Finite element simulation of pin shape influence on material flow, forces in friction stir welding

Selection of tool geometry is an important aspect for an efficient friction stir welding (FSW), as it influences material flow, forces, and other output responses. In the present paper, a three-dimensional coupled thermo-mechanical model is proposed based on Lagrangian method to evaluate the performance of two different pin shapes, i.e., smooth conical and threaded conical. Experimentally obtained axial force and spindle torque are used to validate the model. Particle tracking method is used to visualize the material flow on advancing side, retreating side, and centerline of the weld. Results reveal that material flow is non-symmetric and unstirred region is lower for the threaded pin as compared to the smooth. Higher slip rate is predicted for threaded pin as compared to the smooth pin. Vertical flow is observed for the threaded pin and is almost negligible for smooth pin.