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Dynamic vibration feature analyses for a two-stage planetary gearbox with a varying crack using a rigid-flexible coupled model

Planetary gearbox (PG), especially multi-stage PG, is widely used in various commercial and military applications. A dynamic model of PG is a valuable way to investigate its vibration behaviors in good and faulty statuses for designing a highly reliable PG and corresponding robust monitoring techniques. In this paper, a modified dynamic model is firstly constructed for a two-stage PG with a varying crack. The modifications include the crack propagation path settings as well as the coupled structure of flexible and rigid gear components, which makes a balance between the model accuracy and computational burden. Secondly, using this model, its vibration responses from a healthy PG and faulty PGs with different cracks are collected for the analyses of its frequency components and statistic features. Experiments are also conducted on a two-stage PG in similar conditions. Both results in simulations and experiments demonstrate the usefulness of the presented dynamic model. Moreover, sidebands and some statistic features are verified to be useful tools to monitor and evaluate the healthy status of PG.