SGER: Green's Function-Based Multiscale Modeling of the Micro- and Nanomechanics of Defects in Multilayer Heterostructures

SGER：基于格林函数的多层异质结构缺陷微观和纳米力学多尺度建模

• 批准号: 0723486
• 负责人: Bo Yang
• 金额: --
• 依托单位: Florida Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0723486&HistoricalAwards=false
• 关键词: SGER; Green; Function; Based; Multiscale

This SGER project aims to develop elegant multiscale modeling as well as continuum modeling techniques of defects and to investigate defect behaviors in multilayer heterostructures. Multilayer heterostructures are used as the base structure in many advanced electronic/optoelectronic devices as well as used for protective coating, thermal barrier and body armor. A three-dimensional analysis of stress and defect cores in such a structure of material heterogeneity, high aspect ratio and defect singularities poses a great challenge to the community of computational sciences and engineering. This project takes a Green's function (GF) approach to attack the difficulty of modeling multilayer heterostructures by hierarchically including the planar-layer feature in the reference GF that can be solved semi-analytically on the continuum level. Based on this multilayer matrix, defects are introduced. In this way, the problem of defects in multilayer heterostructures is reduced to numerically treating only the localized defects. Furthermore, the lattice GF (LGF) of multilayer heterostructures is derived based on the continuum GF (CGF) by realizing the asymptotic approach of the former to the latter at the long-wavelength limit. The LGF and CGF in combination facilitate a powerful mathematical tool for efficient and accurate solution of defect problems in multilayer heterostructures. Nonlinear effect in the core of a defect is taken into consideration in an iterative scheme. This project will establish a powerful computational tool that can lead to a profound understanding of the defect mechanics and dynamics on both continuum and lattice scales and in between. This will establish a framework for prediction of defect behaviors that can be used to predict service lives of devices and to tailor-make novel materials with desired nanostructures, and for prevention of defect problems that can improve device performances. The results of the research will be incorporated in and will impact the Computational Mechanics courses that the PI has been teaching and the micro/nanomechanics courses that he has been developing. It will introduce the students to the novel computational tools (i.e., multiscale modeling) in particular and draw their interest in the emerging nanotechnology in general. The research project will involve a graduate student, who will be trained in this multidisciplinary field of Applied Mechanics, Materials Science, and Solid State Physics. Thus, the project contributes to the NSF goal in development of a new generation of capable workers who have knowledge and skills necessary for rapid progress in the emerging nanotechnology. Furthermore, the PI will closely collaborate with scientists at NIST through this project. He will post developed computer codes with user-friendly interface on the NSF/NIST Digital Library of Green's Functions website: http://www.ctcms.nist.gov/gf/ for public access. This will expand the broader impact of this project to enhance the strength of the US industry and to promote the use of GF-based computational tools in the research society.

该 SGER 项目旨在开发优雅的多尺度建模以及缺陷的连续建模技术，并研究多层异质结构中的缺陷行为。多层异质结构被用作许多先进电子/光电设备的基础结构，以及用于防护涂层、热障和防弹衣。在这种材料异质性、高纵横比和缺陷奇点的结构中对应力和缺陷核心进行三维分析对计算科学和工程界提出了巨大的挑战。该项目采用格林函数 (GF) 方法，通过在参考 GF 中分层包含平面层特征来解决多层异质结构建模的困难，该特征可以在连续体级别上进行半解析求解。基于该多层矩阵，引入了缺陷。通过这种方式，多层异质结构中的缺陷问题被简化为仅对局部缺陷进行数值处理。此外，在连续体GF（CGF）的基础上，通过在长波长极限下实现前者对后者的渐近逼近，推导了多层异质结构的晶格GF（LGF）。 LGF 和 CGF 的结合提供了一种强大的数学工具，可以有效、准确地解决多层异质结构中的缺陷问题。在迭代方案中考虑了缺陷核心的非线性效应。该项目将建立一个强大的计算工具，可以帮助人们深入了解连续体和晶格尺度及其之间的缺陷力学和动力学。这将建立一个预测缺陷行为的框架，可用于预测设备的使用寿命，定制具有所需纳米结构的新型材料，并预防可以提高设备性能的缺陷问题。研究结果将被纳入并影响 PI 一直教授的计算力学课程以及他一直在开发的微/纳米力学课程。它将特别向学生介绍新颖的计算工具（即多尺度建模），并引起他们对新兴纳米技术的兴趣。该研究项目将涉及一名研究生，他们将接受应用力学、材料科学和固体物理学多学科领域的培训。因此，该项目有助于实现 NSF 培养新一代有能力的工人的目标，这些工人拥有新兴纳米技术快速进步所需的知识和技能。此外，PI 将通过该项目与 NIST 的科学家密切合作。他将在 NSF/NIST 格林函数数字图书馆网站上发布具有用户友好界面的计算机代码：http://www.ctcms.nist.gov/gf/ 供公众访问。这将扩大该项目更广泛的影响，以增强美国工业的实力并促进基于 GF 的计算工具在研究社会中的使用。