Debonding in Bi-layer Material Systems under Moisture Effects : A Multi-scale Fracture Approach

双层材料系统存在于从电路板中的纳米厚薄膜到建筑物中的大型结构元件的各种应用中。双层材料系统中的断裂行为是一种复杂的现象，现有的分析和数值方法无法描述存在环境影响(如水分)时的物理行为。本研究项目的目的是开发一种经过实验验证的新的模拟技术，以了解双层材料在水分影响下的断裂行为。提出的研究是出于对环氧树脂混凝土体系耐久性的关注，该体系被广泛应用于混凝土结构加固。通过优化技术和大量的实验室实验，将原子尺度的行为和结构水平的有限元方法相结合，建立了多尺度模拟的框架。这项研究将极大地促进具有水分和化学效应的双层材料系统断裂力学领域的科学知识，并为复杂材料系统的工程分析引入一种新的范式。将这一方法应用和发展到涉及混凝土和环氧树脂系统等双材料系统的基础设施问题上，将带来更好的设计，降低维护成本，并有助于确保公共安全，防止意外的结构故障。该项目开发的知识和方法将通过课程课程纳入教育，并通过麻省理工学院的开放式课程网站和专门的研究网站向公众提供。将尽一切努力让本科生、女性和少数民族学生参与研究。

Bi-layer material systems are present in various applications ranging from nanometer thick thin films in circuit boards to large structural elements in a building. Fracture behavior in a bi-layer material system is a complex phenomenon and current analytical and numerical techniques are unable to describe its physical behavior when environmental effects, such as moisture, are present. The objective of this research project is to develop an experimentally validated new simulation technique in order to understand the fracture behavior of bi-layer materials under the effect of moisture. The proposed research is motivated from the durability concern of epoxy-concrete systems that are widely used in retrofitting concrete structures. A framework for multi-scale simulation combining behavior at atomistic scale, and finite element method at structural level, will be developed through an optimization technique and extensive laboratory experiments.This research will significantly advance the scientific knowledge in the area of fracture mechanics in bi-layer material systems with moisture and chemical effects, and introduce a new paradigm in engineering analysis of complex material systems. Application and development of this methodology to infrastructure problems involving bi-material systems, such as concrete and epoxy systems, will lead to a better design, reduced maintenance cost, and help ensure public safety against unanticipated structural failures. Knowledge and methodology developed in this project will be integrated into education via course curricula and made available for public through the OpenCourseware website of Massachusetts Institute of Technology and specialized research websites. Every effort will be made to involve undergraduates, females, and minority students, in the conduct of the research.