Finite Element Modeling of Active Twist in Rotor Blades using IDE-PFC Actuators

Abstract

Blade Vortex Interaction in rotating helicopter blades contributes significantly to the instability and high vibration levels during its operations. It is therefore essential to evolve a mechanism to reduce unwanted vibration. Several methods/devices, like the smart trailing edge flap actuators, active blade twist, etc are suggested. Active blade twist concept deals with changing the angle of attack and thereby reducing vibration and noise. The piezoelectric actuators are the promising devices to achieve the active blade twist. Due to the conformability and positioning aspects, active fiber composite actuators (piezoelectric fiber composite) with interdigitated electrodes gain an edge over the conventional piezoelectric patch actuators. In the present work, a four noded plate finite element is formulated to model the rotor blades with IDE-PFC actuators. The element consists of both mechanical as well as electrical degrees of freedom. The constitutive equations are derived and FE formulation is developed. Results are obtained for static deflection due to piezoelectric actuation and are validated. Subsequently, parametric studies are carried out on laminated composite rotating blades with IDE-PFC actuation and the validity of the developed element for d33 actuation is established.

Keywords: Helicopter Blade, IDE-PFC Actuator, Piezoelectricity, Gyroscope