The effect of the wear evolution on vibration based fault detection in tapered roller bearings

Rolling element bearings are typical tribological components used widely in rotating machines. Their failure could cause catastrophic damage. Therefore, condition monitoring of bearings has always had great appeal for researchers. Usually the detection and diagnostics of incipient bearing faults are achieved by characterising the weak periodic impacts induced by the collision of defective bearing components. However, race wear evolution, which is inevitable in bearing applications, can affect the contact between bearing elements and races, thereby decreasing the impact magnitudes and impeding detection performance. In this paper, the effect of wear evolution on the condition monitoring of rolling bearings is firstly analysed based on internal clearance changes resulting from the wear effect. Then, an experimental study is ingeniously designed to simulate wear evolution and evaluate its influence on well-known envelope signatures according to measured vibrations from widely used tapered roller bearings. The fault type was diagnosed in two indices: the magnitude variation of characteristic frequencies and the deviation of such frequencies. The experimental results give out a signature decrease with regard to wear evolution, suggesting that accurate severity diagnosis needs to take into account both the bearing wear conditions and the signature magnitudes.