Filtered evelope spectrum using short periodograms for bearing fault identification under variable speed

Abstract

This paper introduces a method based on short periodograms, combining, envelope analysis, and spectral kurtosis (SK). In order to highlight an underlying impulsive spectral component of a vibration signal, to do so, the proposed method takes into account the well-known welch’s method of periodograms applied to a non-overlapping filtered signal segment using the SK. An SK short-time approach is considered, due to, a high variable speed even in angle domain has an underlying non-stationarity caused by the fact that the transfer function is angle variant. In the end, it is obtained a noiseless envelope spectrum, averaging the filtered periodograms of each envelope of the non-overlapped signal segments. To prove the effectiveness of the proposed method, it is tested on a highly non-stationary vibration signal measured from an aircraft engine under a run-up test. As a result, we can identify a bearing failure embedded highly non-stationary noise. Besides as the proposed method makes use of short periodograms is fast, reliable, and entirely non-parametric, making it readily applicable to highlight any underlying impulsive behaviour in a vibration signal.