Date of Award

2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Dr. Zhichao Li

Abstract

Rotary ultrasonic machining (RUM) is one of the advanced machining processes for ceramics. Although many research papers about RUM have been published, there are very limited studies focusing on the effects of ultrasonic vibration on surface and subsurface damages. In this research, the surface and subsurface damages are compared for machining of dental ceramics (Al2O3) with and without ultrasonic vibration. The surface chippings are evaluated under microscope and the subsurface cracks are observed and quantified under scanning electron microscope (SEM). The contribution of this research is directed to use Molecular Dynamics (MD) method, which plays an important role in modeling and simulation at the atomic level, to study the material removal mechanism in RUM of dental ceramics and the effect of ultrasonic vibration on surface and subsurface damages. The MD modeling and simulation are conducted through a series of steps. The first step is to develop the MD algorithm to model and predict the properties of a system of interacting particles by repeatedly calculating the interactions between the particles and integrating their equations of motion. The second step is to calculate microscopic properties of the system by combining statistical mechanics and kinetic theory. The last step is to develop a MD simulation model with 2D and 3D functions by using an engineering materials modeling and simulation software named Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). The developed MD simulation model can be used to simulate and predict the change of microscopic properties of the material removal process as the system time elapses in the unit of picosecond.

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