Equations of heat generation during friction stir welding for tapered polygonal tools

Owing to the complex nature of heat generation in friction stir welding, equations are required to understand the effect of process parameters and tool geometry on heat generation. In this study, simplified equations for straight tool profiles have been extended to treat tapered tool profiles for triangular, square, pentagonal and hexagonal geometries. New equations have been implemented to model heat generation in a finite element software package for welding aluminium alloy. The calculated thermal profiles agree better with experimental data than those calculated using the simplified equations. It was also demonstrated that the amount of heat generation increases with increasing number of flats on the tapered tool profile, with a hexagonal tapered tool profile generating the highest temperature.