The Research of Higher-order Cumulant Spectrum for Vibration Signals of Gearbox

In the fault diagnosis of gearbox, the extraction of the fault signal is a key problem. The practical testing vibration signal of gearbox is no stable or Gauss distributing. In different fault states, the vibration signal has different Gauss property and symmetry property, usually including stronger noise and low SNR. Faint fault information is often totally flooded in the noise, so it is very difficult to extract the signal characteristic. Because signal's higher-order cumulant is not sensitive to the adding Gauss noise and symmetry non-Gauss noise, if applied in the fault diagnosis of the gearbox, it can separate signal and noise effectively, improve the SNR and intensify fault information. Based on the contrast and analysis of the vibration signal of some second gearbox under different states, this paper has extracted the power spectrum and higher-order cumulant spectrum (bispectrum) of the gear vibration signals, has set up the characteristic vector of bispectrum used in fault diagnosis. The analysis result shows that, compared with power spectrum, the characteristic extracting from the higher-order cumulant spectrum is more sensitive to the fault characteristic, and easy to realize the digital characteristic extracting in the intelligent diagnosis, can identify the fault of gearbox effectively