Particle-scale numerical modeling of thermo-mechanical phenomena for additive manufacturing using the material point method

A fundamental numerical model at the powder particle scale based on the material point method (MPM) is developed for selective laser sintering (SLS). In order to describe the thermo-mechanical phenomena, a laser heat source model with a Gaussian energy distribution and the Perzyna viscoplastic model with a return mapping algorithm are employed. The principal process conditions, such as the laser power and radius, and the scanning speed are systematically varied. Based on the obtained temperature distribution generated by laser irradiation under these conditions, elastic-viscoplastic stresses were calculated to evaluate the deformation of powder particle pairs under the driving force of surface tension via a simple two-dimensional test case. The developed MPM model can capture minute changes of the deformation behavior and the temperature distribution history during melting and consolidation at the particle scale. Melting and consolidation of particle pairs during SLS are basic nature in determining the final product quality. The model can help to evaluate variations in the fusion of microscopic areas, melted by a laser, resulting from variations in the process conditions.