Chemo-Mechanics of Fracture in Small-Volume Materials

越来越多地考虑将小体积材料用于微器件，例如基于微机电系统（MEMS）的传感器和致动器。这些小部件由于较大的表面积与体积比而易受环境侵蚀。目前，缺乏对小长度尺度下环境对材料强度影响的基本认识。该研究的目的是开发新的实验技术和原子建模方法，用于研究纳米至微米尺度下环境对变形和断裂的化学力学影响。这项工作主要涉及硅基材料的应力腐蚀开裂的研究，这是被广泛用于MEMS结构。一个MEMS使能的机械表征机器将被开发和利用，以检查小规模的骨折的化学机械过程。新的原子建模方法metadaptics和飞行动力学蒙特卡罗将被开发来预测现实的三维裂纹几何形状的裂纹扩展。原子尺度的模拟结果将被集成到前端跟踪有限元方法，使耦合原子连续模拟的动力学（时间相关的，准静态的）裂纹扩展的时间和长度尺度上的实验室experiments.The本研究的基本性质将提供可靠的小型结构和设备的设计和加工的基础，广泛的工程应用。材料失效和可靠性是实施新兴微系统技术的严重障碍，而不是密封在封装中，限制了微器件接收和发送激励的能力。该项目将通过格鲁吉亚理工学院本科生研究经验项目吸引来访的本科生研究人员，该项目旨在增加代表性不足的少数民族学生参与研究并为研究生学习做好准备。在研究生阶段，MEMS启用的测试设备和小尺度断裂机制的化学力学知识将被纳入研究生课程。

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.