Using eddy-current vibration absorbers to design locally resonant periodic structures

Flexural wave bandgaps of traditional periodic structures are narrow and difficult to tune. Damping is an important parameter for controlling those bandgaps, but structural damping is also generally difficult to design and change, which is why there have been relatively few studies that explore the role of damping in bandgap design in the past. In the present paper, adjustable eddy-current vibration absorbers (ECVAs) are used as local resonators installed on a beam. The flexural wave bandgap and the vibration response of the beam with periodic ECVAs with different damping constants are analyzed, and how the damping influences the bandgap and the transmissibility is revealed. The experimental results agree well with the simulation results. The flexural wave is attenuated strongly within the bandgap, and the upper boundary of the bandgap rises gradually with the damping constant of the resonator, thereby widening the bandgap. However, the resonator damping influences the lower boundary of the bandgap only weakly. Moreover, if the periodic ECVAs are mistuned by a small amount and the resonator damping is small, then the structure has a number of separate locally resonant bandgaps. With a sufficient amount of eddy-current damping, the separate bandgaps become interconnected to form a larger bandgap. The present approach is a new way to broaden locally resonant bandgaps.