Model rotor blades are needed to validate numerical models and simulation tools. In order to do so, a proper characterization of the model rotor blades is urgently needed. Over the years a set of techniques was developed to characterize properties of active twist blades. Most of the methods can be applied to standard passive blades as well. Active twist rotor blades have been developed for the use in secondary rotor control such as higher harmonic control (HHC) and individual blade control (IBC). The basic principle of such blades is the implementation of piezoelectric actuators into the blades, using different types of coupling, causing the blades to twist. At the DLR model scale blades have been manufactured to demonstrate the feasibility of such systems. This paper is describing the experimental characterization methods for active twist blades. Both the elastic and mass related properties are discussed as well as the actuation behavior - especially for very low frequencies.
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