Numerical Thermo-Mechanical Simulation Of Friction Stir Welding

Friction stir welding is a new solid-state joining technique which can successfully solvethe problem in joining lightweight metals such as aluminum and magnesium alloys. FSW hasadvantages such as low energy input; no environment pollution and higher strength of joint. Ithas been successful applied in aerospace, auto and ship building industries. Though there aredeeply investigations in microstructure and mechanical response, the mechanism of the FSWhas not been understood clearly. Moreover, this investigation can waste too muchexperimental cost.Numerical simulation is useful to investigate the temperature field and plastic strainhistory in the process of FSW, which can reduce costs by avoiding duplicate experiments.Numerical simulation can optimize the welding parameters which is beneficial for thedevelopment and the application of FSW.In Chapterâ… , the research of FSW development in recent years are reviewed, whichincludes the researches on the microstructure, the mechanical response and the temperaturefield of the joint. The current work is introduced at the end of this chapter.In Chapterâ…¡, the thermal model based on the mechanism of heat generation in FSW ispresented. Firstly the finite element method in heat conduction problem is introduced. Theprocess of building the geometry and the numerical model is presented. The simulation resultsare fully discussed and the influences of the welding parameters on the temperature fields areinvestigated.In Chapterâ…¢, the fully coupled thermo-mechanical model based on finite elementmethod is presented. The algorithm for dynamic analysis is introduced. Two advancedtechniques including mass scaling and adaptive mesh are presented. The simulation results arefully discussed, especially the history of the plastic strain and the influence of the weldingparameters. The current model is validated at last.In the conclusion, the main contributions of the dissertation are summarized and thefurther work is suggested.The research of the dissertation is supported by the National Natural Science Foundationof China (10302007).