Current and potential future research activities in adaptive structures: an ARO perspective

Abstract

The Army Research Office (ARO) has been supporting projects focusing on basic research in the area of smart materials and adaptive structures over recent years. A major emphasis of the ARO's Structures and Dynamics Program has been on the theoretical, computational, and experimental analysis of smart structures and structural dynamics, damping, active control, and health monitoring as applied to rotorcraft, electromagnetic antenna structures, missiles, land vehicles, and weapon systems. The variety of research projects supported by the program have been primarily directed towards improving the ability to predict, control, and optimize the dynamic response of complex, multi-body deformable structures. The projects in the field of smart materials and adaptive structures have included multi-disciplinary research conducted by teams of several faculty members as well as research performed by individual investigators.This paper begins with a brief discussion of smart or active materials, i.e. materials having capabilities of sensing changes from the surrounding environment and actively responding to those inputs in an effective manner. Integrating these materials in structures makes them 'smart', i.e. it provides them with the capability to respond to the external stimuli to compensate for undesired effects and/or to enhance the desired effects. The terms 'active', 'smart', 'adaptive', and 'intelligent' are frequently used interchangeably in this context. This discussion is followed by illustrations from several current ARO-sponsored research projects related to smart materials and adaptive structures. A summary of significant results based upon these investigations is given next. Finally, directions of potential future research in the smart materials and adaptive structures area are discussed.

Experimental Study and Analysis of a Polymer Fiber Bragg Grating Embedded in a Composite Material

“…Traditional nondestructive evaluation techniques are effective in detecting damage in materials and structures, but are difficult to use under operational conditions due to the size and weight of the devices [4]. For these reasons fiber optic sensors have been considered as an alternative for in-situ monitoring of composite materials for both the manufacturing process and during service life [5][6].…”

Measurement of thermal elongation induced strain of a composite material using a polarization maintaining photonic crystal fiber sensor

“…Composite materials, in particular continuous fibre-reinforced composite structures [1] have many attractive properties such as low density, high strength and high stiffness [2,3]. Due to the extensive use of composite materials, structural health monitoring (SHM) of composites is an important function [4,5], which also offers the possibility to develop so-called "smart" composite structures with compact integrated sensors.…”

Piezo-actuated Vibration and Flutter Control

“…Newnham and Ruschu 4 have carried out a comparative study of various smart materials to mimic the biological phenomena with the help of piezoceramics, shape memory alloys, and electro-rheological fluids. Loewy 5 and Garg 6 have also summarised the potential application of active materials in aircraft performance and handling, in general, as well as more specifically, in control of aeroelastic instabilities such as flutter,…”