Vibration-Based Spall Size Tracking in Rolling Element Bearings

This paper extends recent research on the estimation of spall size in rolling element bearings (REBs) using laboratory measurements on a bearing test rig. The prognostics of REBs remains a formidable challenge, partly because many of the classic diagnostic indicators trend non-monotonically with bearing wear, as spalls that develop on the bearing races progress from localised to distributed faults. The direct estimation of spall size from the vibration signal has recently been proposed as a potential solution to this problem. Such estimation techniques typically rely on the identification and enhancement of the events in the signal corresponding to the rolling element entry into and exit from the spall. Identification of the entry event poses the most difficulty, and for this the paper proposes a novel method, which is then applied to signals obtained from a bearing with known spall dimensions. The resulting estimates correlate well with the actual spall size.