Numerical simulation and verification method for welding deformation of aluminum alloy vehicle body of railway vehicle

Abstract

The invention relates to a railway vehicle aluminum alloy vehicle body welding deformation numerical simulation and verification method, relates to the technical field of railway vehicle manufacturing, and solves the technical problems of low prediction precision, long calculation time and low calculation efficiency of a welding simulation method in the prior art. The method comprises the following steps: step 1, modeling an aluminum alloy profile structure; 2, aluminum alloy profile welding structure grid division is carried out; 3, welding seam deformation continuous tracking is carried out; 4, tool constraint and reversible deformation loading are carried out; and 5, deformation verification is carried out. According to the railway vehicle aluminum alloy vehicle body welding deformation numerical simulation and verification method, comprehensive and meticulous standard setting is carried out according to complex tool conditions of railway vehicle aluminum alloy vehicle body and component welding manufacturing, the working condition environment in the welding process is truly restored, and the welding simulation accuracy is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of rail vehicle manufacturing technology, and in particular to a method for numerical simulation and verification of welding deformation of aluminum alloy car bodies for rail vehicles. Background Technology

[0002] In the welding process of aluminum alloy car bodies and major components of rail vehicles, the prediction of welding deformation is quite difficult due to the complex tooling constraints and varied welding sequence combinations involved in the actual welding procedures. Traditional welding simulation methods have low prediction accuracy, excessive computation time, and low computational efficiency, making them unsuitable for the welding process of aluminum alloy car bodies of rail vehicles.

[0003] To effectively predict and control welding deformation, a welding simulation method specifically designed for large components such as aluminum alloy car bodies of rail vehicles needs to be established. This method should simultaneously meet the requirements of computational accuracy and efficiency, systematically standardizing the modeling process for profiles, mesh generation and control standards, and the setting of boundary conditions such as tooling loading and anti-deformation. Furthermore, to verify and calibrate the accuracy of the numerical simulation results, an effective verification method needs to be developed to accurately process and evaluate the predicted deformation. Summary of the Invention

[0004] This invention aims to solve the technical problems of low prediction accuracy, long calculation time, and low calculation efficiency in existing welding simulation methods, and provides a numerical simulation and verification method for welding deformation of aluminum alloy car bodies of rail vehicles.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A numerical simulation and verification method for welding deformation of aluminum alloy car bodies of rail vehicles includes the following steps:

[0007] Step 1: Model the aluminum alloy profile structure;

[0008] Model the aluminum alloy profile structure according to the region;

[0009] Step 2: Mesh division of aluminum alloy profile welding structure;

[0010] The grid is divided based on the geometric characteristics and dimensions of the aluminum alloy profile structure of the aluminum alloy car body and components of the rail vehicle;

[0011] Step 3: Continuous tracking of weld deformation;

[0012] An in-situ tracking element model is established at the location of the weld solid element to record the real-time position and groove gap changes of the inactive welds during each welding sequence.

[0013] Step 4: Tooling constraints and anti-deformation loading;

[0014] Load tooling and fixture constraints;

[0015] Step 5: Deformation verification;

[0016] The deformation after numerical simulation is tested and verified, and the deformation distribution results are post-processed.

[0017] In the above technical solution, step 1 specifically includes:

[0018] Step 11: Treatment of non-welded areas;

[0019] Extract the mid-surface from the geometric model of the non-welded area to create a shell model;

[0020] Step 12: Welding area treatment;

[0021] A solid model of the welding area of ​​the aluminum alloy profile is created;

[0022] Step 13: Model the solid-shell coupling region;

[0023] By binding node degrees of freedom or coupling plate and shell relationships, a combination of solid model and shell model is formed.

[0024] In the above technical solution, step 2 specifically includes: dividing the aluminum alloy car body and components of the rail vehicle into a grid:

[0025] Step 21, Temperature field calculation mesh type: Mesh according to shell and solid;

[0026] Step 22, Stress and Deformation Calculation Mesh Type: Mesh according to shell and solid;

[0027] Step 23, Welding area mesh size: 2-4mm;

[0028] Step 24, Grid size for non-welded areas: 10-30mm;

[0029] Step 25, Solid-shell mesh coupling: Couple the solid mesh and the shell mesh at a ratio of 1:1 or 2:1.

[0030] In the above technical solution, step 23:

[0031] Maximum mesh length for welds and heat-affected zones: Minimum length < 7:1;

[0032] The number of mesh layers in the solid section coupled with the shell is greater than 2.

[0033] In the above technical solution, step 4 specifically includes:

[0034] Step 41, Apply hydraulic / pneumatic clamping constraints: Maintain constant hydraulic or pneumatic pressure during automatic welding, apply it to the surface of the aluminum alloy profile, and press the aluminum alloy profile and the supporting fixture against the template.

[0035] Step 42, Apply mechanical fixture constraints: Maintain constant displacement during automatic welding, acting on the surface of the aluminum alloy profile;

[0036] Step 43, Apply gravity clamp constraint: During the automatic welding process, a heavy object is applied to the surface of the aluminum alloy profile;

[0037] Step 44: Load the structural self-weight and tooling support: uniformly distribute the gravity of the aluminum alloy profile structure.

[0038] In the above technical solution, step 5 specifically includes:

[0039] Step 51: Before solving, set the output node coordinate values ​​for each welding process;

[0040] Step 52: Extract the aluminum alloy profile contour for the solved positive and negative welding process;

[0041] Step 53: Based on the reference point positions of the on-site aluminum alloy profile deformation measurement, level the coordinate positions of the aluminum alloy profile outline by coordinate rotation;

[0042] Step 54: By translating the coordinates, the coordinate positions of the aluminum alloy profile before and after deformation are coincident, and the displacement of each measuring point is statistically analyzed.

[0043] Step 55: Compare the deformation statistics obtained from the numerical simulation with the actual deformation measured on site.

[0044] The present invention has the following beneficial effects:

[0045] The numerical simulation and verification method for welding deformation of aluminum alloy car bodies of rail vehicles of the present invention provides a comprehensive and detailed specification setting for the complex tooling conditions of welding manufacturing of aluminum alloy car bodies and components of rail vehicles, realistically restores the working environment during the welding process, and greatly improves the accuracy of welding simulation.

[0046] The numerical simulation and verification method for welding deformation of aluminum alloy car bodies of rail vehicles of the present invention utilizes simulation contour deformation measurement to achieve accurate statistical data on deformation after multiple loading and component spatial deflection, effectively solving the technical problem in post-processing of numerical simulation calculations of structures, and showing wide applicability for deformation statistics with three-dimensional rigid body displacement characteristics. Attached Figure Description

[0047] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0048] Figure 1 A schematic diagram of the solid-shell coupling modeling method for aluminum alloy profile structures.

[0049] Figure 2 This is a schematic diagram of the grid division for aluminum alloy profiles.

[0050] Figure 3 This is a schematic diagram of solid-shell unit coupling.

[0051] Figure 4 This is a schematic diagram of a weld seam tracking unit tracking structural deformation.

[0052] Figure 5 This is a schematic diagram of tooling constraints for the welding process of aluminum alloy profiles for vehicle body components.

[0053] Figure 6 This is a schematic diagram of the tooling support.

[0054] Figure 7 This is a schematic diagram of the reaction force variation curve of the mold supporting the edge position when the hydraulic clamp is loaded.

[0055] Figure 8 This is a schematic diagram of the statistical process for welding deformation data. Detailed Implementation

[0056] The inventive concept of this invention is as follows:

[0057] The present invention provides a numerical simulation and verification method for welding deformation of aluminum alloy car bodies of rail vehicles. By establishing a welding simulation method specifically for large components such as aluminum alloy car bodies of rail vehicles, the method systematically and standardizedly models, controls the mesh and sets boundary conditions, and develops an effective verification method to ensure the accuracy of welding deformation predicted by numerical simulation, thereby achieving accurate prediction and control of welding deformation.

[0058] The present invention will now be described in detail with reference to the accompanying drawings.

[0059] The present invention provides a method for numerical simulation and verification of welding deformation of aluminum alloy car bodies for rail vehicles, comprising the following steps:

[0060] Step 1: Modeling the aluminum alloy profile structure, specifically including:

[0061] Step 11, Non-welded area processing: The aluminum alloy vehicle body components are mainly made of aluminum alloy profiles. The mid-surface of the geometric model of the non-welded areas is extracted to create a shell model, reducing the mesh size of the computational model and improving computational efficiency. This also avoids hourglass deformation caused by insufficient mesh in thin-walled structures, thus improving computational accuracy.

[0062] Step 12, Welding Area Processing: A solid model is created for the welding area of ​​the aluminum alloy profile to improve the accuracy of welding deformation (angular deformation, lateral shrinkage, and longitudinal shrinkage deformation). The welding area is shown below.Figure 1 As shown.

[0063] Step 13, Solid-Shell Coupled Region Modeling: By binding node degrees of freedom or plate-shell coupling relationships, a combination of solid model and shell model is formed.

[0064] Step 2: Mesh division of aluminum alloy profile welding structure;

[0065] The grid is divided based on the geometric characteristics and dimensions of the aluminum alloy profile structure of the aluminum alloy car body and components of the rail vehicle.

[0066] Step 21, Temperature field calculation mesh type: Mesh is divided according to shell (four-node heat conduction shell element DS4) and solid (three-dimensional eight-node heat conduction solid element DC3D8).

[0067] Step 22, Stress and Deformation Calculation Mesh Type: Mesh according to shell (four-node shell element S4R) and solid (three-dimensional eight-node reduced integral solid element C3D8R).

[0068] Step 23: Welding area (solid model) mesh size: 2-4mm, hexahedral mesh or predominantly hexahedral mesh generation. Maximum mesh length for weld and heat-affected zone: minimum length < 7:1. The number of mesh layers for the solid section coupled to the shell should be greater than 2. Figure 2 The red part is shown in the image.

[0069] Step 24, Non-welded area (shell model) mesh size: 10-30mm, such as... Figure 2 The blue part is shown in the image.

[0070] Step 25, Solid-shell mesh coupling:

[0071] like Figure 3 As shown, the solid mesh (blue part) and the shell mesh (yellow part) are coupled at a ratio of 1:1 or 2:1, that is:

[0072] Solid mesh density: Shell mesh density = 1:1 or 2:1.

[0073] The meshing rules meet the algorithm requirements, namely, the simulation accuracy (the maximum deformation deviation value cannot exceed 3mm) and the computational efficiency (the length of the aluminum alloy profile is ≤24m, and the calculation cycle is <5 days).

[0074] Step 3: Continuous tracking of weld deformation;

[0075] The continuous activation function of weld volume can accurately reflect the changes in the position of weld seams during the welding process of the vehicle body and components, laying the foundation for accurately reproducing the assembly and welding sequence of the vehicle body and components.

[0076] During the welding process, the aluminum alloy profile structure of the vehicle body and components typically undergoes significant macroscopic deformation, such as... Figure 4 As shown, for subsequent welds (inactive state), activation failure (large deformation or negative volume error) may occur, causing the welding calculation to terminate. To ensure the real-time change of structural stiffness during the loading process of different welding sequences in multiple steps (reverse deformation, tooling changes), an in-situ tracking element model needs to be established at the location of the weld solid element to record the real-time position and groove gap change of the inactive welds in each welding sequence. This tracking element model is a purely elastic element, and its element stiffness ratio to the weld solid element stiffness is <0.01 (usually it can be scaled to 0.001-0.0001). Therefore, the connection strength on both sides of the weld position in the inactive position is extremely small, which can simulate the change of structural stiffness in each welding process of aluminum alloy profile structure and provide accurate data deformation and position information for subsequent welds to be activated (activated in stress-free / strain-free state).

[0077] Step 4: Tooling constraints and anti-deformation loading;

[0078] Various tooling and fixture constraints exist during the welding process of aluminum alloy profiles for aluminum alloy vehicle bodies and components, such as... Figure 5 As shown, it includes:

[0079] Step 41: Apply hydraulic / pneumatic clamping constraints: Maintain constant hydraulic or pneumatic pressure during automatic welding, acting on the surface of the aluminum alloy profile to press the profile against the supporting fixture template. This is done through surface pressure. If the welding shrinkage deformation force exceeds the preset pressure of the clamp during welding, the contact surfaces of the aluminum alloy profile and the supporting fixture template will separate.

[0080] Step 42, Apply mechanical fixture constraints: Maintain constant displacement during automatic welding, acting on the surface of the aluminum alloy profile. Loading is controlled by nodal displacement.

[0081] Step 43, Applying Gravity Fixture Constraints: During the automatic welding process, a heavy object (such as a steel weight / block) is applied to the surface of the aluminum alloy profile. This is done in the form of surface pressure. It is assumed that the gravity fixture and the profile remain in contact during the welding process.

[0082] Step 44: Load the structural self-weight and tooling supports: such as Figure 6 , Figure 7 As shown, throughout the process, the aluminum alloy profile structure distributes gravity evenly. The four sets of supporting molds in the middle (such as...) Figure 6 The positions of supports 3, 4, 5 and 6 in the figure are used as displacement constraints to support the self-weight of the aluminum alloy profile and the steel pressure iron.

[0083] When loading hydraulic / pneumatic clamps to hold aluminum alloy profiles, the four sets of support molds at the edges (such as...) Figure 6The positions of supports 1, 2, 7, and 8 may experience arc deformation after weld shrinkage, leading to contact separation between the aluminum alloy profile and the support mold. The actual tooling stiffness during welding significantly affects the residual deformation of the welded structure. To improve simulation accuracy, the edge support molds are set to a load-bearing type (non-displacement constraint), with the applied force being the hydraulic clamp reaction force. When there is a gap between the aluminum alloy profile model and the support mold, the contact reaction force is 0. When the aluminum alloy profile contour moves to the theoretical position of the support mold, the contact reaction force rapidly increases to the hydraulic force. The resistance to further downward movement continuously increases, restricting the aluminum alloy profile from continuing to move downwards. Figure 7 As shown.

[0084] Step 5: Deformation verification;

[0085] like Figure 8 As shown, during the welding deformation process of aluminum alloy profiles, due to multiple welding procedures, as well as the complex tooling arrangement, lifting gravity flipping, reverse deformation, and tooling release of different procedures, the aluminum alloy profile profile obtained by the final numerical simulation solution according to the boundary conditions of this process usually undergoes deflection and translation. It is difficult to directly compare the displacement distribution results with the actual test results.

[0086] To test and verify the deformation after numerical simulation, the deformation distribution results are post-processed according to the following procedure:

[0087] Step 51: Before solving, set the output node coordinate values ​​for each welding process (the spatial coordinates are in the form of x, y, z).

[0088] Step 52: Extract the profile contour of the forward and reverse welding process after solving.

[0089] Step 53: According to the reference point location of the on-site aluminum alloy profile deformation measurement (e.g., Figure 8 The coordinate positions of the aluminum alloy profile are leveled by rotating the coordinates of reference points 1 and 2 shown in the figure.

[0090] Step 54: By translating the coordinates, the coordinate positions of the aluminum alloy profile before and after deformation are coincident, and the displacement of each measuring point is statistically analyzed.

[0091] Step 55: Compare the deformation statistics obtained from the numerical simulation with the actual deformation measured on site.

[0092] The numerical simulation and verification method for welding deformation of aluminum alloy car bodies of rail vehicles of the present invention provides a comprehensive and detailed specification setting for the complex tooling conditions of welding manufacturing of aluminum alloy car bodies and components of rail vehicles, realistically restores the working environment during the welding process, and greatly improves the accuracy of welding simulation.

[0093] The numerical simulation and verification method for welding deformation of aluminum alloy car bodies of rail vehicles of the present invention utilizes simulation contour deformation measurement to achieve accurate statistical data on deformation after multiple loading and component spatial deflection, effectively solving the technical problem in post-processing of numerical simulation calculations of structures, and showing wide applicability for deformation statistics with three-dimensional rigid body displacement characteristics.

[0094] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for numerical simulation and verification of welding deformation of aluminum alloy car bodies for rail vehicles, characterized in that, Includes the following steps: Step 1: Model the aluminum alloy profile structure; Model the aluminum alloy profile structure according to the region; Step 2: Mesh division of aluminum alloy profile welding structure; The grid is divided based on the geometric characteristics and dimensions of the aluminum alloy profile structure of the aluminum alloy car body and components of the rail vehicle; Step 3: Continuous tracking of weld deformation; An in-situ tracking element model is established at the location of the weld solid element to record the real-time position and groove gap changes of the inactive welds during each welding sequence. Step 4: Tooling constraints and anti-deformation loading; Load tooling and fixture constraints; Step 5: Deformation verification; The deformation after numerical simulation is tested and verified, and the deformation distribution results are post-processed.

2. The method for numerical simulation and verification of welding deformation of aluminum alloy car bodies for rail vehicles according to claim 1, characterized in that, Step 1 specifically includes: Step 11: Treatment of non-welding areas; Extract the mid-surface from the geometric model of the non-welded area to create a shell model; Step 12: Welding area treatment; A solid model of the welding area of ​​the aluminum alloy profile is created; Step 13: Model the solid-shell coupling region; By binding node degrees of freedom or coupling plate and shell relationships, a combination of solid model and shell model is formed.

3. The method for numerical simulation and verification of welding deformation of aluminum alloy car bodies for rail vehicles according to claim 1, characterized in that, Step 2 specifically includes: dividing the aluminum alloy car body and components of the rail vehicle into a grid: Step 21, Temperature field calculation mesh type: Mesh according to shell and solid; Step 22, Stress and Deformation Calculation Mesh Type: Mesh according to shell and solid; Step 23, Welding area mesh size: 2-4mm; Step 24, Grid size for non-welded areas: 10-30mm; Step 25, Solid-shell mesh coupling: Couple the solid mesh and the shell mesh at a ratio of 1:1 or 2:

1.

4. The method for numerical simulation and verification of welding deformation of aluminum alloy car bodies for rail vehicles according to claim 3, characterized in that, In step 23: Maximum mesh length for welds and heat-affected zones: Minimum length < 7:1; The number of mesh layers in the solid section coupled with the shell is greater than 2.

5. The method for numerical simulation and verification of welding deformation of aluminum alloy car bodies for rail vehicles according to claim 1, characterized in that, Step 4 specifically includes: Step 41, Apply hydraulic / pneumatic clamping constraints: Maintain constant hydraulic or pneumatic pressure during automatic welding, apply it to the surface of the aluminum alloy profile, and press the aluminum alloy profile and the supporting fixture against the template. Step 42, Apply mechanical fixture constraints: Maintain constant displacement during automatic welding, acting on the surface of the aluminum alloy profile; Step 43, Apply gravity clamp constraint: During the automatic welding process, a heavy object is applied to the surface of the aluminum alloy profile; Step 44: Load the structural self-weight and tooling support: uniformly distribute the gravity of the aluminum alloy profile structure.

6. The method for numerical simulation and verification of welding deformation of aluminum alloy car bodies for rail vehicles according to claim 1, characterized in that, Step 5 specifically includes: Step 51: Before solving, set the output node coordinate values ​​for each welding process; Step 52: Extract the aluminum alloy profile contour for the solved positive and negative welding process; Step 53: Based on the reference point positions of the on-site aluminum alloy profile deformation measurement, level the coordinate positions of the aluminum alloy profile outline by coordinate rotation; Step 54: By translating the coordinates, the coordinate positions of the aluminum alloy profile before and after deformation are coincident, and the displacement of each measuring point is statistically analyzed. Step 55: Compare the deformation statistics obtained from the numerical simulation with the actual deformation measured on site.

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