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Demonstration Of A Smart Material With Embedded Actuators And Sensors For Active Control

A novel class of 'Smart' materials utilizing embedded actuators and sensors has been developed and demonstrated at Virginia Polytechnic Institute & State University. This class of adaptive material with sensing capabilities utilize a shape memory alloy (Nitinol) in a laminated, fiber reinforced composite as the embedded distributed actuators and embedded optical fiber sensors for evaluating the dynamic response of the structure. Shape Memory Alloy (SMA) reinforced composites have the capabilities to: change their material properties, induce large internal forces in the material, modify the stress and strain state of the structure and alter its configuration, all in a controlled manner. The SMA reinforced composite adaptive abilities has resulted in two new concepts for active vibration control; i) Active Strain Energy Tuning, and ii) Active Modal Modification, both of which will be briefly explained in this paper. Results from the experimental demonstration of 'Active Strain Energy Tuning' using the first known composite material containing embedded distributed actuators and sensors will be presented. The variation and controllability of the dynamic response of a beam made of shape memory alloy reinforced composites was determined from a single optical fiber sensor embedded in the material with the distributed actuators. The optical fiber sensing method used was modal domain sensing and the experimental results are compared to accelerometer data. Fast Fourier Transforms (FFT) of both the optical fiber and the accelerometer outputs were performed to compare the two methods for deducing the natural frequency of the structure.