MIXED LUBRICATION

If the simplest rheological model of a lubricant, the newtonian model, is used in the calculation of oil film thickness between elastohydrodynamically lubricated smooth or rough surfaces, oil film breakdown is never experienced. As soon as the oil film thickness over an asperity becomes thin enough, a local pressure will be built up there, squeezing the asperity into the surface and making sure that no metal-to-metal contact takes place. Oil film breakdown and surface contact through the oil film can be explained only if the behaviour of the oil is non-newtonian. In this paper, the influence of the limited lubricant shear strength on the asperity behaviour in the high-pressure zone of an elastohydrodynamic lubrication contact is studied theoretically, experimentally and numerically. © 1990.