Optimization of Thermo-mechanical Conditions in Friction Stir Welding

Several models for the FSW process have been applied. Initially, the thermal models were addressed since they in essence constitute the basis of all other models of FSW, be it microstructural, flow or residual stress models. Both analytical and numerical models were used and combined with the Seqquential Quadratic Programming (SQP) gradient-based optimization algorithm in order to find the welding speed and the heat input that would yield a prescribed average temperature close to the solidus temperature under the tool, thereby expressing a condition which is favourable for the process.