Unified mixed-lubrication modeling for marine water-lubricated bearings under harsh operating conditions

This paper presents an enhanced mixed lubrication (ML) model for marine water-lubricated bearings (WLBs), which are frequently subjected to harsh operating conditions. The model combines a revised average Reynolds equation, suitable for extremely low film thickness ratios, with a deterministic asperity contact model derived from numerical simulations of elastic–plastic surface interactions. Unlike conventional statistical approaches, the contact model captures local asperity deformation and mutual interactions, enabling more accurate predictions of contact pressure and film thickness in boundary-dominated regions. Overall, the framework explicitly incorporates shaft misalignment and provides a unified, computationally stable description of non-uniform lubrication states where hydrodynamic, mixed, and boundary regimes may coexist. The validity of the proposed model is confirmed through friction experiments and benchmarked against a representative ML approach. Simulation results reveal pronounced axial variations in film thickness, load-carrying capacity, and friction force. Parametric analyses further demonstrate that higher elastic modulus, yield strength, and surface roughness increase asperity contact and friction, while longitudinal surface textures weaken hydrodynamic pressure generation. The present study offers new insights into understanding and optimizing ML in WLBs, providing practical guidance for improving their tribological performance in marine applications.