EHD contact regions between roller and ring are divided into lead-in region, Hertzian
region and exit. Due to the release of pressure, in exit zone the damping is negligible.
[WS83] has done a lot of measurements to justify that in Hertzian contact region, the
Hertzian contact stiffness is considerably smaller that the film stiffness. So in Hertzian
contact area, the equivalent stiffness is determined by Hertzian contact stiffness.