关于纳米结构非局部效应的深入探讨和对比研究

项目名称： 关于纳米结构非局部效应的深入探讨和对比研究

项目编号： No.11202145

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 数理科学和化学

项目作者： 李成

作者单位： 苏州大学

项目金额： 26万元

中文摘要： 非局部理论是研究纳米力学的有效方法之一，目前该理论及应用领域内存在两类彼此矛盾的模型，即非局部效应"削弱模型"与"增强模型"。针对这种矛盾，一方面，直接从非局部高阶微分本构入手，深入探寻非局部应力场的结构特征和影响模式，探讨非局部效应的物理内涵和作用趋势，以及确定非局部材料常数的有效途径。另一方面，为判别两种不同的非局部模型的合理性和有效性，采用三种途径：①完善超薄结构动力学的半连续模型，分析表面原子层的弛豫效应对结构动力学行为的影响，将结果所反映的尺度效应与非局部效应作对比；②在半连续模型的基础上构建晶格动力学模型，以晶格点阵结构衡量非局部连续体模型；③通过纳米结构的分子动力学模拟，获取简单结构的动力学行为特征及演化，进而用模拟结果来验证理论模型。本项目通过深入探讨纳米结构的非局部效应，同时以对比研究给出两种非局部模型的内在成因，为纳机电系统中典型结构的性能分析和设计制造提供理论依据。

中文关键词： 非局部理论；半连续模型；分子动力学模拟；尺度效应；微纳米力学

英文摘要： Nonlocal theory is one of the most effective approaches in nano-mechanics. So far two kinds of opposite models exist in nonlocal elasticity theory and its application field, i.e., the weakened model and the enhanced model of nonlocal effect. On one hand, this project proposes to investigate the nonlocal higher-order differential constitutive relation in order to make an in-depth research on the component characteristics and working mode of nonlocal stress field, the physical meaning and developmental trend of nonlocal effect, as well as the effective approach to determine the nonlocal material constant. On the other hand, three methods are proposed to verify the rationality and validity of the two opposite nonlocal models. Firstly, to refine a semi-continuum model for dynamics of ultra-thin structures. The relaxation of atomic layers on surface is considered, and the relaxation effect on dynamical behaviors of nanostructures are analyzed. The size-dependence presented in the semi-continuum model will be compared with the nonlocal effect. Secondly, a lattice dynamical model based on the semi-continuum model will be applied. The two opposite nonlocal elasticity models are comparatively measured by crystal lattice. Thirdly, a molecular dynamic simulation approach will be employed to reveal the dynamical pr

英文关键词： nonlocal theory；semi-continuum model；molecular dynamics simulation；scale effect；micro/nano-mechanics