The effect of viscoelasticity in lubricated contacts in the presence of cavitation*

A technique used to improve the performance of lubricants is in the addition of polymers to mineral oils. Lubricants containing polymer additives exhibit viscoelastic effects and have been observed to possess superior lubrication properties when compared to lubricants without additives. In this study, we propose a model based on the thin film approximation for viscoelastic lubricants that includes also the presence of cavitation described by the mass conserving Elrod-Adams algorithm. We use the Oldroyd-B constitutive relation to model the viscoelasticity of lubricants and assume that the product between ε, i.e. the ratio of the vertical and horizontal length scales, and the Weissenberg number (Wi), i.e. the ratio between polymer relaxation time and flow time scale, is small. In doing so, it becomes possible to linearize the set of thin film equations. Results in a parabolic slider profile representing a journal bearing unwrapped geometry show an increase in load by strengthening viscoelasticity. On the other hand, for pocketed profiles, mimicking a textured surface, the influence of the viscoelasticity on the load depends on the location of the pocket. If the pocket is close to the entry (exit), the load decreases (increases) with Wi.