The analysis of 1/3 octave spectrum and its application in bearing fault diagnosis

Since 1/3 octave spectrum is a usual method in the signal analysis of vibration and noise, the energy distribution on a broad range signal can be analyzed distinctly in each 1/3 octave range by this way. In normal state, the 1/3 octave spectrum of the vibration signal for gear box is definite. But when one certain bearing in gear box goes wrong, its energy distribution of the spectrum must be different; Therefore, the bearing fault can be identified effectively by extracting the characteristic of 1/3 octave spectrum of bearing vibration signal. In this paper, the signals of two gear box in different state is analyzed, the 1/3 octave spectrum of the gear box vibration signal is compared and analyzed in normal and bearing fault state in laboratory condition, the vector of spectrum property is extracted, and then the difference of 1/3 frequency octave spectrum between the normal and fault signal is compared to recognize the bearing fault. Through the analysis of the practical testing signal, the method has such advantages as little characteristic parameter, distinct fault characteristic and so on. It is also proved that this method can apply to the fault diagnosis of roll bearing effectively.