Nonlinear torsional vibrations of a wind turbine gearbox

This paper studies the torsional vibrations of wind turbine gearbox having two planetary gear stages and one parallel gear stage. The nonlinear dynamic model developed considers the factors such as time-varying mesh stiffness, damping, static transmission error and gear backlash. Both the external excitation due to wind gust and the internal excitation due to static transmission error are included. With the help of time history, FFT spectrum, phase portrait, Poincare map and Lyapunov exponent, the effects of the static transmission error, mean-to-alternating force ratio and time-varying mesh stiffness on the dynamic behaviour of wind turbine gearbox components are investigated by using the numerical integration method. It is found that the external excitation has the most influence on the torsional vibrations of the wind turbine gearbox components. The mesh stiffness, being another significant factor, has more influence than the other internal excitation source, the static transmission error. The static transmission error has the least influence.