Experimental assessment on the anti oil interruption capacity of hybrid ceramic ball bearings for aircraft engines

Oil interruption test is a crucial step for the performance assessment of main shaft bearings in the aircraft engines. Hybrid ceramic bearings have excellent advantages of high speed, heavy load, long life, and high temperature resistance, and have a wide range of applications in the aerospace industry. In this paper, an oil interruption test was conducted on an all-scale bearing test rig until bearing failure appeared. The objective of this test is to assess the oil interruption tolerance of the hybrid ceramic ball bearing used in the aircraft engines. Temperature, vibration, speed, load, and other status signals of hybrid bearings were real-Time online monitored in the oil interruption test. The hybrid ceramic ball bearings successfully withstand oil interruption test for 30 s, 60 s, 80 s, 100 s, 110 s, 130 s, 150 s, 180 s in sequence. When the test lasted for an oil-off time of 120 s, the No. 2 bearing seizure occurred. The accumulated time reached 960 s before bearing failure under oil interruption conditions. From monitoring signals obtained in the test process, the temperature of the outer ring of No. 2 bearing has sharply increased from 137°C to 200°C in the end. Through bearing disassembly and inspection, it was found that the No. 2 bearing located near the drive motor had severe adhesive wear and scuffing failure in the inner ring, while the No. 1 bearing located on the other side showed no obvious damage. The main reason for the seizure failure in No. 2 bearing may have been the larger vibration induced by the shaft misalignment from the coupling. This work provides anti oil interruption capacity for engineering applications of the hybrid ceramic ball bearings under extreme conditions of aircraft engines.