The Ampair 600 wind turbine benchmark: Results from the frequency based substructuring applied to the rotor assembly

Prior to any structural system realization during the design phase, the structural dynamic should be characterized. Dynamic characterization provides the designers with local and global dynamic information which can be used to optimize the structures. To characterize the dynamic of too large and complex structures generally Dynamic Substructuring (DS) techniques are used. Experimental DS is one of these techniques and is recently more in use. Many researchers put effort in developing and evolving new concepts. The substructuring focus group at Society for Experimental Mechanics (SEM) uses a small-scale wind turbine, Ampair 600, in a combined effort to validate, classify and advance these techniques. In this paper the substructuring results, obtained with the LM FBS formulation applied to the wind turbines rotor are given. The Interface Deformation Mode (IDM) method is adopted and applied to overcome the lack of Rotational Degrees of Freedom (RDoF) and to minimize the measurement noise. To include the joint stiffness and damping a Substitute (Fixture) is used and two methods are proposed to model flexible and rigid Cyclic Symmetric Structures (CSS). The results obtained in this first substructure analysis of the rotor show that good results can be found in the lower frequency range.