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Vibration Suppression of Flexible Beam Using Electromagnetic Shunt Damper
Tai-Hong Cheng,Il-Kwon Oh IEEE 2009 IEEE transactions on magnetics Vol.45 No.6
<P>In this paper, the electromagnetic shunt damper was newly developed to passively suppress the vibration of the flexible cantilever beams. The electromagnetic shunt damper, which is electro-mechanically coupled with the flexible structures, simply consists of a coil, a permanent magnet, and an R-C circuit. The ends of the conductive coil are connected to the R-C series shunt circuit. The vibration and damping characteristics of the flexible beams with the electromagnetic shunt damper were investigated by tuning the circuit parameters. Also, the effect of the magnetic intensity on the shunt damping was studied with the variation of the gap between the aluminum beam and the permanent magnet. The theoretical model of electromagnetic shunt damper was validated with experimental results. Present results show that the magnet shunt damper can be successfully applied to reduce the vibration of the flexible structures.</P>
A current-flowing electromagnetic shunt damper for multi-mode vibration control of cantilever beams
Cheng, Tai-Hong,Oh, Il-Kwon Institute of Physics Publishing 2009 Smart materials & structures Vol.18 No.9
<P>In this paper, a multi-mode electromagnetic shunt damper employing the current-flowing method is newly developed for the semi-active vibration control of flexible structures. The electromagnetic shunt damper, which is used for the electromagneto-mechanical coupling transduction between vibrating structures and the electrical shunt circuit, consists of a coil and a permanent magnet. The conducting coil is attached to the cantilever beams and the two ends of the coil are connected to the current-flowing shunt circuit for the reduction of vibration. For the analytical and experimental validation of the multi-mode electromagnetic shunt damper, the first two modes of the cantilever beam are semi-actively controlled. In light of the frequency responses, the vibration and damping characteristics of the flexible beams with the electromagnetic shunt damper are investigated with reference to changes in the circuit parameters. Also, the time responses of the integrated systems with an initial condition are experimentally examined for validation of the proposed damper. The effect of the magnetic intensity on the shunt damping is studied by varying the gap between the aluminum beam and the permanent magnet. The theoretical prediction of the frequency response of the electromagneto-mechanically coupled beams shows good agreement with the experimental results. The present results show that the current-flowing electromagnetic shunt damper can be successfully applied to reduce the multi-mode vibration of flexible structures. </P>
Coil-based Electromagnetic Damper and Actuator for Vibration Suppression of Cantilever Beams
Cheng, Tai-Hong,Oh, Il-Kwon SAGE Publications 2009 Journal of intelligent material systems and struct Vol.20 No.18
<P>In this study, both an eddy current coil damper and an electromagnetic actuator were developed for the vibration suppression of a cantilever beam integrated with a copper coil and a permanent magnet. The control system for the vibration suppression of the electro-magneto-mechanically coupled beam that consists of a coil attached to an aluminum beam and a permanent magnet installed below the coil was proposed. Alternatively, the conductive coil can be passively and actively used as a damper and an actuator. The effects of various coil shapes including a cylindrical tube, a square tube and a circular sheet were investigated to determine optimal vibration suppression for the cantilever beam. The frequency response function of a beam with the theoretical model of the magnetic eddy current damping system was predicted and its accuracy was compared to the experimentally measured frequency response. Also, the results of the active control with a positive position feedback method were compared with those of the passive eddy current dampers with open and closed circuits. The experimental data showed that the tube type coils had much higher vibration suppression efficiency than the sheet type coil and the active vibration control strategy can be alternatively used to improve the electromagnetic damper system.</P>