Optimal Extrusion Shape for Fabricating Aluminium Bridge Deck Using Assembly-Based Friction Stir Welding with Bobbin Tool

This article presents an optimal extrusion geometry for fabricating a bridge deck. The profile of the extrusion enables the possibility of welding onto another extrusion through butt joints only. This type of welding joint is optimal in terms of both the ultimate resistance and the fatigue performance. Thus, the aluminium deck will be manufactured by welding these extrusions together through the bobbin tool friction stir welding process, resulting in a full-penetration weld, free of the kissing bond and the flash toe defects, and in which the thermal input and the stirring are symmetrical on both outer sides of the butt joint. Therefore, this geometry addresses the shortcomings of both the MIG and the conventional FSW processes and significantly increases the lifespan of the aluminium deck. This article will present the scientific and technical approach, based on the Canadian standard CSA S6:19, and will present an example of application on an aluminium/glued laminated timber bridge.