Basic numerical analysis of friction stir welding with a combination of MPS and FEM

Abstract

The finite element method (FEM) has been widely employed for estimating the welding distortion and the welding residual stress. However, it is difficult to simulate a large deformation caused by the plastic flow during the friction stir welding (FSW) of two plates by using FEM. On the other hand, in the moving particle semi-implicit (MPS) method, the structures are modeled by the aggregate of particles and the deformations are represented by the movement of particles. So, in order to simulate the large deformation surrounding the rotational tool of FSW precisely, MPS method was employed and the temperature distributions near the tool were obtained. Also, the temperature distributions in the whole model except for the area computed by MPS were calculated by FEM and then the elastic-plastic analysis was conducted using the temperature distributions obtained by MPS and FEM. The inhomogeneous temperature distributions through the thickness near the joint line could be simulated and the maximum temperature distributions computed had a good agreement with the experiments. In addition, the longitudinal plastic strain distributions indicates that this plastic strain near the tool is not governed by only the temperature distributions and the influence of plastic flow should be taken into account.