Thermal and non-Newtonian analysis on mixed liquid–solid lubrication

A mixed liquid–solid lubrication theory is proposed which concerns the effect of solid particle, liquid lubricant and rubbing surface topography. Especially, it focuses on the circumstances when particle diameter, surface composite roughness and oil film thickness are in the same order of magnitude. A mathematical model containing Reynolds equation, particle load carrying equation, asperity contact equation and heat balance equation is constructed to simulate the mixed liquid–solid lubrication. Moreover, the introduction of non-Newtonian constitutive equation and the rheological parameters related to heat and pressure makes the model closer to practical application. Some typical examples have been analyzed to explore the characteristics of mixed liquid–solid lubrication. In these examples, the effects of the mixed liquid–solid lubricant, the particle diameter and mass concentration, the surface composite roughness, and the material properties are discussed. The simulating results are accordant with early experimental researches, which indicated that the mathematical model is in agreement with the practical mixed liquid–solid lubrication. The input parameters in the examples can be adjusted to adapt to versatile applications.