Application of magnetostrictive smart materials in rotor servoflap control

The main theme of this research project has been to analytically develop a proof-of-concept design to demonstrate the effectiveness of a smart material actuator employing ETREMA TERFENOL-DTM for helicopter rotor servoflap control. This design enables the control of the rotor blade flap with an actuator embedded in the blade itself. By moving the control to the rotor blades, the swashplate system could be eliminated. Requirements such as applied load and motions were the key issues that needed to be accounted for in order to achieve a successful design employing the `giant' magnetostrictive material. A series of loading conditions characterized by an additive process of Steady-State. Cyclic, and Active control functions were considered for Sustained flight. Optimization of the overall system gave rise to a system gain of 3.7 for Sustained motion. At this same optimal gain value, and using an ETREMA TERFENOL-DTM rod length of at least 22.7 inches, a net peak-to-peak displacement of as high as 42 mils (1.07 mm) was obtained.