Influences of blade stiffness on structural natural frequencies of offshore wind turbine with monopile foundation

An elaborated structural numerical model of NREL 5MW offshore wind turbine (OWT) with monopile foundation is established by using the code of ABAQUS. The blade stiffness is adjusted by changing the elastic modulus of blade, and the influences of blade stiffness change on the natural frequency of the wind turbine (WT) structure are analyzed. The results show that the change of blade stiffness can significantly change the dynamic property of blade itself and supporting structure for WT in the FA (Fore-Aft) direction. For the 1st bending mode of supporting structure, the natural frequencies in the FA and SS (Side-to-Side) direction increase monotonically with the increasement of blade stiffness; in terms of the 2nd~5th bending modes of the supporting structure, the FA natural frequencies are more sensitive to the change of blade stiffness, while the SS natural frequencies are basically independent on blade stiffness.