A simple frequency-domain algorithm for early detection of damaged gear teeth

Fixed transducers often are used to monitor meshing gear pairs in order to detect tooth damage. A simple frequency-domain damage-detection algorithm is suggested for very early detection of such damage. Ratios of rotational-harmonic amplitudes computed from before and after potential damage are utilized to eliminate effects of transducer and structural-path-caused amplitude changes between tooth-meshing location and transducer output, to minimize attenuating effects of multiple-tooth contact, and thereby, to approximately equally weight rotational-harmonic amplitudes over a wide range of harmonics. Statistical averaging of absolute values of logarithmic ratios of rotational-harmonic amplitudes is used to minimize fluctuations caused by multiple-tooth contact and manufacturing errors on the subject gear. Synchronous averaging is employed to minimize effects of noise and manufacturing errors on the mating gear. Time-windowing tailored to contact ratios of mating gears is utilized to isolate individual tooth locations. Resultant windowing effects on availability of useful rotational harmonics are analyzed. Application of the algorithm to detection of seeded bending-fatigue faults on a planetary ring-gear tooth indicates that successful detections were achieved.