A welding simulation method for realizing dynamic filling of a welding bead

Abstract

The application discloses a welding simulation method and system for realizing weld dynamic filling, and a storage medium, and the method comprises the following steps: importing a simulation model of a welding structure; loading a thermal boundary condition on each weld in sequence according to a welding sequence, hiding a filling unit of a weld which has not been welded, and activating a filling unit of a weld which has been welded, so as to simulate a weld dynamic filling process in an actual welding process; and outputting welding deformation data of the simulation model. In the welding process, the filling unit of the weld which has not been welded is hidden, and the filling unit of the weld which has been welded is activated, so that the structural stiffness of the simulation model is increased and is consistent with the actual structure, thereby improving the accuracy of the simulation result, and the problem that the simulation result is greatly different from the actual welding deformation in the current simulation method is solved.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and more specifically to a welding simulation method for achieving dynamic filling of weld beads. Background Technology

[0002] In welding simulation using the inherent strain method, the inherent strain parameters are applied as initial strain values ​​to the weld seam and its surrounding elements in the welded structure. Elastic-plastic finite element numerical calculations are then performed to achieve mechanical equilibrium between the elements near the weld seam and the entire model. The simulation obtains the welding deformation distribution of the welded structure. Compared with the traditional thermo-elastic-plastic welding simulation, this method has higher simulation efficiency and shorter calculation cycle when simulating the welding deformation of structural components.

[0003] In MAG or TIG filler wire welding, the electric arc heat source melts the welding wire, and the molten wire fills the weld bead—a dynamic process. As the welding torch moves, the weld bead is continuously filled, and as the molten metal cools, a stable and reliable connection is achieved between the weld and the base material, resulting in a continuous increase in the overall structural stiffness and resistance to deformation. For multi-bead structures, there is a significant difference in structural stiffness between welds welded first and welds welded later; the structural stiffness is lower when welds are welded first and higher when welds are welded later. If, during welding simulation, all filler elements of the welds are pre-activated for numerical calculation, ignoring the difference in structural stiffness between welds welded first and later, the accuracy of the simulation results will inevitably decrease.

[0004] Existing welding simulations using the inherent strain method, including the weld-planner submodule in the commonly used commercial software SYSWELD and the shrinkage function in the software Simufact-welding, do not account for the phenomenon of continuous changes in structural stiffness due to the movement of the arc heat source during welding, resulting in insufficient accuracy of the simulation results. For the software Simufact-welding, when performing welding simulations using the inherent strain method (i.e., the shrinkage algorithm), the inherent strain values ​​at all points in the weld are applied to all welds at once, without distinguishing the order of welding. This means the simulation results do not reflect the differences in welding deformation caused by differences in welding sequence. For the software weld-planner, although it uses the shrinkage algorithm to progressively load the mesh elements of each weld pass according to the welding sequence, it pre-activates all weld filler elements to participate in the mechanical equilibrium calculation, ignoring the difference in structural stiffness between welds welded first and later, leading to a decrease in the accuracy of the welding simulation results.

[0005] In summary, existing welding simulation methods based on inherent strain cannot distinguish the changes in structural stiffness caused by differences in the order of welding, resulting in significant discrepancies between simulation results and actual welding deformation. Summary of the Invention

[0006] The purpose of this invention is to provide a welding simulation method, system, and storage medium for realizing dynamic filling of weld beads, so as to solve the problem in the prior art that the structural stiffness changes caused by the welding sequence during the welding process cannot be distinguished, resulting in a large difference between the simulation results and the actual welding deformation.

[0007] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0008] This invention discloses a welding simulation method for achieving dynamic filler of weld beads, comprising:

[0009] Import the simulation model of the welded structure;

[0010] According to the welding sequence, thermal boundary conditions are applied to each weld in turn, the filling units of the welds that have not yet been welded are hidden, and the filling units of the welds that have been welded are activated to simulate the dynamic filling process of the welds in the actual welding process.

[0011] Output welding deformation data from the simulation model.

[0012] Furthermore, the simulation model is constructed by dividing the welded structure into unit meshes, and the root gap of the weld satisfies the following condition when constructing the simulation model:

[0013] When the root gap dimension C of the weld is greater than k·S0, the root mesh of the weld is constructed according to the actual structure dimensions when building the mesh model; where S0 is the average size of the weld element mesh, and k is a scaling factor with a value range of 0.15. <k<0.25;

[0014] When the root gap size of the weld is C≤k·S0, the root gap size of the weld is reset to C=k·S0 when constructing the mesh model.

[0015] Furthermore, before simulating the dynamic filling process of the weld in the actual welding process, the process also includes: fixing the components to be welded in the corresponding positions by spot welding or reinforcement welding;

[0016] When spot welding or reinforcement welding is located at the root of the weld, the node elements at the spot welding or reinforcement welding location are pre-activated during the calculation so that they can participate in the calculation.

[0017] When spot welding or reinforcement welding is not in the weld seam area, set a common node for the node elements at the spot welding or reinforcement welding location, and hide the common node so that it does not participate in the calculation.

[0018] Furthermore, the dynamic weld filling process is a segmented dynamic filling process, which includes:

[0019] The number of segments is determined based on the weld length;

[0020] Based on the welding direction, each segment of the weld is activated sequentially from the start end to the end end, thereby simulating the dynamic filling process of the weld.

[0021] Furthermore, setting the number of segments based on the weld length includes:

[0022] When the weld length is less than a mm, the weld is not segmented, where a is a specific length value, ranging from 30 mm. <a<70mm;

[0023] When the weld length is greater than a mm and less than b mm, the weld is divided into two equal segments, where b is a specific length value, ranging from 80 mm. <b<120mm;

[0024] When the weld length is greater than b mm and less than c mm, the weld is divided into 3 equal segments, where c is a specific length value, ranging from 250 mm. <c<350mm;

[0025] When the weld length is greater than or equal to c mm, the weld is divided into 5 segments.

[0026] Furthermore, the following steps are included between importing the simulation model of the welded structure and simulating the dynamic filling process of the weld during the actual welding process;

[0027] Set material properties, wherein the linear expansion coefficient of the weld filler unit is set according to the inherent strain parameter of the weld;

[0028] Set the initial boundary conditions of the simulation model so that the initial temperature of all elements in the simulation model is set to a constant value;

[0029] Set displacement boundary conditions to make the parent material at the corresponding position in the simulation model fixed in a specific direction of translation or rotation;

[0030] Thermodynamic boundary conditions are set, and a cooling process is set for each weld in sequence according to the welding order; wherein the temperature difference of the weld is set according to the inherent strain parameter of the weld.

[0031] Furthermore, the method for setting the inherent strain parameters includes:

[0032] The welding deformation distribution of standard joint specimens was obtained using actual welding methods, and this was taken as the actual result.

[0033] Construct a simulation model of a standard connector;

[0034] A cooling process is applied to the weld area in the standard joint simulation model, and welding simulation using the inherent strain method is performed. The deformation distribution of the standard joint simulation model is calculated and used as the simulation result of the standard joint simulation model.

[0035] When the difference between the simulation results and the actual results of the standard joint simulation model is less than the set value, the linear expansion coefficient It of the weld and the temperature difference during cooling during simulation will be considered. △ T is the calibrated inherent strain parameter.

[0036] Furthermore, the method for setting the inherent strain parameters includes:

[0037] The thermoelastic method was used to simulate the standard joint model, and the simulation results of welding deformation, welding stress and strain of the standard joint model were obtained.

[0038] Extract the plastic strain value ε of each node in the weld filling module of the standard joint simulation model. p Calculate the average plastic strain ε at each node of the filled element. pm ;

[0039] A cooling process is applied to the entire filler unit of the weld, and a cooling temperature difference is set. △ T, so that its linear expansion coefficient I is similar to that of the filler element of the weld. t The product is the average plastic strain value ε in the arc-starting region of the weld. pm The inherent strain parameter of this weld is the cooling temperature difference. △ T and the linear expansion coefficient I of the filling unit t .

[0040] Furthermore, the cooling process for each weld includes setting the cooling time and cooling temperature difference for each weld filling unit, and cooling the weld according to the cooling time and cooling temperature difference of the weld filling unit; wherein, the temperature difference of the weld is set according to the inherent strain parameters of the weld.

[0041] Furthermore, the initial boundary conditions of the simulation model are set as follows: the initial temperature of all elements in the simulation model is set to 20℃.

[0042] According to the above technical solution, the embodiments of the present invention have at least the following effects: The present invention hides the filling units of the weld seam that has not yet been welded during the welding process and activates the filling units of the weld seam that has been welded, simulating the dynamic filling process of the weld seam during the actual welding process, increasing the structural stiffness of the simulation model and the consistency with the actual structure, thereby improving the accuracy of the simulation results; it solves the problem that the current simulation method cannot distinguish the changes in structural stiffness caused by the order of welding during the welding process when performing welding simulation using the inherent strain method, resulting in a large difference between the simulation results and the actual welding deformation. Attached Figure Description

[0043] Figure 1 Flowchart of the inherent strain method welding simulation for achieving dynamic weld bead filling;

[0044] Figure 2This is a triaxial view of a welded structure.

[0045] Figure 3 This is a front view of a welded structure;

[0046] Figure 4a This is a schematic diagram showing the setting of the root gap for fillet welds;

[0047] Figure 4b This is a schematic diagram showing the setting of the root gap when joining seams.

[0048] In the figure: 8, welded structure; 8-1, first plate; 8-2, second plate; 8-3, backing plate; 8-4, fourth plate; 8-5, fifth plate; I is the bevel weld formed by the first plate and the fifth plate; II is the bevel weld formed by the first plate and the second plate; III is the butt weld formed by the second plate and the fourth plate; IV is the fillet weld formed by the fourth plate and the fifth plate. Detailed Implementation

[0049] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0050] In the field of numerical simulation of welding deformation, this invention provides a welding simulation method for realizing dynamic weld filling in the welding deformation simulation process of the inherent strain method. This invention applies the "birth and death element" technology to the loading process of welding simulation of the inherent strain method, hides the weld filling elements of the weld that has not yet been welded, and activates the weld filling elements of the weld that has been welded, simulating the dynamic filling process of the weld in the actual welding process, increasing the structural stiffness of the simulation model and the matching degree of the actual structure, thereby improving the accuracy of the simulation results.

[0051] Explanation of related terms

[0052] Welding simulation using the inherent strain method: The inherent strain parameters are applied as initial strain values ​​to the weld and its surrounding elements in the welded structure. Elastic-plastic finite element numerical calculations are performed to achieve mechanical equilibrium between the elements near the weld and the entire model. The welding deformation distribution of the welded structure is obtained through simulation.

[0053] Inherent strain parameter: a comprehensive value characterizing welding deformation near the weld, representing the plastic strain value at which thermal strain, constraint, and phase transformation interact to reach equilibrium during thermal cycling. Inherent strain is the total plastic strain at which the weld reaches mechanical equilibrium after undergoing welding thermal cycling, representing the local comprehensive plastic strain value characterizing the degree of welding deformation near the weld.

[0054] In welding simulation using the inherent strain method, to facilitate the application of inherent strain parameters and the loading of boundary conditions, the inherent strain loading process is typically set to involve a specific cooling process within a certain range near the weld. Through finite element numerical simulation, the constraint between the elements near the weld and the entire model reaches a state of mechanical equilibrium, thus obtaining the welding deformation distribution of the welded structure. During the simulation, the temperature difference experienced by the weld near the weld, combined with the linear expansion coefficient in the material properties, constitutes the inherent strain parameters. Each weld corresponds to its own inherent strain parameters, including the initial expansion coefficient of the weld filler elements and the temperature difference experienced during the cooling process. During the welding simulation, the linear expansion coefficient and the temperature difference in the material properties of the filler elements for each weld are set according to the inherent strain parameters of that weld.

[0055] The present invention discloses a welding simulation method for realizing dynamic fill of weld seams, comprising the following steps: importing a simulation model of the welding structure; sequentially applying thermal boundary conditions to each weld seam according to the welding sequence, hiding the filler units of the weld seams that have not yet been welded, and activating the filler units of the weld seams that have already been welded, simulating the dynamic filler process of the weld seam during the actual welding process; and outputting the welding deformation data of the simulation model.

[0056] This invention hides the filling units of the un-welded welds during the welding process and activates the filling units of the already-welded welds, simulating the dynamic filling process of the welds during actual welding. This increases the consistency between the structural stiffness of the simulation model and the actual structure, thereby improving the accuracy of the simulation results. It solves the problem that current simulation methods cannot distinguish the changes in structural stiffness caused by the order of welding during the welding process when performing welding simulation using the inherent strain method, resulting in a large discrepancy between the simulation results and the actual welding deformation.

[0057] Specifically, the present invention comprises two parts: the first part is the calibration of inherent strain parameters, and the second part is the specific process of the simulation method.

[0058] The simulation method implementation process is as follows: Figure 1 As shown:

[0059] The first step is to import the simulation model of the welded structure, which includes a weld module and a base material module.

[0060] The second step is to set the material properties. Different coefficients of linear expansion are set for the base metal and weld filler metal units, and the thermal conductivity is set to 0. Other parameters are the material property values ​​of the base metal and weld at specific temperatures. The coefficient of linear expansion of the weld filler metal unit for each weld is set according to the inherent strain parameters of that weld.

[0061] The third step is to set the initial boundary conditions, and set the initial temperature of all elements in the simulation model to a constant value.

[0062] The fourth step is to set displacement boundary conditions, fixing the translation or rotation in a specific direction at the corresponding position of the simulation model.

[0063] The fifth step is to set thermal boundary conditions. According to the welding sequence, the cooling process is set for the filler metal unit of each weld in turn. The cooling temperature difference of each weld is set according to the inherent strain parameters of that weld.

[0064] When setting boundary conditions, thermal boundary conditions are set separately, and cooling processes are only applied to the filler metal elements of the weld. A general cooling process is applied to the filler metal elements of the entire weld, and then the set cooling temperature difference is adjusted so that the calculated welding deformation is close to the actual welding deformation (the deviation between the two is less than 10%).

[0065] The sixth step is to set the loading order. According to the welding order, thermal boundary conditions are loaded one by one. The core innovation of this invention is to apply the "life and death unit" technology to the loading process, hide the weld filling units of the welds that have not yet been welded, and activate the weld filling units of the welds that have been welded, simulating the dynamic filling process of the weld in the actual welding process.

[0066] Step 7: Numerical calculation of the cooling process, open the simulation results, and output the welding deformation data of the simulation model.

[0067] In a further embodiment, to further simulate the dynamic filling process of the weld bead during actual welding, the structural stiffness of the simulation model is increased to match the actual structure, thereby further reducing the deviation between the simulation results and the actual welding deformation. This step requires special settings during finite element modeling, specifically including root gap settings and pre-weld splice point settings.

[0068] Special settings for root gap

[0069] When constructing the finite element model, see the weld root gap. Figure 4a and Figure 4b To prevent distortion of the element mesh at the weld root, which could affect the reliability of numerical calculations, special requirements are needed. Here, the root gap size is set to C, and the average size of the weld element mesh is set to S0.

[0070] When the actual root gap size of the structure is greater than k times the average mesh size of the weld element, that is, satisfying C>k·S0, the weld root gap of the simulation model is constructed according to the actual structural size. When the actual root gap size of the structure is less than or equal to k times the average mesh size of the weld element, that is, satisfying C≤k·S0, during the element meshing of the weld simulation model, the root gap size of the simulation model is set to be equal to k times the average mesh size of the weld element, that is, C=k·S0, so as to avoid mesh distortion of the weld root element caused by disproportionate proportions. k is a proportionality coefficient with a value range of 0.15<k<0.25, and k is preferably 0.2.

[0071] Special Settings for Pre-Welding Tacking

[0072] Before formal welding, spot welding or reinforcement welding (with a weld length of about 20mm) is usually used to fix the components to be welded at corresponding positions to facilitate subsequent welding.

[0073] (a) When the spot weld or reinforcement weld is located at the weld root and serves as a part of the weld filler metal, the nodal elements at the spot weld or reinforcement weld are pre-activated during calculation to make them participate in subsequent calculations, so as to increase the matching degree between the structural stiffness of the simulation model and the actual structure, ignore its influence on welding deformation and residual stress, and reduce the welding calculation amount.

[0074] (b) When the spot weld or reinforcement weld is not in the weld zone, and is only used for temporarily fixing and connecting two components, and the spot weld or reinforcement weld is removed after welding, common nodes are set for the nodal elements on both sides of the spot weld or reinforcement weld before welding, and the mesh elements of the common nodes at this position are hidden after welding, so as to increase the matching degree between the structural stiffness of the simulation model and the actual structure, ignore its influence on welding deformation and residual stress, and reduce the welding calculation amount.

[0075] In a further embodiment, in order to further simulate the dynamic filling process of the weld bead in the actual welding process, increase the matching degree between the structural stiffness of the simulation model and the actual structure, so as to further reduce the deviation between the simulation result and the actual welding deformation. This step not only requires special settings during finite element modeling, but also requires activating the "birth and death elements" in segments and sequentially when setting the dynamic filling of weld elements.

[0076] The process of activating the "birth and death elements" in segments and sequentially is as follows:

[0077] When performing simulation calculation, the number of segments for each weld is determined according to the length of each weld. Here, assume that the length of a certain weld is L: when the weld length is less than a mm, that is, L < a mm, it is divided into 1 segment, which means no segmentation, where a is a specific length value with a value range of 30 mm < a < 70 mm. Further, a is preferably 50 mm. When the weld length is greater than a mm and less than b mm, that is, a mm ≤ L < b mm, it is equally divided into 2 segments, where b is a specific length value with a value range of 80 mm < b < 120 mm, and further, b is preferably 100 mm. When the weld length is greater than b mm and less than c mm, that is, b mm ≤ L < c mm, it is equally divided into 3 segments, where c is a specific length value with a value range of 250 mm < c < 350 mm, and further, c is preferably 300 mm. When the weld length is greater than or equal to c mm, that is, L ≥ c mm, it is equally divided into 5 segments.

[0078] According to the welding direction, from the start end to the end end of the weld, the element meshes of each segment of the weld are activated in sequence, so as to simulate the dynamic filling process of the weld.

[0079] In this application, the "birth and death element" technology is applied to the loading process to hide the weld filling elements of the weld pass that have not been welded, and activate the weld filling elements of the welded weld pass, so as to simulate the dynamic filling process of the weld pass in the actual welding process, increase the matching degree between the structural stiffness of the simulation model and the actual structure, and ensure the accuracy of the simulation result and the actual welding result.

[0080] In this embodiment, two methods for calibrating inherent strain parameters are disclosed.

[0081] The steps of calibrating the inherent parameters by the actual measurement method are as follows:

[0082] The first step is to obtain the welding deformation distribution by the actual welding method, and obtain the welding deformation distribution of the standard joint sample as the actual result.

[0083] The second step is to construct a simulation model of the standard joint, including three-dimensional modeling and meshing of the joint sample. The joint parameters such as joint form, test plate size, joint gap, and weld leg size are all consistent with those of the joint sample in the first step, and the element size and element type during meshing are both specified parameters.

[0084] The third step is to calibrate the inherent strain parameters, apply a cooling process to the weld area in the simulation model, perform welding simulation by the inherent strain method, and calculate the deformation distribution of the entire model as the simulation result. When the welding deformation degree of the calculation result is close to the actual deformation, the linear expansion coefficient It of the weld element during simulation and the temperature difference of cooling △ T is the calibrated inherent strain parameter.

[0085] The specific steps of calibrating the inherent strain parameters by the simulation method are as follows:

[0086] The first step is to use the thermoelastic welding simulation method to obtain the simulation results of welding deformation, welding stress and strain of the welded joint specimen.

[0087] In the second step of the pre-simulation model, the plastic strain values ​​ε of each node in the weld filling module are calculated. p Calculate the average plastic strain ε at each node of the filled element. pm .

[0088] The third step is to set the inherent strain parameters. The inherent strain parameters are determined by the cooling process. A cooling process is applied to the entire filling unit of the weld, and the cooling temperature difference is set. △ T, so that its linear expansion coefficient I is similar to that of the weld element. t The product is the average plastic strain value ε in the arc-starting region of the weld. pm The inherent strain parameter of this weld is the cooling temperature difference. △ T and the linear expansion coefficient I of the weld element t .

[0089] This embodiment uses a specific welding structure as an example for illustration, such as... Figure 2 and Figure 3 As shown, it comprises 3 plates and 1 backing plate, forming 4 welded joints. The plates are all made of S355D steel, with a thickness of 10mm and a length of 100mm. The first plate 8-1 has a width of 164mm. The angle between the first plate 8-1 and the fifth plate 8-5 is 48.5°, forming bevel weld I. The angle between the first plate 8-1 and the second plate 8-2 is 40.5°, forming bevel weld II. The second plate 8-2 has a width of 102mm, and the fourth plate 8-4 has a width of 76mm. The second plate 8-2 and the fourth plate 8-4 are aligned to form butt joint III. Butt joint III has a bevel angle of 45° on both sides and a root gap of 2mm. Backing plate 8-3 is placed centered on the back of butt joint III. Backing plate 8-3 has a width of 18mm. The fifth plate 8-5 has a width of 150mm and forms fillet weld IV with the outer edge of the fourth plate 8-4. The weld leg of fillet weld IV is 10mm.

[0090] Welding specifications: Manual semi-automatic MAG welding torch, model YT-35CS4, mixed shielding gas 84% ​​Ar + 16% CO2, welding wire grade 50-6, welding wire diameter 1.2mm, shielding gas flow rate 20-25L / min, welding current 280A, welding voltage 29V, welding speed 5mm / s. Tack welding positions: one tack weld at each end of the back of weld I, weld II, and weld IV; one tack weld at each end of both sides of backing plate 8-3. The tack weld length is 8mm, and the weld leg is 6-8mm. The welding sequence is I-II-III-VI. When welding, the structure 8 is placed flat on the operating platform surface. The arc is started from one end of the weld and stopped at the other end. A 5-minute interval is allowed after each weld is completed. After all welds are completed, the structure is allowed to cool to 20℃ in air. The simulation process for welded structure deformation is as follows:

[0091] The first step is to construct a 1:1 three-dimensional model of welded structure 8 and use HyperMesh software to generate a unit mesh, such as... Figure 3 As shown, a two-dimensional mesh composed of triangles and quadrilaterals is divided at the end of the welded structure 8, with a mesh size of 4-5 mm. Then, the two-dimensional mesh is expanded into a three-dimensional mesh along the length of the welded structure 8, with the element types being hexahedral hex8 (C3D8) and triangular prism penta6 (C3D8). The three-dimensional mesh element size is 5-6 mm. A gap of 0.1 mm is set at the contact positions of the plates and the backing plate. The positioning spot weld positions are set to a shared node state. The weld filler metal and the base material on both sides are also set to a shared node state. After the mesh model is built, it is exported in .inp file format and then imported into the software Marc.MSC.

[0092] The second step is to set the material properties. For the base material, the coefficient of linear expansion is set to 0.0002 / K, and the thermal conductivity is set to 0. For the weld filler metal unit, the coefficient of linear expansion for weld I and weld II is set to 0.001 / K, the coefficient of linear expansion for weld III is set to 0.0008 / K, the coefficient of linear expansion for weld IV is set to 0.0011 / K, and the thermal conductivity is set to 0. Other parameters are the material property values ​​of the base material and weld at 20℃.

[0093] The third step is to set the initial boundary conditions, with the initial temperature of all elements in the model set to 20℃.

[0094] The fourth step is to set displacement boundary conditions and fix the translation and rotation in the X, Y, and Z directions for the nodes at the middle positions of the front and rear sides of the back of the model pad 8-3.

[0095] Fifth, set thermal boundary conditions. According to the welding sequence of welds I-II-III-VI, set cooling and temperature reduction processes for all nodes of the filler metal unit of each weld in sequence. The cooling time is 1 second. The cooling temperature differences of the four welds are 19.6℃, 20.4℃, 16.8℃ and 23.2℃ respectively.

[0096] The sixth step is to set the loading order. In the Loadcase interface, according to the welding sequence of welds I—II—III—VI, the thermal boundary conditions are loaded sequentially. "Deactivation / NC Machining" is set to hide the filler elements of welds that have not yet been welded, simulating the dynamic filler process of welds during actual welding. For example, when loading weld I, the filler elements of welds II, III, and IV are hidden, so that these filler elements do not participate in the calculation of weld I. The remaining elements that are not hidden are all active and participate in the calculation to match the overall stiffness of the actual welded structure.

[0097] Step 7: Calculate the cooling process using finite element analysis. Submit the calculation in the Job interface and display the simulation results (Results) of the model. Use the Path plot or History plot function to output the deformation value (displacement) at a specific location.

[0098] Through the above settings, this application has the following advantages: (1) This invention provides a welding simulation method for dynamic filling of weld beads in the welding deformation simulation process of the inherent strain method, which solves the problem that existing commercial software cannot distinguish the changes in structural stiffness caused by the welding sequence during the welding process, resulting in a large difference between the simulation results and the actual welding deformation. (2) This invention applies the "life and death unit" technology to the loading process of the welding simulation of the inherent strain method, hides the weld filling unit of the weld bead that has not yet been welded, and activates the weld filling unit of the weld bead that has been welded, simulates the dynamic filling process of the weld bead in the actual welding process, increases the consistency between the structural stiffness of the simulation model and the actual structure, and thus improves the accuracy of the simulation results. (3) This invention is an upgrade scheme for welding simulation of the inherent strain method, which has the advantages of convenient operation and high reliability.

[0099] In this embodiment, the dimensions, welding parameters, joint type, and spot welding fixing position of the plate and backing plate can be changed as needed. The software used for calculation is Marc.MSC, or other commercial finite element calculation software.

[0100] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or equivalent to the scope of this invention are included in this invention.

Claims

1. A welding simulation method for achieving dynamic fill of weld beads, characterized in that, include: Import the simulation model of the welded structure; According to the welding sequence, thermal boundary conditions are applied to each weld in turn, the filling units of the welds that have not yet been welded are hidden, and the filling units of the welds that have been welded are activated to simulate the dynamic filling process of the welds in the actual welding process. Output welding deformation data from the simulation model; The simulation model is constructed by dividing the welded structure into unit meshes. When constructing the simulation model, the root gap of the weld seam satisfies the following condition: When the root gap dimension C of the weld is greater than k·S0, the root mesh of the weld is constructed according to the actual structure dimensions when building the mesh model; where S0 is the average size of the weld element mesh, and k is a scaling factor with a value ranging from 0.

15. <k<0.25; When the root gap size of the weld is C≤k·S0, the root gap size of the weld is reset to C=k·S0 when constructing the mesh model; Before the dynamic filling process of the weld in the simulated actual welding process, the following steps are also taken: fixing the components to be welded in the corresponding positions by spot welding or reinforcement welding. When spot welding or reinforcement welding is located at the root of the weld, the node elements at the spot welding or reinforcement welding location are pre-activated during the calculation so that they can participate in the calculation. When spot welding or reinforcement welding is not in the weld seam area, set a common node for the node elements at the spot welding or reinforcement welding location, and hide the common node so that it does not participate in the calculation.

2. The welding simulation method for achieving dynamic fill of weld beads according to claim 1, characterized in that, The dynamic weld filling process is segmented dynamic filling, which includes: The number of segments is determined based on the weld length; Based on the welding direction, each segment of the weld is activated sequentially from the start end to the end end, thereby simulating the dynamic filling process of the weld.

3. The welding simulation method for achieving dynamic fill of weld beads according to claim 2, characterized in that, The method of setting the number of segments according to the weld length includes: When the weld length is less than a mm, the weld is not segmented, where a is a specific length value, ranging from 30 mm. <a<70mm; When the weld length is greater than a mm and less than b mm, the weld is divided into two equal segments, where b is a specific length value, ranging from 80 mm. <b<120mm; When the weld length is greater than b mm and less than c mm, the weld is divided into 3 equal segments, where c is a specific length value, ranging from 250 mm. <c<350mm; When the weld length is greater than or equal to c mm, the weld is divided into 5 segments.

4. The welding simulation method for achieving dynamic fill of weld beads according to claim 1, characterized in that, The following steps are also included between importing the simulation model of the welded structure and simulating the dynamic filling process of the weld during the actual welding process; Set material properties, wherein the linear expansion coefficient of the weld filler unit is set according to the inherent strain parameter of the weld; Set the initial boundary conditions of the simulation model so that the initial temperature of all elements in the simulation model is set to a constant value; Set displacement boundary conditions to make the parent material at the corresponding position in the simulation model fixed in a specific direction of translation or rotation; Thermodynamic boundary conditions are set, and cooling processes are sequentially applied to each weld according to the welding sequence.

5. The welding simulation method for achieving dynamic fill of weld beads according to claim 4, characterized in that, The method for setting the inherent strain parameters includes: The welding deformation distribution of standard joint specimens was obtained using actual welding methods, and this was taken as the actual result. Construct a simulation model of a standard connector; A cooling process is applied to the weld area in the standard joint simulation model, and welding simulation using the inherent strain method is performed. The deformation distribution of the standard joint simulation model is calculated and used as the simulation result of the standard joint simulation model. When the difference between the simulation results and the actual results of the standard joint simulation model is less than the set value, the linear expansion coefficient It of the weld and the temperature difference during cooling during simulation will be considered. Δ T is the calibrated inherent strain parameter.

6. The welding simulation method for achieving dynamic fill of weld beads according to claim 4, characterized in that, The method for setting the inherent strain parameters includes: The thermoelastic method was used to simulate the standard joint model, and the simulation results of welding deformation, welding stress and strain of the standard joint model were obtained. Extract the plastic strain value ε of each node in the weld filling module of the standard joint simulation model. p Calculate the average plastic strain ε at each node of the filled element. pm ; A cooling process is applied to the entire filler unit of the weld, and a cooling temperature difference is set. Δ T, so that its linear expansion coefficient I is similar to that of the filler element of the weld. t The product is the average plastic strain value ε in the arc-starting region of the weld. pm The inherent strain parameter of this weld is the cooling temperature difference. Δ T and the linear expansion coefficient I of the filling unit t .

7. The welding simulation method for achieving dynamic fill of weld beads according to claim 4, characterized in that, The cooling process for each weld includes setting the cooling time and cooling temperature difference for each weld filling unit, and cooling the weld according to the cooling time and cooling temperature difference of the weld filling unit; wherein, the temperature difference of the weld is set according to the inherent strain parameters of the weld.

8. The welding simulation method for achieving dynamic fill of weld beads according to claim 4, characterized in that, The initial boundary conditions for the simulation model are set as follows: the initial temperature of all elements in the simulation model is set to 20℃.

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