1998 年 64 巻 619 号 p. 760-766
A CFRP sandwich composite beam containing electro-rheological (ER) fluids as a variable damper is prepared. The vibration strain responses of the composite beam supported under the cantilevered condition are measured by an Extrinsic Fabry Perot Interferometric (EFPI) optical fiber strain sensor. The experiment is conducted under external sinusoidal excitations. The timing of a sinusoidal electric field supplied to the ER fluids is adjusted by observing vibration strain responses with the EFPI optical fiber strain sensor. It is shown that damping properties of CFRP laminates are changed by controlling phase differences of the sinusoidal electric field from the strain response of the composite beam. The sinusoidal electric field having phase lead difference of 90° from the vibration response is most effective for suppressing the vibration of the composite beam. These experimental results are also explained by using a simplified equation of motion for the composite beam with a variable damping factor considering the strain dependency of ER fluids.