On the Stiffness and Damping Characteristics of Line Contacts under Transient Elastohydrodynamic Lubrication

Abstract

The elastohydrodynamic lubrication (EHL) oil film between contact interfaces acts as a spring or damper to reduce wear and vibration for frictional pairs. To analyze the dynamic behaviors of friction pairs in mechanical systems both effectively and accurately, the stiffness and damping parameters under EHL contact states are essential. The presented work develops a numerical model to investigate the EHL stiffness and damping characteristics based on the transient EHL system and elastic contact theory of line contact, in which the stiffness force is separated according to the relationship with approach distance of the contact body established in the steady process, and then the damping can be obtained. The results show that the stiffness force plays an increasingly important role over the applied load conditions while the damping effects is gradually weakened. EHL stiffness is obviously smaller than dry contact stiffness, but the discrepancy is decreasing with the increasing load. Moreover, the higher entrainment velocity, lubricant viscosity and larger curvature radii leads to smaller stiffness and damping. The elastic modulus generates little effect on dynamic characteristics when the load is light while dominates the maximum level of the contact stiffness.