S. Shevtsov, A. Soloviev, and S. Bragin (Russia)
Helicopter, Active Rotor Blade, Composite Tube, Piezoelectric Actuator, Finite Element Modeling
The principal part of active rotor blade technology is a sensing/actuation system – the piezoelectric transducers disposed on a controlled flexible structure. Such devices destined to reduce a noise and vibration in the helicopter. The possibilities to change of rotor blade local bend or twist with aid of distributed power actuators is the necessary condition for adaptive vibration control efficiency. For electronic control schema need also the fast response that require diminishing a number of controlled actuators. Early performed studies concerned to rational placements of actuators on the vibration and shape controlled homogenous beams or plates. But the main component of the helicopter rotor blade –spar has C like or closed cross-section with walls of that thickness sufficiently less then dimensions of a spar cross-section. The focus of this work is a rational placement of discrete actuators, and also a selection between bimorph and unimorph types actuators for a tube-like composite spar subjected to bend and twist deformations. In order to design a scaled active main rotor we investigated a composite spar of tail rotor. All numerical investigations were carried out in Comsol Multiphysics 3.3. Our simulations have demonstrated considerably smaller operational effectiveness of bimorph actuators as contrasted to unimorph actuators for making a bending of tube. Other deficiency bimorph-actuators are exhibited in dynamic. This is an excitation of specific flexural oscillations modes of a tube walls. It is shown that using of two pairs same power unimorph actuators at varying of applied voltage allows obtaining the required bending deflections in two perpendicular planes. For making a torsional strain the X-shape oriented unimorphs were placed symmetrically on the opposite tube walls. The above mentioned conclusions are supplemented by results of composite spar vibration suppression by proposed actuation scheme.
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