Multi-objective optimization of friction stir welding parameters: Integration of FEM and NSGA-II

Abstract

In this investigation, the friction stir welding (FSW) parameters were optimised by integrating the finite element analysis and non-dominated sorting genetic algorithm-II. A thermo-mechanical finite element model to predict the peak temperature and flow stresses during welding were developed using Hyper Weld® FEM tool. The validity of the FE model was validated through experimental results. Using the validated FE model the process responses were predicted for varying conditions of welding speed, tool rotational speed, tilt angle, and shoulder diameter according to the design of experiments. The quadratic models for the process responses were postulated using response surface methodology and their adequacy was verified through analysis of variance. The problem was treated as multi-response optimisation due to the conflicting nature of the process responses and formulated to maximise the peak temperature and minimise the flow stress simultaneously. NSGA-II was then implemented to derive the Pareto-optimal solutions and reported. [Submitted 8 April 2018; Accepted 20 June 2019]