Multi-Criteria Optimization in Friction Stir Welding Using a Thermal Model with Prescribed Material Flow

Friction stir welding (FSW) is an innovative solid-state joining process providing products with superior mechanical properties. It utilizes a rotating tool being submerged into the joint line and traversed while stirring the two pieces of metal together to form the weld. The temperature distribution in the weld zone, as a function of the heat generation, highly affects the evolution of the microstructure and the residual stresses, and also the performance of the weld. Therefore, thermal models play a crucial role in detailed analysis and improvement of this process. In this study, a three-dimensional steady state thermal model of FS welding of AA2024-T3 plates has been simulated. The effect of the tool rotation on the temperature distribution has been also taken into account. This thermal model has been integrated with the non-dominated sorting genetic algorithm (NSGA-II) to solve a common manufacturing problem having conflicting objectives, i.e., maximization of production rate and tool lifetime. The resulting multiple trade-off solutions are then investigated to unveil any design rules which have a strong potential in industrial use. © 2013 Taylor and Francis Group, LLC