Study of Stiffness Reduced Order Model Applied to Line and Elliptical Contact Under EHD Lubrication

Nonconforming contact study is fundamental to model the behavior of mechanical equipment such as bearings and gears. In order to predict lifetime of rolling element bearings, film thickness and pressure distribution can describe the lubrication condition, allowing the analysis of the contact response to load, rotation speed, oil parameters and geometry. The EHD elliptical contact can be approximate to an equivalent line contact when taken the central line at the major ellipsis axis, since the maximum Hertzian pressure, lubrication oil, rotation speed and radius of curvature are identical. A comparison between the stiffness reduced order model of elliptical contact and an equivalent line contact, based on an explicit load-distribution relation, is accomplished. Moes load and lubrication dimensionless parameters describe the contacts along with the elliptical contact ellipticity. The influence of speed and ellipticity were verified on the oil film and pressure in a range of load conditions, as well as EHD stiffness reduced order model parameters. The ellipticity range evaluates the similarity between both kinds of contact and verifies its equivalence.

The present work analyses the contact reduced order model and its main parameter influence, the EHD stiffness. As the contact properties, film thickness and pressure distribution, directly affect the lifetime estimation of rolling element bearings, the study can bring useful insights during project stage. Moreover, an improved EHD nominal model can promisingly be applied in fault identification in rotating systems and other mechanisms.