Thermo-Mechanical Process Modeling of Additive Friction Stir Deposition of Ti-6Al-4V Alloy

Abstract

In this study, a computational fluid dynamics (CFD) model is developed to investigate the thermal-mechanical process in additive friction stir deposition (AFSD), a novel additive manufacturing (AM) process allowing site-specific deposition. Material conversation law with a steady-state heat is applied where the heat generation is measured considering stacking/slipping boundary conditions and the spatial heat flux is incorporated using ANSYS user-defined functions (UDFs). For measuring the temperature evolution throughout the process, the conservation of energy equation is solved where the heat is generated from the dynamic contact between the tool and feed rod interfaces. For material flow, the laminar viscous model is adopted where the feed rod is considered as a non-Newtonian visco-plastic material, and the viscosity and strain rate are temperature-dependent. The simulation results show the temperature evaluation of the deposited material as a highly viscous flow where the temperature is optimized around 20% below the melting point temperature of the feed rod. Since the heat generation depends on the rotational and translational motion of the feed rod, the maximum temperature changes with varying process parameters. Finally, the results of the simulation such as temperature evolution, heat flux, material velocity, etc are exhibited with varying process parameters.