thermomechanical comparison between bobbin and conventional friction stir welding of a356 aluminum alloy

Friction stir welding (fsw) is a welding technique that has brought significant advancements to the field of metal joining. an innovative variation of this technique is known as bobbin tool friction stir welding (btfsw). this study aimed to compare various aspects, including force, temperature, and strain, between fsw and btfsw. for this reason, the finite element method was employed, utilizing the eulerian technique to model the welding process. the findings revealed that the presence of two shoulders in btfsw enhances heat generation by increasing the contact area with the workpiece, resulting in improved frictional heat production. the advancing side of the bfsw sample exhibited the highest recorded peak temperature, reaching 532°c. on the other hand, the cfsw sample displayed a comparatively lower peak temperature of approximately 347°c. the elevated temperature in btfsw enhances material flowability and plasticity, leading to reduced longitudinal forces compared to fsw. in cfsw, the longitudinal force varies between 3500 n and 2500 n, whereas in btfsw, the longitudinal force is significantly lower, approximately 800 n. furthermore, analysis of strain distribution demonstrated that btfsw exhibits an hourglass-shaped strain pattern, indicating a larger area affected by strain when compared to fsw. these results highlight the benefits of btfsw in terms of enhanced heat generation, reduced forces, and a larger strain-affected area, underscoring its potential as a superior welding technique.