Helicopter vibration reduction in forward flight using blade integral twist actuation

An analytical framework has been developed to examine integrally-twisted helicopter blades and their aeroelastic behavior during forward flight. This is accomplished by modifying an existing multi-body dynamics code, DYMORE, with active material constitutive relations. An integral twist-actuated rotor blade was designed within this framework. A four-bladed fully-articulated active rotor system was built and tested to demonstrate the present concept in forward flight. The impact of integral twist actuation on fixed and rotating system loads during forward flight is evaluated by the proposed analysis. While discrepancies are found in the amplitude of the loads under actuation, the predicted trend of load variation with respect to its control phase correlates well with the experiments. Factors affecting the accuracy of the present analysis against the experimental results are described in detail. Based on the present discussion, an improved analysis is planned to be conducted.