An alternative pressure-dependent velocity boundary condition for modeling self-reacting friction stir welding

Abstract

A pressure-dependent velocity boundary condition is developed based on wear theory for modeling self-reacting friction stir welding using computational fluid dynamics approach, which provides a new perspective in understanding the physics of sliding/sticking transition condition. The importance of shear layer in weld formation is emphasized. Effects of welding speed on the weld cross-section geometry can be robustly captured with this newly developed boundary condition. Computational results show that at higher welding speed, the TMAZ boundary moves towards the pin periphery at the advancing side, which corresponds to the experimental observations. This tendency could serve as a numerical criterion to predict void defect formation.