Possible Role of Compressional Viscoelasticity in Concentrated Contact Lubrication

An equation relating liquid density and viscosity under transient pressure conditions is derived. The derivation combines approximate phenomenological descriptions of the viscoelastic compression of a liquid and the dependence of viscosity on pressure and density. Solutions of the equation for a “step”-pressure increase and a semielliptical pressure cycle show that density and viscosity of Newtonian lubricants may significantly lag pressure transients under concentrated-contact lubrication conditions. Qualitatively, the lag effects appear to account at least partially for anomalous experimental observations involving asperity interactions and elastohydrodynamic lubrication of rollers.