Mechanisms developed at the asperity scale for mixed lubrication between parallel surfaces

摘要

This article is based on an existing model to describe mixed lubrication between parallel surfaces. This model uses a statistical description of the microgeometry and includes summit and radius distributions. Depending on these geometric parameters, each asperity works with one of the five following lubrication mechanisms: piezoviscous hydrodynamic, elastohydrodynamic, elastic, elastoplastic, and full plastic. By summing the normal load obtained for each asperity, we derived the normal load for the entire contact. Discussion in this article is based on the repartition of asperities into each of these five possible mechanisms. We first analyze the parameters that are able to significantly change the limit between two neighboring regimes. The number of asperities associated with each regime is also considered. We also analyze the fraction of normal load transmitted by all asperities of a given regime. Generally, only a maximum of four regimes can generate significant contributions for a given situation. Depending on the operating conditions of the contact, these significant regimes change. Consequently, it seems very difficult to suggest reducing the number of regimes for a general description of mixed lubrication between parallel surfaces.