The main objective of this book is a novel integrated multiphysics modeling, testing, and optimization of friction stir welding (FSW) for aluminum alloys, and thereby facilitating a better understating of processing-microstructure-properties relationships in this relatively new welding technique. To this end, first we review various models and optimization methods used in the field of FSW. Next, based on a validated thermal model for aluminum 6061 we explain determining parameters in the resulting mechanical properties of FSW welds. Then, we develop and validate a novel two-dimensional...