摘要:
应用人规模分子动力学方法,模拟了具有不同原子级粗糙形貌的两种刚性球形探头与弹性平面基体的黏附接触行为.研究了载荷与真实接触面积、接触界面排斥力与真实接触面积,以及黏附力与真实接触面积之间的关系.分子模拟得到的载荷与真实接触面积的关系,与连续力学接触理论预测很好地定性一致.无论是原子级光滑探头还是粗糙探头,黏附接触下的排斥力与真实接触面积的关系,都与无黏附接触时的规律相～致,即黏附力对接触行为的影响作用.可以等效为附加在真实外载荷基础上的虚拟载荷,将对黏附接触行为的分析转变为无黏附接触分析.两种探头的黏附力随真实接触面积都呈幂函数形式的增长,但是,原子级光滑探头的幂指数大于1,而原子级粗糙探头的幂指数小于1.
Abstract:
Large-scale molecular dynamics simulations are performed to study the adhesive contact between a rigid spherical tip and an elastic flat substrate.We focus on he relations between the real contact area and the external load and between the repulsive force and attractive force on contact interface.The simulated results are consistent with the corresponding continuum contact theories,which are Hertz model,Ggeenwood-Williamson（or Persson） model and Maugis-Dugdale model according to surface roughness and interfacial adhesion.We show that there are same relations between the real contact area and the repulsive force for both non-adhesive and adhesive contact,which means that the effect of adhesion on contact behavior can be equivalent to that of a virtual load.We demonstrate that the attractive force on contact interface increases with the real contact area in a power-law function,with a power exponent larger than 1 for the atomic-scale smooth tip and with a power exponent smaller than 1 for the atomic-scale rough tip.
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