Stability of friction-induced vibrations in water-lubricated bearings with interfacial mechanical effects

In this work, a friction-induced vibration model for water-lubricated bearings (WLBs) is developed. The model incorporates interfacial mechanical effects, including the stiffness and damping coefficients of the water film, contact stiffness of asperities, elastic deformation of the bush, etc. To evaluate the friction-induced vibration state, i.e., stability of WLBs, complex eigenvalue analysis is employed. A frictional noise experiment for a WLB is performed to validate the effectiveness of the developed model. Based on this model, the stability diagram of friction-induced vibrations in WLBs under various parameters is obtained, and the effects of key parameters, such as radial clearance, angular groove amplitude, and boundary friction coefficient, on the stability are investigated. Numerical results indicate that increasing the boundary of friction, surface roughness, radial clearance, and angular groove amplitude elevates the risk of unstable friction-induced vibration. Furthermore, numerical studies reveal the existence of a critical rotational speed at which friction-induced vibration transitions from being unstable to stable. As the rotational speed approaches the critical value, the risk of unstable friction-induced vibration rapidly decreases. Within the hydrodynamic lubrication regime, the maximum vibration attenuation index tends to remain constant, regardless of any further increases in the rotational speed.