Entropy-based fluid–solid–thermal coupled wear prediction of journal bearing during repeated starting and stopping

Abstract

The novelty of the present study is to construct an Entropy-based wear and fluid-solid-thermal (FST) coupled model for journal bearings, which reveals the transient interaction behavior between wear evolution and FST evolution during repeated starting and stopping. The wear rate is measured experimentally and the contact temperature, friction coefficient and normal contact force are obtained from the validated FST model. Wear tests for the lubricated journal bearing at three constant speeds are used to validate the predicted wear rate. Numerical calculations give the time-varying wear and FST evolution of journal bearings during repeated starting and stopping at the same or different start-stop time, including wear rate, wear depth, temperature, fluid pressure and contact pressure. The effects of the bearing thickness, maximum speed, radial clearance and load on the wear and FST performances are evaluated. The simulation results reveal that the rate of change of wear rate in the start-stop cycle first increases rapidly and then decreases slowly as the number of start-stop cycles increases. The distributions of the contact pressure and the fluid pressure become wider along the circumferential direction with the increase in the number of start-stop cycles while the maximum values become smaller. The maximum wear depth increases with increasing start-stop time for an identical number of start-stop cycles, and the shorter the start-stop time is, the higher the maximum temperature tends to be. Furthermore, the effect on the maximum wear depth and maximum temperature of journal bearings will become significant when the maximum speed and bearing thickness are relatively small or the radial clearance and load are relatively large.