润滑状态下线接触滑动粗糙界面的动摩擦特性研究

滑动粗糙界面的摩擦润滑特性对界面的润滑设计和润滑状态预测具有重要的理论和实际意义。本文通过建立不同润滑状态下的滑动粗糙界面模型，基于界面的法向载荷由润滑油膜和粗糙体共同承担的载荷分配思想，采用Greenwood-Williamson统计模型描述粗糙表面形貌，考虑界面润滑的时变效应和润滑油的粘-压特性，建立了线接触滑动粗糙界面的油膜厚度方程和粗糙体接触压力方程，获得了整个润滑区的润滑油膜载荷比例因子、油膜厚度和摩擦系数随滑动速度的变化关系，推导了界面由混合润滑过渡为液压润滑的临界速度关系表达式，分析了滑动粗糙界面的润滑承载机理，获得了界面油膜厚度、摩擦系数和临界速度随界面形貌参数、法向载荷、润滑油属性参数的变化规律，为机械结构的界面润滑设计、润滑状态预测和润滑优化提供理论和实验参考。

Study of the friction lubrication characteristics of sliding rough interface in line contact

The dynamic friction lubriction characteristics in sliding rough interface are important to lubrication design and lubriation state prediction of mechanical structures. In this paper, the sliding rough interface model describing different lubrication states is established based on the load sharing concept that the total normal load is shared by the hydrodynamic lifting force and the asperity interacting force. The rough surface topography is described using the Greenwood-Williamson statistic model. The film thickness equation and the asperity contact pressure equation at the lubricating interface are established considering the time varient effect and the viscosity-pressure characteristic. The relationship between hydrodynamic scaling factor, film thickness, friction coefficient and sliding velocity are obtained in the full lubrication regimes of boundary lubrication, mixed lubrication and elastohydrodynamic lubrication. Expression of the critical velocity, at which the transition from mixed lubrication to elastohydrodynamic lubrication occurs is derived. The lubrication loading mechanism is analyzed and the evolution of film thickness, friction coefficient and critical velocity with respect to surface roughness, normal load and lubrication viscosity are obtained. The obtained results provide theoretical and experimental guidelines to lubration design, prediction and optimization.