计及表面效应的面心立方纳米板弹性性能分析

Elastic properties of FCC nanoplates taking into account surface effect

基于能量原理建立了面心立方纳米板的拟连续介质力学模型,分析了考虑表面原子弛豫影响的面心立方纳米板的弹性常数。该模型假设纳米板沿厚度方向是离散的,但沿面内方向是连续的。基于通过计算最相近原子对和次相近原子对之间的相互作用,获得了材料变形势能。给出了面心立方纳米板的弹性模量和泊松比的解析表达式,结果反映了表征表面效应的驰豫系数的影响。以金属铱为例,通过算例阐述了不同弛豫下弹性常数随厚度的变化,分析了纳米板的弹性模量和泊松比的尺寸效应。

A quasi-continuum model for face-centered-cubic(FCC)nanoplates incorporating the effect of surface atomic relaxation is proposed based on the energy principle,and the elastic constants of FCC materials are analyzed.It is assumed that the model is discrete along the thickness direction,but continuous along the in-plane direction.The potential energy of deformation is formulated by analysis of the interactions between the nearest atomic pair and the next nearest atomic pair.The analytical expressions for in-plane and out-of-plane elastic moduli and Poisson's ratios of such nano materials are presented,and the surface effect is evaluated by magnitude of an introduced relaxation coefficient.As an example,iridium metal is chosen as the material in computational model.The changes in elastic constants with the thickness are given for different values of the relaxation coefficient,and the size effect of elastic moduli and Poisson's ratios is analyzed.