TWI

A numerical model based on the finite element method and axisymmetric thermo-elastic-plastic analysis was developed to describe the refill friction stir spot welding (RFSSW) process and to predict the temperature distribution in welded joints as a function of process parameters. RFSSW experiments were conducted on AA 7075-T6 aluminium alloy sheets (thickness 0.8 mm) at a rotational speed of 2000 rpm, preheating time of 1 s, and sleeve and pin downward movement times of 0.5-1 s. Temperatures were measured using thermocouples. For numerical modelling, a coupled thermomechanical solution was selected, heat generation was calculated by a model based on the Coulomb friction law, the friction coefficient was defined as a function of temperature and rotational speed was assigned to the contact surfaces of tool parts and sheets. Simulation and experimental results were compared with respect to temperature distribution and thermal cycles.

11th International Symposium, 17-19 May 2016, Session 2B: Modelling I, Paper 03