Application of Cyclic Correlation Analysis to Gearbox Damage Assessment

With regard to the cyclostationarity of gear vibration, cyclic correlation is used to extract the modulation features of gear vibration signals, so as to detect and assess localized gear damage. The cyclic auto-correlation of amplitude modulation and frequency modulation (AMFM) signals is deduced. The ratio between the cyclic auto-correlation slice (with time lag of 0) magnitude at cyclic frequencies of modulating frequency and 0 Hz is a monotonically increasing function of the amplitude modulation magnitude. Since AMFM is characteristic of gear vibration signals, and the modulation magnitude is related to localized gear damage degree, the ratio is used to assess the health status of gears. In the analysis of a gearbox experimental vibration signals, the ratio shows a monotonically increasing trend with the development of the gear tooth spoiling damage. It has potential to early detect incipient damage, to prognosticate severe damage, and to assess gearbox damage.