The friction of a nanosized spherical asperity in commensurate contact with a flat substrate is investigated by performing molecular dynamics simulations. Particular focus is on the distribution of shear stress within the contact region. It is noticed that within the slip zone, the local friction coefficient defined by the ratio of shear stress to normal pressure declines monotonically as the distance to the contact center increases. With the lateral force increasing, the slip zone expands inwards from the contact edge. At the same time, the local friction coefficient at the contact edge decreases continuously, while that at the dividing between the slip and stick zones keeps nearly invariant. These characteristics are distinctly different from the prediction of the conventional Cattaneo-Mindlin model assuming a constant local friction coefficient within the entire slip zone. An analytical model is advanced in view of such new features and generalized based on numerous atomic si...

中文翻译：

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纳米粗糙物与尺度有关的摩擦的半分析模型

通过执行分子动力学模拟，研究了与平面基板相称接触时纳米级球形凹凸的摩擦。特别关注的是接触区域内的剪切应力分布。注意到在滑动区域内，由切应力与法向压力之比定义的局部摩擦系数随着到接触中心距离的增加而单调下降。随着侧向力的增加，滑移区从接触边缘向内扩展。同时，在接触边缘处的局部摩擦系数连续减小，而在滑动区域和粘着区域之间的分界处的局部摩擦系数几乎保持不变。这些特征与常规Cattaneo-Mindlin模型的预测有明显不同，假定整个滑动区域内的局部摩擦系数恒定。鉴于此类新功能，分析模型已得到改进，并基于众多原子模型进行了推广。