Modulation sideband analysis of a two-stage planetary gear system with an elastic continuum ring gear

Abstract

For a planetary gear system, the flexibility of its components can significantly affect mesh excitation, modal property, and dynamic behavior. However, current research has not revealed the influence of flexibility on the sidebands of vibration spectrum. For this purpose, in our earlier work, we addressed a new elastic-discrete planetary transmission model with an elastic continuum ring gear (originally presented in Wei Liu, Zhijun Shuai, Yibin Guo, Donghua Wang, Modal properties of a two-stage planetary gear system with sliding friction and elastic continuum ring gear. Mechanism and Machine Theory, 135 (2019) 251–270). The previous model study is solely based on free vibration without including sideband analysis. The present work aims to investigate modulation behavior of an elastic two-stage planetary gear (TSPG) system, thus expanding the previous work not only for modal property comparison but also for sideband analysis of the elastic planetary gear. First, gear mesh interface excitations with amplitude modulation (AM) and frequency modulation (FM) due to manufacturing errors are developed to analyze the sideband activity. Then, through loading gear mesh excitations with gear manufacturing errors on the previous model, acceleration spectra with and without sidebands are compared by an analysis with an example. To clearly show the modulation behavior, the effect of ring's elasticity and fluctuating torque on the sidebands is investigated. Finally, a TSPG test bench is proposed to measure the acceleration spectra. The measured spectra are compared to demonstrate the capability of the proposed model in predicting the sidebands of a planetary gear with manufacturing errors.