Detection of Incipient Damage in Large Rolling Element Bearings

Abstract

The paper describes a methodology for the reliable detection of incipient damage due to fatigue, fretting and false brinelling in large, heavily loaded rolling element bearings such as found in pedestal slewing cranes and ship azi-pod propulsors. It has been found that combining acoustic emission source location and spectrum analysis of the associated time-domain signatures has produced a powerful diagnostic tool for the detection of micro-damage to the various working faces of the bearing under variable speed and loading conditions, before any metal loss is evident in the bearing lubricant. Other sources of acoustic emission such as fretting at contact faces elsewhere in the body of the bearing and fluid turbulence can be resolved and quantified so as not to interfere with the diagnosis of bearing condition. Results are presented for new and damaged bearings, where the true condition has been verified when the bearings were subsequently replaced.