In-plane motion of wind turbine blade under the combined action of parametric and forced excitations

This paper presents an analysis for the nonlinear in-plane motion of wind turbine blade under the combined action of parametric and forced excitations. The Bernoulli-Euler beam theory is adopted to describe blade motion. Effects including gravity, structural damping and geometric nonlinearity are included in the mathematical model. The rotating speed is considered as a nominal speed with a harmonic perturbation. The periodic oscillation of rotating speed brings about parametric excitations in stiffness and damping terms and forced excitations. The harmonic balance method is applied to get the approximate solution of dynamic response. Numerical integral of original system is used to verify the analytical solution. Influences of structural damping, perturbed amplitude and frequency of rotating speed on blade behaviour are discussed