NUMERICAL ANALYSIS OF INHOMOGENEOUS BEHAVIOR IN FRICTION STIR PROCESSING BY USING A NEW COUPLED METHOD OF MPS AND FEM

摘要

Friction stir processing (FSP) has been developed as one of the surface modification techniques based on the basic principles of friction stir welding (FSW). In FSP, the heat is generated due to the friction between the tool and the base material and it produces the residual stress as same as that in the welding process, where the transient temperature distributions shows the inhomogeneous behavior. In addition, the plastic flow might affect the residual stress. Therefore, in order to reveal the heterogeneous behavior in FSP, a new coupled method of moving particle semi-implicit (MPS) and finite element method (FEM) was developed and it was applied for simulating both thermal and mechanical transient behavior in FSW butt joint of two plates simply and precisely. The computational results suggested that the inhomogeneous transient temperature distributions could be precisely predicted by using this coupled method. Also, it was revealed that the longitudinal plastic strain near the tools can be predicted by assuming the boundary temperature which is the same as the annealing temperature in the welding.