Level-set method based predictive modelling to track the evolution of surface during pulsed laser surface melting

Abstract

The objective of this study is to investigate the evolution of surface geometry during pulsed laser surface melting (pLSM) via level-set method-based interface tracking numerical framework. Existing models to track surface geometry are inaccurate and computationally expensive. Therefore, they have limited use in gaining understanding of the surface evolution during pLSM. A numerical model, integrating the level-set approach, fluid flow and heat transfer dynamics, is detailed in this paper. The muti-phase numerical model achieves accurate tracking of interface for a single pulse by implementing the volumetric laser heat source on the moving interface by modifying the Berr-Lambert's law. The accuracy of the single pulse model is confirmed by comparing its Peak-to-Valley Height (PVH) to experimental data. The deviation in PVH is limited to about 15%, with a maximum Root Mean Square Error (RMSE) of ∼0.24 μm, highlighting the model's reliability. Additionally, the evolved surface of a single pulse from the model is replicated over an area with dedicated overlaps to generate the predicted textured surface with reasonable accuracy. Some inaccuracies in the predicted surface roughness values were observed because the textures were generated based on single pulse geometry computed on an initially flat surface. Nonetheless, the results highlight a significant development in numerical frameworks for pLSM and can be used as a tool to gain deeper insights into the process and for process optimization.