Article
Design of Acoustic metamaterials for broadband sound (en)
* Presenting author
Abstract:
Acoustic metamaterials have the potential to reduce vibrations and sound in a targeted and narrow-band frequency range. Main concepts are based on mechanical resonators that act as vibration absorbers in their natural frequency and thus absorb energy that would otherwise be radiated in the form of airborne sound and perceived as noise. Metamaterials that make use of this mechanism are called locally resonant acoustic metamaterials (LRAM). Although periodicity is not a prerequisite in this case, it is preferable in most cases because it allows a unit cell-based description of the dynamic properties. A key advantage of LRAM is that they display bandgaps at lattice scales two orders of magnitude smaller than the wavelength of the incident wave. This requirement is important for two reasons: (1) it allows LRAM to be used for low-frequency applications (which are of particular interest for sound insulation) and (2) in cases where periodicity is present, it gives the metamaterial the possibility to be considered as an effective medium. In this contribution, we present the design of acoustic metamaterials based on locally resonant structures with the main goal of broadband sound insulation.