Steps toward prognostics of faults in bearings

Abstract

Assessment of the remaining useful life of a rolling-elementbearing is a key element in rotating machines prognostics.Evaluation of the bearing remaining useful life (RUL)requires diagnosis of the fault existence, estimation of its sizeand estimation of the time interval until it reaches a criticalsize. A concept for bearing RUL estimation is proposed. Themain insights which led to the concept development arereviewed. The study focuses on estimation of spall sizelocated in one of the bearing races. A new approach forestimation of spall size in bearing races is developed basedon physical insights obtained from results of a generalbearing dynamic model. Analytical modeling of theinteraction between the spall and the rolling element enablesthe development of an autonomous generic method for spallsize estimation. In this paper the principles for spall sizeestimation are described. The new method was applied toexperimental data including different spall sizes on inner andouter races. The estimation shows satisfactory results witherrors up to 20%.