Induced-shear piezoelectric actuators for rotor blade trailing edge flaps and active tips

Centolanza, Louis; Smith, Edward C.; Morris, Anthony

doi:10.2514/6.2001-1559

Cited by 5 publications

(2 citation statements)

References 16 publications

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“…Figure 2 shows a schematic of this structural actuator. 24). For each of these segments, the ply layup in the thickness direction is mid-plane symmetric and hence JOURNAL OF THE AMERICAN HELICOPTER SOCIETY Fig.…”

Section: Conceptmentioning

confidence: 99%

Hover Test of a Mach-Scale Rotor Model with Active Blade Tips

Bernhard¹,

Chopra²

2002

J. Am. Helicopter Society

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The smart active blade tip (SABT) rotor incorporates blade tips that can be independently pitched with respect to the main blade. The blade tips are used as on-blade control surfaces for vibration reduction. The experimental testing focussed on a small scale four-bladed rotor on a bearingless Bell-412 hub. The fabricated Mach-scale active-tip rotor has a diameter of 1.524 m, a blade chord of 76.2 mm and 10% span active tips. The blade tips are driven by a novel piezo-induced bendingtorsion coupled actuator beam, located spanwise in the hollow mid-cell of the main rotor blade. In 2000 rpm hover (tip Mach 0.47), at 2 deg collective, and for an actuation of 150 V rms , the measured blade tip deflection (pitch angle relative to the main blade) at the first four rotor harmonics is between ±2.1 and ±2.9 deg, increasing to ±5.7 deg at 5/rev with resonant amplification. These blade tip deflections generate respective oscillatory rotor thrust coefficients between 0.9 · 10 −3 and 1.6 · 10 −3 at the first four rotor harmonics, increasing to 2.2 · 10 −3 at 5/rev (single blade tip actuation). The corresponding thrust authority is 19, 13, 23, 19 and 33% at the first 5 rotor harmonics (normalized with respect to steady thrust at nominal 8 deg collective, 378 N). The analytic model predicts the 150 V rms relative blade tip pitch angle and associated change in rotor thrust within 12% at the first five rotor harmonics (except at 4/rev where the model underpredicts more). The active blade tip rotor was also used as a testbed for the evaluation of an adaptive neural-network based control algorithm. Effective reduction of 1/rev hover imbalance hub loads was demonstrated. In addition, the controller was used to generate desired multi-frequency control loads on the hub, based on artificial signal injection into the vibration measurement. The research program demonstrates the technical feasibility of the active blade tip concept for vibration reduction and warrants further investigation in terms of closed loop forward flight tests in the wind tunnel and full scale design studies.

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Section: Conceptmentioning

confidence: 99%