The influence of elastohydrodynamic lubrication on the stiffness of deep groove ball bearing

An accurate modeling of roller bearing element, considering the complex contact behavior and load conditions, is very important to the geared-rotor system design. This paper presents an enhanced bearing stiffness matrix for a deep groove ball bearing by including the elastohydrodynamic lubrication (EHL) effects in the ball-raceway contact. The bearing model is subjected to the coupled lateral-translational loads. The EHL contact is calculated by employing the multilevel method. Then, the EHL result was used to drive the relationship between the contact force and mutual approach. Moreover, the effect of the centrifugal inertial force on the ball elements resulting from the circumferential cage motion is considered. New equilibrium equations of the ball bearing considering the EHL contact model were established, and an enhanced bearing stiffness matrix was given. The dominant stiffness coefficients of deep groove ball bearing due to external loads under both lubricated and dry contact conditions are compared. Parametrical studies are also carried out to investigate the influence of the EHL on the stiffness matrix. Results show that the EHL has a negligible effect on the radial stiffness coefficients for all load conditions. However, the EHL has more influence on the rotational and coupling stiffness coefficients.