A theoretical analysis of mixed lubrication by macro micro approach: Part I - Results in a gear surface contact

Mixed lubrication is a key to bring the performance analysis to the failure analysis in most tribological components. A macro- micro approach to, mixe d lubrication has been developed in the present model. The relation between the average contact pressure and the average gap for a typical rough conta ct patch is first determined numerically in micro scale. Using this relatio n, the average gap, average oil-film pressure, and average contact pressure in a mixed-lubricated elastohydrodynamic contact can be solved simultaneou sly in macro scale by treating the contact to be smooth. The total pressure is assumed a super-position of average asperity contact pressure and lubri cant pressure. The new approach is simple, efficient and robust, and covers entire range of the load ratio,from unity (dry contact) to zero (full-film EHL). In addition, it can be used for a wide range of operating conditions and on a much larger contact area with a much less computing time than det erministic simulation of mixed lubrication. Implementation of the Fast Four ier Transform (FFT) allows for a rapid calculation of the elastic deformati on and asperity contact pressure. As a demonstration to this new approach, a parametric study of dimensionless speed, load and contact shape on the lo ad ratio and gap ratio was conducted for a gear rough surface.