Thermal analysis of Cooling assisted Friction Stir Welding of Dissimmilar Al-Cu metals

Friction Stir Welding (FSW) is a solid state joining technique which is used to join light metals like aluminum and its alloys. It has also shown its capabilities in joining and overcoming challenges imposed by welding of dissimilar metals like AL-Cu, Al-Ti. As welding is a thermomechanical process, the formation of joint and residual stress in the weld joint depends highly on the temperature of the weld zone during welding and the cooling rate. In the current project, a heat transfer model is developed for cooling assisted friction stir welding of Al-Cu system. The frictional heat generated due to the interaction between rotating tool and workpiece is modeled using the various contact condition and cooling flux of the trailing heat sink is applied as negative heat flux. Both heating and cooling flux are coded in user subroutine DFLUX. As it is a dissimilar system, due to interaction between two metals in weld zone, the composition changes. This change in composition due to material mixing and arising change in thermal properties are modeled  based on the concept of functionally graded materials (FGM) and coded in USDFLD subroutine. All the steps of FSW i.e. plunge, dwell, weld and retraction are simulated. Also effect of different cooling source like liquid carbon dioxide on peak temperature is simulated and the thermal profile of the simulation was validated with the experimental results. The project is executed as part of one-year dissertation for the Master of Technology program in Mechanical engineering at Pandit Deendayal Petroleum University (PDPU), Gandhinagar, India under the guidance of Dr Nirav Patel and Dr. Kush Mehta, Assistant Professor, Department of Mechanical Engineering at PDPU. youtube link : https://youtu.be/qfxyoVs6WTc