Tuning Fork Seismic Metamaterial for Low-Frequency Surface Wave Attenuation with Locally Resonant Band Gaps

BackgroundThe development of seismic metamaterials provides new inspiration for controlling the propagation of seismic waves. The unit cell of seismic metamaterials is generally designed as a column structure with a uniform cross-section. However, such column structure requires a large amount of rigid material to generate broadband band gaps in the low-frequency range.ObjectiveA novel tuning fork-shaped seismic metamaterial has been proposed for the utilization of the peculiar vibration modes of the tuning fork structure as the locally resonant to the dissipation of seismic energy.MethodsThe finite element method was applied to calculate the eigenmodes and the seismic shield effects in the commercial software COMSOL Multiphysics.ResultsThe types of eigenmodes with respect to the tuning fork structure have been determined, especially the special eigenmodes different from the traditional column structure. Through the parametric analysis, the vibration frequency of the tuning fork has been optimized to match the primary frequency of the seismic surface wave for enhancing the seismic energy dissipation. Finally, a numerical investigation of the seismic surface wave propagation through an array of tuning fork unit cells has been conducted to verify the seismic shield effects in band gaps.ConclusionThe proposed seismic metamaterial in the form of the optimized tuning fork structure can provide a good attenuation performance with lower steel consumption due to the locally resonant band gaps.