Chemo-Mechanics of Fracture in Small-Volume Materials

小体积材料越来越多地被考虑用于微器件，如基于微机电系统（MEMS）的传感器和执行器。由于表面体积比大，这些小部件很容易受到环境的影响。目前，对于小长度尺度下环境对材料强度的影响还缺乏基本的认识。本研究的目的是开发新的实验技术和原子建模方法，以研究环境对纳米到微米尺度上变形和断裂的化学力学影响。这项工作主要涉及在MEMS结构中广泛应用的硅基材料的应力腐蚀开裂研究。将开发微机电系统（mems）机械表征机，用于检测小尺度断裂的化学-机械过程。新的原子建模方法元动力学和动态蒙特卡罗将被开发，以预测实际三维裂纹几何形状的裂纹扩展。原子尺度的建模结果将集成到前跟踪有限元方法中，以在实验室实验的时间和长度尺度上实现动力学（时间相关的准静态）裂纹扩展的耦合原子连续模拟。这项研究的基本性质将为设计和加工可靠的小型结构和设备提供基础，用于广泛的工程应用。材料失效和可靠性是实施新兴微系统技术的严重障碍，除非在密封包装中，这限制了微设备接收和发送刺激的能力。该项目将通过佐治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，该项目旨在提高代表性不足的少数民族学生在研究中的参与度，并为他们的研究生学习做好准备。在研究生阶段，mems测试设备和小尺度断裂机制的化学力学知识将被整合到研究生课程中。

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.