A three-dimensional thermomechanical Particle Finite Element framework — Towards the simulation of laser directed energy deposition

This work presents a framework for the simulation of the Directed Energy Deposition with a Laser Beam (DED-LB) additive manufacturing process by using the Particle Finite Element Method (PFEM). PFEM offers key advantages, especially its ability to handle large and rapidly changing deformations in the domain of molten metal flow through its remeshing strategy, and to simulate the bonding of separate bodies when they come into close proximity. The developed framework enables the prediction of weld bead geometries formed under various process conditions and will serve as the foundation for subsequent residual stress calculations. A previous work addressed this application in a simplified two-dimensional setting while in the present work the approach is extended to the three-dimensional case. In this context, the contributions of the present work particularly include a three-stage mesh improvement process to significantly increase the numerical stability of the simulations, a methodology for capturing the bonding of hot-flowing metal onto a cold substrate, and a procedure for introducing new material through the laser nozzle into the ongoing deposition process within a Lagrangian framework while employing a temperature-dependent viscoelastic material model.