Bi-objective optimal design of an electromagnetic shunt damper for energy harvesting and vibration control

Owing to the electromechanical energy conversion capacity, electromagnetic shunt dampers (EMSDs) are widely applied to vibration suppression or energy harvesting from vibrating struc-tures. Either one of the two functions can be optimized in the designs of EMSD found in the literature. In this paper, a bi-objective optimization methodology of EMSD is proposed for the simultaneous maximization of energy harvesting from the damper and the suppression of reso-nant vibration of a dynamic structure. An EMSD with opposing magnet pairs configuration is designed to achieve the two design objectives simultaneously in a single-degree-of-freedom (SDOF) system and a dynamic vibration absorber (DVA). It is proved analytically and experi-mentally that maximum energy can be harvested by the EMSD when its internal impedance equals to the external electrical resistance of the electrical circuit. Minimum resonant vibration amplitude of the primary mass can be achieved at the same resistance ratio in the DVA system by selecting the suitable number of opposing magnet pairs of the EMSD without affecting the internal resistance. An EMSD with opposing magnet pairs configuration is designed and tested in a single -degree-of-freedom (SDOF) system and a dynamic vibration absorber. Following a proper pro-cedure, the electromechanical transduction factor of the proposed EMSD can be tuned to achieve both objectives simultaneously. The harvested energy is higher when the EMSD is deployed in the SDOF system than in the DVA system, but the frequency bandwidth for energy harvesting is much wider in the DVA system. Analyses lead to a design guideline of the EMSD for achieving the bi-objective optimization.