Transient tribo-dynamic performance of journal bearings considering wear behavior during start-up

The transient tribo-dynamics and wear model are coupled to study the mixed lubrication-wear behavior during start-up. The coupled numerical model involves the film thickness equation with wear depth and a time-varying wear coefficient to account for the impact of transient mixed lubrication behavior on wear. In this study, the evolution of wear and mixed lubrication performance distribution over time is predicted, and the impact of acceleration mode, acceleration time, external load, lubricant viscosity, and start-up time on the numerical predictions is evaluated. The findings demonstrate that wear behavior, particularly in the analysis of the effects of acceleration mode and acceleration time, has a significant impact on the evaluation of the bearing-rotor system's start-up performance and even changes the determination of optimal parameters. Furthermore, the parametric study demonstrates that wear and mixed lubrication performance are sensitive to the external load and lubricant viscosity. Finally, studies on the effect of start-up times show that proper wear geometry promotes hydrodynamic effects, but severely worn bearing surfaces have a negative effect on start-up.