Integrated structural tailoring and control using adaptive materials for advanced aircraft wings

Abstract

This study combines structural tailoring with the adaptive capabilities of piezoelectric materials for the purpose of controlling the vibration and static aeroelastic characteristics of advanced aircraft wings. The structural model consists of a thin/thick-walled closed cross-sectional cantilevered beam whose constituent layers exhibit elastic anisotropic properties and incorporates a number of nonclassical features. Results reveal that a combination of structural tailoring and control using adaptive materials can play a major role in enhancing the vibrational and static aeroelastic response characteristics of aircraft wings. ECAUSE of their outstanding properties, such as high strength/stiffness to weight ratios, fiber-reinforced laminated thick/thin-walled structures are likely to play an increasing role in the design of advanced aircraft wings. In addition, a number of elastic couplings resulting from anisotropy and the ply-angle sequence of composite material structures can be exploited so as to enhance the response characteristics. In this regard, within the last two decades, a technique referred to as structural tailoring has been used with spectacular results.1 It should be noted, however, that structural tailoring is a passive design technique. This implies that the structure cannot respond adaptively to changes in its parameters or external stimuli. To overcome this shortcoming, additional capabilities must be built into the structure. This is particularly true in view of the fact that future generations of flight vehicles are likely to operate under increasingly severe conditions. An approach showing good promise is based upon the incorporation into the structure of materials featuring sensing and actuating capabilities.25 Piezoelectric materials are excellent candidates for the role of sensors and actuators. In contrast to passive structures, in which the vibrational and aeroelastic response characteristics are predetermined, in adaptive structures these characteristics can be altered in a known and predictable manner. These adaptive capabilities can be used to prevent structural resonance and/or any other type of instability, as well as to improve the static and dynamic response of the structure. In this article, the task of enhancing the static aeroelastic response and free vibration characteristics of aircraft wingtype structures made of advanced composite materials is accomplished through the synergistic combination of structural tailoring and adaptive materials technology. The structure simulating the aircraft wing consists of a thin/thick-walled closed cross-sectional cantilevered beam whose constituent layers feature elastic anisotropic properties. The control capability is achieved by electrically actuating piezoelectric ele