Stiffness and damping of elastohydrodynamic line contact applied to cylindrical roller bearing dynamic model

Abstract

This work aims to propose a roller bearing model introducing a concept of reduced contact force model under elastohydrodynamic lubrication (EHL) by a set of equivalent contact stiffness and viscous damping. The reduced model of EHL contact force has the advantage of inserting the effects of the oil film into systems in order to make the model more realistic without needing to numerically solve EHL system of equations at each new loading condition. The oil film between the bearing elements significantly affects its force equilibrium and its dynamic behavior and, consequently, the response of the rotating system in which it is inserted. The system of EHL equations in time domain is usually solved using multilevel methods for finite line contact at each time step of equation of motion integration. This process can be highly time consuming. The proposed reduced model of contact force is based on the terms of restitutive force and dissipative force. From the parameters of the reduced EHL contact force, the full roller bearing model can be characterized and easily introduced in equation of motion of the rotor. The validation of the rotor dynamics model was accomplished in an experimental test rig. The orbits of the proximity sensors and the Discrete Fourier Transforms (DFTs) of the amplitudes for theoretical and experimental tests are in expressive good agreement.