Fluid Film Lubrication

Lubricants can be solid or fluid (liquid or gaseous). This chapter describes various regimes of fluid film lubrication and presents associated data and mathematical analyses and their application to bearing applications. Regimes of lubrication described include hydrostatic lubrication, hydrodynamic (HD) lubrication, and elastohydrodynamic (EHD) lubrication (EHL). A summary of the lubrication regimes observed in fluid lubrication without an external pumping agency (self-acting) can be found in the familiar Stribeck curve. In hydrostatic, hydrodynamic, and elastohydrodynamic lubrication, the Reynolds equation is used to obtain a relation between the geometry of the surfaces, relative sliding velocity, the property (viscosity and density) of the fluid and the magnitude of the normal load. In the EHL regime, the Reynolds equation, the elastic deformation equation and the equation relating viscosity and pressure are simultaneously solved.