Modeling and simulation
Modeling of Dissimilar FSW: A heat transfer numerical model is developed for friction stir welding of dissimilar materials Al 6061 and AZ31 alloy. Thermophysical properties were experimentally determined for the stir zone and compared with the base alloys. Experimentally determined thermo-physical properties of the stir zone are not strictly the average values of the base alloys but exhibit a complex relationship with the microstructural features and the intermixing of Al and Mg in the weld region. The numerical model is employed to predict the temperature distribution on the advancing and retreating side. A good agreement between computed and experimentally measured results was obtained at 24-mm, 20-mm, and 16-mmtool shoulder diameter. The proposed model can be used to predict the thermal cycle, peak temperature, and thermo-mechanically affected zone for welding of dissimilar materials on friction stir welding.
Modeling of Tool Wear during FSW: Understanding tool wear during friction stir welding (FSW) is important for joining of high melting point metallic (HMPM) materials. Heat transfer and material flow based models developed in past have improved understanding of the FSW process. However, numerical models to predict tool wear and pin profile during FSW of HMPM materials are not available. Thus, the current research has focused on developing a heat transfer and material flow based model to predict tool wear and worn-out tool pin profile of H13 steel during FSW of Cu-0.8Cr-0.1Zr (CuCrZr) alloy. Temperature evolution and material flow are computed by solving conservation equations of mass, momentum and energy. The model thus developed is validated for thermal cycles and tool pin profile for various process parameters. Tool wear is predicted based on forces and stresses acting on the tool. Modified Archard’s wear theory is applied to compute tool wear and worn-out tool pin profile. The wear model successfully predicts the worn-out tool pin profile and self-optimized phenomena for various process parameters. The model is also applied to understand the changes in worn-out pin profile during FSW process.