铜纳米丝的应变率和尺寸效应的分子动力学模拟

用分子动力学方法对铜纳米丝的应变率效应和尺寸效应进行了模拟研究．结果表明,随着加载应变率的增大,铜纳米丝从低应变率下的静态响应逐渐呈现出较高应变率下的准静态以及高应变率下的动态响应特征,其变形机制以及应力一应变曲线的形态也随之发生变化．在静态和准静态区域,位错运动是铜纳米丝塑性变形的主要来源,而在高应变率动态加载时,铜纳米丝出现整体结构的非品化,最大屈服应力也随着应变率的升高而增大,强化现象明显．当铜纳米丝的截面尺寸变化时,其弹性摸量、屈服应力以及屈服应变、进入强化区域的临界应变率等都发生相应的变化,尺寸效应显著。

Molecular dynamics simulation of the strain rate effect and size effect for Cu nanowire

The strain rate effect and size effect of nanowire were studied by using molecular dynamics simulation. The results show that the strain rate effect of nanowire is very obvious. The response characteristic of nanowire transfers from static to quasi-static and furthermore to dynamical response with the increasing of strain rate. The deformation mechanism varies with different strain rates. In the static and quasi-static regions, which were called insensitive and transition region respectively, the main source of plastic deformation is contributed from dislocation movements. However, the whole structure may be amorphous and hardened under high strain rates in strengthening region. The size effect of nanowire is very distinct as well. As the cross section area changes, its Young's modulus, yield stress, yield strain and the critical strain rate will shift correspondingly.