Atomistic simulation of strength and deformation of ceramic materials

This thesis is a study of atomistic measures of strength and deformation of ceramic materials, utilizing molecular dynamics (MD) simulation that incorporates newly developed theoretical models and computational algorithms to probe the microstructural effects in crystalline, amorphous, and nanocrystalline media. Specific issues of a materials property or mechanics of materials nature are addressed in the context of characterizing the limits to strength and mechanisms of structural failure in two physically rather different model ceramics, SiO₂ described by pairwise ionic interactions and ZrC with many-body covalent interactions. These range from stress-strain responses to various applied loading, determination of fracture toughness, structural relaxation effects, to scaling with grain size. Additionally, a study of the thermal conductivity of ZrC is presented. On the computational side, thesis contributions consist of improved MD algorithms for finding neighbors and integrating the Newton's equations of motion, extension of Ewald summation to a binary ionic lattice for phonon dispersion, elastic constant, and heat current calculations, and a stand-alone scheme for coupled MD-continuum simulations based on domain decomposition and control feedback. The onset of structural instability in MD simulation of an initially defect-free lattice gives not only the theoretical or ideal strength of the deforming material, but also the mode of deformation and details of the structural defects nucleated afterwards. This provides a systematic basis for determining the effects of temperature on mechanical response, and stoichiometry effects in the case of carbon vacancies in ZrCl[sub]1-z.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Nuclear Engineering

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2001

Author dc:creator

• Liao, Dongyi, 1975-

Advisor dc:contributor.advisor

• Sidney Yip.

• Nuclear Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/30003

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/30003