Coupled Computational Fluid Dynamic and Finite Element Multiphase Modeling of Laser Weld Bead Geometry Formation and Joint Strengths

Laser welding is used extensively in industry for joining various materials in the assembly of components and structures. Localized melting followed by rapid cooling results in the formation of a weld bead and generation of residual stress. Selection of the appropriate combination of input parameters and understanding their effects is important to achieve the required weld quality with a smooth welding surface. In the present work, a sequentially coupled thermo-structural multiphase analysis was carried out with the objectives of predicting the effect of laser parameters on the change in surface topology of the weld bead and its subsequent effect on structural properties. The work shows that the laser welding parameters strongly affect the weld bead shape, which eventually affects the weld quality. A net shaped weld bead demonstrates better performance in terms of stress distribution and distortion than other weld bead shapes. The numerical simulation results were compared with the experimental observations performed on a mild steel sheet using a fibre laser and the results are in good agreement in terms of weld bead cross-sectional profile and strength.