Theoretical and experimental investigation of traction coefficient in line-contact EHL of rough surfaces

The behavior of traction coefficient in line-contact EHL with provision for surface roughness is studied and a method for its prediction is presented. The statistical elasto-plastic asperity contact model is utilized to determine the traction coefficient with consideration of the free volume properties of the lubricant suitable for a wide range of high pressures and temperatures. The results are validated experimentally and a useful expression is derived for prediction of traction coefficient that takes into account both hydrodynamic and surface asperity effects.