Numerical modeling and analysis of multistage gear transmission system in wind turbine gearbox under load uncertainty

A multistage gear transmission system (MGTS) is widely used in wind turbine gearboxes. Its dynamic responses are closely related to stochastic aerodynamic torque that has a wide interval range between cut-in and cut-out wind speeds. However, most of the dynamic models of MGTS lack attention to dynamic responses caused by uncertainties of multiple parameters under varied input torque. In this study, a dynamic modeling method in conjunction with interval uncertain analysis of MGTS caused by multiple load-related parameters due to varied input torques is proposed. A comprehensive dynamic model of MGTS is developed considering time-varying gear mesh transmission error, load-related gear mesh stiffness and bearing stiffness as well as flexible shafts. The reasonability of simulation is validated, and then the effects of multiple load-related parameters on uncertain dynamic responses are discussed in-depth. Results show that both gear mesh stiffness and bearing stiffness are enlarged with increasing input torque to cause uncertain dynamic responses. These uncertainties would propagate along the flexible shaft and be suppressed by system rigidity. The dominant transverse vibration modes of shafts are sensitive to bearing stiffness, thus, uncertain bearing stiffness has remarkable effects on dynamic responses than gear mesh stiffness.