Frequency-domain assessment of gear-tooth bending-fatigue damage-progression using the average-log-ratio, ALR, algorithm

摘要

Frequency-domain (rotational-harmonic) behavior of the average-log-ratio, ALR, gear-damage detection algorithm [MSSP 24 (2010) 2807-2823] [18] is utilized to explain behavior caused by tooth-bending-fatigue damage progression. For spur and helical gears, the strongest bending-fatigue damage contributions are typically found in the rotational-harmonic region below the tooth-meshing fundamental harmonic where ALR increases almost monotonically with increasing damage. However, when the combined elastic/ plastic deformation of a damaged tooth or teeth exceeds tooth tip/root/end relief magnitude, at tooth-contact initiation and/or termination, the lowest-order transmission-error discontinuity is changed from slope discontinuity to step discontinuity, resulting in transmission-error high-frequency (rotational-harmonic n) behavior changing from proportional to 1~2 to proportional to 1, therefore indicating progression to severe damage. Decomposition of the ALR damage-detection metric into rotational-harmonic frequency bands using accelerometer recordings from a notched-tooth spiral-bevel gear test illustrates the above-described behavior, thereby showing increasing stages of damage progression prior to complete gear failure.