Propagation Characteristics of Surface Waves in a Chiral Seismic Metamaterial Structure

The development of seismic metamaterials (SMs) offers a novel approach for isolating seismic waves. Nevertheless, achieving a broad low-frequency band gap within a compact structure remains a challenging issue that requires further resolution. To address this challenge, the study introduces a chiral structure into SMs. The designed chiral seismic metamaterial structure (CSMS) comprises four commonly used construction materials: soil, steel, rubber, and aluminum. The band structure, along with the sound cone, is explored through the application of the finite element method. The influence of geometric configurations and material properties on the band gaps is examined. In particular, the impacts of the count and curvature of the ligaments in the chiral structure on the band gap are investigated. The findings indicate that geometric and material parameters exert a substantial influence on the band gaps. The vibration energy is mainly concentrated in the chiral structure. Both Love and Rayleigh waves can be effectively attenuated within the band gaps, while seismic waves outside the band gaps cannot be attenuated effectively. Furthermore, the analysis of the frequency domain and time domain further validates the vibration-damping efficacy of the proposed structures in real earthquakes. Therefore, it can be concluded that low-frequency broadband gaps can be obtained to effectively control seismic wave propagation when a chiral structure is incorporated into SMs. The findings of this study can offer a theoretical basis for the application of chiral structures in SMs.