Identifying friction stir welding process parameters through coupled numerical and experimental analysis

Friction Stir Welding (FSW) is a complex thermal-mechanical process. Numerical models have been used to calculate the thermal field, distortion and residual stress in welded components but some modeling parameters such as film coefficient and thermal radiation of the work pieces may be technically difficult and/or expensive to measure experimentally. Therefore, it is important to establish a systematic procedure to identify FSW process parameters. In this paper, a simplified finite element model for analysis of a FSW thermal progress is proposed in which two parameters, tool heat input rate and heat loss through the backing plate, are identified as parameters for optimization through application of a generic algorithm. A genetic algorithm is used to evaluate the two thermal parameters. By comparing the FEM numerical results with experimental results, the FSW process thermal parameters have been successfully identified. This automatic parameters characterization procedure could be used for the FSW process optimization.