Matryoshka Locally Resonant Sonic Crystal

TL;DR

This paper models and analyzes Matryoshka resonant sonic crystals, demonstrating their ability to create broad low-frequency band gaps for noise barrier applications, surpassing traditional sonic crystal limitations.

Contribution

It introduces the concept of locally resonant sonic crystals with Matryoshka configurations, showing their effectiveness in low-frequency sound attenuation through numerical modeling.

Findings

Broad low-frequency band gaps achieved below Bragg frequencies

Matryoshka configuration enhances attenuation performance

Potential for compact noise barrier design

Abstract

The results of numerical modelling of sonic crystals with resonant array elements are reported. The investigated resonant elements include plain slotted cylinders as well as various their combinations, in particular, Russian doll or Matryoshka configurations. The acoustic band structure and transmission characteristics of such systems have been computed with the use of finite element methods. The general concept of a locally resonant sonic crystal is proposed, which utilises acoustic resonances to form additional band gaps that are decoupled from Bragg gaps. An existence of a separate attenuation mechanism associated with the resonant elements, which increases performance in the lower frequency regime has been identified. The results show a formation of broad band gaps positioned significantly below the first Bragg frequency. For low frequency broadband attenuation a most optimal configuration is the Matryoshka sonic crystal, where each scattering unit is composed of multiple concentric slotted cylinders. This system forms numerous gaps in the lower frequency regime, below Bragg bands, whilst maintaining a reduced crystal size viable for noise barrier technology. The finding opens new perspectives for construction of sound barriers in the low frequency range usually inaccessible by traditional means including conventional sonic crystals.