Chemo-Mechanics of Fracture in Small-Volume Materials

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Small-volume materials are being increasingly considered for use in micro-devices such as micro-electro-mechanical system (MEMS) based sensors and actuators. These small components are vulnerable to environmental attack because of large surface-to-volume ratios. Currently, there is a lack of fundamental understanding of environmental effects on material strength at small length scales. The objective of the research is to develop novel experimental techniques and atomistic modeling approaches for studying the chemo-mechanics of environmental effect on deformation and fracture at nanometer to micrometer scales. The work primarily involves the study of stress corrosion cracking in silicon-based materials, which are being widely used in MEMS structures. A MEMS-enabled mechanical characterization machine will be developed and utilized to examine the chemo-mechanical processes of small scale fracture. New atomistic modeling approaches metadynamics and on-the-fly kinetic Monte Carlo will be developed to predict crack extension for realistic three-dimensional crack geometries. The atomic-scale modeling results will be integrated into the front-tracking finite element method to enable coupled atomistic-continuum simulation of kinetic (time-dependent, quasi-static) crack growth on the time and length scales of laboratory experiments.The fundamental nature of this research will provide the basis for the design and processing of reliable small structures and devices for a wide range of engineering applications. Material failure and reliability are serious roadblocks to the implementation of emerging micro-system technologies in anything other than hermetically sealed in packages that limit the capacity for micro-devices to receive and send stimuli. The project will engage visiting undergraduate researchers through the program of Research Experiences for Undergraduates at Georgia Tech, a program designed to increase the participation of underrepresented minority students in research and prepare them for graduate studies. At the graduate level, the MEMS-enabled testing device and knowledge of chemo-mechanics of fracture mechanisms at small scales will be integrated into the graduate courses.