Envelope harmonic-to-noise ratio for periodic impulses detection and its application to bearing diagnosis

Rolling element bearings are one of the fundamental and most important elements in machines and their failures are among the foremost frequent causes of machine breakdown. Vibration and acoustic signals from faulty bearings are typically a mixture of fault-induced periodic impulses and other components. Traditional time-domain features like root-mean-square (RMS) and kurtosis fail to utilize the periodicity property of the impulses, which makes them invalid in some circumstance. Impulses occurring at specific period is the key characteristic of corresponding defect. In the paper, a novel feature named envelope harmonic-to-noise ratio (EHNR) is proposed for periodic impulses detection. The properties of EHNR are illustrated by simulations and bearing full life cycle degradation data. Moreover, an EHNR-based method is proposed to locate periodic impulses in frequency domain. A simulation and a locomotive bearing test rig are used to verify the proposed method. The proposed method has better performances than kurtosis-based method.