Broadband low-frequency bidimensional honeycomb lattice metastructure based on the coupling of subwavelength resonators

Abstract

The development and application of noise control strategies have been recently the focus of attention by several researchers. In the present study, the authors develop a thin low frequency acoustic metamaterial, composed of critically coupled subwavelength Helmholtz resonators, axially arranged, with a focus on wideband perfect absorption and sound transmission problems, which are here denominated Acoustic Honeycomb Metasurface (AHS). Applying fluid equivalent models to describe the viscous thermal losses through the transfer matrix method and nonlinear optimization, it has been possible to investigate the critically coupling condition in local resonances to enhance quasi-perfect (α>0.8) and perfect sound absorption (α=1). The results demonstrate the proposed absorber system works on a subwavelength regime (λ/52), exhibiting high absorption efficiency (>80%) at low-frequency broadband absorption (approx. 300 Hz to 600 Hz). Finally, the present work opens new possibilities to develop subwavelength opened acoustic metamaterials, with potential application in ventilated systems in different engineering areas.