Vibration Characteristics of the Gear–Rotor-Bearing Transmission System Under External Impacts

Many industrial machines inevitably suffer from external impacts which can change the meshing state of gears and thus affect the vibration characteristics of the gear transmission system. Previous studies mostly directly applied external impact excitation to the gear pair, with few considering the gear–shaft-bearing system. In reality, external impact excitation first acts on the bearing ends and then is transmitted to the gear ends through the transmission shaft. Therefore, the paper established a bending–torsion coupled dynamic model of the gear–shaft-bearing transmission system, taking into account external impacts, gear eccentricity, time-varying meshing stiffness, transmission error, shafts elastic deformation and nonlinear reactions forces. The vibration characteristics of the bending–torsion coupled gear–shaft-bearing transmission system under external impacts were analyzed in the time and frequency domains. Additionally, the effects of impact load amplitude and impact duration on gear vibration characteristics were investigated. External impacts instantaneously amplified the vibrational energy of the gear pair, which promotes the generation of impact components and increases the vibration acceleration signal amplitude in the time domain. Distinct sidebands emerge in the frequency domain, with meshing impacts intensified during gear operation. Furthermore, as the impact load amplitude increases and the impact duration is shortened, the vibration characteristics of the gear transmission system become more pronounced. The findings provide important theoretical insights and practical engineering significance for improving the reliability and service life of gear transmission systems.