Novel small-size seismic metamaterial with ultra-low frequency bandgap for Lamb waves

¹ Key Laboratory of Urban and Engineering Safety and Disaster Reduction, Beijing University of Technology Beijing 100124, China
² Beijing Key Laboratory of Engineering Earthquake Resistance and Structural Diagnosis and Treatment, Beijing University of Technology - Beijing 100124, China
³ Beijing Computing Center Co., Ltd, Beijing Academy of Science and Technology - Beijing 100094, China

Received: 24 April 2024
Accepted: 6 August 2024

Abstract

Seismic metamaterials (SMs) possess bandgap characteristics, enabling effective attenuation of seismic waves within a specific frequency range. However, small-sized SMs typically struggle to achieve a wide low-frequency bandgap. This paper proposes four types of SMs. The dispersion curves of these models were analyzed, and their vibration modes were studied to elucidate the bandgap mechanism. To investigate the influence of structural parameters on the bandgap, geometric variables are analyzed. Subsequently, the spectrum and acceleration time history curves of Lamb waves in a finite SM system are analyzed to verify the bandgap's authenticity. The designed structure exhibits a bandgap ranging from 1.24 Hz to 16.86 Hz, with a relative bandwidth as high as 172.6% and over 96% maximum vibration displacement attenuation of the El Centro seismic wave. The designed SMs effectively cover the 2 Hz seismic peak spectrum that leads to structural damage. They possess ideal relative bandwidth and excellent isolation performance, further advancing the engineering application of SMs.