Date of Award

January 2015

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Aeronautics and Astronautics

First Advisor

Vikas Tomar

Committee Member 1

R. Byron Pipes

Committee Member 2

C-T Sun

Committee Member 3

Christian Hellmich

Committee Member 4

Jong H. Choi

Abstract

Biomaterials such as bone and marine exoskeletons have primarily an organic phase (e.g. tropocollagen in bone, chitin in exoskeleton) and an inorganic phase (e.g. hydroxyapatite in bone, calcite in exoskeleton) arranged in a precisely organized multi-level hierarchical arrangement. Interfacial interactions between the organic and inorganic phases significantly affect the mechanical properties of such biomaterials. In presented study, idealized tropocollagen-hydroxyapatite and chitin-calcite interfacial systems are analyzed using a multiscale simulation framework that combines explicit three-dimensional molecular dynamics simulations with finite element simulations that take into account explicit microstructure in a three-dimensional hierarchy. The analyses focus on the shear deformation that occurs in interfaces of such materials when overall three-dimensional hierarchy is subjected to mechanical loading. In order to predict the interface stress magnitude in such systems during deformation, steered molecular dynamics simulations are performed to study the interfacial sliding process between the organic and inorganic phases at the nanoscale. A visco-plastic interfacial sliding model is used to calculate the interface strength and the shear viscosity of each interfacial system. In order to predict the effect of interface on the behavior of the material at the continuum level, a combined

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