Negative Poisson’s ratio locally resonant seismic metamaterials vibration isolation barrier

In recent decades, the application of seismic metamaterials to protect civil infrastructures being free of the damage of earthquakes has been attracting extensive attention. Specifically, the proposed locally resonant seismic metamaterials provide the probability of isolating the low-frequency seismic wave using a small-size isolation barrier. However, in previous studies, the energy absorption properties of locally resonant seismic metamaterials remain one of the least understood aspects of isolation. Benefit from the fascinating energy absorption characteristic of negative Poisson ratio (NPR) metamaterial, we creatively design a new seismic metamaterial structure by assembling the locally resonant seismic metamaterial and NPR metamaterial, to isolate seismic waves. The sound cone technique combining the transmission spectrum is employed to identify the surface wave from the hybrid waves. The generation mechanism of frequency bandgap and the isolation effectiveness of the proposed seismic metamaterial are discussed in detail. The results indicate that the generation of ultra-low and ultra-wide frequency bandgap with the range of 0.65 Hz–18.9 Hz is attributed to the locally resonant and energy absorption of the proposed seismic metamaterial structure and the excellent isolation effect is achieved by transforming the surface wave into the bulk wave. The frequency bandgap narrows as the distance increases between each resonator. In addition, the mechanical properties of the NPR bearing, such as the Poisson ratio, mass density, and elastic modulus, have remarkable impact on the frequency bandgap, especially on the upper bound frequency. In practical engineering, the NPR bearing with a low Poisson ratio, small mass density, and high elastic modulus is suggested for the design of the NPR locally resonant seismic metamaterial structures. Time domain analysis for the practical seismic wave verifies that the proposed seismic metamaterial has a promising application in isolating ultra-low and ultra-wide seismic waves, with the isolation effectiveness larger than 70%. This work contributes a new locally resonance seismic metamaterial design idea for isolating and adjusting the low-frequency seismic wave.