%0 Journal Article
%T Solid State Adaptive Rotor Using Postbuckled Precompressed, Bending-Twist Coupled Piezoelectric Actuator Elements
%A Ronald M. Barrett
%A Ryan Barnhart
%J Smart Materials Research
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/832939
%X This paper is centered on a new actuation mechanism which is integrated on a solid state rotor. This paper outlines the application of such a system via a Post-Buckled Precompression (PBP) technique at the end of a twist-active piezoelectric rotor blade actuator. The basic performance of the system is handily modeled by using laminated plate theory techniques. A dual cantilevered spring system was used to increasingly null the passive stiffness of the root actuator along the feathering axis of the rotor blade. As the precompression levels were increased, it was shown that corresponding blade pitch levels also increased. The PBP cantilever spring system was designed so as to provide a high level of stabilizing pitch-flap coupling and inherent resistance to rotor propeller moments. Experimental testing showed pitch deflections increasing from just peak-to-peak deflections at 650£¿V/mm field strength to more than at the same field strength with design precompression levels. Dynamic testing showed the corner frequency of the linear system coming down from 63£¿Hz (3.8/rev) to 53£¿Hz (3.2/rev). Thrust coefficients manipulation levels were shown to increase from 0.01 to 0.028 with increasing precompression levels. The paper concludes with an overall assessment of the actuator design. 1. Introduction For more than two decades, adaptive rotors, flaps and helicopter flight and vibration control systems have been actively pursued by a small army of technologists scattered around the world. The work of Crawley and his team at MIT in the mid-1980s laid the foundations of adaptive aerostructures by investigating the properties of bending and twist-active plates [1¨C3]. These early studies lead to several broad reviews which examined material properties and their associated energy and power densities when used as actuator elements [4, 5]. 1.1. Adaptive Flaps The earliest twist, camber, and bending active aerodynamic plates were followed by the first of the adaptive flap studies [6]. A host of adaptive flaps flowed into the technical literature at a steady rate from the early 1990s through their implementation in a full-scale rotor test bed (right) [7¨C19]. Through much effort it was shown that blade loads could indeed be manipulated as fast as 4/rev with appreciable deflection levels. However, the weight, cost, and complexity issues still prevent full transition to prototype flying aircraft and serial production aircraft. Efforts with ¡°Smart Active Blade Tips¡± (SABT) showed good results, but fell prey to the same issues as conventional flaps, but with exacerbated propeller
%U http://www.hindawi.com/journals/smr/2012/832939/