Ultra-Low-Frequency Vibration Attenuation Characteristics of Multi-Span Metamaterial Dual-Beam Structures

In this work, a novel multi-span metamaterial dual-beam (MMDB) structure is proposed for the effective suppression of ultra-low-frequency vibrations in beam structures. The MMDB is composed of a periodic array of units, with each simply supported unit including beams at the top and bottom, and a spring-mass-spring resonator connecting two beams. For analyzing the dynamic behavior of the MMDB, the spectral element method (SEM) is utilized to establish a dynamic model. A comparative analysis is conducted with a traditional metamaterial dual-beam model, highlighting the advantages of the proposed MMDB. The vibration transmittance of the MMDB under base excitation is analyzed, during which the bandgap frequency beginning from zero is generated. The MMDB is further modeled by the finite element method (FEM), and the simulation results of transmittance agree well with those obtained through SEM, validating the effectiveness of the utilized approach. The band structure of the MMDB structure is further obtained and local resonance and Bragg bandgaps are simultaneously found. Subsequently, parameter study is conducted to investigate the effects of material and geometry parameters on the bandgap characteristics of the MMDB. This work provides valuable guidelines for the design of multi-layer beam structures aimed at efficiently suppressing vibrations within the ultra-low-frequency range.