尺寸效应对纳米银杆拉伸力学特性的影响

采用分子动力学方法研究了圆柱纳米银杆沿001]晶向单向拉伸时的力学特性，纳米银杆拉伸时所表现出的特性与其宏观特性基本一致．拉伸过程分为弹性变形和塑性延展2个阶段：在弹性变形阶段，应力随应变的增大呈线性增大；在塑性延展阶段，应力则表现出反复振荡，系统由一种结构经错动、滑移演化为另一种结构，是造成此种现象的一个重要原因．研究结果表明，随纳米银杆整体尺寸的增大，纳米杆的弹性模量增大、弹性极限应力减小，并都随整体尺寸的增大而趋于宏观值．随着纳米杆单方向的减小，纳米银杆的弹性模量和弹性极限应力均有不同程度的增加，并不随单方向的增加表现出趋于宏观值的一致规律．

Size Effects on Tension Properties of Silver Nanorod

The mechanical characteristics of silver nanorod subjected to\ uniaxial tensile strain are simulated with molecular dynamics.The tension properties of nanorod are similar to that of macroscopic material.The stress increases linearly as strain grows within the process of elastic deformation,and the dislocations and slips of structure lead to a stress oscillation during the process of plastic elongation.The influences of size effects are investigated simultaneously.Young's modulus heightens and the elastic ultimate stress decreases with the increasing global size of nanorod.Both of them approach to that of macroscopic material as the global size increases,and Young's modulus is enhanced with the reducing unidirectional size,e.g.,the height of nanorod,while the elastic ultimate stress increases slightly.Thus the increment of unidirectional size unables the tension properties to coincide with those of macroscopic material.