Simulation of laser attenuation and heat transport during direct metal deposition considering beam profile

A laser-powder coupling model for direct metal deposition (DMD) with discontinuous powder feeding is presented based on homogeneous transformation, Lambert-Beer law and energy balance. This model can simulate two key physical events including laser attenuation and heat transport during laser-powder coupling. Super-Gaussian function and our previously-proposed beam characteristic parameter identification method (BCPIM) are employed to reconstruct the spatial intensity of the focused beam. Compared with ideal Gaussian beam model, the predicted value of the super-Gaussian beam model is in favorable agreement with the measurements of actual beam. Laser power loss rate induced by particle group is independent of the beam profile and power when the laser spot is far below the discontinuous coaxial powder stream (DCPS) spot. The mass-weighted mean temperature distributions of the DCPS and particle intensity display a cruciform tower-like shape under super-Gaussian beam and Gaussian beam, but some significant differences exist in terms of the profile and magnitude. Both the mean mass-weighted mean temperature (MWMT) and mean particle intensity within the laser spot under the super-Gaussian beam are slightly lower than those under the ideal Gaussian beam.