Abstract
This paper investigates a modified acoustic metamaterial system with local resonators coupled through linear springs. The proposed acoustic metamaterial system can provide three band gaps for broadband vibration suppression. First, the band structure of the modified acoustic metamaterial is calculated by using Bloch’s theorem under the assumption of infinite lattice. The existence of three band gaps is confirmed in the band structure. Effects of mass and spring parameters on the band gap behaviour of the modified metamaterial are investigated through a dimensionless parametric study. Based on the parametric study, optimal dimensionless parameters are proposed to achieve maximal total band gap width in the low frequency range. Subsequently, a more realistic finite lattice model is established. The transmittances of the conventional and modified metamaterial systems are compared. The three band gaps predicted from transmittances and broadband vibration suppression behaviour are consistent with the predictions from infinite lattice model using Bloch’s theorem. Finally, the time-domain responses are simulated and the superiority of the modified acoustic metamaterial over the conventional one is demonstrated.
Highlights
Acoustic metamaterial proposed in recent years is a kind of artificial material with exotic properties
In analogy to photonic crystal, acoustic metamaterial is often termed as “locally resonant phononic crystal”,2 where “locally resonant” is added in order to distinguish it from the Bragg Scattering phononic crystal[5] that was proposed based on a different mechanism about two decades ago
This paper has presented a modified acoustic metamaterial system in which the local resonators in the lattice are coupled by springs alternately
Summary
Acoustic metamaterial proposed in recent years is a kind of artificial material with exotic properties. Based on the lattice model, their study showed that the effective frequency-dependent mass density of the acoustic metamaterial could be negative near resonance, which corresponded to the band gap. Huang and Sun[10] proposed the concept of multi-resonator acoustic metamaterials in which each unit cell of the lattice model consists of three masses connected in series by linear springs. Chen et al.[21] presented a theoretical study of band gap control of acoustic metamaterials through the use of negative capacitance shunted piezoelectric elements They connected the inner mass to the outer mass in one unit cell by a piezoelectric element that is shunted to a negative capacitance circuit. We propose a modified acoustic metamaterial system with local resonators (inner masses) coupled by springs. The superior vibration suppression ability of the modified acoustic metamaterial is confirmed, which results from the three band gaps by coupling its local resonators
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