Development of Trivex friction stir welding tool Part 2 - three-dimensional flow modelling

This paper describes the application of the computational fluid dynamics (CID) code, FLUENT, to modelling the metal flow in friction stir welding (FSW). Building on a two-dimensional model, and preliminary trials with a novel 'Trivex' tool design, discussed in the companion paper immediately before this one, a full three-dimensional model was developed. The model predicted the temperature, and the traversing and down forces, which were compared against experiments. The model incorporated a novel 'slip' boundary condition, based on that developed in two dimensions. A conventional 'Triflute' tool was modelled and compared with the new 'Trivex' tool design. The model correctly predicted that the Trivex tool had lower traversing and down forces than its Triflute counterpart. To assist understanding of the material flow, streamlines around each of the tools were plotted. Ultimately the technique could be used to size the pin features reducing the need for costly experiments.