![](https://congressarchive.cimne.com/sim-am_2023/assets/logo-sim-am-03_00000002.jpg)
A Discrete Element and Ray Tracing Framework for the Numerical Analysis of Powder Bed Based Additive Manufacturing Processes
Please login to view abstract download link
Despite the widespread use of various Additive Manufacturing (AM) methods in industry, several aspects of printer and product development still rely on a trial-and-error approach. This is because AM methods involve complex, multi-physical processes, which makes it challenging to anticipate how printer input settings will affect product quality. To address this, numerical analysis can offer a foundational understanding and enhance insights into how process and material parameters impact product properties. In this paper, we present a Discrete Element Method designed to simulate powder bed-based Additive Manufacturing processes. The method considers a range of interactions to mimic both the powder state and the solid state of the material, as well as the bond mechanisms. Specifically, particles bond when they come into contact and reach a critical temperature. Thermo-mechanical coupling is achieved by incorporating shrinkage due to neck-growth and thermal expansion. The material properties are temperature dependent. To model the laser, ray tracing simulations are utilized. The ray tracer enables a precise simulation of the interaction between the laser and powder bed. The heat source is segmented into multiple rays and their trajectories are simulated while taking into account reflection, refraction and absorption models. The method allows to determine the exact heat profile in a powder bed for a specific laser spot size and shape. This hybrid model is validated with experiments. To this end, single scan lines have been printed with 316L stainless steel powder. The dimensions of these tracks have been measured by profilometry and the melting pool depth has been obtained by polishing and etching cross-sections of the samples. The performance of the model is demonstrated by means of several case studies of single line scans. By deriving the laser's volumetric heat source geometry through ray tracing simulations, it is shown that the analytical description, commonly employed in literature, is only valid in certain instances. In addition, it is demonstrated how laser power, spot size, and speed affect the height and width of single line scans.