Harnessing Multiple Internal Reflections to Design Highly Absorptive Acoustic Metasurfaces

Chen Shen, Steven A. Cummer
2018 Physical Review Applied  
The rapid development of metasurfaces has enabled numerous intriguing applications with acoustically thin sheets. Here we report the theory and experimental realization of a non-resonant sound absorbing strategy using metasurfaces by harnessing multiple internal reflection. We theoretically and numerically show that the higher order diffraction of thin gradient-index metasurfaces is tied to multiple internal reflection inside the unit cells. Highly absorbing acoustic metasurfaces can be
more » ... by enforcing multiple internal reflection together with a small amount of loss. A reflective gradient-index acoustic metasurface is designed based on the theory, and we further experimentally verify the performance using three-dimensional printed prototype. Measurements show over 99% energy absorption at the peak frequency and a 95% energy absorption bandwidth of around 600 Hz. The proposed mechanism provides an alternative route for sound absorption without the necessity of high absorption of the individual unit cells.
doi:10.1103/physrevapplied.9.054009 fatcat:c7daiz3kcjcy3fvykiffmcnexu