Ultra broadband low-frequency vibration and pulse mitigation of electromagnetic induction-based metastructure

Elastic metastructures have attracted extensive research interest for their unique properties of generating bandgaps to mitigate vibration. However, it is difficult for conventional metastructures to obtain ultra-wide bandgap in low-frequency domain. To address this challenge, a novel bandgap active control mechanism is proposed and applied to locally resonant metastructures. The magnetic resonator perfectly combines the dual mechanism of negative stiffness and electromagnetic induction, which allows the start and end frequencies of bandgap to be tuned flexibly to obtain ultra-broadband and low-frequency wave mitigation domain. The theoretical bandgap is derived from extended plane wave expansion method and verified by numerical simulation and experiment. The results show that the bandwidth is broadened by about 3.5 times than before and the quasi-bandgap with extremely-low frequency is induced under the action of electromagnetic damping. By regulating the spacing, the quasi-bandgap and bandgap can be coupled to form strong wave mitigation domain covering the frequency below 300Hz. Besides, the proposed metastructures exhibit stronger pulse mitigation and resonance peak attenuation in low-frequency domain. This study is expected to provide a new design concept for the performance development of smart elastic/acoustic wave devices such as low-frequency vibration energy harvester, vibration isolator and metasurface, etc.