Welding deformation simulation method based on thermal strain cycle compensation
Through the welding deformation simulation method based on thermal strain cycle compensation, the problem of imbalance between accuracy and efficiency in welding numerical simulation is solved, and efficient and high-precision welding deformation simulation is achieved to meet the needs of modern manufacturing.
Patent Information
- Application Number
- CN202511012217.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-22
- Publication Date
- 2025-10-17
AI Technical Summary
Existing welding numerical simulation methods have an imbalance between accuracy and efficiency in engineering applications. The thermoelastic method has high calculation cost and takes a long time, while the inherent strain method lacks accuracy and is difficult to adapt to the high efficiency and high precision requirements of the modern manufacturing industry.
A welding deformation simulation method based on thermal strain cycle compensation is adopted. By introducing a thermal strain compensation algorithm, the structural stiffness difference between the overall heating of the weld and the moving heat source is compensated, the welding deformation simulation accuracy is improved and the calculation cycle is shortened.
Under the same conditions, the calculation accuracy is improved to less than 10%, and the calculation cycle is shortened by about 70 times. In particular, the efficiency of large structures with long welds is increased by 103 times, meeting the high efficiency and high precision requirements of modern manufacturing.
Smart Images
Figure CN120805601A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of welding stress deformation simulation, and particularly relates to a welding deformation simulation method based on thermal strain cycle compensation. BACKGROUND
[0002] It is an urgent means for large-scale engineering structures to introduce welding manufacturing numerical simulation in the design, manufacturing and service links to predict deformation and internal stress. However, the current welding numerical simulation analysis algorithm (such as the thermal-elastic-plastic algorithm of thermal-mechanical coupling) has the problems of high calculation cost and long cycle, and the welding simulation of large structures often takes months or even years, which is difficult to match the product design and manufacturing cycle. If a simplified calculation algorithm (such as the inherent strain algorithm) is applied, the stress simulation accuracy will be seriously reduced, and the deformation simulation will be difficult to adapt to the dynamic changes of the work constraints and structural stiffness in the actual welding manufacturing process, and the optimization of the manufacturing scheme such as the welding sequence is of limited help. Therefore, it is urgent to build a new type of welding numerical simulation algorithm with high efficiency and high precision to meet the needs of modern manufacturing industry and improve the intelligentization and precision level of production and manufacturing.
[0003] The contradiction existing in the engineering application of the existing welding numerical simulation method is the imbalance between precision and efficiency. Although the thermal-elastic-plastic method can capture the plastic strain accumulation process, the calculation cost increases by n³, which cannot adapt to the production and manufacturing cycle; the efficiency of the inherent strain method is improved, but the material nonlinear characteristics are lost, and the response to the structural stiffness, boundary constraint and welding sequence and other characteristics is insufficient. SUMMARY
[0004] In view of the above deficiencies in the prior art, the welding deformation simulation method based on thermal strain cycle compensation provided by the application solves the problem of imbalance between precision and efficiency existing in the engineering application of the existing welding numerical simulation method.
[0005] In order to achieve the above-mentioned application purposes, the technical scheme adopted by the application is as follows: a welding deformation simulation method based on thermal strain cycle compensation, comprising the following steps: S1, heating the whole weld; S2, based on the thermal strain cycle algorithm of introducing thermal strain compensation, compensating the plastic deformation of the material in the near-weld zone in the transient moving heat source heating stage, and completing the welding deformation simulation of the heat source.
[0006] Further, in S2, the thermal strain after thermal strain compensation is The expression of the thermal strain after thermal strain compensation is specifically as follows:
[0007] In the formula, is the thermal strain, is the thermal strain compensation, and the expression thereof is specifically as follows:
[0008] In the formula, k s and k m respectively as the structural stiffness coefficient and the material stiffness coefficient, as the plastic deformation, as the thermal strain increment of the moving heat source, as the temperature change amount.
[0009] Further: in S2, the simulated welding deformation The expression is specifically:
[0010] In the formula, as the elastic deformation.
[0011] The beneficial effects of the present application are: (1) The present application provides a welding deformation simulation method based on thermal strain cycle compensation. In order to compensate for the visible strain difference caused by the overall heating of the weld, the present application constructs a thermal strain cycle algorithm, introduces the structural stiffness difference of the thermal strain compensation material, so that the simulated welding deformation can be equivalent to obtain the calculation accuracy of the moving heat source, and the welding deformation simulation accuracy is improved.
[0012] (2) The present application is verified by experiment. Under the same temperature thermal cycle conditions and boundary conditions, the application of thermal strain compensation makes the calculation error of welding stress and deformation of the overall heating of the weld and the gradual filling heating of the moving heat source less than 10%. And the calculation period is shortened by about 70 times. When the weld is longer, such as a high-speed rail aluminum alloy car body (about 25m in length), the calculation efficiency will be improved by 10 3 The above. BRIEF DESCRIPTION OF DRAWINGS
[0013] Figure 1 It is a welding deformation simulation method flow chart based on thermal strain cycle compensation of the present application.
[0014] Figure 2 It is a schematic diagram of thermal strain distribution under the quasi-steady temperature field of the moving heat source.
[0015] Figure 3 It is a schematic diagram of thermal strain distribution under the temperature field of the overall heating heat source.
[0016] Figure 4 It is a schematic diagram of strain (total strain, elastic strain, plastic strain, thermal strain) change with time under the quasi-steady temperature field of the moving heat source.
[0017] Figure 5Strain (total strain, elastic strain, plastic strain, thermal strain) variation with time under temperature field of whole heating heat source.
[0018] Figure 6 Strain (total strain, elastic strain, plastic strain, thermal strain) variation with time of thermal cycle algorithm with thermal strain compensation. DETAILED DESCRIPTION
[0019] The specific embodiments of the present application are described below to enable those skilled in the art to understand the present application, but it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the present application defined and determined by the appended claims, and all the inventions using the concept of the present application are within the scope of protection.
[0020] As shown in Figure 1 , in one embodiment of the present application, a welding deformation simulation method based on thermal strain cycle compensation includes the following steps: S1, heating the whole weld bead; S2, compensating the plastic deformation of the material in the near-weld zone in the transient moving heat source warming-up stage based on the thermal strain cycle algorithm with thermal strain compensation, and completing the welding deformation simulation of the heat source.
[0021] In this embodiment, in order to improve the welding deformation simulation accuracy of the instantaneous heat source, a thermal cycle strain algorithm is proposed to compensate for the difference in structural restraint stiffness of the equivalent whole heating and moving heat source through thermal strain compensation. The principle of the thermal cycle strain algorithm is as follows: Welding deformation of the welding structure ε t composed of thermal strain ε T , elastic deformation ε e and plastic deformation ε p :
[0022] Among them, the thermal strain ε T is free deformation, which depends on the linear expansion coefficient of the material and the temperature change. In the case of quasi-steady temperature field, the front end of the weld is the warming-up area and is in the expansion thermal strain state ( ε T >0); the rear end of the weld is the cooling area and is in the contraction thermal strain state ( ε T <0), as Figures 2-3As shown. Due to the small temperature range, the material mechanical properties soften, the thermal strain of this area is constrained by the rigidity of the surrounding cooler metal material, and it is also constrained by the rigidity of the rear end cooling area, so the visible deformation generated in the heating stage is small, that is, as shown by the black curve of Figure 4 The visible deformation in the heating stage is reduced ε t , which means that there is more plastic deformation ε p to compensate, so the quasi-steady temperature field of the moving heat source will generate more internal deformation.
[0023] When the whole weld is heated, the thermal constraint is small, the expansion thermal strain of the weld area leads to obvious deformation of the structure contour, and the ε t is large, and the internal deformation is small, as shown by the black curve of Figure 5 The visible strain evolution.
[0024] In order to compensate for the visible strain difference caused by the whole weld heating, the present application constructs a thermal strain cycle algorithm, tries to introduce a nonlinear free deformation increment, compensates for the difference in structural stiffness of the material, so that the simulated welding deformation can be equivalent to obtain the calculation precision of the moving heat source, as shown in Figure 5 .
[0025] In this embodiment, the simulated welding deformation The expression of the simulated welding deformation is as follows:
[0026] In the formula, is the elastic deformation.
[0027] As shown in Figure 6 , for the plastic deformation zone near the weld seam area, due to the whole weld heating of the instantaneous heat source, the structural constraint and material constraint of the near weld seam area are reduced, more macro deformation occurs in the heating stage, and the internal plastic deformation is small. In order to compensate for the plastic deformation of the material in the near weld seam area in the heating stage of the transient moving heat source, the thermal strain compensation is introduced, and the thermal strain after thermal strain compensation is obtained.
[0028] The expression of the thermal strain after thermal strain compensation is as follows:
[0029] In the formula, is the thermal strain, is the thermal strain compensation, wherein the thermal strain compensation is applied to compensate the increment of the thermal strain (free deformation) in the heating stage, and the expression thereof is as follows:
[0030] wherein, k s and k m are the structural stiffness coefficient and the material stiffness coefficient, respectively, is the plastic deformation, is the thermal strain increment of the moving heat source, is the temperature change. Thermal strain compensation ε TSC In the cooling stage, it is 0, and in the heating stage, it compensates for the plastic deformation of the moving heat source near the weld seam area, so that the overall heating of the weld bead achieves the same effect as the instantaneous heat source calculation of the welding deformation (visible deformation / total deformation).
[0031] In order to verify the effect of the method of the present application, the following experimental case 1 is also provided in this embodiment: Model description: finite model of aluminum alloy profile structure, comparison of welding moving heat source and weld seam overall heating welding deformation.
[0032] (1) Shell-solid coupling modeling: the weld seam area grid size is 2 mm, and the shell area grid size is 4 mm. The number of solid grids is 80000, and the number of shell grids is 55000.
[0033] (2) Grid type: Shell (temperature field: DS4; stress field: S4R); Solid (temperature field: DC3D8; stress field: C3D8R).
[0034] (3) Welding heat source: double-ellipsoid heat source of arc welding, instantaneous heat source (comparison: moving heat source heating, weld seam overall heating).
[0035] Welding speed: 20 mm / s.
[0036] Welding current: 220 A, welding voltage: 25 V.
[0037] Welding sequence: from one end of the weld seam to the other end.
[0038] (4) Welding stress calculation: thermal elastoplastic finite element (comparison: moving heat source sequential coupling, thermal strain cycle method).
[0039] (5) Profile size: width 1260 mm, profile weld seam length is 500 mm.
[0040] Calculation efficiency comparison:
[0041] Conclusions: The error of the welding stress and deformation is less than 10% for the whole bead heating and the step-by-step filling heating by the moving heat source, under the same thermal cycle conditions and boundary conditions.
[0042] Experiment Case 2: Model Description: The finite model of the aluminum alloy floor profile structure of the high-speed train body, comparing the welding deformation of the moving heat source and the whole bead heating.
[0043] (1) Shell-solid coupling modeling: The mesh size of the weld area is 2 mm, and the mesh size of the shell area is 4-20 mm. The number of solid grids is 1,500,000, and the number of shell grids is 1,000,000.
[0044] (2) Mesh type: Shell (temperature field: DS4; stress field: S4R); Solid (temperature field: DC3D8; stress field: C3D8R).
[0045] (3) Welding heat source: double-elliptical heat source of arc welding, instantaneous heat source (comparison: moving heat source heating, whole bead heating).
[0046] Welding speed: 20 mm / s. Welding current: 220 A, welding voltage: 25 V.
[0047] Welding sequence: from one end of the weld to the other end.
[0048] (4) Welding stress calculation: thermal elastoplastic finite element (comparison: moving heat source sequential coupling, thermal strain cycle method).
[0049] (5) Profile size: about 3000 mm wide, profile weld length is 24 m.
[0050] The calculation efficiency comparison is shown in Table 1.
[0051] Table 1 Calculation efficiency comparison
[0052] Conclusions: The error of the welding stress and deformation is less than 10% for the whole bead heating and the step-by-step filling heating by the moving heat source, under the same thermal cycle conditions and boundary conditions.
[0053] For short weld structure, the calculation efficiency is improved by about dozens of times by using the thermal cycle algorithm of thermal strain compensation. For long weld large structure, the calculation efficiency is improved by more than 1000 times.
[0054] In the description of the application, it needs to be understood that the terms "center", "thickness", "upper", "lower", "horizontal", "top", "bottom", "inner", "outer", "radial" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implying the number of technical features indicated. Therefore, the features defined by "first", "second", "third" can explicitly or implicitly include one or more of the features.
Claims
1. A welding deformation simulation method based on thermal strain cycle compensation, characterized in that: The following steps are involved: S1. Heat the entire weld bead; S2. Based on the thermal strain cycle algorithm that introduces thermal strain compensation, the plastic deformation of the material near the weld area during the transient moving heat source heating stage is compensated to complete the welding deformation simulation of the heat source.
2. The welding deformation simulation method based on thermal strain cycle compensation according to claim 1 is characterized in that: In S2, the thermal strain after thermal strain compensation The specific expression is: Where, is the thermal strain, is the thermal strain compensation, and its specific expression is: Where, k s and k m are the structural stiffness coefficient and the material stiffness coefficient, is plastic deformation, is the thermal strain increment of the moving heat source, is the temperature change.
3. The welding deformation simulation method based on thermal strain cycle compensation according to claim 1 is characterized in that: In S2, the simulated welding deformation The specific expression is: Where, It is elastic deformation.