A vibration simulation method based on seam welding of aluminum substrate

Abstract

This invention proposes a vibration simulation method based on seam welding of aluminum substrates. First, MIG / MAG seam welding is performed on aluminum materials of different grades and arbitrary shapes using lap, corner, T-joint, and butt joint methods. The weld nugget thickness and heat-affected zone (HAZ) range are obtained using a metallographic microscope. A mesh is then created based on the geometry of the welded sample. Based on the metallographic scanning results, the entire weld joint is divided into three regions: weld nugget, HAZ, and base material, establishing a MIG / MAG seam welding model. After verification with random vibration experiments on actual battery packs, it can be concluded that this invention can achieve a 90% accuracy rate in simulating MIG / MAG seam welding of aluminum alloy substrates under random vibration conditions. Therefore, this application can quickly and conveniently generate weld nugget meshes and determine the material strength of the weld nugget in finite element preprocessing software; it can also batch distinguish the HAZ range and characterize it in a CAE model.

Description

Technical Field

[0001] This application relates to the field of seam welding technology, and specifically to a vibration simulation method based on seam welding of aluminum substrate. Background Technology

[0002] With the increasing demand for lightweighting in industries such as new energy vehicles and energy storage, aluminum and its alloys, due to their advantages of low density and high specific strength, are widely used in the manufacturing of power and energy storage battery pack housings. This has led to increased attention being paid to MIG / MAG welding (gas inert gas welding / gas active gas welding), a suitable welding technology for aluminum. MIG / MAG welding, as a mature welding technology, offers advantages such as high welding efficiency, strong penetration, wide applicability, good welding quality, and ease of automation, making it an excellent choice for large-scale aluminum alloy welding. It can meet the quality and efficiency requirements of aluminum battery pack housing welding. The strength of the MIG / MAG seam weld joints in the battery pack housing has a significant impact on the overall structural strength of the battery pack. Therefore, to ensure the battery pack housing's ability to protect the internal cells / modules from dust, water, and vibration, the strength of the weld joints must be guaranteed. Currently, the main joint types in battery pack housing structures include butt joints, lap joints, corner joints, and T-joints. These different joint types are key considerations when the battery pack housing experiences vibration.

[0003] In the early stages of battery pack development, extensive finite element simulations are used to assist structural engineers in designing and developing battery packs that meet national standards and strength requirements for various application scenarios. Regarding the random vibration fatigue requirements of national standards, the overall strength of the battery pack casing primarily depends on the structure itself and the connection strength of the welded joints. Accurately simulating whether MIG / MAG seam welds will fail / fracture under vibration is a key focus of the simulation work. Existing finite element simulation methods for MIG / MAG welded joints mainly include the common node method, rigid element connection method, beam element connection method, and solid element modeling method. Among these, the beam element and rigid element connection methods are characterized by stress insensitivity and distortion. While the common node method and solid element modeling method can simulate connection point failure, they cannot accurately simulate the non-uniformity of the mechanical properties of this type of welded joint, especially in the heat-affected zone where the high heat source of MIG / MAG seam welds causes performance degradation in the aluminum substrate due to the high welding temperature. The overall accuracy of existing simulation methods is less than 50%. Therefore, with the widespread adoption of MIG / MAG welding in battery pack aluminum casings, developing a highly accurate seam weld simulation method is particularly important. Summary of the Invention

[0004] To address the above technical problems, this application provides a vibration simulation method based on aluminum substrate seam welding, applicable to various grades of aluminum alloys and finite element simulation methods for MIG / MAG seam welding with different welding forms, in order to solve the problem of low CAE simulation accuracy of existing aluminum battery pack box seam welding.

[0005] In a first aspect, this application proposes a vibration simulation method based on seam welding of aluminum substrate, the method comprising:

[0006] S1: Grid division based on the geometry of the welded sample;

[0007] S2: Use the built-in definition connection function in the ANSA platform to create seam weld connection lines. In the connection manager interface, generate a row of shell element meshes as weld nuggets by selecting the LASER-WELD-SHELL type for the seam weld connection lines, and automatically modify the mesh nodes of the connected base material so that the base material and the weld nugget are connected with common nodes.

[0008] S3: Based on the metallographic scanning results, the weld nugget unit generated in S2 is displayed separately, along with a surrounding grid, resulting in two rows of grids in the base material connected to the weld nugget. These two rows of grids in the base material are then classified as the heat-affected zone of the weld seam by assigning new properties. The weld nugget thickness is calculated based on the metallographic scanning results.

[0009] S4: Based on the defined weld nugget, heat-affected zone, and base material, establish a MIG / MAG seam welding model.

[0010] The steps preceding step S1 also include:

[0011] Based on the temperature change during base metal welding, the welding wire raw material is heat-treated, and then the heat-treated welding wire is made into tensile specimens for tensile testing. The mechanical properties of the material after heat treatment are obtained by using a tensile machine.

[0012] MIG / MAG seam welding was performed on base materials of different grades and shapes using lap joints, corner joints, T-joints, and butt joints. The weld nugget thickness and heat-affected zone range were obtained using a metallographic microscope.

[0013] Among them, all seam welds on the same part are classified into the same property for their heat-affected zones;

[0014] The thickness of the heat-affected zone is the same as that of the base material;

[0015] Reduce the strength of the heat-affected zone to 60% of that of the base material.

[0016] Based on the metallographic scanning results, the weld nugget thickness can be calculated using the following formula:

[0017] H = (T1 + T2) / 2 + c;

[0018] Where H is the weld nugget thickness, T1 is the thickness of the base material 1 of the weld joint, T2 is the thickness of the base material 2, and c is a constant, which can range from 0.5 to 1.5.

[0019] Among them, based on the simulation conditions and result reading format, a failure evaluation standard for seam welds is formulated, specifically as follows:

[0020] In the ANSA platform, a random vibration analysis step was set for the MIG / MAG seam welding model, and the solution file was exported and submitted to the server for solving.

[0021] Open the solved result file with a post-processing module or software to read the RMS Mises stress results;

[0022] When the stress in the heat-affected zone of the weld is higher than the stress in the base metal and the weld nugget, the 3σ criterion is used for risk assessment.

[0023] The RMS Mises stress results are as follows:

[0024] Multiply the RMS stress value of the heat-affected zone by 3 to obtain an approximate 3σ result. Compare this 3σ stress with the yield strength of the material multiplied by 60%. If the 3*RMS stress value does not exceed the yield strength multiplied by 60%, the weld seam is considered to have no risk of cracking; otherwise, there is a risk of cracking.

[0025] Secondly, this application proposes a computer-readable storage medium storing computer-executable instructions, which, when executed by a control processor, implement a vibration simulation method based on aluminum substrate seam welding as described in the first aspect.

[0026] Compared with the prior art, this application has at least the following beneficial effects:

[0027] After verification with random vibration experiments on actual battery packs, it was found that the vibration simulation method based on aluminum substrate seam welds described in this application simulated 10 seam welds in the battery pack housing that were at risk of cracking. However, the actual number of cracked seam welds in the battery pack was 11. Considering the possibility that seam weld cracking would reduce the overall structural strength of the pack and subsequently lead to other seam weld cracking, and based on the vibration benchmark results of a large number of different battery packs, it can be concluded that the simulation method for MIG / MAG seam welds using aluminum alloy as the substrate can achieve an accuracy of 90% under random vibration conditions. Therefore, this application can quickly and conveniently generate weld nugget meshes in finite element preprocessing software, determine the material strength of the weld nuggets, and batch distinguish the range of the heat-affected zone and characterize it in the CAE model. Attached Figure Description

[0028] Figure 1This is a flowchart illustrating a vibration simulation method based on seam welding of aluminum substrate, as shown in an embodiment of this application.

[0029] Figure 2 The metallographic results of the T-weld shown in the embodiments of this application are as follows.

[0030] Figure 3 These are the overlapping, corner, T-shaped, and butt joint methods shown in the embodiments of this application.

[0031] Figure 4 This is a partial detailed schematic diagram of the overlapping interface shown in the embodiments of this application.

[0032] Figure 5 This is a comparison chart of simulation results shown in the embodiments of this application, as well as other modeling methods for seam welding and experimental results. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. Example 1:

[0034] like Figure 1 As shown, this application proposes a vibration simulation method based on seam welding of aluminum substrate, the method comprising:

[0035] S1: Grid division based on the geometry of the welded sample;

[0036] S2: Use the built-in definition connection function in the ANSA platform to create seam weld connection lines. In the connection manager interface, generate a row of shell element meshes as weld nuggets by selecting the LASER-WELD-SHELL type for the seam weld connection lines, and automatically modify the mesh nodes of the connected base material so that the base material and the weld nugget are connected with common nodes.

[0037] S3: Based on the metallographic scanning results, the weld nugget unit generated in S2 is displayed separately, along with a surrounding grid, resulting in two rows of grids in the base material connected to the weld nugget. These two rows of grids in the base material are then classified as the heat-affected zone of the weld seam by assigning new properties. The weld nugget thickness is calculated based on the metallographic scanning results.

[0038] S4: Based on the defined weld nugget, heat-affected zone, and base material, establish a MIG / MAG seam welding model.

[0039] The steps preceding step S1 also include:

[0040] Based on the temperature change during base material welding, the welding wire raw material is heat-treated, and then the heat-treated welding wire is made into tensile specimens for tensile testing. The mechanical properties of the material after heat treatment are obtained by using a tensile machine.

[0041] Preferably, when preparing tensile specimens from heat-treated welding wire for tensile testing, the core temperature during welding reaches 1500-2000℃. Heating the welding wire material to this high temperature requires expensive equipment and specialized operation. Therefore, in this embodiment, the welding wire can be butt-welded onto two thickened tensile specimens, with the welding distance extended so that the fracture point during tensile testing is located on the weld body. Using the above method, welding wire specimens equivalent to those after heat treatment can be quickly obtained. The post-weld material properties of the welding wire can be obtained through tensile testing. Since the aluminum used in battery pack housings is mostly 5-series and 6-series aluminum, the welding wire material is basically uniformly 4043 aluminum alloy. Therefore, this method obtains the post-weld mechanical properties of the welding wire, which can characterize the mechanical properties of the weld nugget after aluminum-aluminum welding.

[0042] For base materials of different grades and shapes, according to the lap joint, corner joint, T-joint, and butt joint methods (such as... Figure 3 MIG / MAG seam welding was performed (as shown), and the weld nugget thickness and heat-affected zone range were obtained using a metallographic microscope.

[0043] Specifically, based on the battery pack casing design requirements, any combination of base materials, such as 6063T6-6082T6, is selected as the welding base material for various forms of MIG / MAG seam welding, including lap joints, butt joints, T-joints, and corner joints. The welded parts are then cut using manual / automatic equipment, and the cut samples are polished (if necessary). The weld nugget thickness and heat-affected zone range are obtained using a metallographic microscope. This method provides the size of the heat-affected zone and the weld nugget thickness after MIN / MAG welding, providing a basis for the next step of constructing a seam weld CAE model.

[0044] Preferably, the range of the heat-affected zone can be easily and quickly obtained by measuring the hardness change using hardness testing equipment (Rockwell hardness tester / Vickers hardness tester). Although the specific value of the weld height cannot be known, the approximate range of the weld height can be obtained through engineering experience and databases.

[0045] To obtain more welding data, the pairwise welding combinations can be diversified. For example, the commonly used 5-series aluminum and 6-series aluminum can be welded together, and 6-series aluminum of different grades and heat treatment methods can be cross-combined to obtain more welding data, understand the subtle differences in the heat-affected zone and weld nugget of different aluminum materials under the same welding conditions, and improve the modeling accuracy.

[0046] Before meshing based on the geometry of the welded sample, the preferred method is to import the 3D digital model of the part into ANSA software for geometry cleanup, specifically including:

[0047] Launch the ANSA software and create a new project or open an existing one;

[0048] In ANSA, select the "Import" option and choose your 3D model from the file (usually a file in STEP, IGES, CATIA, SolidWorks, or other formats).

[0049] Import the 3D model of the part into the working environment using ANSA's import tool;

[0050] Use the geometry inspection tools provided by ANSA to check for common geometric problems in the model, such as self-intersections, holes, overlapping surfaces, and non-closed bodies.

[0051] Ensure the model is closed, without any discontinuous boundaries or holes.

[0052] Remove unnecessary details, such as small holes, tiny features, or assembly marks, as these details can affect the quality of the mesh.

[0053] The geometric features that affect welding simulation should be retained.

[0054] Merge adjacent faces or volumes to reduce model complexity and simplify subsequent meshing.

[0055] Use the repair tools in ANSA to repair geometric defects, such as filling holes, repairing broken surfaces or boundaries;

[0056] The geometry is smoothed to eliminate unnecessary sharp angles or protrusions, ensuring uniformity in mesh generation.

[0057] Based on the requirements of the welding area, the model is divided into different regions. The model can be divided into different parts as needed, facilitating subsequent mesh generation and attribute assignment.

[0058] Define the contact surfaces and boundary conditions between different components in the model to prepare for subsequent simulation settings;

[0059] Before meshing, check the mesh generation settings to ensure that the mesh density and quality meet the requirements of the welding simulation.

[0060] Before meshing, assign the correct material properties and welding parameters to the model to ensure that these settings are correctly reflected in the mesh.

[0061] In this embodiment, the grid size can be 5mm, so the grid size of the weld substrate / base material is about 5mm, which maps to the grid size of the entire battery pack box.

[0062] By following the steps above, you ensure that the 3D model imported into ANSA is thoroughly cleaned, thus laying a solid foundation for subsequent mesh generation and welding simulation. A cleaned geometry not only improves the quality of mesh generation but also enhances the accuracy and efficiency of the simulation.

[0063] The process after step S3 also includes:

[0064] For all seam welds on the same part, their heat-affected zones are classified under the same attribute; the attribute includes at least: material properties, geometric properties, mesh properties, boundary properties, load conditions, welding properties, heat-affected zone properties, etc.

[0065] The thickness of the heat-affected zone is the same as that of the base material;

[0066] Reduce the strength of the heat-affected zone to 60% of that of the base material.

[0067] Since the strength of the heat-affected zone decreases due to the high temperature of welding, in this embodiment, it is more reliable to reduce the strength of the heat-affected zone to 60% of the base material, that is, the elastic stage remains unchanged, and the stress of the elastic-plastic curve is reduced to 60%.

[0068] For example, in the above example, the seam welds with base materials of 6063T6-6082T6 have a heat-affected zone thickness of 3mm on parts with a 6063T6 thickness of 3mm and a material strength of 6063T6. On the other hand, the heat-affected zone thickness of the seam welds on parts with a 6082T6 thickness of 4mm is 4mm and the material strength is 60% of 6082T6.

[0069] Using the above method, weld nuggets of common-node shell elements for seam welds can be created in batches, and a large number of reasonably sized heat-affected zones can be quickly defined, while also taking into account the overall mesh size, ensuring both computational resources and computational accuracy. In addition, the base material can also be a solid element, that is, the base material of both shell elements and solid elements can be simulated by using this common-node shell element as the weld nugget and defining the heat-affected zone.

[0070] Based on the metallographic scanning results, the weld nugget thickness is calculated. The actual height of the weld nugget is the shell element thickness. Since the weld nugget is a common-node connection of shell elements, it will not interfere with the heat-affected zone mesh, thus not affecting stress transfer. Figure 2 The metallographic results of a T-weld show an effective weld nugget thickness of 4.6 mm. Besides these limited metallographic results, approximate weld nugget heights can be obtained from the engineering experience of institutions with metallographic inspection capabilities and welding professionals, leading to calculation rules for weld nugget thickness. For example, the weld nugget thickness can be estimated using the following formula.

[0071] Preferably, the weld nugget thickness is calculated using the following formula:

[0072] H = (T1 + T2) / 2 + c;

[0073] Where H is the weld nugget thickness, T1 is the thickness of the base material 1 of the weld joint, T2 is the thickness of the base material 2, and c is a constant, which can range from 0.5 to 1.5.

[0074] like Figure 4 As shown, (101) Mid-surface mesh of base material 1 (102) Mid-surface mesh of base material 2 (201) Weld core shell element (202) Heat-affected zone of base material 1 (203) Heat-affected zone of base material 2

[0075] Using the above method, the material and thickness of the weld nugget can be determined, and all the seam welds of the entire battery pack can be simulated. Then, other steps required in the simulation can be carried out, such as setting constraints and loads.

[0076] In this embodiment, step S4: Based on the defined weld nugget, heat-affected zone, and base material, a MIG / MAG seam welding model is established in the ANSA platform. The specific implementation process is as follows:

[0077] Import the geometric model containing the weld area, heat-affected zone, and base material into ANSA; check that the imported geometric model is complete and ensure that there are no overlapping or missing parts.

[0078] Based on the results of S1-S3, define the weld nugget region, heat-affected zone, and base material region; set material properties; and define boundary conditions and loads. Select the appropriate analysis type according to the analysis requirements, such as static analysis, thermal analysis, or fatigue analysis. Export the model in ANSA to a solver-recognizable file format (e.g., .dat, .inp), ensuring that the exported file contains all necessary information and settings for analysis within the solver.

[0079] The system includes: Weld nugget material properties: setting specific material properties for the weld nugget area, such as the elastic modulus, density, and Poisson's ratio of the welding material; Heat-affected zone material properties: setting the material properties of the heat-affected zone according to actual conditions, including strength reduction; Base material properties: setting actual material properties for the base material area to ensure that the data accurately reflects the performance of the base material; and Load settings: setting load conditions for the model, including force, pressure, and acceleration.

[0080] Furthermore, based on the simulation conditions and result reading format, a failure evaluation standard for seam welds was formulated, specifically as follows:

[0081] Load the MIG / MAG seam welding model into the ANSA platform, enter the analysis settings interface (usually under the "Solver" or "Analysis" menu), select "Random Response Analysis" as the analysis type, and perform random vibration analysis step settings for the MIG / MAG seam welding model, that is, set the frequency range and constraints of random vibration analysis, including defining the start frequency, end frequency and frequency interval, inputting the power spectral density function (PSD) of the vibration load, and exporting the solution file for the server to solve;

[0082] Open the solved result file with a post-processing module or software to read the RMS Mises stress results; wherein, the RMS Mises stress results are:

[0083] Multiply the RMS stress value of the heat-affected zone by 3 to obtain an approximate 3σ result, and compare it with the yield strength of the material multiplied by 60%. If the 3*RMS stress value does not exceed the yield strength multiplied by 60%, it is determined that the weld seam has no risk of cracking; otherwise, there is a risk of cracking.

[0084] Risk assessment is performed using the 3σ criterion.

[0085] For example, if the 3σ stress is less than the material yield strength, there is no risk of cracking. However, the material used in the heat-affected zone of the weld is 60% of the strength of the base material. But the vibration calculation is a frequency domain calculation, which only considers elastic behavior and does not involve plastic strength. The material parameters (Young's modulus, Poisson's ratio, density) of the heat-affected zone and the base material are consistent in the model. Therefore, the heat-affected zone is downgraded in post-processing. That is, the criterion for whether the weld will crack is that if the 3σ stress is less than 60% of the base material yield strength, there is no risk.

[0086] like Figure 5 As shown, Figure 5 (1) The simulation results obtained by using this invention are the weld cracking results after a random vibration test of a battery pack. Figure 5 (2) shows that the RMS mises stress in the heat-affected zone of this weld is indeed greater than the yield strength of the base material * 1 / 3 * 60% (43MPa), so it can be judged that this weld has a risk of cracking, and other weld modeling methods should be used ( Figure 5 (3) In this example, the stress result obtained by RBE3-SPRING-RBE3 is too low to be considered as having a risk of cracking.

[0087] After verification with random vibration experiments on actual battery packs, it was found that the simulation method of this seam weld simulated 10 seams in a certain battery pack housing that were at risk of cracking, while the actual number of cracked seams in the battery pack was 11. Considering the possibility that the cracking of seams would reduce the overall structural strength of the pack and thus cause other seams to crack, and based on the vibration benchmark results of a large number of different battery packs, it can be concluded that the simulation method of MIG / MAG seam welds with aluminum alloy as the base material can achieve an accuracy of 90% under random vibration conditions. Example 2:

[0088] This application proposes a computer-readable storage medium storing computer-executable instructions, which, when executed by a control processor, implement a vibration simulation method based on seam welding of an aluminum substrate as described in the first aspect.

[0089] In the several embodiments provided in this application, it will be understood that each block in the flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those shown in the figures. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved.

[0090] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause an electronic device to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0091] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit the scope of protection of this application. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application for those skilled in the art.

Claims

1. A vibration simulation method based on aluminum substrate welds, characterized in that, The method includes: S1: Grid division based on the geometry of the welded sample; Prior to step S1, the following steps are also included: Based on the temperature change during base metal welding, the raw material of welding wire is heat-treated, and then the heat-treated welding wire is made into tensile specimens for tensile testing. The mechanical properties of the material after heat treatment are obtained by tensile testing machine. MIG / MAG seam welding is performed on base metals of different grades and shapes according to lap joint, corner joint, T-joint and butt joint methods. The weld nugget thickness and heat-affected zone range are obtained by metallographic microscope. S2: Use the built-in definition connection function in the ANSA platform to create weld connection lines. In the connection manager interface, generate a row of shell element meshes as weld nuggets by selecting the LASER-WELD-SHELL type for the weld connection lines, and automatically modify the mesh nodes of the connected base material so that the base material and the weld nugget are connected by common nodes. S3: Based on the metallographic scanning results, display the weld nugget unit generated in S2 separately, and display a grid around it to obtain two rows of grids in the base material connected to the weld nugget. Classify the two rows of grids in the base material as the heat-affected zone of the current weld by assigning new attributes; calculate the weld nugget thickness based on the metallographic scanning results. S4: Based on the defined weld nugget, heat-affected zone, and base material, establish a MIG / MAG seam welding model; This also includes: formulating weld failure judgment criteria based on simulation working condition settings and result reading format, specifically: setting random vibration analysis steps for the MIG / MAG weld model in the ANSA platform, exporting the solution file and submitting it to the server for solving; opening the solved result file with a post-processing module or software to read the RMS Mises stress results; and using the 3σ criterion for risk assessment.

2. The vibration simulation method based on aluminum substrate weld seam according to claim 1, characterized in that, For all welds on the same part, their heat-affected zones are classified into the same property; The thickness of the heat-affected zone is the same as that of the base material; Reduce the strength of the heat-affected zone to 60% of that of the base material.

3. The vibration simulation method based on aluminum substrate weld seam according to claim 2, characterized in that, The method further includes: Based on the metallographic scanning results, the weld nugget thickness can be calculated using the following formula: H = (T1 + T2) / 2 + c; Where H is the weld nugget thickness, T1 is the thickness of base material 1 of the weld connection, T2 is the thickness of base material 2, and c is a constant with a value between 0.5 and 1.

5.

4. The vibration simulation method based on aluminum substrate weld seam according to claim 1, characterized in that, The method further includes: The RMS Mises stress result is obtained by multiplying the RMS stress value of the heat-affected zone by 3 to obtain an approximate 3σ result. This 3σ stress is then compared with the yield strength of the material multiplied by 60%. If the 3*RMS stress value does not exceed the yield strength multiplied by 60%, the weld is determined to have no risk of cracking; otherwise, there is a risk of cracking.

5. A computer storage medium storing computer-executable instructions, characterized in that, When the computer-executable instructions are executed by the control processor, they implement a vibration simulation method based on aluminum substrate welds as described in any one of claims 1-4.

Images