Effects of waveform and frequency of electric fields on vibration responses of an electro-rheological fluids based CFRP cantilevered beam

Abstract

Effects of waveform and frequency of electric fields applied to Electro-rheological Fluids (ERF) are examined on vibration responses of a CFRP (Carbon Fiber Reinforced Plastics) composite cantilevered beam containing ERF. Two types of sinusoidal and rectangular waveform are used for the vibration tests. As the experimental results, the superposed and the beat responses of the composite beam have been observed if applied the electric fields with frequencies less than the first natural frequency of the composite beam. These peculiar responses are explained in vibration analysis. For this purpose, a simplified mass-spring-damper system is adopted to feature the first flexural mode of the composite beam, where the damping factor is changed in time as a function of electric fields applied to ERF. Numerical analysis is performed to solve the equation of motion.

電気レオロジー流体(ERF)を含有するCFRP(炭素繊維強化プラスチック)複合材片持梁の振動応答について、ERFに印加した電場の波形および周波数の影響を調べた。振動試験には正弦波および矩形波を用いた。実験結果として、複合材梁の持つ第一固有周波数以下の周波数の電場を印加したとき、複合材梁の重ね合わせ、およびうなり応答を観測した。これら特異な応答を振動解析で解明した。この解析のために、複合梁の第一曲げモードの特色を出すため、減衰係数がERFに印加した電場の関数として遅れずに変わる、単純化した質量・ばね・ダンパシステムを採用した。運動方程式を解くために数値解析を行った。