Physical Modeling for Selective Laser Sintering Process

Abstract

The process of selective laser sintering (SLS) involves selective heating and fusion of powdered material using a moving laser beam. Because of its complicated manufacturing process, physical modeling of the transformation from powder to final product in the SLS process is currently a challenge. Existing simulations of transient temperatures during this process are performed either using finite-element (FE) or discrete-element (DE) methods which are either inaccurate in representing the heat-affected zone (HAZ) or computationally expensive to be practical in large-scale industrial applications. In this work, a new computational model for physical modeling of the transient temperature of the powder bed during the SLS process is developed that combines the FE and the DE methods and accounts for the dynamic changes of particle contact areas in the HAZ. The results show significant improvements in computational efficiency over traditional DE simulations while maintaining the same level of accuracy.

An Adaptive Discrete Element Method for Physical Modeling of the Selective Laser Sintering Process

“…Moreover, in order to reduce computation time, an adaptive method has been developed which will adjust particle sizes with respect to their temperature and distance from the moving heat source. This approach builds upon the multi-scale model developed previously by authors [8].…”

“…Validation of the powder packing method and the use of discrete element method for heat transfer simulations of granular materials has been previously performed by authors in [8]. In this section we…”

“…However, because of the large number of particles involved in the fabrication of each part (usually in the order of millions), performing DEM simulations of the SLS process is extremely computationally expensive. For this reason, the authors have previously developed a multi-scale combined DEM/FEM method for rapid simulation of the SLS process [8].…”

Evolving Material Porosity on an Additive Manufacturing Simulation with the Generalized Method of Cells

“…Previous physical modeling of the SLS thermo-mechanical process include finite element (FE) methods, where a transient thermo-mechanical model is solved [3]. However, there have been disagreements between these models and experimental results, even after mesh refinements and temperature-dependent material properties [3]. Typically, these FE simulations model the material as a homogenous material.…”

“…Discrete element methods have also been used to account for the heterogeneous nature of the metal powder, simulating an individual or a group of particles and their thermo-mechanical behavior. However, the discrete element method suffers from large computational time requirements [3].…”