Unified model integrating level set and modified ray-tracing methods for laser welding simulation

A novel approach to modeling and simulating multiple reflections of a laser beam in keyhole mode welding is developed based on a revised version of the conventional ray-tracing method. The ray velocity is artificially reduced to ensure compatibility with commercial finite element solvers used for thermohydrodynamic simulations. A dedicated coupling strategy is then implemented between ray-based geometrical optics and the level-set method. This integration allows both ray-tracing and level-set methods to operate within the same software environment and the same temporal solver, eliminating the need for external programming and facilitating the simulation of beam trapping phenomena in a Eulerian framework. The model dynamically solves heat transfer and fluid flow equations in solid, liquid, and gas phases, enabling a comprehensive description of both keyhole formation and melt pool behavior. Applications to laser welding of aluminum, in both static and fusion line scenarios, demonstrate promising agreement with theoretical predictions and experimental observations in terms of melt pool dimensions for different laser powers and welding speeds. The numerical results of the 3D model show its capacity to predict porosity formation.