A Semianalytical Thermal Model for Fiction Stir Welding

The main difficulty in the formulation of any model for friction stir welding (FSW) is due to the high coupling between thermal and mechanical phenomena. In the analytical models present in the literature, the fundamental unknown parameter, under the assumption of sticking between the tool/matrix interface, is the yield shear stress, which is temperature dependent. For this reason, any fully analytical model is unable to predict the temperatures for conditions not supported by measurements of the heat input. In this work a semianalytical thermal model for FSW is proposed. The formulation of heat flow during the welding process is based on generic solutions of the differential equation for heat conduction in a solid body, formulated for a point heat source with constant linear velocity. The heat generation was considered as a function of the tool-matrix interface temperature, which is calculated by means of a numerical routine written in Matlab code. Comparison with the experimental measurements taken from the literature shows that the results from the present semianalytical model are in good agreement with the test data.