Coupled Thermo-mechanical Analysis for Frictional Stir Welding Processes

摘要

We propose in this paper a fully coupled thermo-mechanical formulation for the numerical simulation of Friction Stir Welding (FSW). FSW is an important joining technique used in many practical applications (such as automobiles, ships and airplanes) where the quality of the resultant joint is of essential importance. Several models for FSW were proposed over the past two decades. However, they were mainly restricted either in the representation of the geometries, or the material behavior, or the boundary conditions. The model proposed here aims at representing the phenomenon in its entire complexity leading to an efficient and robust numerical tool. A combination of Arbitrary Lagrangian Eulerian (ALE), Lagrangian and Eulerian for different zones of the computational domains is introduced and the coupling in-between is defined. This results in a setting that permits treating arbitrary pin geometries and facilitates boundary conditions application. Both heat generation via viscous dissipation and frictional heating due to contact are taken into account. The material behavior is characterized by two alternative rigid thermo-visco-plastic constitutive models: Norton-Hoff and Sheppard-Wright. A pressure stabilized mixed linear velocity/linear pressure finite element method is used to solve the mechanical problem while linear temperature formulation with convection stabilization is used for the thermal one. The resulting coupled system of equations is treated in a staggered manner in which the mechanical and thermal parts are solved sequentially. The results of the simulation using the proposed thermo-mechanical model are presented and compared with the experimental evidence and results published in literature. Several non-circular pin shapes are analyzed.