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Tunable electromagnetic shunt damper with opposing magnets configuration

Electromagnetic damper (EMD) has been widely studied in the control of vibrating structures. It has higher tunability when compared with a viscous damper and lower cost when compared with a magnetorheological damper. However, its use is limited mainly due to the high ratios of system mass/volume to the damping force produced. In this paper, an electromagnetic shunt damper (EMSD) with opposing magnets configuration to provide a tunable damping force is proposed for vibration damping applications. The proposed EMSD configuration allows a significant reduction in size in comparison with other similar designs of EMSD found in the literature. Both simulations and experiments are conducted to verify the improvements of this proposed design over existing ones. In particular, an ESMD comprising six opposing magnets is designed and tested on a single-degree-of-freedom (SDOF) vibration system. The damping coefficient of the proposed EMSD offers a large tunable range with maximum damping coefficient about nine times or 900% of the minimum damping coefficient. As a result, the force and displacement transmissibilities can be minimized in a wide frequency band by varying the damping ratio in the SDOF system at different vibrating frequencies.