Conceptual Models of SMA Actuators for Blade Twist

Abstract:
Blade shape control may enhance the general performance of helicopters. Two static SMA-based actuators for morphing rotors twist are herein investigated. The scope is to enhance the figure of merit at different flight regimes (hover, forward flight…). A first device is made of a bundle of SMA wires connecting two opposite blade cross sections. Any relative rotation of the sections induces stretching into the wires that can be recovered by heating. The second actuator is a SMA solid torque tube; in a similar way, any imposed torsion can be recovered by heating. A dedicated modelling approach has been adopted to estimate the transmitted rotation to the blade. After having identified the most relevant design parameters, a trade off has been organized to point out strength and weakness aspects of the two architectures. The work has been carried out within the H2020 SABRE (Shape Adaptive Blades for Rotorcraft Efficiency) Project.