Study on the importance of thermo-elastic effects in FE simulations of linear friction welding

Abstract

Thermo-elastic effects generally influence the distribution of contact variables in contact pair of two components undergoing dynamic loading. A 3D fully coupled finite element model with a plastic/plastic friction pair was used to evaluate the effects of thermo-elastic deformation. Two workpieces were in conforming contact at the beginning of welding, when workpieces were aligned, after which friction heat input resulted in local thermal expansion which caused a reduction in the real contact area between the two workpieces. Thermal expansion deformation also resulted in non-uniform contact pressure and interfacial temperature distributions. With the softening of materials around the hot region, the initiation of gross plastic deformation resulted in an increase in the real contact area. Thermo-elastic effects at different welding parameters on the minimum real contact area fraction, and the time taken to recover 100 % of apparent contact area, were investigated numerically. Compared to the LFW model with the rigid/plastic friction pair, the LFW model with the plastic/plastic friction pair could better reflect the thermo-elastic effects in LFW. The study provided a support to understand the LFW physical mechanism using simulation.