• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.2
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• pp.52-58
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• 2002

Measurment of dynamic strain is important to monitor structural integrity. In this paper, the new type of EFPI is proposed to measure the dynamic strain. The second reflecting surface of fiber in this new sensor is deposited gold on to increase its reflectivity. So, it is called the gold-deposited EFPI (G-EFPI) in this paper. In order to explain the principle of measurement of the dynamic strain, two models for the loss of intensity are proposed and an experiment is performed. If a cavity between two reflecting surface increases, the loss of the light that passes through the cavity increases, causing a subsequent decrease in the output intensity of the sensor. Conversely, if the cavity decreases, the amount of loss decreases and the output intensity increases. Also the optimal length of the cavity is proposed to manufacture the G-EFPI with high sensitivity. Finally, the dynamic strainof a composite specimen was measured successfully using the G-EFPI.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.135-138
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• 2002

Experimental studies on vibration control of a composite beam with a piezoelectric actuator and an extrinsic Fabry-Perot interferometer (EFPI) have been performed using a neural network controller and an LQG controller. Vibration control performance was investigated in the nonlinear sensing range according to the vibration amplitudes. Using a neuro-controller, adaptive vibration control experiment has been performed for the structure with frequency variations, and its performance is compared with that of an LQG controller. The vibration control results show that the neuro-controller has good performance and robustness with respect to the system parameter variations.