Detecting the onset, propagation and location of non-artificial defects in a slow rotating thrust bearing with acoustic emission

Condition monitoring using high-frequency acoustic emission (AE) technology has remained a subject of intense study since the late 1960s. This paper demonstrates the use of AE measurements to detect, locate and monitor natural defect initiation and propagation in a conventional rolling element thrust bearing rotating at 72 r/min. To facilitate the investigation a special purpose test-rig was employed, which allowed for accelerated crack initiation on a bearing race. It is concluded that the onset of sub-surface cracks and the subsequent propagation and development to a surface spall was detectable with the AE technology. The paper also investigates the effects of attenuation and source characterisation on AE signals associated with the natural initiation and propagation of cracks on a thrust bearing race whilst in operation.