混合润滑状态下粗糙界面法向接触刚度计算模型与特性研究

A calculation model for the normal contact stiffness of rough surface in mixed lubrication

机械装备系统的静态特性和动力学特性取决于系统接触界面法向接触刚度。基于粗糙表面形貌的Greenwood-Williamson统计模型描述与液体润滑界面的油膜共振模型和弹簧模型,推导了机械结构混合润滑粗糙界面固体接触刚度和液体润滑介质接触刚度,并实现粗糙微凸体固体接触刚度与液体润滑介质接触刚度的耦合,提出了一种混合润滑状态下粗糙界面法向接触刚度的计算模型,分析了接触界面形貌参数、润滑介质和接触基体材料属性对界面法向接触刚度的影响规律。结果表明:润滑介质的声阻抗是影响液体接触刚度的主要因素,声阻抗增大时,液体接触刚度减小;接触基体材料的表面形貌和弹性模量是影响固体接触刚度的主要因素,界面粗糙度和弹性模量增大时,固体接触刚度增大。混合润滑粗糙界面接触刚度计算模型的提出,为机械结构润滑接触界面的刚度计算、性能预测与优化提供理论和实验参考。

The normal contact stiffness is an essential parameter for describing the interface characteristics and exhibits significant influence on both the static and dynamic behavior of the mechanical system.In this work,a general contact stiffness model was proposed to study the mixed lubricated contact for rough surface contact.The total interfacial contact stiffness was composed of the dry rough surface contact stiffness and the liquid lubricant contact stiffness.The Greenwood-Williamson model was used for surface topography description and the whole dry rough contact stiffness was obtained.The liquid film stiffness was derived based on the film resonance model and the spring model spring model.Effects of surface roughness,property of lubricant layer and property of contact solid on the normal contact stiffness were analyzed.Results show that the acoustic impedance is the main factor determining the liquid film stiffness and the liquid film stiffness decreases with acoustic impedance.The surface topography and elastic modulus are the main factor determining the solid contact stiffness.The proposed calculation model for normal contact stiffness of rough surface in mixed lubrication provides foundation for stiffness calculation,performance predication and optimization of mechanical structure.