Friction prediction of rolling-sliding contact in mixed EHL

A new numerical model for the friction prediction of the mixed elastohydrodynamic lubrication (EHL) is presented. The overall friction coefficient was calculated by integrating the uniform shear stress contributed by the fluid film and asperity interactions. Numerical results demonstrate that: (1) a large load often induces a large friction coefficient, (2) an increase in the surface roughness increases the friction coefficient both in mixed EHL and full film EHL, and (3) the rolling velocity decreases the friction coefficient in mixed EHL due to the increases in hydrodynamic effect and lubricant film thickness. In addition, a stribeck curve is presented to reveal the transition of friction and lubrication conditions from boundary lubrication to mixed EHL and full film EHL. The current approach has proven to be able to predict the friction coefficient over a wide range of loading conditions.