Failure Analysis Of Skidding Damage Of Rear Bearing Aero-engine Main Shaft

Aeroengine is developing towards the directions of high speed and high power ratio.Unfortunately,the rear bearing,as one of the key part in the main shaft bearings,its reliability has been severely undermined by skidding damage except for the fatigue.Skidding damage in the rear bearing because of the high speed and low load existed in the work conditions account for 34.46% among the bearings’ failure,which has been the main factor in bearings failure.At present,there are few researches in skidding damage from the perspective of failure analysis,therefore,under the guidance of the modern tribological theory,this paper aims at processing systematically studies on the skidding damage of cylindrical roller bearing.Eventually,the mechanism of the skidding damage of the rear bearing will be revealed in this process.In addition,it has great reference value for the domains where skidding damage protection is necessary to aeroengine.According to the paper,there are three types of rear bearings: skidding damaged bearings during trial run,skidding damaged bearings after revision,undamaged bearings after revision.The morphology,composition and microstructure were obtained by using micro-hardness tester,optical microscopy(OM),field emission scanning electron microscope(FE-SEM),scanning electron microscope(SEM),energy-dispersive X-ray spectroscopy(EDX)and surface profilometry.The main conclusions are as follows:(1)From the morphology and composition analysis of rear bearings,adhesive wear and abrasive wear are the primary cause of skidding damage for the inner ring raceway and roller surface during the skidding process.EDX results reveal that the skidding damaged bearings experienced oxidation wear.(2)From the surface profilometry analysis of rear bearings,those damaged bearings suffered rough and significant dimensional reduction than the undamaged inner ring,which implies offset grinding happens during the skidding process.In addition,the profile of skidding damaged rollers was depressed.(3)From the metallographic structure analysis of rear bearings,there are discontinuousand continuous white bands on the surface inner ring and roller,respectively.The occurrence of white bands indicates the formation of new structures,most likely as a result of high temperatures.In comparison with the new bearing,the residual austenite content decreases and the martensite content increases.