Crack Fault Diagnosis for Spur Gears Using Gear Frequency-RPM spectrum

The vibration signal developed by an affected gear pair in the gearbox and its detection is possible in the vibration signal analyzer through various signal processing techniques. The persistence spectrum (pspectrum) is one of the techniques used to detect the energy in the time-frequency plane by reassigning energy in frequency for a fixed time. However, such an analysis is deficient in fault diagnosis in spur gearbox systems. The results do not give enough information through the time, and frequency components of the signal regarding the cracked tooth cannot. Its modulated signal analysis cannot detect any faults due to the crack. This paper describes an alternative technique to enhance the crack's diagnosis and detection of the crack on a single gear tooth in the gearbox system. The technique is based on the time domain, Fast Fourier Transform (FFT), and the combination of Short-Time Fourier Transform (STFT) and Frequency-RPM map fault diagnosis methodology. The technique enables to detect a crack in a 6 degree of freedom (6-DOF) torsional-lateral coupled model of a spur gear which is not the case of the frequency and time-frequency with the function pspectrum alone. Results and analysis reveal that the proposed technique can detect and diagnose early-stage crack tooth effects in the gearbox.