Abstract
In bobbin tool friction stir welding the material flow around the tool is of great importance for the process stability and weld seam quality. The material is extruded around the retreating side of the tool pin and forms a shear layer. This study presents a CFD model of the shear layer implemented and solved using Comsol Multiphysics™ FE Software. The material used is AA2024 in T3 condition. The metal is treated as a highly viscous shear thinning liquid governed by an inverse hyperbolic sine relationship for the viscosity. The boundary condition at the interface between tool and work piece can be either sticking or slipping in any ratio. This information is part of the output of the model. The temperature information as well as the applied machine torque is taken from previous numerical and experimental work. The predicted shear layer shape and machine torque are experimentally validated.
