Development of Coupled Double Ellipsoid Heat Source Model for Hybrid Laser TIG Welding of Thick Steel Plate

Modern welding techniques like hybrid laser TIG welding (HLTW) have considerable advantages in both weld quality, penetration, joint strength, and joint efficiency in comparison with conventional Tungsten Inert Gas (TIG) welding and laser beam welding (LBW) for thick and deep weld sections. The numerical analysis of HLTW is cumbersome since it includes two powerful energy source and its complex and dynamic energy interactions. In the present study, a new hybrid heat source model is developed for simulating HLTW by modifying existing double ellipsoid model. A coupled model is proposed which combines two distinct double ellipsoid model with unique sets of weld pool model parameters for modelling HLTW. The newly defined heat source parameters can adjust the ellipsoid model to suit for keyhole effect and deeper penetration of Laser heat source. Arc and laser weld have entirely different weld pool characteristics and shape due to the difference in energy density and penetration capabilities. Finite element (FE) modelling for HLTW is done with Ansys Parametric Design Language (APDL) software, and the proposed model is capable for predicting the weld bead dimensions and temperature profiles of HLTW, with good agreement with experimental results. The weld pool predicted by proposed numerical model has an error of 4.44% in the weld bead width is observed at the top surface and 20% is observed at the bottom surface from the comparison studies between numerical and experimental data.