Based on free interface component modal synthesis method, the free vibration behavior of wind turbine structures is investigated. The wind turbine structure is divided into three parts including tower, wheel hub-cabin and rotor. The tower is modeled as an isotropic metal cantilever beam, the blade as thin-walled composite beam and the wheel hub-cabin as a rigid body due to its large extensional stiffness, bending stiffness and torsion stiffness compared with tower and blades. The displacements of the blades are described by thin-walled composite beam theory. Galerkin’s method is used to discretize blades and tower. Employing Lagrange method, the motion equations of blades are derived and then stiffness and mass matrices are obtained. The natural frequencies and mode shapes of the wind turbine structure are predicted by numerical simulations. Numerical results using the present model are validated by ANSYS software results
