In this study, a structural optimization method driven by tribo-dynamic mechanism is proposed for the staved water-lubricated bearings (SWLBs). To this end, a tribo-dynamic model considering mass conservation cavitation is established, and the accuracy of this model is verified by comparing it with the experimental and numerical results in published literature studies. The comparative studies emphasize the significant role of mass conservation cavitation on the tribo-dynamic responses of SWLBs under the mixed lubrication regime. Based on numerical simulations, the optimal stave structure for a specific working operation under heavy load condition is identified from the perspective of the tribo-dynamic mechanism. Furthermore, in order to evaluate the applicability of the proposed optimization method, the influences of key parameters, including the rotational speed, the radial clearance, and the surface roughness, on the optimization results are comparatively analyzed. The comparative results reveal that the optimal stave structure is highly dependent on the mentioned key parameters, and the optimal method is effective for a wide range of working conditions. Moreover, the effects of the stave parameters, including stave width and number, on tribo-dynamic characteristics of SWLBs are also investigated, suggesting a more comprehensive optimization scheme for SWLBs.

This study explores the effects of wear and shaft-shape error defects on the tribo-dynamic responses of water-lubricated bearings under nonlinear propeller disturbance using a numerical model. The model proposed in this paper is verified by comparing the results from experiments and simulations in published studies. Numerical simulation studies reveal the effects of nonlinear propeller disturbance on the dynamic behavior and lubrication performance, such as hydrodynamic force, contact force, and journal trajectory, of the water-lubricated bearings with wear and shaft-shape errors. In addition, the effects of the critical factors for wear and shaft-shape errors, including wear depth, deviation angle, magnitude, and waviness order, on the tribo-dynamic responses of water-lubricated bearings are identified. The results of numerical spectrum analyses show that the nonlinear disturbance significantly affects the dynamic behavior (shown as the fluctuation range of the journal trajectory increases), and reasonable wear parameters can improve the lubrication performance of the water-lubricated bearing. Moreover, the effects of shaft-shape errors on the transient hydrodynamic force, contact force, film thickness, pressure, and journal trajectory are greater than that of wear.

The main purpose of this study is to investigate the dynamic mixed elastohydrodynamic lubrication (DMEHL) behavior of the water-lubricated bearing with unbalanced rotor during start-up. To achieve this, a DMEHL model that couples the rotor dynamic model considering the unbalanced load with the transient mixed lubrication model is established. The validity of the calculation procedure is verified by comparisons with published experimental and numerical results. Using numerical studies, the optimal accelerating mode for reducing the transient asperity contact during start-up is identified. Numerical results indicate that during start-up, the rotor dynamic characteristic and hydrodynamic force are more sensitive to the unbalanced load than the transient contact force, and the rotor imbalance eccentricity will affect the transient contact behaviors if the surface roughness is relatively large. In addition, the DMEHL responses are affected by the unbalanced load only when the accelerating time is small. Finally, the DMEHL responses during start-up using three different water-lubricated materials, namely, polymer, Thordon, and ceramic, are compared. It is found that DMEHL performance at the start-up stage highly depends on the elastic modulus and hardness of the water-lubricated material.

The purpose of this study is to investigate the role of the misalignment journal, caused by linear shaft misalignment, on the transient wear and mixed lubrication performances using a numerical model. In the numerical model, the transient geometry lubrication clearance considering the journal misalignment, the transient elastic deformation, and the transient wear depth of the bearing are incorporated to evaluate the transient film thickness during the wear process. The evolutions, under different external loads, of the wear depth of the bearing, wear-rate, elastic deformation of the bearing, film thickness, fluid pressure, and contact pressure are calculated by the numerical model. Furthermore, the calculated results of the misaligned journal bearing are compared with those of the aligned journal bearing. The results show that the distributions of the wear depth of the bearing, film pressure, and elastic deformation of the bearing are asymmetric along the axial direction and the peak values of them shift toward the back end when the journal misalignment is considered. The maximum wear depth, maximum fluid pressure, maximum contact pressure, and maximum bearing’s elastic deformation of the misaligned journal condition are significantly larger than those of the aligned journal condition.

The study presents a dynamic wear model for micro-grooved water-lubricated bearings considering the transient mixed elastohydrodynamic lubrication (mixed-EHL) condition. In the established model, the modified Archard wear model and the mixed-EHL model are bridged to study the transient interdependent relationship between the sliding wear behavior and the mixed-EHL performance. In order to consider the effect of the transient mixed-EHL performance on the sliding wear, the Archard model is extended to include the time-varying wear coefficient based on the fatigue concept. To verify the presented model, the comparisons with the experimental results available in the literatures have been conducted. In this study, the evolution of the wear and mixed-EHL performance distribution over time is predicted, and the impact of the radial clearance, boundary friction coefficient, and surface parameters on the numerical predictions is evaluated. The simulation results reveal that the worn region moves toward the rotational direction slowly. The simulation results also reveal that the wear rate and the wear coefficient first decrease considerably, and then decrease gently, and the sliding wear geometry promotes the hydrodynamic effects and reduces the asperity contact during the operation. Furthermore, the parametric study demonstrates that dynamic wear and mixed-EHL performance is sensitive to the radial clearance, boundary friction coefficient, and surface parameters.