低维纳米结构弹性性能的尺寸效应研究

项目名称： 低维纳米结构弹性性能的尺寸效应研究

项目编号： No.10802057

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 郭建刚

作者单位： 天津大学

项目金额： 23万元

中文摘要： 本项目研究了低维纳米结构（包括纳米薄膜、纳米线、石墨烯纳米带和碳纳米管等）尺寸和表面相关的弹性性能。基于连续介质力学和晶体结构理论，构建了纳米结构的晶格模型，在模型中引入表面效应的影响，利用能量方法，建立了低维纳米结构的本构关系，导出了纳米结构尺寸和表面相关的弹性模量、剪切模量以及热膨胀系数的解析表达式，分析了纳米结构的弹性性能随结构特征尺寸的减小而增强或减弱的物理机制。基于连续介质力学和分子动力学之间的联系，建立了石墨烯纳米带的结构力学模型，利用有限元法计算了石墨烯纳米带的拉伸弹性性能，证明其是尺寸和手性相关的。另外还分析了表面缺陷对石墨烯力学性能的影响。 本项目研究了可适用于纳米结构材料的力学性能测量的微拉曼光谱测试理论和技术，原位测量了碳纳米管纤维材料的力学性能参数，分析了碳纳米管纤维在拉伸过程中的变形机理和应力传递机制。针对低维纳米结构的应用，本项目研究了纳米结构器件和纳米结构作为填充物的复合材料中的表面/界面力学问题。

中文关键词： 低维纳米结构；弹性性能；尺寸效应；表面/界面；微拉曼光谱

英文摘要： In this project, size- and surface-dependent elastic properties of low-dimensional nanostructures (including nanofilms, nanowires, graphene nanosheet and carbon nanotube, etc.) are studied. Based on continuum mechanics and theory of crystal structure, a crystal lattice model is presented to predict the elastic properties of nanostructures taking surface effects into account. Via the method of energy, the constitutive relation of low-dimensional nanostructures is derived, and the analytical expressions of size- and surface-dependent elastic properties, including elastic modulus, shear modulus and thermal expansion coefficient, are obtained. The physical nature that elastic properties of nanostructures are enhanced and weakened with decreasing the characteristic dimensions of the nanostructures is analyzed. According to the linkage between classical structural mechanics and interatomic potential energy in molecular mechanics, the models of space frame structures are developed to simulate the graphene nanosheets. By using finite element method, elastic properties of the graphene nanosheets are calculated, and are proved to be size- and chirality- dependent. In addition, the influence of surface defect is analyzed on mechanical properties of graphene nanobelt. In the research, theory and technique of micro-Raman spectroscopy to measure mechanical properties of nanostructural materials are investigated. The elastic properties of carbon nanotube (CNT) fibres under tensile loading are measured by means of in situ Raman spectroscopy, and the deformation mechanisms and stress transfer are studied in the process of stretching. In addition, as for the application of low-dimensional nanostructures, the surface and interfacial mechanical problems are also studied in the nanodevices and nanocomposites where low-dimensional nanostructures serve as structural units or filler.

英文关键词： Low-dimensional nanostructures; Elastic properties; Size effects; Surface/interface; Micro-Raman spectroscopy