Vibration mechanism and improved phenomenological model of planetary gearbox with broken sun gear fault

Multiple vibration signal models for planetary gearboxes have been built, but details in the signals are often ignored when verifying their correctness. The main reason is that the vibration mechanism of the gearbox is not well studied. To overcome this problem, the stiffness model of the faulty external gear pair is firstly developed and the end meshing time of the broken tooth under different fault sizes is explored. Based on this, an improved phenomenological model is established, and the assisted phases for verifying its correctness are proposed. Subsequently, the simulated signal is decomposed into two components, which mainly contain meshing impacts and fault impacts, respectively. Based on the time difference between these two types of impacts, the mapping relationship between the assisted phases and the fault size is verified. Finally, the correctness of the vibration mechanism of the gearbox and the improved phenomenological model are verified by simulation and experiments.