in the prior art.

[0044] In this example, according to the kinetic energy formula and the moment of inertia formula, it can be concluded that the rotational kinetic energy of the anti-collision bar assembly is related to the moment of inertia, and the moment of inertia can be directly obtained through the software, so the rotational kinetic energy E can be quickly obtained.

[0045] The bumper assembly is connected to the inner panel through a weld. The kinetic energy of the bumper assembly when the door is closed is also released through the weld. Therefore, by analyzing the relationship between the connection strength of the weld and the moment of inertia and angular velocity, the threshold of the connection strength can be derived. There are three main evaluation indicators for the connection strength of the weld: welding parameters, the number of welds and the plate thickness ratio. Without considering the influence of welding parameters (without considering the influence of process factors), only the number of welds and the plate thickness ratio directly affect the connection strength. Therefore, the threshold K can be obtained through the relationship between the above two factors and the moment of inertia and angular velocity. By comparing the values ​​of E and K, the welding strength risk can be evaluated.

[0046] This evaluation method has been verified on a number of actual vehicles in the factory. After being adopted, the thickness of the rear bracket of the bumper was reduced and the workload of CAE analysis was reduced. No weld cracking problems were found after actual vehicle tests.

[0047] In addition, the present invention has the following advantages:

[0048] (1) Greatly improve the consistency between the early design analysis and the later test results, with the consistency not less than 80%;

[0049] (2) Greatly improve the efficiency of design analysis. No dedicated modeling is required. Only four parameters are needed to evaluate welding strength.

[0050] (3) It can provide data support for the design of component thickness and number of welds, thereby improving design robustness.

[0051] The specific implementation modes described above are preferred implementation modes of the present invention, and are not intended to limit the specific implementation scope of the present invention. The scope of the present invention includes but is not limited to the specific implementation modes, and all equivalent changes made according to the present invention are within the protection scope of the present invention.

Claims

1. The welding strength analysis method of the automobile side door anti-collision bar assembly and the door inner panel is characterized in that: The steps include: Model selection step: Select the model to be evaluated; Steps to obtain rotational energy E: Obtain the moment of inertia I c And the door rotation angular velocity ω, then according to the moment of inertia I c The energy E of the anti-collision bar assembly is obtained by the door rotation angular velocity ω; The step of obtaining the threshold value K of the cracking of the weld point is as follows: obtaining the thickness ratio a of the rear bracket thickness to the inner plate thickness and the number b of the weld points, and then calculating the threshold value K of the cracking of all weld points based on the thickness ratio a and the number b of the weld points; Welding strength evaluation steps: Evaluate welding strength based on the E / K value. The calculation formula of the rotational energy E is: Where E is the energy of the anti-collision bar assembly rotation; I c is the moment of inertia of the anti-collision bar assembly; ω is the angular velocity of the door rotation, the moment of inertia I c It is directly obtained through the system software that the angular velocity ω is set to 1rad / s. The moment of inertia I c The calculation method is: Among them, the m i is the mass of particle i, r i is the rotation radius of mass point i around the hinge axis, i is a mass point on the anti-collision bar assembly, and all mass points constitute the anti-collision bar assembly. The cracking threshold K of the solder joint is calculated based on an empirical formula of the cracking threshold obtained by fitting a large amount of data. The empirical formula is:

2. The method for analyzing the welding strength of the automobile side door anti-collision bar assembly and the door inner panel according to claim 1 is characterized in that: In the welding strength evaluation step, when the E / K≥1, the risk of cracking is high. By adjusting the thickness ratio a of the rear bracket thickness to the inner plate thickness and the value of the number of welds b, E / K<1; when E / K<1, the risk of cracking is low and the design remains unchanged.

3. A system for implementing the method for analyzing the welding strength of the automobile side door anti-collision bar assembly and the door inner panel according to claim 1 or 2, characterized in that: include: Model selection module: used to select the model to be evaluated; Rotational energy E acquisition module: used to obtain the moment of inertia I c And the door rotation angular velocity ω, then according to the moment of inertia I c The energy E of the anti-collision bar assembly is obtained by the door rotation angular velocity ω; A module for obtaining a threshold value K for cracking of welding points: used to obtain a thickness ratio a between the thickness of the rear bracket and the thickness of the inner plate, and the number of welding points b, and then calculate the threshold value K for cracking of all welding points based on the thickness ratio a and the number of welding points b; Welding strength evaluation module: used to evaluate welding strength according to the E / K value.

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