Computational modeling and simulation of thermal-fluid flow and topology formation in laser metal additive manufacturing

The field of metal additive manufacturing holds great promise in several industries for its potential to reduce cost and open the doors to new design paradigms as well as agile and efficient logistical systems. However, the complex, multi-faceted physics of additive metals processing has proved to be a significant barrier to quickly deploying and utilizing this technology. The connection between processing parameters and build quality remains an active field of research, further complicated by the particular intricacies of each process implemented by various equipment manufacturers. As direct experimentation remains relatively costly in this field, a clear opportunity exists for developing accurate and cost efficient simulation tools to aid in untangling the relationships between process specifics and build outcomes. In this work, the salient physical phenomena were analyzed for a blown powder and a powder bed process. Models were then formulated based on this analysis to capture the effects of build parameters on micro-scale topology and temperature distributions. These models were then implemented using the OpenFOAM Finite Volume software library. A steady-state model and simulation code was developed for the blown powder process and the topology predictions were validated quantitatively using experimental data from the literature. A time-dependent model and simulation code was developed for the powder bed process with an emphasis on capturing the complex interaction of thermally induced fluid flow with deformation of the gas-liquid interface of the melt pool. The salient aspects of this code were verified using simplified application cases and the code was demonstrated using a representative test case, which showed qualitative agreement with previous work. These two new codes enhance the field of additive metals processing by potentially reducing the effort necessary to produce parts by minimizing defects and maximizing microstructure quality