Fatigue evaluation test method using the inertia generator for the ultra-large offshore wind turbine blade

Abstract

To commercialize a wind turbine, the wind turbine blade must pass a fatigue test for certification during the blade development process. The method used at this time is to excite using the resonance phenomenon and to control the mode shape to be imposed on each section by additional masses using the direct attachment method. Due to the length and mass of the offshore wind turbine blades are increased for more energy collection, the amount of the additional masses required for mode shape control is also increased. However, additional masses can create a large mean flap moment owing to the gravity on the blade, which causes unrealistic failure on the blade. Therefore, in this study, we developed and evaluated a device that can generate an inertia force on the blade by installing it outside of the blade to overcome the problems of the direct attachment method of additional masses. Furthermore, using the principle of leverage, the required large inertial force was generated using a relatively small mass. Thus, a fatigue test method with high efficiency and accuracy was suggested.