Chemo-Mechanics of Fracture in Small-Volume Materials

小体积材料越来越多地被考虑用于微型器件，如基于微电子机械系统(MEMS)的传感器和执行器。这些小部件很容易受到环境的攻击，因为它们的表面积与体积比很大。目前，对小尺度环境对材料强度的影响缺乏基本的了解。这项研究的目的是开发新的实验技术和原子模拟方法，以研究纳米到微米尺度上环境对变形和断裂的影响的化学力学。这项工作主要涉及硅基材料的应力腐蚀开裂的研究，这种材料在MEMS结构中得到了广泛的应用。将开发一台MEMS驱动的机械表征设备，并用于研究小尺寸骨折的化学机械过程。将发展新的原子模拟方法，元动力学和动态动力学蒙特卡罗方法来预测真实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沿跟踪有限元方法中，以实现在实验室实验的时间和长度尺度上对动态(时间相关的、准静态的)裂纹扩展的原子-连续耦合模拟。这项研究的基本性质将为设计和加工可靠的小型结构和器件提供基础，用于广泛的工程应用。材料故障和可靠性是实施新兴微系统技术的严重障碍，除非密封在限制微设备接收和发送刺激的能力的封装中。该项目将通过佐治亚理工学院本科生研究体验计划吸引来访的本科生研究人员，该计划旨在增加未被充分代表的少数族裔学生参与研究，并为他们的研究生学习做好准备。在研究生阶段，启用MEMS的测试设备和小规模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.