Demodulation Analysis Based on Fourier Decomposition Method and its Application for Gearbox Fault Diagnosis

Because the modulating frequency and its magnitude of gearbox vibration signals relate to gear faults, demodulation analysis methods are commonly used to diagnose gear fault. The conventional envelope spectrum helps us to identify the dominant amplitude modulation frequency. However, it fails to locate the gear fault precisely when the modulation frequency corresponds to multiple gears. To address this issue, a gear fault diagnosis method is proposed to locate the faulty gear precisely based on the Fourier decomposition and demodulation analysis. Firstly, the Fourier decomposition is employed to extract analytical Fourier intrinsic band functions (FIBFs) from the given signal. Then, some FIBFs including modulation information are selected for further demodulation analysis. Finally, the faulty gear is detected by jointly considering the dominant modulation frequency and modulation strength. Simulated and experimental signal analysis results verify the effectiveness of the proposed method in obtaining modulation information in a specific frequency band and locating the faulty gear precisely.