Discrete element modeling of powder flow and laser heating in direct metal laser sintering process

摘要

A novel particle-based discrete element model (DEM) is developed to simulate the whole Direct Metal Laser Sintering (DMLS) process, which includes simplified powder deposition, recoating, laser heating, and holding stages. This model is first validated through the simulation of particle flow and heat conduction in the powder bed, and the simulated results are in good agreement with either experiment in the literature or finite element method. Then the validated model is employed to the DMLS process. The effects of laser power, laser scan speed, and hatch spacing on the temperature distributions in the powder bed are investigated. The results demonstrate that the powder bed temperature rises as the laser power is increased. Increasing laser scan speed and laser hatch spacing will not affect the average temperature increase in the powder bed since energy input is kept same. However, a large hatch spacing may cause non-uniform temperature distribution and microstructure inhomogeneity. The model developed in this study can be used as a design and optimization tool for DMLS process. (C) 2017 Elsevier B.V. All rights reserved.