Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Mechanical and Materials Engineering

Supervisor

Tutunea-Fatan, Remus O.

2nd Supervisor

Bordatchev, Evgueni V.

Joint Supervisor

Abstract

Laser polishing (LP) represents one of the finishing/superfinishing technologies that has experienced a rapid growth over the past two decades. However, while undeniable progress has been achieved on the experimental and/or practical side, the development of the mathematical models continue to be somewhat slower and still dominated by significant simplifying assumptions.

To address this research gap, after identification of underlying thermo-physical processes during LP through a comprehensive literature review, two CFD (Computational Fluid Dynamics) models are developed to simulate the laser-material interactions and eventually predict the final geometry of the irradiated surface. In this context, a 3D CFD model is proposed which contains all heat transfer mechanisms influencing the formation of the laser track. Also, a 2D CFD model is developed using VOF (Volume of Fluid) technique to capture the change of surface geometry due to irradiation of continuous wave (CW) stationary and moving laser beam. To validate proposed models through comparing their results with experimental data, a post-processing methodology is developed and formulated in a computer algorithm. While CFD models’ outcome is in good agreement with experimentations, probable causes of variance between them are elaborated.

Developed post-processing methodology and CFD models enable comparative evaluation of experimentally measured and simulated surface geometries thoroughly, which increased the knowledge about underlying thermo-physical processes, especially the mechanisms of molten material redistribution. It has been concluded that while conduction is the main heat transfer mechanism throughout the workpiece, surface tension is the dominant driving force in the melt pool.

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