Abstract
Selective laser sintering (SLS) is an additive manufacturing technology whereby one can 3D print parts out of a powdered material. However, in order to produce defect free parts of sufficient strength, the process parameters (laser power, scan speed, powder layer thickness, etc.) must be carefully optimized depending on material, part geometry, and desired final part characteristics. Computational methods are very useful in the quick optimization of such parameters without the need to run numerous costly experiments. Most published models of this process involve continuum-based techniques, which require the homogenization of the powder bed and thus do not capture the stochastic nature of this process. Thus, the aim of this research is to produce a reduced order computational model of the SLS process which combines the essential physics with fast computation times. In this work the authors propose a coupled discrete element-finite difference model of this process. The powder particles are modeled as discrete, thermally and mechanically interacting spheres. The solid, underneath substrate is modeled via the finite difference method. The model is validated against experimental results in the literature and three-dimensional simulations are presented.













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The powder bed density is calculated by adding the volume of all portions of all particles located within a 30 \(\upmu \)m layer from the bottom substrate and then dividing by the volume of this layer (the cross section of the layer is 1000 \(\upmu \)m \(\times \) 500 \(\upmu \)m and height is 30 \(\upmu \)m).
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Acknowledgments
The authors would like to express their gratitude towards Ramesh Subramanian and Marco Brunelli of Siemens Energy, Inc. for funding this research. Additionally, the input of other members of the Siemens Corporation was useful in the formulation and validation of this approach. Finally the authors would like to thank fellow members of the CMRL lab at UC Berkeley for many fruitful discussions and their aid in the proofreading and editing of this paper.
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Ganeriwala, R., Zohdi, T.I. A coupled discrete element-finite difference model of selective laser sintering. Granular Matter 18, 21 (2016). https://doi.org/10.1007/s10035-016-0626-0
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DOI: https://doi.org/10.1007/s10035-016-0626-0