Application of Shape Memory Alloys for Flutter Suppression in a Propeller-Driven Typical Section

ifasd2024 Tracking Number 70

Future aerial mobility will likely be powered by propeller propulsion, as it is more suitable for use in combination with electric motors. Therefore avoiding rotor instabilities becomes a major concern in the early project phases for the next generation of aircraft. Within this context, this work focuses on the application of Shape Memory Alloys (SMA) for Whirl Flutter (WF) suppression in propeller-driven aircraft. SMAs have a thermal-dependent modulus of elasticity, which allows the use of this class of materials to locally control the stiffness of the connections between the motor and the wing. For most of the flight, the mounting stiffness could be maintained at a minimum to better isolate the vibration coming from the motor, and only at high speeds it could be increased to avoid aeroelastic instabilities. To conduct the study, a 4 Degree of Freedom (DoF) model of a wing section with an installed rotor was implemented and verified. This model combines a typical aeroelastic section, with springs associated with pitch and plunge DoF, and the classical rotor model used in WF studies, which idealizes the rotor mounting by two torsion springs associated with pitch and yaw DoF. Predictions obtained using the proposed model were compared with previous results from the literature. Following the model verification, the application of SMA was implemented by assuming that the connecting stiffeness associated with the rotor installation is dependent on temperature, simulating an SMA-made mounting. Thus, it was possible to map the final flutter velocity of the system as a function of the temperatures associated with the rotor installation. The obtained results demonstrate that the flutter speed of the system may be significantly modified using this approach. They also indicate that the control of the SMA temperature shifts the dominant flutter mechanism from whirl flutter to the classical wing flutter, increasing even more the flutter speed of the system.