Vibration Diagnosis For The Fault Of The Gear And Rolling Element Bearing

Vibration analysis is widely used in the condition monitoring and fault diagnosis of thegears and rolling element bearings.The vibration theory and fault theory of the gears and rolling element bearings havebeen researched in this thesis, and the common invalidation of them has been analyzed.Then the procedure of the vibration test is introduced. And all kinds of equipments usedin the test are introduced too.The experiment instruments for fault diagnosis of the gears and rolling element bearingsare built. Some faults, for example, tooth crack and outer nick are simulated. And thesoftware, HSGD2006, having been compiled, is used to detect the faults of gears androlling element bearings. Some experiments have been done with this software.The basic theory of traditional fault diagnosis of gear and rolling element bearings isintroduced. In time-domain methods, time-domain synchronization average andtime-domain statistics are discussed. And in frequency-domain, the envelopedemodulation and cepstrum are discussed. The validity and the limitation are verified bythe simulation data and the experimental data.The Research shows that the noise makes large influence for envelope demodulation.The modulation characteristic of the vibration signal is not changed by theautocorrelation function, and the autocorrelation function may reduce the influence ofthe noise. And then a method of delayed correlation-commutate-envelop is put forward.The autocorrelation functions of vibration signals measured on bearings are firstcomputed, which will reduce the noise greatly. Then the autocorrelation functions aredelayed for some time lags, which will reduce the noise further. The delayedautocorrelation is commutating. At last the commutated signal is demodulated. Thevalidity and feasibility are verified by the simulation data and the experimental data.Time-frequency analysis is an effective method for non-stationary signals. The mainadvantage is that it is able to identify a multi-component signal, and the time position ofthe component can be given. Since the vibration signal of gear and rolling elementbearings is also non-stationary. Finally, the wavelet transform and wigner distributionare introduced. And the vibration signal is analyzed by the two methods in order toverify the validity and the feasibility.The theory researching and experiment analyzing verified that the methods of delayedcorrelation-commutate-envelop and time-frequency analysis are validity.