Authors:
Shaoyi Wen
Yung C. Shin
Center for Laser-Based Manufacturing, School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907

Direct laser deposition is a very useful method of fabricating complex parts directly from CAD drawings. Despite its usefulness, many parameters that affect the final quality of the fabricated part make the selection of optimal operating conditions difficult. In this paper, new comprehensive numerical modeling is presented to describe the underlying physics in multitrack direct laser deposition processes including laser powder interaction, mass addition, fluid motion, melting, and solidification. The model rigorously considers the continuous mass addition effects in the set of governing equations. An improved level-set equation is adopted for complex evolution of interfaces for multitrack deposition. Distinct thermal-fluidic behavior and complex three-dimensional part geometry are revealed by accurately modeling the molten pool shape, liquid melt flow, heat affected zone and final deposition track height and width during multitrack direct laser deposition. In addition, an experimental parametric study on various operating parameters on the final quality is presented. The model presented in the paper can be used to design graded or/and desired material structures and properties for multitrack laser deposition processes.