A rigid-flexible coupled model for a planetary gearbox with tooth crack and its dynamic response analyses

Abstract

A planetary gearbox is widely used in many areas. Considering that it has complicated structures and relative motions, its dynamic responses are much more complex. It is difficult to analyze its internal and real situation when there exist faults on its surface. Many dynamic models have been established to study its dynamic responses when having a crack on one of teeth. However, most of models are built based on the assumption that the crack propagation path is simplified as a straight line, and it results in obvious deviation on the dynamic responses. In this paper, a rigid-flexible coupled model is established for a one-stage planetary gearbox. In this model, the sun is set as a flexible body and the whole planetary gearbox is a rigid object. The tooth crack propagations are simulated along both the tooth width and the crack depth that can be respectively described as two parabolas. Different crack sizes on one gear tooth are simulated in ADAMS and the dynamic responses are then generated. Based on these, five commonly used statistical indicators, i.e. peak-to-peak, mean, root mean square (RMS), kurtosis, and energy are used to investigate the relationship between the different crack sizes and the response. The results show that RMS and energy are more sensitive to the growth of tooth crack for propagation whatever along the tooth width and the crack length. The frequency spectra also indicate that sidebands caused by the tooth crack obviously change with the crack growing. It provides a reference for studying the dynamic response and crack assessment of the planetary gearbox.