Nonlinear thermal simulation of laser metal deposition

Simulation of Laser Metal Deposition (LMD) is central to the planning of Additive Manufacturing processes. This manuscript presents the computational implementation of a 2D-plus-thickness nonlinear thermal simulation of LMD, which considers: (i) temperature-dependent material properties, (ii) heat losses due to convection and radiation, (iii) geometrical update during material deposition, (iv) phase change and (v) the interaction between the laser and the substrate. The implementation computes the history of the temperature field at a cross-cut normal to the laser trajectory and the history of the bead accumulation. The material deposition model is based on the spatial distribution of the delivered powder. This manuscript presents the mathematical and numerical foundations to execute an efficient local re-meshing of the growing bead. The numerical estimation of the bead geometry is compared with experimental results found in the existing literature. The present model shows reasonable accuracy to predict the bead width (15% error) and bead height (22% error). This implementation is an in-house one, which allows for the inclusion of additional physical effects. Additional work is needed to account for the particle (thermo) dynamics over the substrate, responsible for a significant material and energy waste, which in turn leads to the actual temperature and molten depth being over-estimated in the executed simulations.