| Welding structures with the advantages of strong integrity and good compactness,affordable, and applies to all shapes and sizes of parts, were being widely used in national economic sectors.But welding technology also has prominent problems, such as there will produce large residual stress and residual deformation after welding in workpiece.And the stress and deformation will affect machining precision and operational performance. So, in order to achieve the goal of further optimal process, the distribution of residual stress and deformation of different welding processes is needed to be known. While, Research can also be carried by the welding numerical simulation technology though there have no experimental condition, and it can greatly reduce the cost. At the same time, it also can predict welding deformation, simulate welding process, optimize welding parameters and welding structure, and guide actual welding process. Because of these advantages, the welding numerical simulation technology is increasingly concernedIn this paper, finite element model of T-joint double side synchronous welding process was established based on APDL language, the accuracy of the model is verified by welding experiment. Through contrast simulation results of the double side synchronous welding and welding in turn,we can find that the double side synchronous welding can effectively reduce the uneven distribution of stress and deformation, the residual stress of ending process is significantly greater than other area. The new model was used to simulate the welding process of welding beam which used the double side synchronous welding procedure in large bridge steel box girder.Temperature changing course, residual stress and residual deformation results were got. The simulation results show that the largest welding deformation is concentrated on the edge of roof steel.Welding residual stress concentrated near the weld beam and the stress value is big.Based on the results of thermal elastic-plastic method, the inherent deformation distribution rule of T-joint double side synchronous welding was studied in this paper.The results show that along the weld direction transverse shringkage distortion increases first and then decreases, transverse shringkage distortion on the arc starting and arc extinguishing is slightly bigger than the metal nearby due to the end effect. Longitudinalinherent deformation along the weld direction decreases first and then increases.Angular distortion from welding starting point along the weld direction gradually increased. At the same time, the influence of welding speed, welding sequence, web plate thickness, thickness and width of flange plate on the inherent strain were respectively studied. The results show that the welding speed, web plate thickness and thickness of the flange plate have great influence on the inherent strain, and inherent strain is affected by the other factors in a certain range.Contrasted residual deformation of T-joint calculated by thermal elastic-plastic method and inherent strain method, it was found that the deformation distribution and the vertical deflection of flange plate are almost consistent. So, the reliability of inherent strain method predicting deformation of welding was verified.Meanwhile, compared the deformation of T-joint predicted by inherent strain with the shell element and with entity element,it was also found that the difference is small. So, use shell element can achieve very good calculation precision.Then thermal elastic-plastic method was used to calculate average inherent strain of each joint in large bridge steel box girder,and the average inherent strain was applied to its welding deformation prediction calculation. By analyzing the results of the deformation, relevant Suggestions of welding process were put forward. |
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