Welding Sequence in Large Thin-Walled Structures by Means of Local-Global and Welding Macro Element

  • Zhilian Zhang, Yunfeng Xiao, Xiaoping Tan


For multi-pass welding process of complex and large structures, traditional 3D nonlinear FEM analysis would exceed acceptable computation time and memory size and could not be applied in engineering. A local-global finite element method and welding macro element technology were used to predict the deformation of a LP cylinder component of steam turbine with 34 pass welds. The precise local models were established and analyzed using thermo-elasto-plastic method, taking into account all coupled phenomena of welding. 3D welding macro elements were assembled to the global 2D shell model, and then deformation of the whole structure was computed by elastic method. In addition, four different welding sequences were compared and analyzed. The results show that the welding sequences have significant effects on deformation, both in the magnitude and distribution mode. This method proves to be efficient for quickly predicting welding deformation   and optimize welding sequence for large thin-walled welding structure.