Dynamic analysis of the wind turbine drivetrain considering shaft bending effect

In the previous research, shaft torsional flexibility was only considered in the wind turbine drivetrain. However, if shaft is longer and thinner than other parts, two components which are connected by shaft affect each other by rotation about bending axis. It means that there are deflections of shaft about not only torsional direction but also bending direction. In this research, we introduced spherical joint which have 3 spring stiffness about all rotational axis to define shaft. And we analyzed that how shaft bending affect drivetrain rotation, translation motion and gear mesh contact force. To do these processes, we simulated the 3-dimensional wind turbine drive train model which has bearing stiffness, gear mesh stiffness, and shaft flexibility. The gear mesh stiffness was defined by Fourier series. And the equation of motion was acquired by Lagrange equation and kinematical constraints to represent shaft flexibility. About numerical analysis, the Newmark method was used to get results. Lastly, fast Fourier transform which converts results from time domain to frequency was used.