A method and system for controlling instability of thin plate fillet welding based on welding-induced heating

Abstract

The present application provides a kind of based on welding induction heating sheet corner welding instability control method and system, it is related to ship lightweight sheet precision construction technical field, this method includes: based on the size parameter of sheet corner welding joint, constructs the finite element grid model corresponding to sheet corner welding joint;In finite element grid model, set welding heat source, solve longitudinal plastic strain and first post-weld face deformation;The integral summation of longitudinal plastic strain is carried out, obtains first welding longitudinal shrinkage force, according to the trend mode of first post-weld face deformation, judge whether welding buckling instability occurs;If sheet corner welding joint occurs welding buckling instability, introduce induction heating heat source in finite element grid model, solve residual plastic strain and second face welding deformation, calculate second welding longitudinal shrinkage force;If less than critical buckling instability condition, confirm the process parameters of the sheet corner welding joint in the process of welding induction heating, and carry out welding hot stretching treatment.

Description

Technical Field

[0001] This invention relates to the field of precision construction technology for lightweight thin plates in shipbuilding, and in particular to a method and system for controlling instability in fillet welds of thin plates based on induction heating during welding. Background Technology

[0002] Lightweight stiffened components are often connected to the base plate using fillet welds to form the segmented structure of ships. In lightweight design and construction, advanced ship segments extensively utilize high-strength steel thin plates. The longitudinal shrinkage force generated during welding can cause weld buckling instability, significantly affecting the construction accuracy of the segmented structure. It is crucial to eliminate this during welding to avoid post-weld correction and subsequent assembly errors. Fillet weld buckling of thin plates is a typical structural compressive stability problem, which can be eliminated and controlled by increasing structural stiffness or reducing mechanical loads. Currently, increasing the thickness of stiffened components can effectively eliminate fillet weld buckling instability of thin plates; however, increasing plate thickness increases the weight of the segmented structure. Simultaneously, achieving full penetration in thicker plates requires larger bevels and multiple layers of welding, increasing welding heat input and longitudinal shrinkage force, which is detrimental to controlling fillet weld instability and also increases construction costs and time.

[0003] Chinese patent CN114619161B discloses a model construction and leveling method for thin plate welding deformation. The method includes: obtaining material properties based on the material of the thin plate to be leveled; collecting welding process parameters from the site; establishing a mathematical model of welding deformation based on the corresponding data and inherent strain theory, and correcting the model through actual sampling; determining the welding deformation type based on the model output and arranging corresponding leveling heating lines; applying electromagnetic induction heating to level the deformed workpiece according to the heating line positions; measuring the flatness of the workpiece after leveling, and then judging whether it meets the standards according to actual requirements. If it does not meet the standards, further leveling is performed until the standards are met. However, the above solution mainly focuses on the prediction and leveling of the overall deformation of the thin plate after welding, and does not provide real-time control of the torsional buckling instability of the thin plate fillet weld. It still requires correction after the instability deformation occurs, making it difficult to guarantee the manufacturing accuracy of the thin plate fillet weld structure. Therefore, it is essential to provide a method and system for controlling the instability of thin plate fillet welds based on induction heating during welding to improve the manufacturing accuracy of thin plate fillet weld joints. Summary of the Invention

[0004] In view of this, the present invention proposes a method and system for controlling instability of fillet welds in thin plates based on induction heating during welding.

[0005] This invention provides a method for controlling instability in thin plate fillet welds based on induction heating during welding, the method comprising: Based on the dimensional parameters of the thin plate corner weld joint, a finite element mesh model corresponding to the thin plate corner weld joint is constructed; A welding heat source is set in the finite element mesh model to solve for the longitudinal plastic strain and the external deformation after the first weld in the finite element mesh model during the welding process; The longitudinal plastic strain is integrated and summed along the weld length of the thin plate fillet weld to obtain the first longitudinal shrinkage force of the weld. Based on the trend mode of the external deformation after the first weld, it is determined whether the thin plate fillet weld has experienced weld buckling instability. If the fillet weld of the thin plate experiences weld buckling instability, an induction heating source is introduced into the finite element mesh model to solve for the residual plastic strain and the second out-of-plane weld deformation of the finite element mesh model under the combined action of the welding heat source and the induction heating source. The second longitudinal shrinkage force corresponding to the residual plastic strain is also calculated. The induction heating source and the welding heat source are relatively fixed and move synchronously with the welding trajectory. The induction heating source and the welding heat source are located on opposite sides of the weld of the fillet weld of the thin plate. The second out-of-plane weld deformation represents the out-of-plane deformation after the weld is subjected to welding induction heating. The second longitudinal shrinkage force represents the longitudinal shrinkage force of the weld under welding induction heating. If the longitudinal shrinkage force of the second weld is less than the critical buckling instability condition, the process parameters of the thin plate fillet weld joint during the induction heating process are confirmed, and the thin plate fillet weld joint is subjected to induction heating treatment according to the process parameters.

[0006] Based on the above technical solutions, preferably, a finite element mesh model corresponding to the thin plate fillet weld is constructed based on the theory of inherent deformation in welding, the instability mechanism of thin plate fillet welds, and the dimensional parameters of the thin plate fillet weld joint, specifically including: Geometric modeling is performed on the thin plate fillet weld joint composed of a base plate and an upright plate, wherein both the base plate and the upright plate are high-strength marine steel thin plates. Based on the bevel form of the fillet weld to be welded in the thin plate fillet weld joint and the expected weld pool shape, the weld toe, weld root and weld transition rounded corner area are defined at the junction of the base plate and the vertical plate, and the key pressure zone around the weld is determined based on the instability mechanism of thin plate fillet weld. The base plate and the vertical plate are meshed using three-dimensional Solid elements. Fine meshes are arranged in the weld and the critical pressure zone adjacent to the weld, and coarse meshes are arranged in the region away from the weld to form a finite element mesh model suitable for the analysis of inherent deformation of welding.

[0007] Based on the above technical solution, preferably, the step of setting a welding heat source in the finite element mesh model to solve for the longitudinal plastic strain and the external deformation after the first weld in the finite element mesh model during the welding process specifically includes: In the finite element mesh model, the spatial distribution of the welding heat source is defined based on the shape of the weld pool. The welding heat source is set as a volume heat source that moves with time along the weld path in the thin plate corner weld joint. The heat input intensity of the welding heat source is determined according to the preset welding specification parameters. In the finite element mesh model, surface heat transfer and thermal radiation are applied as temperature boundary conditions, and the rigid body displacement of the thin plate fillet weld joint is constrained as a mechanical boundary condition. Material thermophysical parameters and mechanical performance parameters that vary with temperature are also introduced. Based on transient plastic finite element calculation, the first transient temperature field of the finite element mesh model is solved throughout the entire process of the welding heat source movement, and the first equivalent plastic strain distribution and the welding deformation corresponding to the first equivalent plastic strain distribution are obtained based on the first transient temperature field. At the end of the welding cooling time of the finite element mesh model, the longitudinal plastic strain distribution along the weld direction is extracted as the longitudinal plastic strain, and the displacement distribution of the thin plate fillet weld joint in the thickness direction is extracted as the first post-weld external deformation.

[0008] More preferably, the step of integrating and summing the longitudinal plastic strain along the weld length of the thin plate fillet weld joint to obtain the first longitudinal shrinkage force specifically includes: Multiple integral sections are selected in the finite element mesh model along the weld length direction of the thin plate fillet weld joint, and the weld and the corresponding longitudinal plastic strain distribution are extracted on each integral section; The longitudinal plastic strain distribution on each integral section is averaged by area weighting to obtain the average longitudinal plastic strain of the section distributed along the weld length. The average longitudinal plastic strain of the cross section is taken as the longitudinal inherent strain. Combined with the equivalent stiffness parameter of the corresponding cross section, the integral of each integral cross section along the weld length direction is summed to calculate the first welding longitudinal shrinkage force characterizing the overall longitudinal shrinkage effect of the weld.

[0009] More preferably, determining whether the thin plate fillet weld joint has experienced weld buckling instability based on the trend mode of the external deformation after the first weld specifically includes: After applying the welding heat source to the finite element mesh model and cooling it to room temperature, the first weld post-deformation corresponding to the thin plate corner weld joint is extracted from the finite element mesh model. Multiple monitoring sections are set along the weld length direction of the thin plate fillet weld and in the plate width direction perpendicular to the weld, and the out-of-plane deflection curves on each monitoring section are obtained. The outward deformation after the first weld is normalized to obtain a trend mode characterizing the outward bending morphology in the thin plate fillet weld joint. When the maximum out-of-plane deflection of the first weld exceeds the preset deformation critical value, and the correlation coefficient between the trend mode and any preset buckling mode is greater than the preset correlation threshold, it is determined that the thin plate corner weld joint has experienced welding buckling instability.

[0010] More preferably, the step of introducing an induction heating source into the finite element mesh model to solve for the residual plastic strain and the second out-of-plane welding deformation of the finite element mesh model under the combined action of the welding heat source and the induction heating source specifically includes: An induction heating area is defined along the weld path on the side of the thin plate corner weld joint away from the weld. The induction heating heat source is set as a volume heat source that moves with time along the length of the weld. The moving speed of the induction heating heat source is the same as that of the welding heat source, and it has a preset lateral spacing relative to the weld centerline and a preset vertical gap with the base plate. The heat input of the induction heating source is superimposed on the finite element mesh model in the form of a time function, and the welding heat source and the induction heating source are applied simultaneously at each time step to solve the second transient temperature field of the entire welding process. Based on the second transient temperature field, the second equivalent plastic strain distribution and the structural deformation corresponding to the second equivalent plastic strain distribution are calculated at each time step under the combined action of the welding heat source and the induction heating heat source. The second equivalent plastic strain distribution represents the equivalent plastic strain distribution under the action of welding induction heating. When the thin plate fillet weld joint cools to room temperature, the longitudinal residual plastic strain distribution along the weld length direction is extracted from the second equivalent plastic strain distribution as the residual plastic strain, and the displacement distribution of the thin plate fillet weld joint in the plate thickness direction is extracted as the second out-of-plane welding deformation.

[0011] More preferably, the process parameters include the lateral distance between the induction heating source and the weld, the gap between the induction heating source and the surface of the thin plate fillet weld, the induction heating power of the induction heating source, and the frequency of the induction heating source.

[0012] A second aspect of this application provides a thin plate fillet weld instability control system based on induction heating during welding. The thin plate fillet weld instability control system includes a model building module, a data processing module, and a dynamic adjustment module. The model building module is used to construct the finite element mesh model corresponding to the thin plate corner weld joint by measuring the dimensional parameters of the thin plate corner weld joint. The data processing module is used to set a welding heat source in the finite element mesh model to solve for the longitudinal plastic strain and the first post-weld external deformation within the finite element mesh model during welding. The longitudinal plastic strain is integrated and summed along the weld length of the thin plate fillet weld to obtain the first longitudinal shrinkage force. Based on the trend mode of the first post-weld external deformation, it is determined whether the thin plate fillet weld has experienced welding buckling instability. If welding buckling instability occurs, an induction heating heat source is introduced into the finite element mesh model to solve for the longitudinal shrinkage force during welding. The residual plastic strain and second out-of-plane welding deformation of the finite element mesh model under the combined action of the heat source and the induction heating heat source are calculated, and the second longitudinal shrinkage force corresponding to the residual plastic strain is calculated. The induction heating heat source and the welding heat source are relatively fixed and move synchronously with the welding trajectory. The induction heating heat source and the welding heat source are located on opposite sides of the weld of the thin plate fillet weld. The second out-of-plane welding deformation represents the out-of-plane deformation after the weld under the action of welding induction heating, and the second longitudinal shrinkage force represents the longitudinal shrinkage force of the weld under the action of welding induction heating. The dynamic adjustment module is used to confirm the process parameters of the thin plate fillet weld joint during the induction heating process if the second welding longitudinal shrinkage force is less than the critical buckling instability condition, and to perform induction heating treatment on the thin plate fillet weld joint according to the process parameters.

[0013] A third aspect of this application provides an electronic device including a processor, a memory, a user interface, and a network interface, wherein the memory is used to store instructions, the user interface and the network interface are used to communicate with other devices, and the processor is used to execute the instructions stored in the memory.

[0014] A fourth aspect of this application provides a non-transitory computer-readable storage medium having a computer program stored thereon, the computer program being executed by a processor to implement the steps of a method for controlling instability in fillet welds of thin plates based on induction heating during welding.

[0015] The present invention provides a method and system for controlling instability in thin plate fillet welds based on induction heating during welding, which has the following advantages over the prior art: (1) By establishing a finite element mesh model based on the theory of inherent deformation of welding and the instability mechanism of thin plate fillet weld, and solving the longitudinal plastic strain and the first weld post-external deformation during the welding process, the longitudinal shrinkage force of the weld area can be quantitatively predicted before / during welding. Furthermore, the trend mode of out-of-plane deformation can be used to determine whether buckling instability will occur, thus realizing the early prediction and quantitative determination of the instability of thin plate fillet weld. When it is determined that welding buckling instability will occur, an induction heating heat source that is relatively fixed with the welding heat source and moves synchronously with the welding trajectory is introduced. Through the reasonable configuration of the heat source spatial position and energy, the uneven shrinkage and warping deformation caused by unilateral welding can be effectively offset or weakened, suppressing the buckling instability of the thin plate fillet weld joint, thereby improving the manufacturing accuracy of the thin plate fillet weld joint. At the same time, the threshold criteria of the second out-of-plane welding deformation and the second welding longitudinal shrinkage force are introduced. This dual-index constraint not only controls the external dimensions and the degree of warping, but also controls the longitudinal residual stress that affects the load-bearing capacity and fatigue performance, thereby improving the overall service reliability of the weld and components.

[0016] (2) By explicitly introducing an induction heating volume heat source in the finite element model and moving it over time, with its moving speed consistent with the welding heat source and having a preset transverse spacing and vertical gap, the accurate simulation of the synchronous loading condition of welding and induction heating is realized. Based on the second transient temperature field, the second equivalent plastic strain distribution of each time step is calculated, which can comprehensively reflect the influence of induction heating on the yielding, softening and plastic accumulation process of the material. When cooled to room temperature, the longitudinal residual plastic strain distribution along the weld length direction is extracted as a quantitative characterization of residual plastic strain, thus realizing the fine prediction and evaluation of residual plastic strain in space. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic flowchart of a method for controlling instability in thin plate fillet welds based on induction heating during welding, provided by the present invention; Figure 2 This is a schematic diagram of the structure of the finite element mesh model provided by the present invention; Figure 3 Transient temperature field cloud map distribution of thin plate fillet weld joint provided by the present invention; Figure 4 The longitudinal plastic strain distribution cloud map after welding corresponding to the fillet weld joint of thin plate provided by the present invention; Figure 5The post-weld external welding deformation distribution cloud map corresponding to the fillet weld joint of thin plate provided by the present invention; Figure 6 The transient temperature field of the thin plate fillet weld joint under dynamic thermal stretching during welding provided by the present invention; Figure 7 The longitudinal plastic strain distribution cloud map of the thin plate fillet weld joint during dynamic thermal stretching during welding, provided by the present invention; Figure 8 The out-of-plane bending deformation distribution cloud map of the thin plate fillet weld joint during dynamic thermal stretching during welding, provided by the present invention; Figure 9 The present invention provides a multi-turn wound induction heating coil structure for a circular tube; Figure 10 This is a schematic diagram of the structure of the dynamic hot stretching equipment provided by the present invention. Figure 11 This is a schematic diagram of the structure for controlling the instability of fillet welds in thin plates provided by the present invention; Figure 12 This is a schematic diagram of the structure of the electronic device provided by the present invention.

[0019] Explanation of reference numerals in the attached diagram: 1. Thin plate fillet weld instability control; 11. Model building module; 12. Data processing module; 13. Dynamic adjustment module; 2. Electronic equipment; 21. Processor; 22. Communication bus; 23. User interface; 24. Network interface; 25. Memory. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] This invention discloses a method for controlling instability in thin plate fillet welds based on induction heating during welding, with reference to... Figure 1 The steps of this method include S1 to S5.

[0022] Step S1: Based on the dimensional parameters of the thin plate corner weld joint, construct the finite element mesh model corresponding to the thin plate corner weld joint.

[0023] Step S2: Set a welding heat source in the finite element mesh model to solve the longitudinal plastic strain and the external deformation after the first weld in the finite element mesh model during the welding process. The welding heat source can be a welding torch.

[0024] Step S3: Integrate and sum the longitudinal plastic strain along the weld length of the thin plate fillet weld joint to obtain the first longitudinal shrinkage force of the weld, and determine whether the thin plate fillet weld joint has experienced weld buckling instability based on the trend mode of the external deformation after the first weld.

[0025] Step S4: If the fillet weld of the thin plate experiences weld buckling instability, an induction heating source is introduced into the finite element mesh model to solve for the residual plastic strain and the second out-of-plane weld deformation of the finite element mesh model under the combined action of the welding heat source and the induction heating source. The second longitudinal shrinkage force corresponding to the residual plastic strain is also calculated. The induction heating source and the welding heat source are relatively fixed and move synchronously with the welding trajectory. The induction heating source and the welding heat source are located on opposite sides of the weld of the fillet weld of the thin plate. The induction heating source can be an induction heating coil. The second out-of-plane weld deformation represents the out-of-plane deformation after the weld under the action of welding induction heating. The second longitudinal shrinkage force represents the longitudinal shrinkage force of the weld under the action of welding induction heating.

[0026] Step S5: If the longitudinal shrinkage force of the second weld is less than the critical buckling instability condition, then confirm the process parameters of the thin plate fillet weld joint during the induction heating process, and perform induction heating and stretching treatment on the thin plate fillet weld joint according to the process parameters.

[0027] The process parameters include the lateral distance between the induction heating source and the weld, the gap between the induction heating source and the surface of the thin plate fillet weld, the induction heating power of the induction heating source, and the frequency of the induction heating source.

[0028] In this embodiment, a finite element mesh model is established based on the theory of inherent welding deformation and the instability mechanism of thin plate fillet welds. By solving the longitudinal plastic strain and the out-of-plane deformation after the first weld during the welding process, the longitudinal shrinkage force in the weld area can be quantitatively predicted before / during welding. Furthermore, the trend mode of out-of-plane deformation can be used to determine whether buckling instability will occur, thus enabling early prediction and quantitative determination of thin plate fillet weld instability. When it is determined that welding buckling instability will occur, an induction heating heat source that is relatively fixed to the welding heat source and moves synchronously with the welding trajectory is introduced. Through the reasonable configuration of the heat source's spatial position and energy, the uneven shrinkage and warping deformation caused by unilateral welding can be effectively offset or weakened, suppressing the buckling instability of the thin plate fillet weld joint, thereby improving the manufacturing accuracy of the thin plate fillet weld joint. At the same time, a threshold criterion of the second out-of-plane welding deformation and the second welding longitudinal shrinkage force is introduced. This dual-index constraint not only controls the external dimensions and the degree of warping, but also controls the longitudinal residual stress that affects the load-bearing capacity and fatigue performance, thereby improving the overall service reliability of the weld and the component.

[0029] Based on the above embodiments, as an optional embodiment, step S1, which involves constructing a finite element mesh model of the thin plate fillet weld joint based on the theory of inherent welding deformation, the instability mechanism of thin plate fillet welds, and the dimensional parameters of the thin plate fillet weld joint, may further include the following: Step S11: Perform geometric modeling on the thin plate fillet weld joint composed of the base plate and the vertical plate. Both the base plate and the vertical plate are high-strength marine steel thin plates.

[0030] In this step, a geometric model is created for the fillet weld joint consisting of a base plate and a vertical plate, both of which are high-strength marine steel thin plates. Specifically, a three-dimensional geometric model of the fillet weld joint is established using 3D modeling software or finite element preprocessing software. The length, width, and thickness parameters of the base plate are defined in a unified coordinate system. A vertical plate is then placed along one edge of the base plate according to the designed height and thickness parameters, forming a perpendicular or near-perpendicular fillet joint with the base plate. Preferably, the thickness of both the base plate and the vertical plate is 3–8 mm, and both are made of high-strength marine steel conforming to classification society specifications, such as AH series or EH series marine steel plates, to reflect the typical characteristics of welding residual stress and fillet weld buckling instability on high-strength steel thin plates. To facilitate subsequent parametric analysis, the geometric dimensions of the base plate and the vertical plate can be defined as variables, allowing fillet weld joints of different lengths, widths, and heights to be quickly generated within the same geometric modeling framework. Simultaneously, the geometric position and width of the weld area are reserved in the model.

[0031] Step S12: Based on the bevel form of the fillet weld to be welded in the thin plate fillet weld joint and the expected weld pool shape, define the weld toe, weld root and weld transition rounded corner area at the junction of the base plate and the vertical plate, and determine the key pressure zone around the weld based on the instability mechanism of thin plate fillet weld.

[0032] In this step, the weld toe, weld root, and weld transition fillet area are defined at the junction of the base plate and the vertical plate based on the bevel form of the fillet weld to be welded and the expected weld pool shape in the thin plate fillet weld joint. The critical pressure zone around the weld is determined based on the instability mechanism of thin plate fillet welds.

[0033] The buckling mechanism of thin plate fillet welds refers to the significant non-uniform temperature field generated in the weld and its adjacent areas during the welding process of thin plate fillet welds due to the melting and solidification of the weld metal and the local heating and cooling of the base material. This leads to large residual welding stress and welding deformation. For thin plate fillet welds consisting of a base plate and a vertical plate, the longitudinal welding shrinkage near the weld induces large in-plane compressive stress in the base plate and vertical plate. When this compressive stress exceeds the critical buckling load that the structure can withstand under existing constraints, weld buckling instability will occur.

[0034] Specifically, fillet welds on thin plates typically have large length and width dimensions and small plate thickness, belonging to thin plate structures with high aspect ratios and low inherent bending stiffness. The welding thermal cycle causes significant irreversible plastic deformation in the weld and heat-affected zone, resulting in longitudinal shrinkage along the weld direction and non-uniform bending deformation on the plate surface. This causes initial geometric defects and residual stresses to be superimposed on the base plate and vertical plate in the compression zone around the weld. Upon cooling to room temperature after welding, these compressive residual stresses are unevenly distributed along the plate thickness and within the plate surface, creating a state similar to "pre-compression" in locally critical compression zones. When this pre-compression state acts in conjunction with external constraints or additional loads, it easily induces localized wavy out-of-plane bending deformation near the weld toe, weld root, and the central area of ​​the plate surface.

[0035] During the instability process of thin plate fillet welds, a small out-of-plane deflection first appears in the critical pressure zone near the weld. This deflection is further amplified during subsequent unloading and secondary loading, ultimately manifesting as obvious bulging, depression, or twisting of the base or vertical plate surface, i.e., the weld buckling instability morphology. Since the distribution of longitudinal residual compressive stress is closely related to the inherent deformation along the weld length, factors such as uneven welding heat input, unreasonable welding sequence, or excessive assembly gaps can lower the critical instability threshold of the thin plate fillet weld joint, causing the structure to fail due to out-of-plane bending before reaching its yield strength. In summary, the instability mechanism of thin plate fillet welds is caused by the coupling effect of inherent deformation and residual compressive stress induced by welding heat input and the low buckling stiffness resulting from the slender geometry of the thin plate.

[0036] Furthermore, based on the actual welding process, the fillet weld is selected as either a single-sided or double-sided fillet weld, and geometric parameters such as weld leg size, penetration depth, and weld width are set. A weld geometry with a certain excess height and transition fillet radius is constructed near the intersection of the base plate and the vertical plate, making the weld toe and weld root positions clearly identifiable in the geometric model. Combining the buckling instability mechanism analysis of thin plate fillet welds, key pressure zones are delineated on the plate surface and near the weld toe on the compressed side according to theoretical buckling waveforms and engineering experience. These typically include a strip-shaped area on the base plate near the weld and a plate surface area within a certain height range at the root of the vertical plate. These areas are prone to local out-of-plane bending and large compressive plastic strain during buckling instability.

[0037] Step S13: Use three-dimensional Solid elements to perform finite element mesh generation on the base plate and the vertical plate. Arrange fine mesh in the critical pressure zone of the weld and adjacent weld, and arrange coarse mesh in the area far away from the weld to form a finite element mesh model suitable for welding inherent deformation analysis.

[0038] In this step, finite element meshing is performed on the base plate and the vertical plate using three-dimensional solid elements. Fine meshes are applied to the weld and the critical pressure zone adjacent to the weld, while coarse meshes are applied to areas far from the weld to form a finite element mesh model suitable for analyzing the inherent deformation of the weld. Specifically, a hybrid meshing strategy using hexahedral solid elements or a combination of hexahedral elements as the primary element and tetrahedral elements as the secondary element is preferred. Smaller element sizes, such as 1–5 mm, are used in the weld metal, heat-affected zone, and the critical pressure zone determined in step S12 to accurately capture the welding temperature gradient, plastic strain concentration, and out-of-plane deformation distribution. Larger element sizes, such as 5–20 mm, are used in the base plate and vertical plate areas far from the weld to reduce the overall number of elements and computational cost. During meshing, the aspect ratio, torsion, and node connection quality of the control units are optimized to ensure the mesh meets the accuracy requirements of thermo-elastic-plastic analysis. A transition mesh band is set between the weld area and the far-field region to avoid numerical instability or result distortion caused by abrupt changes in element size. The final three-dimensional finite element mesh model can reflect both the local response of the weld and its surrounding thin plate, and also take into account the global deformation characteristics of the overall fillet weld.

[0039] In one example, such as Figure 2 As shown, in the finite element mesh model, the base plate of the corner weld joint has a length of 600mm, a width of 400mm, and a thickness of 5mm, while the vertical plate has a length of 600mm, a height of 200mm, and a thickness of 5mm. The material is AH36 high-strength steel.

[0040] Based on the above embodiments, as an optional embodiment, step S2, which involves setting a welding heat source in the finite element mesh model to solve for the longitudinal plastic strain and the external deformation after the first weld during the welding process, may further include the following: Step S21: Define the spatial distribution of welding heat source in the finite element mesh model based on the shape of the weld pool, set the welding heat source as a volumetric heat source that moves with time along the weld path in the thin plate corner weld joint, and determine the heat input intensity of the welding heat source according to the preset welding specification parameters.

[0041] In this step, based on the geometric model and finite element mesh model obtained in step S1, the centerline of the fillet weld to be welded in the thin plate fillet weld joint is defined in the preprocessing software. The weld centerline is discretized into several path nodes, and the weld start and end points are determined according to the welding sequence. On this basis, a parametric path coinciding with the weld centerline is constructed to describe the movement trajectory of the welding heat source during the welding process.

[0042] Based on the expected spatial shape and energy distribution characteristics of the weld pool, a volumetric heat source model is selected in the finite element mesh model to model the welding heat source. Specifically, an ellipsoidal heat source, a double ellipsoidal heat source, or other volumetric heat source models that can reflect the asymmetric characteristics of the weld pool before and after the weld can be selected. The geometric dimensions of the volumetric heat source are matched with the actual weld leg size, weld penetration, and weld width. The weld metal zone and the heat-affected zone are defined as the main heated areas in the model, so that the spatial distribution of the heat source can cover the weld metal and its adjacent areas.

[0043] In the time domain, the welding process is discretized into several time steps. Within each time step, the center position of the welding heat source is positioned at a corresponding point on the weld path, and the movement of the heat source along the path is controlled according to a preset welding speed, so that the volumetric heat source moves continuously along the weld path over time. For solid elements within the range of the heat source, a volumetric heat flux load is applied in the corresponding time step, realizing the dynamic application of welding heat input in the finite element mesh model.

[0044] Finally, based on the preset welding specification parameters, such as welding current, welding voltage, welding speed, and welding thermal efficiency, the welding line energy and heat input per unit time are determined, and the volume heat source model is calibrated accordingly to ensure that the total heat input in the numerical model is consistent with the actual process conditions, thereby ensuring that the temperature field, plastic strain field, and welding deformation obtained in subsequent solutions are comparable to those in engineering.

[0045] Step S22: Apply surface heat transfer and thermal radiation as temperature boundary conditions in the finite element mesh model, constrain the rigid body displacement of the thin plate corner weld joint as mechanical boundary conditions, and introduce material thermal property parameters and mechanical property parameters that vary with temperature.

[0046] In this step, regarding temperature boundary conditions, the outer surface of the thin plate fillet weld exposed to the environment is defined as the heat transfer boundary, on which both convective heat transfer and thermal radiation boundary conditions are applied simultaneously. For any point on the model surface, the convective heat flux density per unit area is... and radiative heat flux density They can be represented by the following functions:

[0047]

[0048]

[0049] in, This represents the instantaneous temperature at any surface point in a fillet weld joint of thin plates. Indicates ambient temperature. Indicates the convective heat transfer coefficient. Indicates surface emissivity, This represents the Stefan-Boltzmann constant. Correspondingly, it represents the total boundary heat flux function at that surface point. It can be represented as:

[0050]

[0051] When solving the finite element method, It is used as a temperature boundary condition in solving the transient temperature field.

[0052] Regarding the mechanical boundary conditions, to eliminate the interference of overall rigid body translation and rotation on the welding deformation results, several nodes at one edge of the base plate or other reasonable locations are selected as constraint nodes in the finite element mesh model. Appropriate displacement constraints are applied to these nodes to restrict the rigid body degrees of freedom of the thin plate fillet weld joint. Taking displacement boundary conditions as an example, the constraint boundaries can be... The displacement function of the upper node is expressed as:

[0053]

[0054] in, Represented as position on the constraint boundary In time The displacement vector function, Represented as position on the constraint boundary In time The given displacement function. In typical cases, it can be... Take it as the zero vector, that is:

[0055]

[0056] At this moment This means that the corresponding degrees of freedom of the nodes on the constrained boundary are fixed, thereby effectively suppressing the overall rigid body motion, while not restricting the relative deformation caused by the temperature field and plastic strain.

[0057] Regarding material properties, to accurately reflect the evolution of material thermodynamic properties during welding heating and cooling, temperature-dependent thermophysical and mechanical property parameters are introduced into the material property definition. These include, but are not limited to, temperature-dependent thermal conductivity, specific heat capacity, coefficient of linear expansion, as well as temperature-dependent elastic modulus, yield strength, Poisson's ratio, and plastic hardening parameters. By setting these parameters as temperature functions, the corresponding material properties are automatically invoked at different temperature levels during the finite element solution process, achieving a thermo-mechanical coupled characterization of material behavior throughout the welding process.

[0058] Step S23: Based on transient plastic finite element calculation, solve the first transient temperature field of the finite element mesh model during the entire process of the welding heat source movement, and obtain the first equivalent plastic strain distribution and the welding deformation corresponding to the first equivalent plastic strain distribution at each time step based on the first transient temperature field.

[0059] In this step, the entire process of moving the welding heat source from the arc-starting position to the arc-extinguishing position, as well as the subsequent cooling process, is discretized in time into several consecutive time steps: Let the total welding and cooling time interval be... Divide the time interval into Each time step, with the time node being... ,in, .

[0060] Within each time step, the position of the welding heat source and the heat input distribution are updated according to the movement law of the welding heat source in step S21. At each time step, the transient temperature field is solved first, and then the transient thermo-plastic mechanical field is solved based on the temperature field corresponding to that time step.

[0061] Based on the aforementioned time discretization, the transient heat conduction finite element method is used to solve the first transient temperature field of the finite element mesh model at each time step: At each time step, the temperature increment of each mesh node is solved by integrating the thermal boundary conditions such as the welding volume heat source, surface heat transfer and thermal radiation, as well as temperature-related thermophysical parameters. By time integration or time step progression, the temperature distribution of each node in the finite element mesh model at each time step is obtained throughout the entire process from arc initiation to welding cooling. The obtained temperature distribution is used as the basis for updating the temperature load and material parameters in subsequent thermo-elastoplastic mechanical analysis.

[0062] The above transient plastic finite element calculation process can be formalized by a transient plastic finite element calculation function that jointly solves the temperature field and the mechanical field as follows:

[0063] in, This represents the time series of the transient temperature field, i.e., its position at each time step. Temperature distribution at that location The time series representing the equivalent plastic strain distribution, i.e., its position at each time step. Equivalent plastic strain at the point, This represents the time series of the welding deformation field, i.e., the position at each time step. The displacement vector at that point This represents the operator for solving transient plastic finite element methods. Represents the initial temperature field function. This represents a set of temperature-related material parameters, such as thermal conductivity, specific heat capacity, coefficient of linear expansion, elastic modulus, Poisson's ratio, yield strength, and plastic hardening parameters.

[0064] After completing the transient plastic finite element calculations for all time steps, the first equivalent plastic strain distribution at each time step within the finite element mesh model during the entire welding and cooling process is obtained by summarizing the time step results. Simultaneously, the welding deformation field corresponding to each time step is acquired, including in-plane and out-of-plane deformation of the plate surface. The final time step... The equivalent plastic strain distribution and displacement field can serve as the basic data for post-weld residual plastic strain and post-weld residual deformation, providing a basis for the subsequent extraction of longitudinal plastic strain and external deformation after the first weld.

[0065] Step S24: At the end of the welding cooling of the finite element mesh model, extract the longitudinal plastic strain distribution along the weld direction as the longitudinal plastic strain, and extract the displacement distribution of the thin plate fillet weld joint in the thickness direction as the first post-weld external deformation.

[0066] In this step, based on the transient analysis results of step S23, the end time of welding cooling is determined. This moment corresponds to the final moment in the finite element calculation. Or a time point close to room temperature. The temperature field, equivalent plastic strain field, and displacement field at this moment are used as numerical results for the post-weld state.

[0067] exist Based on the plastic strain results at a given time, the longitudinal plastic strain distribution is extracted along the weld path, specifically including: In the finite element mesh model, one or more representative node / element sequences are selected along the weld path to form a sampling line in the weld direction. The plastic strain tensor components of the elements near the sampling line are processed to extract the plastic strain components along the weld direction (e.g., the plastic normal strain components along the longitudinal axis), and averaging can be performed along the thickness direction or several integration points as needed. The obtained longitudinal plastic strain components along the weld path are sorted according to the weld length direction to form a longitudinal plastic strain distribution curve or data sequence along the weld direction. The above distribution result is defined as the longitudinal plastic strain in this embodiment, which is used to characterize the cumulative plastic deformation level along the weld direction after welding.

[0068] exist Based on the displacement results at each moment, the displacement distribution of the fillet weld joint in the thin plate in the thickness direction is extracted, specifically including: In the finite element mesh model, nodes or elements covering the weld and its neighboring plate area are selected, with a focus on the positions near the weld and heat-affected zone. The displacement components of the above nodes in the thickness direction (i.e., the direction perpendicular to the plate surface) are extracted to obtain the out-of-plane displacement distribution of the plate surface. Different plate surfaces (such as the inner side and the outer side) or different thickness positions (such as the middle surface and the surface) can be compared and analyzed according to actual needs, and a continuous out-of-plane deformation field representation can be formed by interpolation or averaging methods. The displacement distribution result in the thickness direction is defined as the first post-weld out-of-plane deformation in this embodiment, which is used to quantitatively characterize the warping, deformation degree and distribution characteristics of the thin plate fillet weld joint after welding.

[0069] After obtaining the longitudinal plastic strain distribution and the out-of-plane deformation after the first weld, these can be output in the form of data tables, curves, or cloud maps to further establish a quantitative relationship model or prediction model between longitudinal plastic strain and out-of-plane deformation.

[0070] Based on the above embodiments, as an optional embodiment, step S3, which involves integrating and summing the longitudinal plastic strain along the weld length of the thin plate fillet weld to obtain the first longitudinal shrinkage force, may further include the following: Step S31: Select multiple integral sections in the finite element mesh model along the weld length direction of the thin plate fillet weld joint, and extract the weld and the corresponding longitudinal plastic strain distribution on each integral section.

[0071] In this step, in the finite element preprocessing model, the weld length direction is discretized into several representative locations based on the geometric path of the weld centerline. At each location, a section orthogonal to the weld centerline is set for subsequent strain integration and statistical analysis.

[0072] Preferably, the spacing between each integral section is reasonably selected based on the weld length and deformation gradient to reduce post-processing workload while ensuring calculation accuracy. Then, after the welding and cooling process is completed, the post-processing module of the finite element software is invoked to select elements or integration points covering the weld metal, heat-affected zone, and the base material region adjacent to the weld on each integral section, and extract the plastic strain components of these elements or integration points along the weld direction as longitudinal plastic strain data. By reading and storing all relevant elements or integration points in each integral section one by one, the spatial distribution of longitudinal plastic strain in the weld and its surrounding area on each integral section can be obtained.

[0073] Step S32: Perform area-weighted averaging on the longitudinal plastic strain distribution on each integral section to obtain the average longitudinal plastic strain of the section distributed along the weld length direction.

[0074] In this step, the longitudinal plastic strain of each element or integration point extracted from each integration section in step S31 is categorized according to its corresponding area or volume within the section, with each element or integration point associated with a corresponding area weight. Subsequently, within each integration section, the longitudinal plastic strain values ​​of all elements or integration points contained in that section are subjected to area-weighted averaging, so that the longitudinal plastic strains corresponding to the weld metal, heat-affected zone, and adjacent base metal regions participate in averaging according to their area proportions within the section, thereby obtaining the section-averaged longitudinal plastic strain that can characterize the overall longitudinal plastic deformation level of the section. By sequentially performing the above area-weighted averaging process on each integration section arranged along the weld length direction, a section-averaged longitudinal plastic strain distribution curve that varies with the weld length is finally formed. This distribution curve quantitatively reflects the spatial variation characteristics of the inherent shrinkage of the weld along its length.

[0075] Step S33: The average longitudinal plastic strain of the cross section is taken as the longitudinal inherent strain. Combined with the equivalent stiffness parameter of the corresponding cross section, the integral of each integral cross section along the weld length direction is summed to calculate the first welding longitudinal shrinkage force characterizing the overall longitudinal shrinkage effect of the weld.

[0076] In this step, the average longitudinal plastic strain of the cross-section distributed along the weld length direction obtained in step S32 is regarded as the inherent strain input of the weld and its adjacent area in the longitudinal direction, that is, it is assumed that the cross-section has a corresponding free shrinkage tendency under the action of no external force. Then, for each integral cross-section, based on the actual geometric dimensions and material parameters of the weld and adjacent base material areas within the cross-section, the equivalent stiffness parameter of the cross-section in the longitudinal direction of the weld is calculated or equivalently determined to characterize the cross-section's ability to resist longitudinal shrinkage. On this basis, the longitudinal inherent strain on each integral cross-section is combined with the corresponding equivalent stiffness to obtain the equivalent longitudinal shrinkage internal force generated when each cross-section is constrained, and the longitudinal shrinkage internal force corresponding to all integral cross-sections is integrated and summed or discretely summed along the weld length direction to obtain the first welding longitudinal shrinkage force characterizing the total effect of the entire weld's longitudinal inherent shrinkage.

[0077] Based on the above embodiments, as an optional embodiment, step S3, which involves determining whether the thin plate fillet weld joint has experienced weld buckling instability based on the trend mode of the external deformation after the first weld, may further include the following: Step S34: After applying the welding heat source to the finite element mesh model and cooling it to room temperature, extract the first weld post-deformation corresponding to the fillet weld of the thin plate from the finite element mesh model.

[0078] In this step, within the established finite element mesh model of the thin plate fillet weld, only the welding process parameters and welding heat source settings determined in step S2 are applied to the welding volume heat source. No induction heating or other additional heat sources are introduced. Transient thermo-elastic-plastic numerical calculations are performed on the entire welding process and its cooling process. Through this calculation, the temperature field, stress-strain field, and structural deformation evolution results of the thin plate fillet weld are obtained throughout the entire process, from arc initiation at the welding heat source, movement along the weld path until arc extinguishing, and subsequent natural cooling to room temperature. When the calculation time progresses to the point where the overall temperature of the component has essentially recovered to the preset room temperature range, this moment is considered the end of welding cooling. At this moment, the displacement components in the thickness direction of each node of the thin plate fillet weld are extracted from the finite element analysis results, particularly the displacement distribution perpendicular to the plate surface on the bottom and vertical plates. This is stored and post-processed as the out-of-plane deflection distribution after welding. In this embodiment, the plate thickness direction displacement field calculated under the condition of applying only the welding heat source and cooling to room temperature is defined as the first post-weld out-of-plane deformation.

[0079] Step S35: Set multiple monitoring sections along the weld length direction of the thin plate fillet weld joint and the plate width direction perpendicular to the weld, and obtain the out-of-plane deflection curve on each monitoring section.

[0080] In this step, within the geometric coordinate system of the thin plate fillet weld, several longitudinal monitoring sections perpendicular to the weld direction are defined, with the weld centerline as a reference, at equal intervals or as needed along the weld length. Simultaneously, on the base plate and vertical plate surfaces, multiple transverse monitoring sections are arranged along the plate width direction perpendicular to the weld, starting from the weld centerline, ensuring that both longitudinal and transverse sections cover the vicinity of the weld and critical pressure areas. At each monitoring section, a finite element node is selected or a monitoring line is defined on the section, and the displacement result in the plate thickness direction corresponding to the first weld's outward deformation is read. By sorting and interpolating the out-of-plane displacements of the nodes along the section direction, discrete node displacements are converted into continuous out-of-plane deflection distribution curves, which are recorded as out-of-plane deflection curves along the weld direction and perpendicular to the weld direction, respectively. These deflection curves reflect the out-of-plane bending deformation characteristics of the thin plate fillet weld at different locations after welding, providing fundamental data for subsequent trend mode normalization processing and comparative analysis with preset buckling modes.

[0081] Step S36: Normalize the out-of-plane deformation after the first weld to obtain the trend mode characterizing the out-of-plane bending morphology in the thin plate fillet weld joint.

[0082] In this step, based on the out-of-plane deflection curves of multiple monitoring sections and the out-of-plane deformation displacement distribution after the first weld in the entire field obtained in step S35, all out-of-plane displacement data are uniformly organized and represented as an out-of-plane deflection field related to the weld length direction and plate width direction. On this basis, to eliminate the influence of the magnitude of the out-of-plane deformation after the weld on shape recognition, the out-of-plane deflection field is normalized. For example, the maximum absolute deflection value of the out-of-plane deformation after the first weld or the characteristic deflection value of a representative position is used as a reference scale to scale the entire deflection distribution proportionally, so that the normalized out-of-plane deflection field has dimensionless characteristic values. Through normalization, the shape information of the out-of-plane deformation in spatial distribution is preserved, and the influence of the absolute deformation is weakened, thereby forming a trend mode that can characterize the overall out-of-plane bending shape of the thin plate fillet weld joint. Furthermore, the normalized out-of-plane deflection data can be smoothed or interpolated in the weld length direction and plate width direction respectively to reduce local numerical noise and discretization errors, making the obtained trend mode closer to the actual out-of-plane bending shape after the weld. In this embodiment, the obtained trend mode can be regarded as the out-of-plane bending "shape feature" caused only by the inherent deformation and residual stress of welding, and is used to compare its correlation with the theoretical buckling mode or the preset buckling mode.

[0083] Step S37: When the maximum out-of-plane deflection of the first weld exceeds the preset deformation critical value, and the correlation coefficient between the trend mode and any preset buckling mode is greater than the preset correlation threshold, it is determined that the thin plate corner weld joint has experienced welding buckling instability.

[0084] In this step, based on the design specifications, production experience, or theoretical analysis results of the thin plate fillet weld, a pre-set deformation threshold for judging weld instability is established. This threshold can be the maximum allowable out-of-plane deflection limit of the thin plate or a limit determined according to a multiple of the plate thickness. After obtaining the first weld out-of-plane deformation, the maximum out-of-plane deflection value within the base plate and vertical plate range is calculated, and this maximum deflection is compared with the pre-set deformation threshold. When the maximum out-of-plane deflection exceeds the threshold, the weld deformation amplitude is considered to have reached a dangerous level that may lead to instability. Next, based on the buckling deformation morphology obtained through linear elastic buckling analysis or experimental measurements, one or more representative pre-set buckling modes are pre-stored. These buckling modes are used to characterize the typical out-of-plane bending shape of the thin plate fillet weld under different buckling instability modes. After obtaining the trend mode in step S36, its morphology is compared with each pre-set buckling mode at the same node or position. The correlation index between the trend mode and each pre-set buckling mode is calculated, for example, using the correlation coefficient or other similarity measurement methods, and compared with a pre-set correlation threshold. When the correlation coefficient between the trend mode and any preset buckling mode is greater than the correlation threshold, and the maximum out-of-plane deflection of the first weld exceeds the preset deformation threshold, it is considered that the out-of-plane bending morphology of the thin plate fillet weld has reached the buckling instability state in terms of both amplitude and shape. In this embodiment, it is determined that the thin plate fillet weld has experienced welding buckling instability; otherwise, it is determined that welding buckling instability has not yet occurred or that only general welding deformation exists.

[0085] Please see Figures 3 to 5 , Figure 3 The transient temperature field distribution of a thin plate fillet weld joint is shown in the image. As the welding heat source moves along the weld path, a localized high-temperature region forms at the junction of the base plate and the vertical plate. This high-temperature region gradually expands from the current position of the welding heat source towards its trailing edge. Its isotherms are distributed in a wedge-shaped or spindle-shaped pattern within the plane of the base plate, exhibiting significant asymmetry along the weld length. The plate temperature near the weld and heat source is significantly higher than that further away from the weld, gradually decreasing along the plate thickness from the weld toe and root towards the interior of the plate, indicating that the welding heat is mainly concentrated in the weld metal and its adjacent heat-affected zone. With increasing distance from the weld centerline and the heat source, the plate surface temperature rapidly approaches ambient temperature. Figure 3 The lowest temperature value marked in the figure is basically consistent with the room temperature, indicating that the area not effectively covered by the heat source is still in the initial temperature state.

[0086] Figure 4This is a contour map of the longitudinal plastic strain distribution after welding for a fillet weld joint in thin plates. Along the weld length, a band-shaped region is formed at the junction of the base plate and the vertical plate, running the entire length of the weld. The longitudinal inherent strain value within this band-shaped region differs significantly from that in the base metal region far from the weld, indicating that the weld metal and its heat-affected zone underwent significant longitudinal shrinkage deformation during welding. This band-shaped region maintains a nearly uniform distribution in the middle of the weld, while exhibiting some localized strain concentration near the ends of the weld plates. This suggests that the longitudinal plastic shrinkage at the weld ends differs slightly from that in the middle due to constraints and thermal cycling. The inherent strain distribution in the base plate and vertical plate regions far from the weld is relatively uniform and close to zero, indicating that no significant permanent longitudinal deformation occurred in these areas, and the inherent shrinkage was mainly confined to the weld and its adjacent heat-affected zone.

[0087] Figure 5 The image shows the out-of-plane deformation distribution cloud map of the fillet weld joint of the thin plates. Both the base plate and the vertical plate exhibit significant overall out-of-plane deflection deformation after welding. The base plate shows a deflection distribution that gradually changes from one side to the other in the direction perpendicular to the weld width, with an overall shape approaching unidirectional bending or tilting. Along the weld length, the out-of-plane deflection change is relatively gentle, indicating that the out-of-plane deformation after welding is mainly controlled by the inherent shrinkage difference in the plate width direction. The deformation of the vertical plate is continuous with that of the base plate on the side near the weld, and its upper edge also shows a certain tendency to tilt or twist along the plate width direction, indicating that the longitudinal weld shrinkage causes the base plate and the vertical plate to bend together. Figure 5 The maximum deformation value marked in the figure is located in an edge area of ​​the base plate or the vertical plate. The out-of-plane deflection at this location reaches the maximum value within the calculation range of this embodiment, and can be used as a characteristic index for evaluating the severity of post-weld deformation.

[0088] Based on the above embodiments, as an optional embodiment, step S4, which involves introducing an induction heating source into the finite element mesh model to solve for the residual plastic strain and the second out-of-plane welding deformation of the finite element mesh model under the combined action of the welding heat source and the induction heating source, may further include the following: Step S41: Define an induction heating area along the weld path on the side of the thin plate fillet weld joint away from the weld. Set the induction heating heat source as a volumetric heat source that moves with time along the length of the weld. The moving speed of the induction heating heat source is the same as that of the welding heat source, and it has a preset lateral spacing relative to the weld centerline and a preset vertical gap with the base plate.

[0089] In this step, based on the geometry of the thin plate fillet weld and the position of the weld centerline, an induction heating trajectory line is arranged along the weld path on the outer surface of the base plate on the side away from the weld in the finite element mesh model. This trajectory line is basically parallel to the weld centerline and maintains a preset lateral distance from the weld centerline to correspond to the horizontal offset distance between the actual induction heating coil and the weld. In the vertical direction, according to the installation gap between the induction coil and the plate surface in the actual induction heating fixture, a preset vertical gap is set for the induction heating heat source along the plate thickness direction, so that the geometric position of the induction heating heat source in the numerical model can reasonably reflect the spatial relationship between the coil and the base plate. Then, a three-dimensional volumetric heat source region is defined on the induction heating trajectory line, and a volumetric heat source distribution form suitable for the simulation of the induction heating temperature field is selected. The induction heating heat source is set to move along the weld length direction over time, and its moving speed is kept consistent with the moving speed of the welding heat source, thereby achieving synchronous or relatively synchronous movement under a given relative positional relationship before and after the welding heat source.

[0090] Step S42: The heat input of the induction heating source is superimposed on the finite element mesh model in the form of a time function, and the welding heat source and the induction heating source are applied simultaneously at each time step to solve the second transient temperature field of the entire welding process.

[0091] In this step, based on the rated power and frequency of the selected induction heating power source and the preset induction heating process parameters, the on-time, maintenance, and off-time patterns of the induction heating process are determined. In the finite element analysis, the heat input intensity of the induction heating source is defined through a time history function, allowing it to vary over time according to a predetermined pattern, including constant heat input, segmented constant heat input, or gradual increase / decrease. Subsequently, in the thermal analysis step, the heat input of the induction heating volume heat source is superimposed onto the finite element model acting on the original welding heat source as an additional heat source. Within each calculation time step, according to the spatial position and time function of the welding heat source and the induction heating heat source, their respective element sets and heat input magnitudes are determined and uniformly loaded onto the corresponding elements in a superposition manner. In this way, during the entire overlapping period of welding and induction heating, both the welding heat source and the induction heating heat source exist simultaneously in the finite element model, thus obtaining the second transient temperature field considering the combined action of the two heat sources. This second transient temperature field reflects the regulatory effect of induction heating on the temperature distribution, cooling rate, and thermal cycle characteristics near the weld.

[0092] Step S43: Based on the second transient temperature field, calculate the second equivalent plastic strain distribution at each time step under the combined action of the welding heat source and the induction heating heat source, and the structural deformation corresponding to the second equivalent plastic strain distribution. The second equivalent plastic strain distribution represents the equivalent plastic strain distribution under the action of welding induction heating.

[0093] In this step, the second transient temperature field obtained in step S42 is used as the heat input, and the temperature distribution corresponding to each time step is loaded into the structural mechanics analysis. This allows the finite element model to automatically update the temperature-dependent elastic modulus, yield strength, and coefficient of thermal expansion of the material according to the current temperature field in each time step. Secondly, driven by the temperature field, a thermo-elastic-plastic analysis is performed on the thin plate fillet weld joint to calculate the thermal strain caused by temperature changes and the subsequent elasto-plastic stress-strain response. The incremental plasticity algorithm is used to gradually accumulate plastic strain at each integration point, thereby obtaining the second equivalent plastic strain distribution that evolves over time. Simultaneously, the nodal displacement results for each time step are obtained by solving the structural equilibrium equations, thus obtaining the structural deformation cloud map generated by the thin plate fillet weld joint during the entire welding and induction heating process. Compared to the case where only a welding heat source is applied, in this embodiment, due to the influence of the induction heating heat source on the temperature field and stress redistribution, the second equivalent plastic strain distribution and corresponding structural deformation can reflect the synergistic control effect of induction heating in reducing longitudinal compressive plastic strain and suppressing out-of-plane instability deformation.

[0094] Step S44: When the fillet weld of the thin plate cools to room temperature, extract the longitudinal residual plastic strain distribution along the weld length direction from the second equivalent plastic strain distribution as the residual plastic strain, and extract the displacement distribution of the fillet weld of the thin plate in the plate thickness direction as the second out-of-plane welding deformation.

[0095] In this step, the transient analysis under the combined action of welding and induction heating is extended until the overall temperature of the thin plate fillet weld joint basically recovers to room temperature or the preset ambient temperature. This moment is defined as the cooling end moment after the combined heat source action. At this moment, multiple cross-sections arranged along the weld length direction are selected from the second equivalent plastic strain results obtained in step S43. The longitudinal plastic strain corresponding to the weld and its adjacent area in each cross-section is statistically analyzed and organized to form a longitudinal residual plastic strain curve continuously distributed along the weld direction. In this embodiment, this is defined as the residual plastic strain after considering the control of induction heating. At the same time, the nodal displacement field results at the cooling end moment are read, and the displacement component perpendicular to the plate surface is extracted. Out-of-plane deflection cloud diagrams and out-of-plane displacement curves of multiple typical cross-sections are plotted in the base plate and vertical plate areas. The displacement distribution of the thin plate fillet weld joint in the plate thickness direction at this moment is taken as the second out-of-plane welding deformation. By comparing the second out-of-plane welding deformation with the first out-of-plane welding deformation obtained when only the welding heat source is applied, the suppression effect of the induction heating process on the unstable deformation of the fillet weld after welding can be quantitatively evaluated.

[0096] In this embodiment, by explicitly introducing an induction heating volume heat source in the finite element model and moving it over time, with its moving speed consistent with the welding heat source and having a preset lateral spacing and vertical gap, accurate simulation of the synchronous loading condition of welding and induction heating is achieved. Based on the second transient temperature field, the second equivalent plastic strain distribution at each time step is calculated, which can comprehensively reflect the influence of induction heating on the material yielding, softening and plastic accumulation process. When cooled to room temperature, the longitudinal residual plastic strain distribution along the weld length direction is extracted as a quantitative characterization of residual plastic strain, realizing the fine prediction and evaluation of residual plastic strain in space.

[0097] Please see Figures 6 to 8 , Figure 6 The transient temperature field of a thin plate fillet weld joint under dynamic thermal stretching during welding is shown, illustrating the field distribution results. These results demonstrate the non-uniform distribution characteristics near the weld path under the influence of welding heat: the field quantity is significantly concentrated near the weld centerline and extends in a band along the weld length; simultaneously, along the plate width direction perpendicular to the weld and along the plate thickness direction, the field quantity gradually decreases from the area adjacent to the weld to the area farther away. This distribution indicates that the welding heat input mainly acts on the weld and its adjacent area, forming a significant gradient change at the intersection of the base plate and the vertical plate of the fillet weld structure. Figure 6 The effective length of the weld and its coordinate direction are also marked, which are used to characterize the spatial variation of the field quantity along the weld direction and the plate surface direction.

[0098] Figure 7 This image shows the longitudinal plastic strain distribution contour plot of a thin plate fillet weld joint under dynamic thermal stretching during welding, and the in-plane strain / deformation correlation field distribution results for the thin plate fillet weld joint. The results indicate that along the weld length, a continuous strip-shaped distribution area forms in the weld and its adjacent region, with more significant local variations near the weld start and end points. Along the direction perpendicular to the weld, the field gradually stabilizes from near the weld towards the region farther from the plate surface. This distribution reflects the irreversible deformation characteristics of the material in the weld and heat-affected zone during welding, and reveals the accumulation and non-uniformity of the longitudinal shrinkage effect along the weld length. Figure 7 The maximum and minimum values ​​of this field quantity are given, which are used to quantitatively characterize the degree of difference between the weld area and the non-weld area and the overall deformation level.

[0099] Figure 8The image shows the out-of-plane bending deformation distribution of the fillet weld joint during dynamic thermal stretching of the thin plate, and the out-of-plane displacement (thickness direction displacement) distribution of the fillet weld joint after cooling to room temperature. The results indicate that the overall out-of-plane displacement of the structure after welding is relatively small, and the plate surface does not exhibit obvious wavy deflection or local bulging. The bottom plate and the vertical plate maintain a relatively straight and continuous shape in the corner joint area. No significant out-of-plane displacement concentration area is formed in the vicinity of the weld, and the overall deformation is mainly characterized by the structure maintaining its original shape. Figure 8 The maximum out-of-plane displacement, marked as 0.00, can be used to characterize that the out-of-plane deformation after welding is negligible or close to zero under this condition, thus indicating that no significant out-of-plane buckling instability characteristics of the weld have occurred under this condition. The maximum out-of-plane bending deformation decreased from -43.71 mm to -3.96 mm, a reduction of 91%.

[0100] Please see Figure 9 The induction heating heat source is an induction heating coil. To produce a good dynamic thermal stretching effect during welding, the copper tube of the induction heating coil is designed with a diameter of 6mm and a wall thickness of 1mm; the material is copper, and the outer surface of the copper tube is wrapped with insulating glass fiber to prevent damage from excessive heat. Simultaneously, the copper tube is bent and wound into the following shape... Figure 9 The induction heating coil shown has four turns in total, with the inner coil having a diameter of 20mm and a 2mm gap between the copper tubes. To concentrate the magnetic field and enhance its strength, magnetic powder is attached to the coil surface. Additionally, the extended copper tube is 300mm long and entirely wrapped with insulating fiberglass. To improve on-site operability, an extension hose of 3m in length and 5cm in diameter, weighing 5kg, is added; it is connected to the extended copper tube via a coaxial transformer. The induction heating power supply is 40kW with an oscillation frequency of 35kHz. Simultaneously, the circulating water cooling system has a power of 5P, and the circulating water tank's dimensions are no greater than 600mm in length, 500mm in width, and 800mm in height, facilitating on-site relocation.

[0101] Furthermore, such as Figure 10 As shown, this application also provides a dynamic hot stretching equipment for welding, which is integrally arranged above and to the side of the base plate of the thin plate fillet weld joint. It mainly includes a traveling mechanism, a welding torch clamping fixture, a column, a crossbeam, a horizontal slider, a vertical slider, an extension rod, and an induction heating device, among other components. The traveling mechanism is mounted on the base plate and arranged along the weld direction. It drives the entire equipment to move at a constant speed along the weld path, achieving synchronous operation with welding. The welding torch clamping fixture is mounted on the traveling mechanism to clamp and position the welding torch, ensuring that the height, angle, and front-to-back distance of the welding torch nozzle relative to the weld remain stable during travel, thereby maintaining constant welding process conditions.

[0102] The column is fixed to the base plate or independent support base to provide vertical guidance and support for the induction heating device. The upper part of the column is connected to the crossbeam, which spans the weld and is arranged approximately parallel to the weld in its length direction, allowing the crossbeam to cover the full width of the weld. A slidable horizontal slider is installed on the crossbeam, which can move along the length of the crossbeam to adjust the lateral position of the induction heating device relative to the weld centerline, accommodating workpieces with different weld positions or plate widths.

[0103] A vertical slider is installed at or connected to the horizontal slider. The vertical slider can move up and down along the column or a special guide to precisely adjust the vertical gap between the induction heating device and the base plate, thereby ensuring that the induction heating area and induction intensity meet the predetermined process requirements. One end of the extension rod is connected to the vertical slider, and the other end extends towards the weld seam. The induction heating device is fixedly installed at its end, so that the induction heating device is located on the side of the weld seam and maintains a preset lateral distance from the weld seam centerline, while forming a predetermined vertical gap with the base plate.

[0104] With the above structural arrangement, when the traveling mechanism moves along the weld direction, the welding torch and the induction heating device move synchronously under the drive of the same motion mechanism. While the welding torch completes the weld metal deposition, the induction heating device performs dynamic heating and thermal stretching in the area near the weld. The multi-degree-of-freedom adjustment mechanism composed of the column, crossbeam, and horizontal and vertical sliders allows this equipment to flexibly adjust the spatial position and gap of the induction heating device for different specifications of thin plate fillet welds, thereby ensuring the stability and controllability of the dynamic thermal stretching process during welding.

[0105] Based on the above method, this application discloses a thin plate fillet weld instability control system based on induction heating during welding, referencing... Figure 11 The thin plate fillet weld instability control 1 includes a model building module 11, a data processing module 12, and a dynamic adjustment module 13, wherein, Model building module 11 is used to construct the dimensional parameters of the thin plate fillet weld joint and build the corresponding finite element mesh model of the thin plate fillet weld joint. The data processing module 12 is used to set up a welding heat source in the finite element mesh model to solve the longitudinal plastic strain and the first outward deformation after welding in the finite element mesh model during the welding process. The longitudinal plastic strain is integrated and summed along the weld length direction of the thin plate fillet weld to obtain the first welding longitudinal shrinkage force. Based on the trend mode of the first outward deformation after welding, it is determined whether the thin plate fillet weld has experienced welding buckling instability. If the thin plate fillet weld has experienced welding buckling instability, an induction heating heat source is introduced into the finite element mesh model to solve the residual plastic strain and the second outward welding deformation of the finite element mesh model under the combined action of the welding heat source and the induction heating heat source. The second welding longitudinal shrinkage force corresponding to the residual plastic strain is calculated. The induction heating heat source and the welding heat source are relatively fixed and move synchronously with the welding trajectory. The induction heating heat source and the welding heat source are located on opposite sides of the weld of the thin plate fillet weld. The second outward welding deformation represents the outward deformation after welding under the action of welding induction heating. The second welding longitudinal shrinkage force represents the welding longitudinal shrinkage force under the action of welding induction heating. The dynamic adjustment module 13 is used to confirm the process parameters of the thin plate fillet weld joint during the induction heating process of welding if the second welding longitudinal shrinkage force is less than the critical buckling instability condition, and to perform induction heating and stretching treatment on the thin plate fillet weld joint according to the process parameters.

[0106] In one example, the model building module 11 performs geometric modeling of a thin plate fillet weld joint consisting of a base plate and a vertical plate, both of which are high-strength marine steel thin plates. Based on the bevel form of the fillet weld to be welded in the thin plate fillet weld joint and the expected shape of the weld pool, the weld toe, weld root, and weld transition fillet area are defined at the junction of the base plate and the vertical plate. The critical pressure zone around the weld is determined based on the instability mechanism of thin plate fillet welds. The base plate and the vertical plate are meshed using three-dimensional solid elements. Fine meshes are arranged in the critical pressure zone of the weld and adjacent welds, and coarse meshes are arranged in the region far from the weld to form a finite element mesh model suitable for the analysis of inherent deformation of the weld.

[0107] In one example, the data processing module 12 is used to define the spatial distribution of the welding heat source in the finite element mesh model based on the shape of the weld pool, set the welding heat source as a volumetric heat source that moves along the weld path in the thin plate fillet weld joint over time, and determine the heat input intensity of the welding heat source according to the preset welding specification parameters; apply surface heat transfer and thermal radiation as temperature boundary conditions in the finite element mesh model, constrain the rigid body displacement of the thin plate fillet weld joint as mechanical boundary conditions, and introduce material thermophysical parameters and mechanical performance parameters that change with temperature; based on transient plastic finite element calculation, solve the first transient temperature field of the finite element mesh model during the entire process of the welding heat source movement, and obtain the first equivalent plastic strain distribution and the welding deformation corresponding to the first equivalent plastic strain distribution at each time step based on the first transient temperature field; at the end of the welding cooling in the finite element mesh model, extract the longitudinal plastic strain distribution along the weld direction as the longitudinal plastic strain, and extract the displacement distribution of the thin plate fillet weld joint in the thickness direction as the first post-weld external deformation.

[0108] In one example, the data processing module 12 is used to select multiple integral sections in the finite element mesh model along the weld length direction of the thin plate fillet weld joint, and extract the weld and the corresponding longitudinal plastic strain distribution on each integral section; perform area-weighted averaging on the longitudinal plastic strain distribution on each integral section to obtain the cross-sectional average longitudinal plastic strain distributed along the weld length direction; take the cross-sectional average longitudinal plastic strain as the longitudinal inherent strain, combine it with the equivalent stiffness parameter of the corresponding section, and perform integral summation on each integral section along the weld length direction to calculate the first welding longitudinal shrinkage force characterizing the overall longitudinal shrinkage effect of the weld.

[0109] In one example, the data processing module 12 is used to extract the first post-weld outward deformation corresponding to the fillet weld joint of the thin plate from the finite element mesh model after the welding process with only the welding heat source applied and the model is cooled to room temperature; multiple monitoring sections are set along the weld length direction of the fillet weld joint and the plate width direction perpendicular to the weld, and the out-of-plane deflection curves on each monitoring section are obtained; the first post-weld outward deformation is normalized to obtain the trend mode characterizing the out-of-plane bending morphology in the fillet weld joint; when the maximum out-of-plane deflection of the first post-weld outward deformation exceeds the preset deformation critical value, and the correlation coefficient between the trend mode and any preset buckling mode is greater than the preset correlation threshold, the fillet weld joint is determined to have experienced welding buckling instability.

[0110] In one example, the data processing module 12 defines an induction heating area along the weld path on the side of the thin plate fillet weld joint away from the weld. The induction heating heat source is set as a volumetric heat source that moves with time along the weld length direction. The induction heating heat source moves at the same speed as the welding heat source and has a preset lateral spacing relative to the weld centerline and a preset vertical gap with the base plate. The heat input of the induction heating heat source is superimposed onto the finite element mesh model as a time function, and both the welding heat source and the induction heating heat source are applied simultaneously at each time step to solve for the second instant of the entire welding process. The second transient temperature field is used to calculate the second equivalent plastic strain distribution and the corresponding structural deformation at each time step under the combined action of the welding heat source and the induction heating heat source. The second equivalent plastic strain distribution represents the equivalent plastic strain distribution under the action of welding induction heating. When the fillet weld of the thin plate cools to room temperature, the longitudinal residual plastic strain distribution along the weld length direction is extracted from the second equivalent plastic strain distribution as the residual plastic strain, and the displacement distribution of the fillet weld of the thin plate in the plate thickness direction is extracted as the second out-of-plane welding deformation.

[0111] In one example, the process parameters include the lateral distance between the induction heating source and the weld, the gap between the induction heating source and the surface of the fillet weld joint, the induction heating power of the induction heating source, and the frequency of the induction heating source.

[0112] Please see Figure 12 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Figure 12 As shown, the electronic device 2 may include: at least one processor 21, at least one network interface 24, user interface 23, memory 25, and at least one communication bus 22.

[0113] The communication bus 22 is used to enable communication between these components.

[0114] The user interface 23 may include a display screen and a camera. Optionally, the user interface 23 may also include a standard wired interface and a wireless interface.

[0115] The network interface 24 may optionally include a standard wired interface or a wireless interface (such as a Wi-Fi interface).

[0116] The processor 21 may include one or more processing cores. The processor 21 connects to various parts of the server using various interfaces and lines, and performs various server functions and processes data by running or executing instructions, programs, code sets, or instruction sets stored in the memory 25, and by calling data stored in the memory 25. Optionally, the processor 21 may be implemented using at least one hardware form of Digital Signal Processing (DSP), Field-Programmable Gate Array (FPGA), or Programmable Logic Array (PLA). The processor 21 may integrate one or a combination of several of the following: Central Processing Unit (CPU), Graphics Processing Unit (GPU), and modem. The CPU primarily handles the operating system, user interface, and applications; the GPU is responsible for rendering and drawing the content required for display; and the modem handles wireless communication. It is understood that the modem may also be implemented as a separate chip without being integrated into the processor 21.

[0117] The memory 25 may include random access memory (RAM) or read-only memory. Optionally, the memory 25 may include non-transitory computer-readable storage medium. The memory 25 can be used to store instructions, programs, code, code sets, or instruction sets. The memory 25 may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function (such as touch function, sound playback function, image playback function, etc.), instructions for implementing the above-described method embodiments, etc.; the data storage area may store data involved in the above-described method embodiments, etc. Optionally, the memory 25 may also be at least one storage device located remotely from the aforementioned processor 21. Figure 12 As shown, the memory 25, which serves as a computer storage medium, may include an operating system, a network communication module, a user interface module, and an application program for controlling instability in thin plate fillet welds based on induction heating during welding.

[0118] exist Figure 12In the electronic device 2 shown, the user interface 23 is mainly used to provide an input interface for the user and to obtain the user input data; while the processor 21 can be used to call an application program stored in the memory 25 that is a method for controlling instability of thin plate fillet welds based on induction heating during welding. When executed by one or more processors, the electronic device performs one or more methods as described in the above embodiments.

[0119] A non-transitory computer-readable storage medium stores instructions that, when executed by one or more processors, cause a computer to perform one or more methods as described in the above embodiments.

[0120] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0121] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0122] In the several embodiments provided in this application, it should be understood that the disclosed apparatus can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the shown or discussed mutual couplings or direct couplings or communication connections may be through some service interfaces; indirect couplings or communication connections between apparatuses or units may be electrical or other forms.

[0123] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0124] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0125] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage device (CMD). Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a memory and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned memory includes various media capable of storing program code, such as USB flash drives, portable hard drives, magnetic disks, or optical disks.

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for controlling instability in thin plate fillet welds based on induction heating during welding, characterized in that, The method includes: Based on the dimensional parameters of the thin plate corner weld joint, a finite element mesh model corresponding to the thin plate corner weld joint is constructed; A welding heat source is set in the finite element mesh model to solve for the longitudinal plastic strain and the external deformation after the first weld in the finite element mesh model during the welding process; The longitudinal plastic strain is integrated and summed along the weld length of the thin plate fillet weld to obtain the first longitudinal shrinkage force of the weld. Based on the trend mode of the external deformation after the first weld, it is determined whether the thin plate fillet weld has experienced weld buckling instability. If the fillet weld of the thin plate experiences weld buckling instability, an induction heating source is introduced into the finite element mesh model to solve for the residual plastic strain and the second out-of-plane weld deformation of the finite element mesh model under the combined action of the welding heat source and the induction heating source. The second longitudinal shrinkage force corresponding to the residual plastic strain is also calculated. The induction heating source and the welding heat source are relatively fixed and move synchronously with the welding trajectory. The induction heating source and the welding heat source are located on opposite sides of the weld of the fillet weld of the thin plate. The second out-of-plane weld deformation represents the out-of-plane deformation after the weld is subjected to welding induction heating. The second longitudinal shrinkage force represents the longitudinal shrinkage force of the weld under welding induction heating. If the longitudinal shrinkage force of the second weld is less than the critical buckling instability condition, the process parameters of the thin plate fillet weld joint during the induction heating process are confirmed, and the thin plate fillet weld joint is subjected to induction heating treatment according to the process parameters.

2. The method for controlling instability of thin plate fillet welds based on induction heating during welding as described in claim 1, characterized in that, Based on the dimensional parameters of the thin plate fillet weld joint, a finite element mesh model corresponding to the thin plate fillet weld joint is constructed, specifically including: Geometric modeling is performed on the thin plate fillet weld joint composed of a base plate and an upright plate, wherein both the base plate and the upright plate are high-strength marine steel thin plates. Based on the bevel form of the fillet weld to be welded in the thin plate fillet weld joint and the expected weld pool shape, the weld toe, weld root and weld transition rounded corner area are defined at the junction of the base plate and the vertical plate, and the key pressure zone around the weld is determined based on the instability mechanism of thin plate fillet weld. The base plate and the vertical plate are meshed using three-dimensional Solid elements. Fine meshes are arranged in the weld and the critical pressure zone adjacent to the weld, and coarse meshes are arranged in the region away from the weld to form a finite element mesh model suitable for the analysis of inherent deformation of welding.

3. The method for controlling instability in thin plate fillet welds based on induction heating during welding as described in claim 1, characterized in that, The step of setting a welding heat source in the finite element mesh model to solve for the longitudinal plastic strain and the external deformation after the first weld in the finite element mesh model during the welding process specifically includes: In the finite element mesh model, the spatial distribution of the welding heat source is defined based on the shape of the weld pool. The welding heat source is set as a volume heat source that moves with time along the weld path in the thin plate corner weld joint. The heat input intensity of the welding heat source is determined according to the preset welding specification parameters. In the finite element mesh model, surface heat transfer and thermal radiation are applied as temperature boundary conditions, and the rigid body displacement of the thin plate fillet weld joint is constrained as a mechanical boundary condition. Material thermophysical parameters and mechanical performance parameters that vary with temperature are also introduced. Based on transient plastic finite element calculation, the first transient temperature field of the finite element mesh model is solved throughout the entire process of the welding heat source movement, and the first equivalent plastic strain distribution and the welding deformation corresponding to the first equivalent plastic strain distribution are obtained based on the first transient temperature field. At the end of the welding cooling time of the finite element mesh model, the longitudinal plastic strain distribution along the weld direction is extracted as the longitudinal plastic strain, and the displacement distribution of the thin plate fillet weld joint in the thickness direction is extracted as the first post-weld external deformation.

4. The method for controlling instability of thin plate fillet welds based on induction heating during welding as described in claim 1, characterized in that, The step of integrating and summing the longitudinal plastic strain along the weld length of the thin plate fillet weld joint to obtain the first longitudinal shrinkage force specifically includes: Multiple integral sections are selected in the finite element mesh model along the weld length direction of the thin plate fillet weld joint, and the weld and the corresponding longitudinal plastic strain distribution are extracted on each integral section; The longitudinal plastic strain distribution on each integral section is averaged by area weighting to obtain the average longitudinal plastic strain of the section distributed along the weld length. The average longitudinal plastic strain of the cross section is taken as the longitudinal inherent strain. Combined with the equivalent stiffness parameter of the corresponding cross section, the integral of each integral cross section along the weld length direction is summed to calculate the first welding longitudinal shrinkage force characterizing the overall longitudinal shrinkage effect of the weld.

5. The method for controlling instability in thin plate fillet welds based on induction heating during welding as described in claim 4, characterized in that, The step of determining whether the thin plate fillet weld joint has experienced welding buckling instability based on the trend mode of the external deformation after the first weld includes: After applying the welding heat source to the finite element mesh model and cooling it to room temperature, the first weld post-deformation corresponding to the thin plate corner weld joint is extracted from the finite element mesh model. Multiple monitoring sections are set along the weld length direction of the thin plate fillet weld and in the plate width direction perpendicular to the weld, and the out-of-plane deflection curves on each monitoring section are obtained. The outward deformation after the first weld is normalized to obtain a trend mode characterizing the outward bending morphology in the thin plate fillet weld joint. When the maximum out-of-plane deflection of the first weld exceeds the preset deformation critical value, and the correlation coefficient between the trend mode and any preset buckling mode is greater than the preset correlation threshold, it is determined that the thin plate corner weld joint has experienced welding buckling instability.

6. The method for controlling instability of thin plate fillet welds based on induction heating during welding as described in claim 2, characterized in that, The method of introducing an induction heating source into the finite element mesh model to solve for the residual plastic strain and the second out-of-plane welding deformation of the finite element mesh model under the combined action of the welding heat source and the induction heating source specifically includes: An induction heating area is defined along the weld path on the side of the thin plate corner weld joint away from the weld. The induction heating heat source is set as a volume heat source that moves with time along the length of the weld. The moving speed of the induction heating heat source is the same as that of the welding heat source, and it has a preset lateral spacing relative to the weld centerline and a preset vertical gap with the base plate. The heat input of the induction heating source is superimposed on the finite element mesh model in the form of a time function, and the welding heat source and the induction heating source are applied simultaneously at each time step to solve the second transient temperature field of the entire welding process. Based on the second transient temperature field, the second equivalent plastic strain distribution and the structural deformation corresponding to the second equivalent plastic strain distribution are calculated at each time step under the combined action of the welding heat source and the induction heating heat source. The second equivalent plastic strain distribution represents the equivalent plastic strain distribution under the action of welding induction heating. When the thin plate fillet weld joint cools to room temperature, the longitudinal residual plastic strain distribution along the weld length direction is extracted from the second equivalent plastic strain distribution as the residual plastic strain, and the displacement distribution of the thin plate fillet weld joint in the plate thickness direction is extracted as the second out-of-plane welding deformation.

7. The method for controlling instability of thin plate fillet welds based on induction heating during welding as described in claim 1, characterized in that, The process parameters include the lateral distance between the induction heating source and the weld, the gap between the induction heating source and the surface of the thin plate fillet weld, the induction heating power of the induction heating source, and the frequency of the induction heating source.

8. A control system for instability in thin plate fillet welds based on induction heating during welding, characterized in that, The thin plate fillet weld instability control includes a model building module, a data processing module, and a dynamic adjustment module, wherein... The model building module is used to construct the finite element mesh model corresponding to the thin plate corner weld joint based on the size parameters of the thin plate corner weld joint; The data processing module is used to set a welding heat source in the finite element mesh model to solve for the longitudinal plastic strain and the first post-weld external deformation within the finite element mesh model during welding. The longitudinal plastic strain is integrated and summed along the weld length of the thin plate fillet weld to obtain the first longitudinal shrinkage force. Based on the trend mode of the first post-weld external deformation, it is determined whether the thin plate fillet weld has experienced welding buckling instability. If welding buckling instability occurs, an induction heating heat source is introduced into the finite element mesh model to solve for the longitudinal shrinkage force during welding. The residual plastic strain and second out-of-plane welding deformation of the finite element mesh model under the combined action of the heat source and the induction heating heat source are calculated, and the second longitudinal shrinkage force corresponding to the residual plastic strain is calculated. The induction heating heat source and the welding heat source are relatively fixed and move synchronously with the welding trajectory. The induction heating heat source and the welding heat source are located on opposite sides of the weld of the thin plate fillet weld. The second out-of-plane welding deformation represents the out-of-plane deformation after the weld under the action of welding induction heating, and the second longitudinal shrinkage force represents the longitudinal shrinkage force of the weld under the action of welding induction heating. The dynamic adjustment module is used to confirm the process parameters of the thin plate fillet weld joint during the induction heating process if the second welding longitudinal shrinkage force is less than the critical buckling instability condition, and to perform induction heating treatment on the thin plate fillet weld joint according to the process parameters.

9. An electronic device, characterized in that, The device includes a processor, a memory, a user interface, and a network interface. The memory is used to store instructions, the user interface and the network interface are used to communicate with other devices, and the processor is used to execute the instructions stored in the memory to cause the electronic device to perform the method as described in any one of claims 1-7.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1-7.

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