Numerical Simulation Of Temperature Fields And Residual Stress Fields In Circumferential Welding

Because the process of closed circular welding is under larger restrain stress, residual stress is more complicated than straight welding line, it is prone to produce welding defects, such as double residual stress, cracks, deformation. It is very important to analyze and predict successfully the temperature fields and residual stress fields of weldments for optimizing process parameters and improving welding quality in welding of closed circular patch. However, there is not enough experience to reference in practice, it will cost a lot of time and material resources by experimentation. ANSYS is convenient, effective and accurate, that's very appropriate to analyze the temperature fields and residual stress fields.In this thesis, the finite element analysis of temperature fields and stress fields in the circumferential welding of circular patch was simulated dynamically based on the ANSYS. Temperature fields at different time, circumferential and radial residual stress in different locations and deformation were analyzed. It is shown that the simulation results are in good accordance with the theoretic results. The simulation results can provide an effective basis for welding parameters selection of circumferential welding of circular patch, which can be a good reference for the selection of the process parameter in welding simulation of closed circular patch.A specific finite element model for circumferential welding of circular patch was founded. A general double ellipsoidal distribution model was selected for heat sources in the welding pool. Dynamic process simulation of welding filled has been carried out by applying life-and-death element technique of finite element analysis. Taking similar characters of the electrode with work pieces into consideration, the paper simpled the algorithm by taking the same thermal physical parameters in both the patches and the weld without influence on the precision of computed results. Load was applied by APDL and equations were solved correspondingly. Results were disposed by strong post system of ANSYS.In the temperature fields, the curves of thermal cycle at the different distance sections were analyzed and the simulation results are accordant with the theoretical situation. In the stress fields, after circular patch welding, the weld line experienced shrinkage, this leaded to a circumferential residual stress, which is almost close to the material's yield strength. In the center of the patch there was a region where residual circumferential and radial stresses are similar. If the patch size was smaller, there was a higher residual stress in the patch center, especially, the residual stress is highest in the patch center when the inner patch size is close zero. Because the temperature was distributed asymmetrically on the cross section of the weld, the patch produced warp deformation, the results have shown that there was similar between the computed values and theoretical values.