A novel approach for modeling misaligned water-lubricated stern bearings with wave-shock effects during start-up

Water-lubricated stern bearings during the start-up stage exhibit pronounced multi-physical coupling characteristics, with their tribo-dynamic performance significantly influenced by journal misalignment and sea wave shocks. This study proposes a novel multi-physics coupling approach to predict the start-up tribo-dynamic behavior of misaligned water-lubricated stern bearings under sea wave-induced shocks. The approach integrates transient mixed elastohydrodynamic lubrication with a rotor dynamics model, comprehensively accounting for factors such as surface topography, bearing elastic deformation, transient start-up process, journal eccentricity and misalignment, as well as external wave-induced excitations. The method is first validated for its reliability and accuracy, and then applied to predict the dynamics and tribological characteristics of misaligned water-lubricated stern bearings under wave-induced excitation of the time-varying misalignment moments and loads. The results demonstrate that the start-up performance is highly sensitive to external shock loads and journal misalignment, while increasing journal acceleration improves lubrication performance and mitigates the adverse effects of shock loads during start-up. This study provides valuable insights for enhancing the design and operational stability of marine water-lubricated bearings, contributing to improved reliability and longevity under dynamic wave shock conditions.