Henry Granjon prize competition 2004 winner, category A "joining and fabrication technology" modelling and development of the trivex™ friction stir welding tool

This work has demonstrated the development and benefits of the Trivex™ tool over the conventional MX-Triflute™ tool in friction stir welding of aluminium alloys. This tool was developed from 2 dimensional models. Experiments made on 7075-T7351 aluminium alloy verified this result. Three dimensional thermal models that used the experimental heat input predicted the weld thermal profile, which correlated well with the experimental curves. The work also demonstrated several novel modelling techniques. The first was the slip boundary condition in 3 dimensions, where a limiting shear stress was applied at the surface and the material was allowed to slip against the tool. The second involved adjusting the limiting shear stress so that the weld power of the model matched that obtained experimentally. The final technique was the inclusion of the temperature profile by interpolating the result from a thermal model. This obviated the need to solve the thermal profile in conjunction with the flow model.