Prediction and suppression method of welding deformation of large structural parts based on multi-layer inherent strain

Abstract

The present invention relates to the technical field of structural welding, and in particular to a method for predicting and suppressing welding deformation of large structural parts based on multi-layer inherent strain, comprising the following steps: Step S100, extracting all types of typical joints in large and complex structural parts, performing welding experiments on the typical joints without constraints, setting characteristic points for welding deformation measurement on the typical joints, measuring the cross-sectional area of ​​each layer of the molten pool of the typical joints, and measuring the deformation amount and the total deformation amount generated by the characteristic points during each layer of welding. By calibrating and simulating the inherent strain existing in the fusion zone of the welding joint, the deformation trend and prediction accuracy of the welding joint are ensured, and the subsequent trend prediction of the welding deformation of large structural parts is reasonable, and the deformation amount prediction is reliable. In addition, for the constrained structure, the constraint phenomenon attached to the fixture can be better reflected, and the deformation conforms to the mechanical process.

Description

Technical Field

[0001] The invention relates to the technical field of structural component welding, and in particular to a method for predicting and suppressing welding deformation of large structural components based on multi-layer inherent strain. Background Art

[0002] Welding technology is a material connection process, which is widely used in the field of mechanical parts forming and manufacturing. At present, the multi-weld welding deformation coupling phenomenon in the welding forming process of large structural parts is obvious, the deformation trend is complex, and deformation prediction and suppression are challenging. In the welding process of thick plates, there are multiple layers of welds, which need to be welded layer by layer from base, filling to cover. For double-sided grooves, the filling sequence of the front and back sides needs to be formulated. Therefore, it is necessary to develop a finite element model that simulates the influence of each welding layer on welding deformation to guide the implementation of the welding process and the design of the welding fixture.

[0003] In addition, multiple welds of large structural parts usually adopt multi-station simultaneous welding process to shorten the production cycle, which also makes it urgent for welding simulation to match the actual process. Since welding deformation usually exceeds the permitted range in an unconstrained state, it is necessary to design corresponding anti-deformation tooling according to the deformation trend of the weldment, and it is also necessary to develop corresponding deformation suppression models to evaluate the suppression effect, so as to adjust and optimize the anti-deformation tooling.

[0004] In view of this, it is necessary to improve the existing methods for predicting and suppressing welding deformation of large structural parts to solve the above problems. Summary of the invention

[0005] The present invention aims at the deficiencies in the prior art and provides the following technical solutions:

[0006] The method for predicting and suppressing welding deformation of large structural parts based on multi-layer inherent strain includes the following steps:

[0007] Step S100, extracting all types of typical joints in large complex structural parts, performing welding experiments on the typical joints under unconstrained conditions, setting characteristic points for welding deformation measurement on the typical joints, measuring the cross-sectional area of ​​each layer of the molten pool of the typical joints, and measuring the deformation amount generated by the characteristic points during welding of each layer and the total deformation amount;

[0008] Step S200, based on the typical joints and welding experiments, creating a thermoelastic-plastic welding analysis model of all the typical joints, extracting the deformation results of the thermoelastic-plastic welding analysis model, comparing the results with the deformation amount of the characteristic points generated during welding of each layer and the total deformation amount, correcting the thermoelastic-plastic welding analysis model according to the comparison results, and extracting the residual transverse plastic strain and longitudinal plastic strain of each layer from the corrected results;

[0009] Step S300, based on the typical joints and welding experiments, creating an inherent strain welding analysis model of all the typical joints, determining the inherent strain application area of ​​each layer based on the cross-sectional area of ​​the molten pool of each layer, wherein the inherent strain application area of ​​each layer is applied with transverse inherent strain and longitudinal inherent strain, extracting the deformation result of the inherent strain welding analysis model, and comparing the result with the deformation amount generated by the characteristic point during welding of each layer and the total deformation amount, correcting the values ​​of the transverse inherent strain and the longitudinal inherent strain according to the error of the comparison result until the error of the comparison result is within the allowable range, and determining the final values ​​of the transverse inherent strain and the longitudinal inherent strain of all layers;

[0010] Step S400, establishing a large-scale structural member inherent strain welding deformation prediction model, assigning the final values ​​of the transverse inherent strain and the longitudinal inherent strain of the different typical joints to the large-scale structural member inherent strain welding deformation prediction model, analyzing the trend and mechanism of the large-scale structural member welding deformation without constraints according to the results of the large-scale structural member inherent strain welding deformation prediction model, arranging the welding sequence according to the deformation increment, establishing the large-scale structural member inherent strain welding deformation suppression model, designing the large-scale structural member welding deformation suppression special tooling, establishing the large-scale structural member inherent strain welding deformation suppression model including the special tooling, and optimizing the constraint conditions according to the suppression results until the deformation value is within the allowable range.

[0011] As an improvement of the above technical solution, the thermoelastic-plastic welding analysis model, the inherent strain welding analysis model, the large structural component inherent strain welding deformation prediction model and the large structural component inherent strain welding deformation suppression model at least include the required material parameters, boundary conditions, interactions and mesh parameters.

[0012] As an improvement of the above technical solution, the cross-sectional area of ​​each layer of the inherent strain application region is the same as the cross-sectional area of ​​each layer of the molten pool.

[0013] As an improvement of the above technical solution, the initial value of the transverse inherent strain of the inherent strain welding analysis model is the same as the residual transverse plastic strain extracted from the thermoelastic-plastic welding analysis model, and the initial value of the longitudinal inherent strain of the inherent strain welding analysis model is the same as the residual longitudinal plastic strain extracted from the thermoelastic-plastic welding analysis model.

[0014] As an improvement of the above technical solution, the method for applying the transverse inherent strain and the longitudinal inherent strain is to assign an anisotropic thermal expansion coefficient to the welding analysis model, the application direction of the transverse inherent strain is perpendicular to the weld direction, the application direction of the longitudinal inherent strain is along the weld direction, the anisotropic thermal expansion coefficient is set to 0 in other directions, the initial temperature of the inherent strain welding analysis model is set to 0°C, and the inherent strain application area of ​​each layer is assigned an activation temperature, and the activation temperature is -1°C.

[0015] As an improvement of the above technical solution, the inherent strain application area of ​​each layer is controlled by a birth and death unit, and the activation temperature needs to be activated according to the welding sequence of the welding experiment.

[0016] As an improvement of the above technical solution, the inherent strain application area, the values ​​of the transverse inherent strain and the longitudinal inherent strain of all layers, and the activation temperature of the inherent strain suppression model of large structural parts and the inherent strain prediction model of large structural parts are the same.

[0017] As an improvement of the above technical solution, a plurality of inherent strain welding analysis models are established, and each typical joint corresponds to at least one inherent strain welding analysis model.

[0018] As an improvement of the above technical solution, at least one characteristic point is set on each of the typical joints.

[0019] Beneficial effects of the present invention:

[0020] 1. By calibrating and simulating the inherent strain in the fusion zone of the welded joint, the deformation trend and prediction accuracy of the welded joint are ensured, and the subsequent prediction of the welding deformation trend of large structural parts is reasonable and the deformation prediction is reliable. In addition, for the constrained structure, the constraint phenomenon attached to the fixture can be better reflected, and the deformation trend is consistent with the mechanical process, which can guide the formulation and implementation of the large structural parts welding deformation suppression plan.

[0021] 2. It can more accurately analyze the influence of welding on deformation with the welding layer as the smallest unit, which is more helpful for analyzing the evolution law of welding deformation and the research on deformation mechanism. It can simulate complex behaviors such as simultaneous or alternating welding of multiple joints at multiple stations, and accurately track the welding process in actual production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a flow chart of a method for predicting and suppressing welding deformation of large structural parts based on multi-layer inherent strain of the present invention;

[0023] Figure 2 It is a schematic diagram of the typical joint form and inherent strain application area of ​​multi-pass welded thick plates;

[0024] Figure 3 is the residual plastic strain extracted by the thermoelastic-plastic method of the butt joint in one embodiment;

[0025] Figure 4 The welding deformation caused by layer-by-layer welding of a T-joint without restraint in one embodiment;

[0026] Figure 5 The welding deformation generated by layer-by-layer welding of a T-joint under constraints in one embodiment;

[0027] Figure 6 A schematic diagram of the structure and joints of a large structural member in one embodiment;

[0028] Figure 7 The welding deformation of a large structural part in one embodiment during welding process without restraint;

[0029] Figure 8 A deformation suppression scheme for a large structural member in one embodiment;

[0030] Fig. 9 The welding deformation of a large structural part in one embodiment under constraints during each welding process;

[0031] Fig.10 The welding deformation of a large structural part during the simultaneous welding process of multiple welds under constraints in one embodiment.

[0032] Figure numerals: 1. Typical joint; 2. Intrinsic strain application area; 3. Characteristic point; 4. Transverse rib plate; 5. Outer shell; 6. Longitudinal rib plate; 7. Inner shell; 8. Reinforcement rib; 9. Welding tooling; 10. Clamping mechanism; 11. Anti-deformation back plate. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] Large structural parts usually have multiple welds, and the problem of welding deformation coupling under complex welding sequences is prominent. In an unconstrained state, welding deformation usually exceeds the permitted range, which requires the development of accurate and efficient numerical simulation methods to predict welding deformation and the development of corresponding deformation suppression models to evaluate the suppression effect, so as to adjust and optimize the anti-deformation tooling. Therefore, it is necessary to improve the existing methods for predicting and suppressing welding deformation of large structural parts.

[0035] To solve the above problems, the present invention provides a technical solution for predicting and suppressing welding deformation of large structural parts based on multi-layer inherent strain:

[0036] See attached Figure 1 As shown in the figure, a method for predicting and suppressing welding deformation of large structural parts based on multi-layer inherent strain is used to accurately track and simulate the complex welding sequence of multiple welds of large structural parts in the actual welding process, and formulate reasonable deformation suppression tooling and evaluate the suppression effect according to the deformation prediction results, so that the final welding deformation is within the allowable range, including the following steps:

[0037] Step S100, extract all types of typical joints 1 in large and complex structural parts, perform welding experiments on typical joints 1 under unconstrained conditions, set characteristic points 3 for welding deformation measurement on typical joints 1, measure the cross-sectional area of ​​each layer of the molten pool of typical joints 1, measure the deformation generated by characteristic points 3 during welding of each layer and the total deformation.

[0038] See attached Figure 2 As shown, in one embodiment, the extracted typical joints 1 include a straight line and a T-shape, and the characteristic points 3 are set on the surface of the welded joint as needed, and according to the welding test, the deformation of the characteristic points 3 with the number of welding layers is measured.

[0039] Step S200, based on typical joints 1 and welding experiments, create a thermoelastic-plastic welding analysis model for all typical joints 1, extract the deformation results of the thermoelastic-plastic welding analysis model, compare the results with the deformation generated by the characteristic point 3 during each layer of welding and the total deformation, correct the thermoelastic-plastic welding analysis model according to the comparison results, and extract the residual transverse plastic strain and longitudinal plastic strain of each layer from the corrected results.

[0040] See attached Figure 3 As shown, in one embodiment, by extracting the residual transverse plastic strain and the longitudinal plastic strain, it is found that the plastic strain mainly exists near the weld, and the value of the transverse plastic strain is much larger than the longitudinal plastic strain. Ignoring the end effect, along the welding line direction, the plastic strain is approximately a constant value.

[0041] Step S300, based on the typical joint 1 and the welding experiment, the inherent strain welding analysis model of all typical joints 1 is created, based on the cross-sectional area of ​​each layer of the molten pool, the inherent strain application area 2 of each layer is determined, and the transverse inherent strain and the longitudinal inherent strain are applied to the inherent strain application area 2 of each layer. The deformation result of the inherent strain welding analysis model is extracted, and the result is compared with the deformation amount generated by the characteristic point 3 during each layer of welding and the total deformation amount. The values ​​of the transverse inherent strain and the longitudinal inherent strain are corrected according to the error of the comparison result until the error of the comparison result is within the allowable range, and the final values ​​of the transverse inherent strain and the longitudinal inherent strain of all layers are determined.

[0042] Generally, the total structural strain includes elastic strain, plastic strain, phase change strain, thermal strain and creep strain, among which plastic strain accounts for the largest proportion. Therefore, for the convenience of calculation, in this scheme, the residual plastic strain is equated with the inherent strain, and the cross-section of each layer of inherent strain application area 2 is the same as the cross-sectional area of ​​each layer of molten pool.

[0043] The method for applying the transverse inherent strain and the longitudinal inherent strain is to assign an anisotropic thermal expansion coefficient to the welding analysis model, the application direction of the transverse inherent strain is perpendicular to the weld direction, the application direction of the longitudinal inherent strain is along the weld direction, the anisotropic thermal expansion coefficient is set to 0 in other directions, the initial temperature of the inherent strain welding analysis model is set to 0°C, and each layer of the inherent strain application area 2 is assigned an activation temperature, and the activation temperature is -1°C.

[0044] The inherent strain application area 2 of each layer is controlled by a birth and death unit, and the activation temperature needs to be activated according to the welding sequence of the welding experiment.

[0045] The initial values ​​of the transverse and longitudinal inherent strains of the inherent strain welding analysis model are the same as the residual transverse and longitudinal plastic strains extracted from the thermoelastic-plastic welding analysis model. By comparing with the deformation of the characteristic point 3, the values ​​of the calibrated transverse and longitudinal inherent strains are finally obtained.

[0046] Multiple inherent strain welding analysis models are established, each typical joint 1 corresponds to an inherent strain welding analysis model, and according to actual needs, one or more characteristic points 3 are set on each typical joint 1 to more accurately compare deformation data.

[0047] See attached Figure 4 As shown, in one embodiment, the prediction results of the inherent strain welding analysis model under unconstrained T-joint are given, and the welding deformation generated after layer-by-layer shrinkage is consistent with the experiment.

[0048] See attached Figure 5 As shown, in one embodiment, the deformation suppression result under the constraint of T-shaped joint is given. Under the effect of reinforcing ribs, the deformation caused by welding of each layer is significantly reduced.

[0049] Step S400, establish a large-scale structural part inherent strain welding deformation prediction model, assign the final values ​​of the transverse inherent strain and the longitudinal inherent strain of different typical joints 1 to the large-scale structural part inherent strain welding deformation prediction model, analyze the trend and mechanism of large-scale structural part welding deformation without constraints according to the results of the large-scale structural part inherent strain welding deformation prediction model, arrange the welding sequence according to the deformation increment, establish a large-scale structural part inherent strain welding deformation suppression model, design a special tooling for large-scale structural part welding deformation suppression, establish a large-scale structural part inherent strain welding deformation suppression model including the special tooling, and optimize the constraint conditions according to the suppression results until the deformation value is within the allowable range.

[0050] The inherent strain application area, the values ​​of the transverse inherent strain and the longitudinal inherent strain of all layers, and the activation temperature of the inherent strain welding deformation suppression model and the inherent strain welding deformation prediction model of the large structural component are the same.

[0051] In the above process, the inherent strain application area 2 and the inherent strain value of each layer of different typical joints 1 are determined. The thermoelastic-plastic welding analysis model, the inherent strain welding analysis model, the large structural component inherent strain welding deformation prediction model and the large structural component inherent strain welding deformation suppression model at least include the required material parameters, boundary conditions, interactions and mesh parameters.

[0052] See attached Figure 6 As shown, in one embodiment, a structural schematic diagram and a knot form of a large structural member are provided.

[0053] In this embodiment, the size of the large structural member is 1200mm×1300mm×170mm, and the structure includes an inner shell 7 (40mm thickness), an outer shell 5 (26mm thickness), a transverse rib plate 4 (26mm thickness) and a longitudinal rib plate 6 (26mm thickness), and is formed by welding.

[0054] Among them, the two inner shells are welded with U-shaped groove butt joints, the longitudinal and transverse ribs are welded to the inner shell with double V-groove T-joints, and are connected to each other with double V-groove T-joints. The last four ribs are welded to the outer shell with single-sided J-groove, with a total of 13 welds.

[0055] The inherent strain application area 2 and the final value of the inherent strain obtained from the above-mentioned different typical joints 1 are assigned to the large structural parts.

[0056] See attached Figure 7 As shown, in one embodiment, the welding deformation of a large structural part welded one by one without constraints is given. According to the welding sequence, the welding of each joint has an impact on the deformation, and finally the overall welding deformation is obtained. The suppression scheme is designed by analyzing its deformation trend.

[0057] See attached Figure 8 As shown, in one embodiment, a deformation suppression scheme for large structural parts is provided, wherein a clamping mechanism 10 is used to suppress deformation in the first step of welding the inner shell, a reinforcing rib 8 is used to suppress deformation in steps 2 to 5, and an anti-deformation back plate 11 is used to suppress deformation in step 6. The clamping mechanism 10 is fixed on a welding tool 9.

[0058] See attached Fig. 9 As shown, in one embodiment, the welding deformation of a large structural part under constraint is given one by one in the welding process, and it is found that the welding deformation is significantly reduced. It should be noted that the first step of welding here simulates the clamping constraint by applying a load to the constraint point selected on the surface, so no entity fixture model is introduced.

[0059] The influence of different welding sequences on the deformation of the above-mentioned large structural parts can be obtained by setting the activation sequence of different joints, so as to find the welding method with the smallest welding deformation. Therefore, the implementation process is similar, so it will not be repeated.

[0060] In addition, the welding method of the above-mentioned large structural parts is that the welding of the next part will not be carried out until one part is fully welded.

[0061] Since the corresponding transverse and longitudinal inherent strains are equivalent to the welding layer of each joint form, when multiple joints of large structural parts are simultaneously subjected to base, filling or cover welding, it is only necessary to set multiple welding layers and activation temperatures to take effect at the same time.

[0062] See attached Fig.10 As shown in FIG. 1 , in one embodiment, the welding process of one corner is partially magnified. Since the four corners have the same welding method, the total welding deformation is finally obtained. It can be found that due to the welding behavior, the frame structure has a strong rigidity to resist the welding deformation, making the total deformation ratio Fig. 9 The deformation of the embodiment shown is small, so the simulation results are reasonable.

[0063] In summary, by calibrating and simulating the inherent strain in the fusion zone of the welded joint, the deformation trend and prediction accuracy of the welded joint are ensured, and the subsequent prediction of the welding deformation trend of large structural parts is reasonable and the deformation prediction is reliable. In addition, for the constrained structure, the constraint phenomenon attached to the fixture can be better reflected, and the deformation conforms to the mechanical process.

[0064] The advantage of the present invention is that it can more accurately analyze the influence of welding on deformation with the welding layer as the smallest unit, which is more helpful for analyzing the evolution law of welding deformation and the research on deformation mechanism. It can meet the welding deformation prediction of large structural parts under complex welding sequences, and can also help and guide the formulation and implementation of welding deformation prediction and suppression schemes for large structural parts in actual engineering applications.

[0065] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them.

Claims

1. A method for predicting and suppressing welding deformation of large structural parts based on multi-layer inherent strain, characterized in that: The following steps are involved: Step S100, extracting all types of typical joints in large complex structural parts, performing welding experiments on the typical joints under unconstrained conditions, setting characteristic points for welding deformation measurement on the typical joints, measuring the cross-sectional area of ​​each layer of the molten pool of the typical joints, and measuring the deformation amount generated by the characteristic points during welding of each layer and the total deformation amount; Step S200, based on the typical joints and welding experiments, creating a thermoelastic-plastic welding analysis model of all the typical joints, extracting the deformation results of the thermoelastic-plastic welding analysis model, comparing the results with the deformation amount of the characteristic points generated during welding of each layer and the total deformation amount, correcting the thermoelastic-plastic welding analysis model according to the comparison results, and extracting the residual transverse plastic strain and longitudinal plastic strain of each layer from the corrected results; Step S300, based on the typical joints and welding experiments, creating an inherent strain welding analysis model of all the typical joints, determining the inherent strain application area of ​​each layer based on the cross-sectional area of ​​the molten pool of each layer, wherein the inherent strain application area of ​​each layer is applied with transverse inherent strain and longitudinal inherent strain, extracting the deformation result of the inherent strain welding analysis model, and comparing the result with the deformation amount generated by the characteristic point during welding of each layer and the total deformation amount, correcting the values ​​of the transverse inherent strain and the longitudinal inherent strain according to the error of the comparison result until the error of the comparison result is within the allowable range, and determining the final values ​​of the transverse inherent strain and the longitudinal inherent strain of all layers; Step S400, establishing a large-scale structural member inherent strain welding deformation prediction model, assigning the final values ​​of the transverse inherent strain and the longitudinal inherent strain of the different typical joints to the large-scale structural member inherent strain welding deformation prediction model, analyzing the trend and mechanism of the large-scale structural member welding deformation without constraints according to the results of the large-scale structural member inherent strain welding deformation prediction model, arranging the welding sequence according to the deformation increment, establishing the large-scale structural member inherent strain welding deformation suppression model, designing the large-scale structural member welding deformation suppression special tooling, establishing the large-scale structural member inherent strain welding deformation suppression model including the special tooling, and optimizing the constraint conditions according to the suppression results until the deformation value is within the allowable range.

2. The method for predicting and suppressing welding deformation of large structural parts based on multi-layer inherent strain according to claim 1 is characterized in that: The thermoelastic-plastic welding analysis model, the inherent strain welding analysis model, the large structural component inherent strain welding deformation prediction model and the large structural component inherent strain welding deformation suppression model at least include the required material parameters, boundary conditions, interactions and mesh parameters.

3. The method for predicting and suppressing welding deformation of large structural parts based on multi-layer inherent strain according to claim 1 is characterized in that: The cross-sectional area of ​​each layer of the inherent strain application region is the same as the cross-sectional area of ​​each layer of the molten pool.

4. The method for predicting and suppressing welding deformation of large structural parts based on multi-layer inherent strain according to claim 1 is characterized in that: The initial value of the transverse inherent strain of the inherent strain welding analysis model is the same as the residual transverse plastic strain extracted from the thermoelastic-plastic welding analysis model, and the initial value of the longitudinal inherent strain of the inherent strain welding analysis model is the same as the residual longitudinal plastic strain extracted from the thermoelastic-plastic welding analysis model.

5. The method for predicting and suppressing welding deformation of large structural parts based on multi-layer inherent strain according to claim 1 is characterized in that: The method for applying the transverse inherent strain and the longitudinal inherent strain is to assign an anisotropic thermal expansion coefficient to the welding analysis model, the application direction of the transverse inherent strain is perpendicular to the weld direction, the application direction of the longitudinal inherent strain is along the weld direction, the anisotropic thermal expansion coefficient is set to 0 in other directions, the initial temperature of the inherent strain welding analysis model is set to 0°C, and the inherent strain application area of ​​each layer is assigned an activation temperature, and the activation temperature is -1°C.

6. The method for predicting and suppressing welding deformation of large structural parts based on multi-layer inherent strain according to claim 5 is characterized in that: The inherent strain application area of ​​each layer is controlled by a birth and death unit, and the activation temperature needs to be activated according to the welding sequence of the welding experiment.

7. The method for predicting and suppressing welding deformation of large structural parts based on multi-layer inherent strain according to claim 5 is characterized in that: The inherent strain application area, the values ​​of the transverse inherent strain and the longitudinal inherent strain of all layers, and the activation temperature of the inherent strain suppression model for large structural parts and the inherent strain prediction model for large structural parts are the same.

8. The method for predicting and suppressing welding deformation of large structural parts based on multi-layer inherent strain according to claim 1 is characterized in that: A plurality of inherent strain welding analysis models are established, and each typical joint corresponds to at least one inherent strain welding analysis model.

9. The method for predicting and suppressing welding deformation of large structural parts based on multi-layer inherent strain according to claim 1, characterized in that: Each of the typical joints has at least one characteristic point.

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