Seismic metamaterials: Generating low-frequency bandgaps induced by inertial amplification

In the last two decades, seismic metamaterials have attracted significant attention of researchers because of the characteristic of the bandgap which can be used to control seismic surface waves. The inertial amplification mechanism has been used to design metamaterials capable of isolating elastic waves in rods, beams, and plates at low frequencies. In this work, we propose an alternative type of seismic metamaterial with a low-frequency bandgap induced by inertial amplification for isolating seismic surface waves. The characteristics of the bandgap induced by inertial amplification are experimentally demonstrated by using a metamaterial plate composed of 25 unit cells. The propagation of the flexural waves imaged by scanning laser Doppler vibrometer shows strong attenuation effects induced by the metamaterial plate in the bandgap. The broadband attenuation is investigated by using two kinds of unit cells. Finally, similar structures with inertial amplification are introduced to design the seismic metamaterials to isolate seismic surface waves at low frequencies.