Material flow and defect formation during FSW processes
By Narges Dialami (CIMNE), Miguel Cervera (CIMNE), Michele Chiumenti (CIMNE), Antonio Segatori (Hydro)

This work predicts the defect formation in Friction Stir Welding (FSW) through analyzing the flow of the material. A coupled thermomechanical model is used for the FSW simulation. To follow the flow of the material, a material tracing technique is incorporated in the numerical model. In this approach, the tracers represent the material particles.
A fast and accurate two-stage numerical strategy is adopted to analyze the FSW process. The speed-up stage intends to reach the steady state quickly. The material tracing is performed in the periodic stage where the rotation of the tool is modelled.
The computationally obtained patterns are compared with the experimental evidence. The effect of the process parameters and the pin features on the defect formation is studied. The results show that using the proposed model significant agreement can be attained between the computed and measured post-FSW results.