Precision and Efficiency Sensitivity of Some Key Techniques in Thermo-mechanical Numerical Simulation of Welding Process

摘要

Numerical simulation is a powerful method in analysing the thermal and thermo-mechanical process in welding. It can provide field and history information of the process and it is easy to analyse the development of variables such as temperature, displacement, stress and strain. However, the low efficiency and precision of numerical simulation prevent its application and further development. Some key techniques to increase the calculating efficiency are introduced in this paper. These techniques include: adaptive meshing, domain decomposition in parallel computing and the proper treatment of material properties at high temperature. In adaptive meshing, the mesh refinement corresponds to the character of locally rapid change temperature field during welding process and reduces the calculating time significantly. The parallel computing is high effective in engineering simulation including welding process. The speed up ratio (ratio between calculating time with 1 CPU and that with multi-CPUs) can be higher than the number of CPUs in this research and there has no such report. The influence of high temperature material properties on precision and efficiency are studied because lack of relevant data and variations in the extrapolation methods to predict the high temperature values. The results show that different material property at high temperature has obvious influence on the calculating time while the influence on residual stress and distortion can be neglected. The above techniques make numerical simulation of welding process a more practical proposition.