A method and system for calculating inherent deformation of a welded joint

Abstract

The present application belongs to the technical field of welding deformation prediction, and particularly relates to a kind of calculation method and system of inherent deformation of welded joint.The present application is a kind of calculation method of inherent deformation of welded joint, comprising the following steps: A1. obtaining the initial parameters of typical welded joint of welded structure member;A2. constructing the thermal elastic-plastic finite element model of welded joint;A3. solving the thermal elastic-plastic finite element model;A4. evaluating and judging the temperature field and deformation field solved in step S3;A5. model correction;A6. extraction and calculation of inherent deformation data of welded joint;A7. output inherent deformation data of welded joint.Through establishing the thermal elastic-plastic finite element model same as the actual joint type, the deformation of x, y, z three directions of sampling point is obtained, and then the inherent deformation of welded joint is calculated.The method obtains the temperature field and deformation field corresponding to the welded joint based on the thermal elastic-plastic simulation results, which improves the efficiency and realizes the high-precision acquisition of inherent deformation data.

Description

Technical Field

[0001] This invention belongs to the field of welding deformation prediction technology, specifically relating to a calculation method and system for the inherent deformation of welded joints. Background Technology

[0002] Welding is an essential joining process in industrial production. Uneven heating and cooling during welding, as well as the volume shrinkage of the weld seam caused by the molten metal changing from a liquid to a solid state, are the main causes of deformation and stress in welded parts. Severe deformation and stress can lead to the scrapping of the entire weldment or component, resulting in economic losses. Some deformations can be eliminated through corrective measures, but these are time-consuming, and some corrective processes may not achieve the desired effect. Severe welding deformation and stress can affect the local strength and stability of structural components, reducing product performance. Therefore, how to take appropriate measures to reduce welding deformation and stress and improve welding quality during the welding process is a long-standing concern.

[0003] Due to the complexity of structural components in engineering machinery, it is difficult to predict welding deformation of the entire component using analytical calculation methods, empirical formulas, or thermo-elastic-plastic finite element methods. The inherent strain method, a finite element analysis method based on elasticity theory, is relatively simple to establish and solve for problems with complex geometries or boundary conditions. It can effectively handle the nonlinear behavior of materials and has very high computational efficiency, making it suitable for predicting welding deformation in large models. However, accurately obtaining the inherent strain of the joint is a key problem that needs to be solved and is fundamental to the efficient and accurate prediction of welding deformation.

[0004] Common methods for obtaining the inherent deformation of welded joints mainly include actual measurement methods, methods based on thermo-elastic-plastic finite element integration, and empirical formula methods. Among these, actual measurement methods are complex, requiring specialized equipment and operators, and are also costly. Empirical formula methods are based on experimental data and empirical summaries, but their accuracy is relatively low, unable to provide precise prediction results like numerical simulation methods such as finite element analysis. Furthermore, their applicability is limited, only suitable for describing the characteristics or laws of specific materials or structures under specific conditions. Representative existing technologies for obtaining welded joint deformation data based on the thermo-elastic-plastic finite element method are as follows:

[0005] Patent CN116372406A discloses a method for predicting deformation in butt welds of sheet metal based on the inherent strain method. It obtains the initial inherent strain through empirical formulas and converts this strain into anisotropic thermal expansion coefficients, which are then applied to the weld and nearby elements for elastic calculations. However, this method can only qualitatively determine the basic trend of deformation and cannot obtain the precise magnitude of the deformation. Furthermore, the empirical formulas only consider the influence of welding process parameters on inherent deformation and cannot account for other factors.

[0006] Patent number CN115143927A provides a low-cost indirect measurement method for inherent strain parameters. This method combines experimental methods with simulation methods based on inherent strain. It calculates the inherent deformation data of the welded joint based on experimental test results, and then performs simulation analysis based on these results to obtain the deformation results of the welded joint. However, this method primarily relies on experimental methods to obtain the inherent deformation data of the welded joint, resulting in a complex measurement process and high experimental costs. Furthermore, to ensure the accuracy of the experimental results, it specifies the dimensional deviations of the experimental sample, which are difficult to achieve in actual welding processes. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies, such as the basic trend of only being able to qualitatively determine deformation, significant limitations in calculation, complex measurement processes, and high costs, and to provide a programmed method and system for calculating the inherent deformation of welded joints that covers a wide range of parameters and is highly accurate.

[0008] The technical solution adopted by this invention to solve its technical problem is:

[0009] As a first aspect, a method for calculating the inherent deformation of a welded joint includes the following steps:

[0010] A1. Obtain the initial parameters of a typical welded joint in a welded structural component;

[0011] A2. Construct a thermo-elastic-plastic finite element model of the welded joint, that is, construct a thermo-elastic-plastic finite element model of the welded joint based on the obtained initial parameters;

[0012] A3. Solve the thermo-elastic-plastic finite element model, that is, solve the temperature field and deformation field corresponding to the weld joint.

[0013] A4. Evaluate and determine the temperature field and deformation field obtained in step S3, that is, evaluate and determine the rationality of the singularity ratio of the temperature field and deformation field, the convergence of the model, and the welding deformation and welding residual stress.

[0014] A5. Model correction, i.e., the model correction of the thermo-elastic-plastic finite element model based on the evaluation results of the temperature field and deformation field;

[0015] A6. Extraction and calculation of inherent deformation data of welded joints, that is, the temperature field and deformation field obtained by solving the modified thermo-elastic-plastic finite element model are used to extract and calculate the inherent deformation data of welded joints through the calculation formulas corresponding to different types of welded joints;

[0016] A7. Output the inherent deformation data of the welded joint.

[0017] Specifically, the initial parameters include one or more of the following: joint type, joint bevel size, thickness of the two base materials, welding method, joint gap, base material properties, material properties of the welding material, welding position, and welding process parameters.

[0018] Specifically, the construction of the thermo-elastic-plastic finite element model of the welded joint in step S2 includes the following steps:

[0019] A21. Determining the dimensions of the geometric model, i.e., determining the size of the thermo-elastic-plastic finite element model based on the thickness of the base material;

[0020] A22. The establishment of the mesh model is to determine the coordinate system (x, y, z) of the model using the right-hand rule, and to use hexahedral eight-node elements for mesh generation. Each weld pool section contains at least 4 meshes.

[0021] A23. The establishment of the material model, that is, inputting the thermophysical parameters of the base material and welding material that change with temperature to define the hardness model of the material, wherein the hardness model is isotropic hardening + kinematic hardening;

[0022] A24. Heat source model setting and heat source parameter setting, that is, determining the heat source model and the corresponding parameters of the heat source model according to the welding method, welding position and welding process parameters;

[0023] A25. Setting the calculation conditions, namely, setting the thermal boundary conditions and mechanical boundary conditions of the model;

[0024] A26. Model inspection, namely, checking the mesh quality and model settings.

[0025] Specifically, the thermophysical properties of the welding material in step A23 include one or more of the following: elastic modulus, coefficient of thermal expansion, specific heat capacity, and yield strength.

[0026] Specifically, the thermal boundary conditions in step A25 mainly include welding thermal boundary conditions, thermal convection boundary conditions, and thermal radiation boundary conditions; when the model is freely welded without external constraints, auxiliary displacement constraints restricting 6 rigid body degrees of freedom are applied.

[0027] Specifically, the main parameters for mesh quality inspection in step A26 include one or more of the following: element normal, aspect ratio, Jacobian, interior angle, warpage, and skewness.

[0028] The model setup check includes setting material parameters, thermal boundary conditions, and one or more mechanical boundary conditions.

[0029] Specifically, the inherent deformation data includes the inherent lateral shrinkage δ T Inherent longitudinal contraction δ L Inherent transverse bending θT and inherent longitudinal bending θ L .

[0030] Specifically, the welded joints include butt joints, T-joints, and lap joints;

[0031] The inherent lateral shrinkage δ of the mating joint T The calculation formula is:

[0032]

[0033] The inherent longitudinal shrinkage δ of the mating joint L The calculation formula is:

[0034] δ L =-{[LC1-(x 09 -x 01 )] / (x 09 -x 01 )+[LC2-(x 012 -x 04 )] / (x 012 -x 04 )}×B / 2; where,

[0035]

[0036]

[0037] The inherent lateral bending θ of the mating joint T The calculation formula is:

[0038] θ T ={(Uz5-Uz6) / (y6-y5)+(Uz8-Uz7) / (y8-y7)};

[0039] The inherent longitudinal bending θ of the mating joint L The calculation formula is:

[0040] θ L ={(Uz6-Uz2) / (x6-x2)} 2 -(Uz6-U z10 ) / (x 10 -x6) 2 -(Uz7-Uz3) / (x7-x3) 2 -(Uz7-Uz 11 ) / (x 11 -x7) 2} / 2;

[0041] In the formula, LC is the curve distance between two sampling points, B is the width of the mating joint, dz is the chord length of the curve corresponding to the two sampling points, and x 0i For any sampling point P in the finite element model i The initial x-coordinate, y 0i For any sampling point P in the finite element model i The initial ordinate, x i For any sampling point P in the finite element model i The deformed abscissa, yi, represents any sampling point P in the finite element model. i The deformed ordinate, U zi For any sampling point P in the finite element model i The displacement in the z-direction, where i is an integer from 1 to n.

[0042] As a second aspect, a calculation system for the inherent deformation of a welded joint is characterized by employing a calculation method for the inherent deformation of a welded joint as described above, comprising:

[0043] The result data reading module is used to read the result file of welding deformation calculation and form raw data.

[0044] The model parameter acquisition module is used to determine the type of the weld joint to be calculated and provides basic information of the thermo-elastic-plastic finite element model corresponding to the weld joint.

[0045] The automatic sampling point coordinate determination module calculates the coordinates of each sampling point based on the obtained basic information and welding joint type, determines the number of the nearest node for each sampling point, and extracts the deformation in the x, y, and z directions of each node.

[0046] The inherent deformation meter module calculates the inherent deformation data of different types of welded joints based on the calculation formula corresponding to the welded joint.

[0047] The results output module is used to output the inherent deformation data of the joint welding as a .dat file in a specific format, which is convenient for subsequent calling and analysis.

[0048] Specifically, the model parameter acquisition module automatically determines the type of welded joint based on the initial data read in, and provides the basic information of the thermo-elastic-plastic finite element model based on the coordinate information of each node.

[0049] The basic information includes the length, width, and height of the thermo-elastic-plastic finite element model, as well as the plate thickness information of the welded structural components.

[0050] The beneficial effects of the method and system for calculating the inherent deformation of welded joints according to the present invention are:

[0051] By establishing a thermo-elastic-plastic finite element model identical to the actual joint type, the model is solved to obtain the deformation in the x, y, and z directions of the sampling points, thereby calculating the inherent deformation of the welded joint and directly outputting the file for system calculation. This method obtains the temperature and deformation fields corresponding to the welded joint based on thermo-elastic-plastic simulation results. By acquiring the coordinate values ​​and deformation amounts of different nodes, the inherent deformation data of the welded joint is calculated, achieving high-precision acquisition of inherent deformation data while improving efficiency.

[0052] The modeling process fully considers the influence of gaps, bevels, and other factors on the deformation of welded joints. At the same time, it replaces the integration of the weld cross-section with algebraic calculation of the deformation of specified sampling points, which improves the accuracy of the inherent deformation of the weld and improves the calculation efficiency. It transforms the size and point coordinates of the thermo-elastic-plastic finite element model into a function of the material thickness, which is not dependent on the specific model and has wide applicability. It is also easy to implement in a program. Attached Figure Description

[0053] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0054] Figure 1 This is a flowchart of the calculation method according to an embodiment of the present invention.

[0055] Figure 2 This is a flowchart of the calculation method according to an embodiment of the present invention.

[0056] Figure 3 This is a flowchart illustrating the steps involved in constructing a thermo-elastic-plastic finite element model of a welded joint according to an embodiment of the present invention.

[0057] Figure 4 This is a schematic diagram of the sampling points of the docking joint corresponding to the calculation method of this embodiment of the invention.

[0058] Figure 5 This is a schematic diagram of the T-shaped connector sampling points corresponding to the calculation method of this embodiment of the invention.

[0059] Figure 6 This is a schematic diagram of the sampling points of the lap joint corresponding to the calculation method of this embodiment of the invention.

[0060] Figure 7 This is a block diagram of the computing system according to an embodiment of the present invention.

[0061] Figure 8 This is a diagram showing the thermal properties of the materials in an embodiment of the present invention.

[0062] Figure 9 This is a diagram showing the welding process parameters of the butt joint according to an embodiment of the present invention.

[0063] In the diagram: 1. Result data reading module, 2. Model parameter acquisition module, 3. Automatic determination module for sampling point coordinates, 4. Inherent deformation calculation module, 5. Result output module. Detailed Implementation

[0064] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0065] like Figures 1-9 A specific embodiment of the method for calculating the inherent deformation of a welded joint according to the present invention is shown, comprising the following steps:

[0066] A1. Obtain the initial parameters of a typical welded joint of a welded structural component. The initial parameters include one or more of the following: joint type, joint groove size, thickness of the two base materials, welding method, joint gap, base material properties, material properties of the welding material, welding position, and welding process parameters.

[0067] A2. Construct a thermo-elastic-plastic finite element model of the welded joint, that is, construct a thermo-elastic-plastic finite element model of the welded joint based on the obtained initial parameters.

[0068] It should be further explained that the welded joints in this implementation include butt joints, T-joints and lap joints. The thermo-elastic-plastic finite element model is established according to the type of welded joint corresponding to different original parameters. The modeling process uses hexahedral eight-node elements. At the same time, the size of the model is determined according to the thickness of the base material, and the model is meshed. It is required that a weld pool section contains at least 4 meshes.

[0069] A3. Solve the thermo-elastic-plastic finite element model, that is, solve the temperature field and deformation field corresponding to the weld joint. When performing welding simulation analysis on structural components with a plate thickness of no more than 5mm, a large strain model is adopted, and a lumped mass heat capacity matrix is ​​used to overcome the step phenomenon in transient temperature field analysis, and the welding deformation calculation results of each node are output.

[0070] A4. Evaluate and judge the temperature field and deformation field obtained in step S3, that is, evaluate and judge the rationality of the singularity ratio of the temperature field and deformation field, the convergence of the model, and the welding deformation and welding residual stress. After the calculation is completed, compare and judge the model calculation results, and compare and analyze the rationality of the model's singularity ratio, model convergence, and welding deformation and welding residual stress.

[0071] A5. Model correction, which is to correct the thermo-elastic-plastic finite element model based on the evaluation results of the temperature field and deformation field.

[0072] A6. Extraction and calculation of inherent deformation data of welded joints, i.e., extracting and calculating the inherent deformation data of welded joints using the temperature field and deformation field obtained from the modified thermo-elastic-plastic finite element model, and applying the calculation formulas corresponding to different types of welded joints. In this embodiment, the inherent deformation data includes the inherent transverse shrinkage δ. T Inherent longitudinal contraction δ L Inherent transverse bending θ T and inherent longitudinal bending θ L .

[0073] A7. Output the inherent deformation data of the welded joint.

[0074] This method utilizes the thermo-elastic-plastic finite element method to accurately predict weld joint deformation data. By establishing a weld finite element model identical to the actual joint type, the model is solved to obtain the deformation in the x, y, and z directions at sampling points, thereby calculating the inherent deformation of the weld joint and directly outputting a file for software calculation. This method fully considers the influence of gaps, bevels, and other factors on weld joint deformation during modeling. Furthermore, it improves the accuracy of inherent weld deformation and computational efficiency by replacing integration of the weld cross-section with algebraic calculation of the deformation at specified sampling points, while also being easily programmable.

[0075] Reference Figure 3 The construction of the thermo-elastic-plastic finite element model of the welded joint in step S2 includes the following steps:

[0076] A21. Determining the dimensions of the geometric model, i.e., determining the size of the thermo-elastic-plastic finite element model based on the thickness of the base material;

[0077] A22. The establishment of the mesh model is to determine the coordinate system (x, y, z) of the model using the right-hand rule, and to use hexahedral eight-node elements for mesh generation. Each weld pool section contains at least 4 meshes.

[0078] A23. Establishment of the material model, that is, inputting the thermophysical parameters of the base material and welding material that change with temperature to define the hardness model of the material. The hardness model is isotropic hardening + kinematic hardening.

[0079] A24. Heat source model setting and heat source parameter setting, that is, determining the heat source model and the corresponding parameters of the heat source model based on the welding method, welding position and welding process parameters;

[0080] A25. Setting the calculation conditions, namely, setting the thermal boundary conditions and mechanical boundary conditions of the model;

[0081] A26. Model inspection, namely, checking the mesh quality and model settings.

[0082] In this embodiment, the thermal properties of the welding material in step A23 include one or more of the following: elastic modulus, coefficient of thermal expansion, specific heat capacity, and yield strength. The thermal boundary conditions in step A25 mainly include welding thermal boundary conditions, thermal convection boundary conditions, and thermal radiation boundary conditions. When the model is freely welding without external constraints, auxiliary displacement constraints restricting the six rigid body degrees of freedom are applied to ensure the convergence of the model calculation.

[0083] In one implementation method, step A24 determines the heat source model and its corresponding parameters based on the welding method, welding position, and welding process parameters. Specifically, for gas shielded welding, a double ellipsoidal heat source is recommended; for laser welding, a rotating Gaussian body heat source is used; and for laser-arc hybrid welding, a combination of a double ellipsoidal and a Gaussian body heat source is used. The determination of heat source parameters is mainly calibrated through comparison of the macroscopic metallographic structure of the weld. The main parameters for mesh quality checking in step A26 include one or more of the following: element normal, aspect ratio, Jacobian, interior angle, warpage, and skewness. Model setting checks include setting material parameters, thermal boundary conditions, and one or more of the following: mechanical boundary conditions. It should be understood that, depending on the specific application, selective checks can be performed on the above items; in this embodiment, all of the above items are checked.

[0084] In this embodiment, the calculation process for the inherent deformation data of the three types of welded joints is as follows:

[0085] For butt joints, the welding direction is the X-axis of the coordinate system, and the base material thickness direction is the Z-axis. The Y-axis is determined using the right-hand rule, with the origin at the center of the base material's bottom surface. The specimen length is 100t, and the specimen width is 50t, where t is the base material thickness. (See...) Figure 4 As shown.

[0086] For butt joints, the inherent deformation does not require differentiation between the left and right plates during the calculation. The inherent deformation calculation uses 12 sampling points; for ease of parameterization, refer to... Figure 4 The coordinate system shown represents the coordinates of the sampling points using the plate thickness t, as shown in Table 1. The inherent lateral shrinkage δ of the butt joint... T The calculation formula is:

[0087]

[0088] The inherent longitudinal shrinkage δ of the mating joint L The calculation formula is:

[0089] δ L =-{[LC1-(x 09 -x 01 )] / (x 09 -x 01 )+[LC2-(x012 -x 04 )] / (x 012 -x 04 )}×B / 2; where,

[0090]

[0091]

[0092] The inherent lateral bending θ of the mating joint T The calculation formula is:

[0093] θ T ={(Uz5-Uz6) / (y6-y5)+(Uz9-Uz7) / (y8-y7)};

[0094] The inherent longitudinal bending θ of the mating joint L The calculation formula is:

[0095] θ L ={-(Uz6-Uz2) / (x6-x2)} 2 -(Uz6-Uz 10 ) / (x 10 -x6) 2 -(Uz7-Uz3) / (x7-x3) 2 -(Uz7-Uz 11 ) / (x 11 -x7) 2} / 2;

[0096] In the formula, LC is the curve distance between two sampling points, B is the width of the mating joint, dz is the chord length of the curve corresponding to the two sampling points, and X... 0i For any sampling point P in the finite element model i The initial x-coordinate, y 0i For any sampling point P in the finite element model i The initial ordinate, x i For any sampling point P in the finite element model i The deformed abscissa, yi, represents any sampling point P in the finite element model. i The deformed ordinate, U zi For any sampling point P in the finite element model i The displacement in the z-direction, where i is an integer from 1 to n, and the unit is millimeters (mm).

[0097] Table 1 Coordinates of sampling points for the butt joint

[0098] x 20t 20t 20t 20t 50t 50t 50t 50t 80t 80t 80t 80t y -25t -2t 2t 25t -25t -2t 2t 25t -25t -2t 2t 25t z t t t t t t t t t t t t

[0099] In the table, t represents the thickness of the base material of the butt joint.

[0100] For T-joints, the welding direction is the X-axis of the coordinate system, and the height direction of the vertical plate is the Z-axis. The Y-axis is determined using the right-hand rule, with the origin at the center of the base plate. The sample length OL is 100t, the base plate width B is 50t, and the vertical plate height H is 50t, where t is the thickness of the base material. Figure 5 As shown.

[0101] When calculating the inherent deformation data of the T-joint, a calculation method that distinguishes between the base plate and the web plate is adopted. Fifteen sampling points are collected for the inherent deformation calculation. For ease of parameterization, refer to... Figure 5 The coordinate system shown represents the coordinates of the sampling points using the plate thickness t, as shown in Table 2. The inherent lateral contraction δ of the base plate... TP Inherent longitudinal contraction δ LP Inherent lateral bending θ TP Inherent longitudinal bending θ LP The inherent transverse contraction δ of the web TW Inherent longitudinal contraction δ LW Inherent lateral bending θ TW Inherent longitudinal bending θ LW The calculation process is as follows.

[0102] First calculate d1, d2, e1, e2, b, L, ΔL, Δb, ΔL W Intermediate parameters:

[0103] d1=((y 14 -y1)+(y 15 -y9)) / 2

[0104] d2=((y2-y 14 )+(y 10 -y 15 )) / 2;

[0105] b=((y4-y3)+(y6-y5)+(y8-y7)) / 3;

[0106] L=((x 09 -x 01 )+(x 010 -x 02 )) / 2;

[0107] e1=((z1-z 14 )+(z9-z 15 )) / 2;

[0108] e2=((z2-z 14 )+(z 10 -z15 )) / 2;

[0109] ΔL=((x 09 -x 01 )+(x 010 -x 02 )) / 2-((x9-x1)+(x 10 -x2)) / 2;

[0110] Δb=((y4-y3)+(y6-y5)+(y8-y7)) / 3-((y 04 -y 03 )+(y 06 -y 05 )+(y 08 -y 07 )) / 3;

[0111] ΔL W =((x) 09 -x 01 )+(x 010 -x 02 )) / 2-((x 15 -x 14 )+(x 13 -x 11 )) / 2;

[0112] Calculate the shrinkage ΔH of the web height after welding:

[0113] ΔH=((z 011 +z 012 +z 013 ) / 3-(z 014 +z 015 ) / 2)-((z 11 +z 12 +z 13 ) / 3-(z 14 +z 15 ) / 2); Calculate the lateral displacement C at the top of the web after welding:

[0114] c=((y 11 -y 011 )+(y 12 -y 012 )+(y 13 -y 013 )) / 3;

[0115] Calculate the inherent lateral shrinkage δ of the base plate TP :

[0116] θ T =sin -1 (e1 / d1)+sin -1(e2 / d2)=θ T1 +θ T2 ;

[0117] Calculate the inherent longitudinal shrinkage δ of the base plate LP :

[0118] δ LP =ΔL×B / L;

[0119] Calculate the inherent longitudinal shrinkage δ of the base plate LP :

[0120] δ TP = b - [(b + Δb) / 2] / cos(θ) T1 )-[(b+Δb) / 2] / cos(θ T2 );

[0121] Calculate the inherent transverse bending θ of the base plate TP :

[0122] θ TP =sin -1 (e1 / d1)+sin -1 (e2 / d2)=θ T1 +θ T2 ;

[0123] Calculate the inherent transverse contraction δ of the web TW :

[0124] δ TW =H-[(H-ΔH) / cos(tan -1 (c / H))];

[0125] Calculate the inherent longitudinal shrinkage δ of the web LW :

[0126] δ LW =ΔL w ×H / L;

[0127] Calculate the inherent transverse bending θ TW :

[0128] θ TW =sin -1 (c / H)-[sin -1 (e1 / d1)-sin -1 [(e2 / d2)] / 2;

[0129] Calculate the inherent longitudinal bending θ LW :

[0130] θ LP =θ LW =0;

[0131] In the formula, d1, d2, e1, e2, b, L, ΔL, Δb, and ΔLW are intermediate calculation parameters, ΔH represents the shrinkage of the web height after welding, c represents the lateral displacement of the top of the web after welding, and x 0i For any sampling point P in the finite element model i The initial x-coordinate, y-coordinate 0i For any sampling point P in the finite element model i The initial y-coordinate, z-coordinate 0i For any sampling point P in the finite element model i The initial z-coordinate, x i Let x and y be the deformed x-coordinates of any sampling point Pi in the finite element model. i For any sampling point P in the finite element model i The deformed y-coordinate, z-coordinate i For any sampling point P in the finite element model i The deformed z-coordinate, in millimeters (mm).

[0132] Table 2 Coordinates of sampling points for T-joints

[0133] x 20t 20t 35t 35t 50t 50t 65t 65t y -20t 20t -15t 15t -15t 15t -15t 15t z t t t t t t t t

[0134] Table 2 Coordinates of sampling points for T-joints (continued)

[0135] x 80t 80t 20t 50t 80t 20t 80t y -20t 20t 0 0 0 0 0 z t t 50t+t 50t+t 50t+t t t

[0136] The welding direction of the butt joint is the X-axis of the coordinate system, and the thickness direction of the base material is the Z-axis. The Y-axis is determined according to the right-hand rule, with the origin at the center of the base material's bottom surface. The specimen length is 100t + c, and the specimen width is 50t + c, where t is the base material thickness and c is the lap length. See [reference needed]. Figure 6 As shown.

[0137] When calculating the inherent deformation parameters of lap joints, the left and right sides of the plate are distinguished. The left side is joint 1, and the inherent transverse shrinkage δ of joint 1 is calculated separately. T1 The inherent longitudinal shrinkage δ of joint 1 L1 The inherent lateral bending θ of joint 1 T1 The inherent longitudinal bending θ of joint 1 L1 The right side is joint 2. Calculate the inherent lateral shrinkage δ of joint 2. T2 The inherent longitudinal shrinkage δ of joint 2 L2 The inherent lateral bending θ of joint 2 T2 The inherent longitudinal bending θ of joint 2 L2 .

[0138] The inherent lateral shrinkage δ of joint 1 T1Calculation formula:

[0139]

[0140] The inherent longitudinal shrinkage δ of joint 1 L1 :

[0141] δ L1 =-{[LC1-(x 09 -x 01 )] / (x 09 -x 01 )+[LC2-(x 010 -x 02 )] / (x 010 -x 02 )} / 2×[(B+c) / 2+t] / 3;

[0142] in,

[0143]

[0144] The inherent lateral bending θ of joint 1 T1 Calculation formula:

[0145] θ T1 = [(Uz5-Uz6) / (y6-y5)] / 2;

[0146] The inherent longitudinal bending θ of joint 1 L1 Calculation formula:

[0147] θ L1 ={-[(Uz6-Uz2) / [(x6-x2)} 2 ]]-[(Uz6-Uz 10 ) / [(x 10 -x6) 2 ]]} / 4;

[0148] The inherent lateral shrinkage δ of joint 2 T2 Calculation formula:

[0149] δ T2 =δ T1 ;

[0150] The inherent longitudinal shrinkage δ of joint 2 L2 Calculation formula:

[0151] δ L2 =-{[LC3-(x 011 -x 03 )] / (x 011 -x 03 )+[LC4-(x 012 -x 04)] / (x 012 -x 04 )} / 2×[(B+c) / 2+t] / 3;

[0152] in,

[0153]

[0154] The inherent lateral bending θ of joint 2 T2 Calculation formula:

[0155] θ T2 = [(Uz8-Uz7) / (y8-y7)] / 2;

[0156] The inherent longitudinal bending θ of joint 2 L2 Calculation formula:

[0157] θ L2 ={-[(Uz7-Uz3) / [(x7-x3)} 2 ]]-[(Uz7-Uz 11 ) / [(x 11 -x7) 2 ]]} / 4

[0158] Table 3 Coordinates of sampling points for lap joints

[0159] x 20t 20t 20t 20t 50t 50t 50t 50t 80t 80t 80t 80t y -25t -2t-c / 2 2t+c / 2 25t -25t -2t-c / 2 2t+c / 2 25t -25t -2t-c / 2 2t+c / 2 25t z t1 t1 t1+t2 t1+t2 t1 t1 t1+t2 t1+t2 t1 t1 t1+t2 t1+t2

[0160] The following example uses the calculation method for the inherent deformation of a butt joint. Specifically, it involves obtaining the initial parameters of the butt welded joint. The joint type is a butt joint, the bevel type is an I-groove, the base metal thickness is 3mm, the welding method is MAG welding, the joint gap is 1mm, the joint position is 10mm from each end, and both the base metal and welding material are X5CrNi 18-10 stainless steel. The welding position is PA. In the finite element model, the specimen length OL is 100t = 300mm, and the specimen width B is 50t = 150mm. Figure 6 The geometric model of the mating joint is shown.

[0161] Based on the obtained initial parameters, a thermo-elastic-plastic finite element model of the weld joint was established. The modeling process used hexahedral eight-node elements, and the model was meshed, requiring that each weld pool section contain at least four meshes. Input parameters were as follows: Figure 8 The material thermophysical parameters shown are as follows: Figure 9 The welding process parameters shown are used to select a double ellipsoidal heat source based on the welding method.

[0162] The thermal and mechanical boundary conditions of the model are set. The thermal boundary conditions mainly include welding thermal boundary conditions, thermal convection boundary conditions, and thermal radiation boundary conditions. The model is assumed to be freely welded without external constraints. Auxiliary displacement constraints restricting six rigid body degrees of freedom are applied to ensure the convergence of the model calculation. The mesh quality and model settings are checked. The main parameters for mesh quality checking include element normals, aspect ratio, Jacobian, interior angles, warpage, and skewness. The model settings check mainly includes the setting of material parameters and thermodynamic boundary conditions.

[0163] The model is solved using a large strain model, and a lumped mass heat capacity matrix is ​​employed to overcome the step phenomenon in transient temperature field analysis. The calculated welding deformation results for each node are output. After calculation, the model results are compared and evaluated, primarily focusing on the singularity ratio, convergence, and the rationality of welding deformation and residual stress. The inherent deformation parameters of the welded joint, including inherent transverse shrinkage, inherent longitudinal shrinkage, inherent transverse bending, and inherent longitudinal bending, are extracted and calculated based on the coordinate points shown in Table 1 and the formulas described above. The inherent transverse shrinkage δ is calculated. T The intrinsic longitudinal shrinkage is δ = 0.1582 mm. L The inherent lateral bending θ is 0.4063 mm. T The inherent longitudinal curvature θ is 0.0906 rad. L It is -0.0003 rad.

[0164] x0 56.61 60 60 56.61 146.03 150 150 146.03 236.00 240 240 236.00 y0 -77.15 -5.22 5.21 77.15 -77.17 -5.22 5.22 77.17 -77.17 -5.22 5.22 77.17 z0 3 3 3 3 3 3 3 3 3 3 3 3 ux -0.49 -0.31 -0.31 -0.49 -0.79 -0.75 -0.75 -0.79 -0.86 -1.02 -1.02 -0.86 uy 0.20 0.19 -0.19 -0.20 0.24 0.18 -0.18 -0.23 0.24 0.18 -0.18 -0.24 uz 9.55 7.19 7.19 9.54 16.03 12.77 12.77 16.02 16.79 12.85 12.95 16.78 x 56.12 59.69 59.69 56.12 145.24 149.25 149.25 145.24 235.14 238.98 238.98 235.14 y -76.95 -5.03 5.02 76.95 -76.93 -5.04 5.04 76.94 -76.93 -5.04 5.04 76.93 z 12.55 10.19 10.19 12.54 19.03 15.77 15.77 19.02 19.79 15.85 15.95 19.78

[0165] In the calculation process, the dimensions of the finite element model and the coordinates of the sampling points are transformed into a function of the plate thickness. This method is independent of specific models, has broad applicability, and is easy to program. By obtaining the changes in the coordinates of the sampling points before and after deformation, the inherent deformation parameters of the welded joint are calculated using the formula in this embodiment. Compared with existing integral methods and experimental methods based on thermo-elastic-plastic models, this algorithm is more accurate and specific, easier to operate, and easier for humans to parameterize, enabling rapid extraction of inherent deformation data of the welded joint. The method for obtaining inherent deformation based on thermo-elastic-plastic simulation results calculates the inherent deformation of the welded joint by acquiring the coordinate values ​​and deformation amounts of different nodes, improving efficiency while achieving high-precision acquisition of inherent deformation parameters.

[0166] The calculation system based on the above-mentioned calculation method for the inherent deformation of welded joints includes: a result data reading module 1, a model parameter acquisition module 2, a sampling point coordinate automatic determination module 3, an inherent deformation meter module, and a result output module 5, such as... Figure 7As shown, the result data reading module 1 reads the result file of the welding deformation calculation to form the raw data; the model parameter acquisition module 2 determines the type of the weld joint to be calculated and provides the basic information of the thermo-elastic-plastic finite element model corresponding to the weld joint; the sampling point coordinate automatic determination module 3 calculates the coordinates of each sampling point according to the obtained basic information and the type of weld joint, determines the number of the nearest node for each sampling point, and extracts the deformation in the x, y, and z directions of each node; the inherent deformation meter module calculates the inherent deformation data of different types of weld joints according to the calculation formula corresponding to the weld joint. The result output module 5 outputs the inherent deformation data of the joint welding as a .dat file in a specific format for easy subsequent calling and analysis.

[0167] The result data reading module 1 uses the MSC.MARC calculation result reading unit and the Simufact.wedding calculation result reading unit to read the initial data. The model parameter acquisition module 2 automatically determines the welding joint type based on the read initial data and provides the basic information of the thermo-elastic-plastic finite element model based on the coordinate information of each node. The basic information includes the length, width, and height of the thermo-elastic-plastic finite element model and the plate thickness information of the welded structure.

[0168] The automatic sampling point coordinate determination module 3 includes a coordinate extraction unit for each sampling point and a deformation extraction unit for each measurement point, realizing the automatic determination of the coordinates of the sampling points. In the modeling process, the system of this application fully considers the influence of gap, bevel, etc. on the deformation of the weld joint. At the same time, it replaces the integration of the weld cross-section with the algebraic calculation of the deformation of the specified sampling points, which improves the accuracy of the inherent deformation of the weld and improves the calculation efficiency. It transforms the size of the thermo-elastic-plastic finite element model and the coordinates of the sampling points into a function of the material thickness, which is not dependent on the specific model and has wide applicability. At the same time, it is easy to implement in a program.

[0169] It should be understood that the specific embodiments described above are for illustrative purposes only and are not intended to limit the scope of the invention. Obvious variations or modifications derived from the spirit of the invention are still within the protection scope of the invention.

Claims

1. A method for calculating the inherent deformation of a welded joint, characterized in that, Includes the following steps: A1. Obtain the initial parameters of a typical welded joint in a welded structural component; A2. Construct a thermo-elastic-plastic finite element model of the welded joint, that is, construct a thermo-elastic-plastic finite element model of the welded joint based on the obtained initial parameters; A3. Solve the thermo-elastic-plastic finite element model, that is, solve the temperature field and deformation field corresponding to the weld joint. A4. Evaluate and determine the temperature field and deformation field obtained in step A3, that is, evaluate and determine the rationality of the singularity ratio of the temperature field and deformation field, the convergence of the model, the welding deformation and welding residual stress. A5. Model correction, i.e., the model correction of the thermo-elastic-plastic finite element model based on the evaluation results of the temperature field and deformation field; A6. Extraction and calculation of inherent deformation data of welded joints, that is, the temperature field and deformation field obtained by solving the modified thermo-elastic-plastic finite element model are used to extract and calculate the inherent deformation data of welded joints through the calculation formulas corresponding to different types of welded joints; A7. Output the inherent deformation data of the welded joint; The construction of the thermo-elastic-plastic finite element model of the welded joint in step A2 includes the following steps: A21. Determining the dimensions of the geometric model, i.e., determining the size of the thermo-elastic-plastic finite element model based on the thickness of the base material; A22. The establishment of the mesh model is to determine the coordinate system (x, y, z) of the model using the right-hand rule, and to use hexahedral eight-node elements for mesh generation. Each weld pool section contains at least 4 meshes. A23. The establishment of the material model, that is, inputting the thermophysical parameters of the base material and welding material that change with temperature to define the hardness model of the material, wherein the hardness model is isotropic hardening + kinematic hardening; A24. Heat source model setting and heat source parameter setting, that is, determining the heat source model and the corresponding parameters of the heat source model according to the welding method, welding position and welding process parameters; A25. Setting the calculation conditions, namely, setting the thermal boundary conditions and mechanical boundary conditions of the heat source model; A26. Checking the heat source model, i.e., checking the mesh quality and heat source model settings.

2. The method for calculating the inherent deformation of a welded joint according to claim 1, characterized in that, The initial parameters include one or more of the following: joint type, joint bevel size, thickness of the two base materials, welding method, joint gap, base material properties, material properties of the welding material, welding position, and welding process parameters.

3. The method for calculating the inherent deformation of a welded joint according to claim 2, characterized in that, The thermophysical properties of the welding material mentioned in step A23 include one or more of the following: elastic modulus, coefficient of thermal expansion, specific heat capacity, and yield strength.

4. The method for calculating the inherent deformation of a welded joint according to claim 2, characterized in that, The thermal boundary conditions in step A25 include welding thermal boundary conditions, thermal convection boundary conditions, and thermal radiation boundary conditions; when the model is freely welded without external constraints, auxiliary displacement constraints restricting 6 rigid body degrees of freedom are applied.

5. The method for calculating the inherent deformation of a welded joint according to claim 2, characterized in that, The main parameters for mesh quality inspection in step A26 include one or more of the following: element normal, aspect ratio, Jacobian, interior angle, warpage, and skewness. The model setup check includes setting material parameters, thermal boundary conditions, and one or more mechanical boundary conditions.

6. The method for calculating the inherent deformation of a welded joint according to claim 1, characterized in that, The inherent deformation data includes inherent lateral shrinkage δ T Inherent longitudinal contraction δ L Inherent transverse bending θ T and inherent longitudinal bending θ L .

7. The method for calculating the inherent deformation of a welded joint according to claim 6, characterized in that, The welded joints include butt joints, T-joints, and lap joints; The inherent lateral shrinkage δ of the mating joint T The calculation formula is: ； The inherent longitudinal shrinkage δ of the mating joint L The calculation formula is: ;in, ； ； The inherent lateral bending θ of the mating joint T The calculation formula is: ； The inherent longitudinal bending θ of the mating joint L The calculation formula is: ； In the formula, LC is the curve distance between two sampling points, B is the width of the mating joint, dz is the chord length of the curve corresponding to the two sampling points, and x 0i For any sampling point P in the finite element model i The initial x-coordinate, y 0i For any sampling point P in the finite element model i The initial ordinate, x i For any sampling point P in the finite element model i The deformed abscissa, yi, represents any sampling point P in the finite element model. i The deformed ordinate, U zi For any sampling point P in the finite element model i The displacement in the z-direction, where i is an integer from 1 to n.

8. A calculation system for the inherent deformation of a welded joint, characterized in that, The method for calculating the inherent deformation of a welded joint as described in any one of claims 1-7 includes: The result data reading module (1) is used to read the result file of welding deformation calculation and form the raw data; The model parameter acquisition module (2) is used to determine the type of the weld joint to be calculated and to provide the basic information of the thermo-elastic-plastic finite element model corresponding to the weld joint. The automatic sampling point coordinate determination module (3) calculates the coordinates of each sampling point based on the obtained basic information and welding joint type, determines the number of the nearest node of each sampling point, and extracts the deformation in the x, y, and z directions of each node. The inherent deformation calculation module (4) calculates the inherent deformation data of different types of welded joints according to the calculation formula corresponding to the welded joint; The result output module (5) is used to output the inherent deformation data of the joint welding as a .dat file in a specific format, which is convenient for subsequent calling and analysis.

9. The calculation system for the inherent deformation of a welded joint according to claim 8, characterized in that, The model parameter acquisition module (2) automatically determines the welding joint type based on the read initial data and provides the basic information of the thermo-elastic-plastic finite element model based on the coordinate information of each node. The basic information includes the length, width, and height of the thermo-elastic-plastic finite element model, as well as the plate thickness information of the welded structural components.

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