The spectral kurtosis: application to the vibratory surveillance and diagnostics of rotating machines

In the previous paper, the authors have demonstrated the high potential of the spectral kurtosis (SK) to detect and characterise non-stationary signals. The present paper brings together these ideas and shows how the SK can be efficiently used in the vibration-based condition monitoring of rotating machines. First, and in contrast to classical kurtosis analysis, the SK provides a robust way of detecting incipient faults even in the presence of strong masking noise. Second, the SK offers an almost unique way of designing optimal filters for filtering out the mechanical signature of faults. The first property is of practical importance for monitoring purposes, whereas the second one proves very useful in diagnostics. Another originality of the paper is the introduction of the concept of kurtogram, from which optimal band-pass filters can be deduced, for instance as a prelude to envelope analysis. All the original findings presented in the paper are illustrated using actual industrial cases.