Multi-layer thermo-fluid modeling of powder bed fusion (PBF) process. (November 2022)

• Record Type: Journal Article
• Authors: Fotovvati, Behzad; Chou, Kevin
• Is Part Of: Journal of manufacturing processes. Volume 83(2022)
• Page Start: 203
• Page End: 211
• Publication Date: 2022-11
• Subjects: Multi-layer simulation -- Powder-bed fusion -- Selective laser melting -- Discrete element method -- Computational fluid dynamics; Production management -- Data processing -- Periodicals; Manufacturing processes -- Periodicals; Procestechnologie; Productietechniek; Production -- Gestion -- Informatique -- Périodiques; Fabrication -- Périodiques; Manufacturing processes; Production management -- Data processing; Periodicals; 670.5
• DOI: 10.1016/j.jmapro.2022.09.003
• Languages: English
• ISSNs: 1526-6125

Abstract

Abstract: In this study, a 3D thermo-fluid computational method has been developed and employed to simulate the laser powder bed fusion (PBF) process. The particular objective is to demonstrate the feasibility of multi-layer simulations of the laser PBF process and to discuss the potential and challenges of this approach. The approach includes using the discrete element method (DEM) to simulate particle spreading on a powder bed, as well as computational fluid dynamics (CFD) and heat transfer to simulate laser-powder/matter interactions, in a sequential manner to about 10 layers only with a small scan area, limited by currently available computational power. The simulation results can offer insight such as melt pool shapes and sizes, also solidified surface morphology along different build layers. The model also includes a surface tracking algorithm to account for the formation of voids and lack-of-fusion pores. In addition to achieving the main objective of this study, i.e., feasibility demonstration of this computational process, it is also noted that, for the case studied, the defects in a former layer may shrink, or even vanish, due to the extra thermal energy received from laser scanning of subsequent layers. This study has successfully demonstrated the sequential linkage between a discrete element method and a thermo-fluid model in a multi-layer deposition fashion and the experimental validation will be performed in future work. With significantly greater computational capabilities in the future, the developed method may potentially be utilized as a means to understand physical phenomena and select key process parameters for PBF fabrications of small features. Graphical abstract: Unlabelled Image Highlights: The feasibility of multi-layer simulations in building small features by L-PBF is demonstrated. The average total melt height increases by increasing the number of layers for the first few layers. The top surface roughness is not significantly influenced by the number of layers. Pores form, shrink, or disappear due to the interaction with the molten pool during of subsequent layers. This method has the potential to investigate the local morphology at up-skin and down-skin surfaces of inclined parts.