Application Of Resonance Demodulation Method Based On LCD And Spectral Kurtosis In Gearbox Fault Diagnosis

Because of its stable transmission ratio,large transmission torque and compact structure,gears play an indispensable role in changing the speed of the equipment and transmitting power.It is widely used in modern machinery and equipment in various fields of society.Although the gear in the mechanical equipment can not be replaced,but the failure rate is also very high,its operating status will seriously affect the performance of the machine.Therefore,the gear box for fault diagnosis is of great significance.The main contents of the paper are as follows:(1)Introduce the basic method of gearbox fault diagnosis,and study the fault type,vibration mechanism and signal characteristics of gear box.The mean value curve of the local characteristic-scale decomposition(LCD)and other three time-frequency decomposition methods is analyzed and analyzed.(2)To establish the gearbox failure experiment plan,respectively,in different speed under normal gear box and three typical gearbox failure data,including broken teeth,cracks and wear failure data.The time domain and frequency domain analysis of the experimental data show that the simple time domain and frequency domain analysis can not effectively identify the gearbox fault characteristics.(3)The vibration signal of gearbox has the characteristics of frequency modulation and amplitude modulation.The key of fault diagnosis is to demodulate the gear box vibration modulation signal,so as to extract the fault characteristics of gear box.In addition,the actual conditions of the gear box signal also contains a large number of noise signals.In view of this situation,this paper presents a resonant demodulation method based on LCD and spectral kurtosis,fault diagnosis of gearbox.The method uses LCD to decompose the signal into a series of single-component FM modulation signal.The signal is reconstructed by calculating the correlation coefficient and relative entropy of each component and the original entropy,and then calculating the spectral kurtosis of the reconstructed signal,According to the principle of spectral kurtosis,the best parameters of the bandpass filter for extracting the fault y impact components are selected.Finally,the filtered signal is subjected to resonance demodulation analysis.Through the analysis of the gearbox simulation signal and the experimental signal,the method can effectively extract the fault characteristics of the gearbox.(4)Under the actual conditions of the gear box vibration signal modulation sideband often cross together to form an asymmetric sideband structure,the general frequency domainanalysis method is difficult to identify.In this case,the local feature scale decomposition method and the cepstrum method are applied to the gearbox fault diagnosis.First,the signal is decomposed by LCD method,and the single component signal is analyzed by cepstrum method.The analysis results of the gearbox simulation signal and the experimental signal show that the method can extract the fault characteristics of the gear box,but the analysis effect will be affected by the fault degree.