Accelerated wear test and failure mechanism analysis of PEEK water-lubricated thrust Bearing

The water-lubricated thrust bearing of the Rim-Driven Thruster (RDT) is responsible for carrying the thrust generated by the propeller and transmitting it to the hull. Due to the low-speed and heavy-load working condition, the thrust bearing faces the risk of abnormal wear and failure, and the failure mode and mechanism are still unclear. Taking the thrust bearing with aluminum bronze thrust collar and PEEK fixed pads as object, 48-hour accelerated wear test were carried out under four working conditions on the water-lubricated bearing test bench. The surface topography features of the pad and thrust collar are extracted before and after wear. The variation law of the friction coefficient, temperature difference between the inlet and outlet water, vibration signal, and floating amount of the thrust collar with time are studied, and the failure mode and mechanism of the bearing are analyzed. The results show that the PEEK-aluminum bronze friction pair wears severely under low-speed and heavy-load conditions, and the failure mode changes from adhesive wear to abrasive wear. The cuneiform water film is formed on the center of the pad surface, which is the main load region. It is difficult to form a water film near the inner and outer diameters of the pad, resulting in obvious ablation and plastic deformation, and the overall pad surface is concave. The maximum temperature difference between the inlet and outlet water is 14.2 °C, but the instantaneous high temperature that carbonizes the PEEK material appears on the pad surface. The traditional water temperature monitoring methods are difficult to reflect the working status of the water-lubricated bearing. The sudden change in amplitude at the feature frequency of 13500 Hz indicates that the bearing will deteriorate rapidly, and the impulse factor and waveform factor in the time domain feature can well characterize the degradation trend of the bearing.