Summary
Most dynamic analyses of wind turbine towers are conducted in a simplified manner, only considering harmonic load and no nonlinear modal coupling. However, a more realistic model should take into account the coupled behavior, where the wind turbine rotor and tower are simultaneously influenced by each other. This study aims to explore the impact of modal coupling and the associated nonlinearities on the tower and turbine responses. A nonlinear model is developed based on the Lagrangian function of the coupled system, followed by the application of Hamilton's principle, resulting in a two-degree of freedom system of nonlinear equations of motion. The study also investigates the effect of imperfections in the form of blade mass distributions. The results highlight the significance of such coupling on the performance and reliability of wind turbine towers.
