Investigation on dynamic characteristics of the planetary gearbox with tooth root crack fault under variable speed conditions

Abstract As a crucial component of the wind turbines, the planetary gearbox has a high transmission ratio and precise transmission. However, its long-term operation is likely to cause gear failure under variable speed conditions (VSCs). This paper is devoted to model the dynamic response and investigate its failure mechanism under VSCs. The gear rotation angle is used instead of time to represent the meshing period, and the Fourier series is used to precisely fit the time-varying meshing stiffness under VSCs. The dynamic model for analysis under VSCs is established and the vibration response is obtained by solving the dynamic model. The cracking failure mechanism of gears under VSCs is researched by spectrum analysis. Considering the influence of VSC on the dynamic characteristics of the transmission system, the order envelope method is used to analyze the characteristics of the vibration response. Finally, the reasonableness of the variable working condition model is verified by bench test and it provides mechanism support for the research of fault diagnosis method under VSCs.