Numerical simulation of one-stage gearbox dynamics in the presence of simultaneous tooth cracks

Abstract

Gears are vital components in various industrial machinery. Tooth fatigue crack is amongst the most common causes of gear failure. Early detection of tooth cracks is crucial for effective con-dition-based monitoring. This study aims at investigating the dynamics of a one-stage spur gear-box, having multiple tooth cracks located simultaneously on the pinion and the gear. The numer-ical simulation of the vibration behaviour is obtained using a 6 DOF dynamic model, that takes into account the lateral and the torsional motions of the two gears of the gearset. The effect of inter-tooth friction was taken into consideration in this study. The time-varying mesh stiffness was evaluated using the finite element method, while the vibration response is obtained using a developed MATLAB code. Different vibration signal features were applied on the time and fre-quency domains of the residual signals, to examine their sensitivity. The hunting tooth phenome-non, where a cracked tooth on the pinion gets in contact with a cracked tooth on the gear, was particularly investigated. To make the analysis more realistic, different scenarios of various depths and number of cracks were considered. For each one of these scenarios, the use of statis-tical signal features showed contradictory patterns and the use of such features could be deceptive if not considered properly. This study has the potential to improve the early detection of simulta-neous gear tooth cracks.