Optimized metamaterial using quarter-wavelength resonators for broadband acoustic absorption
* Presenting author
Abstract:
This paper discusses the design and validation of an optimized acoustic metamaterial targeting broadband sound absorption. The design is based on a parallel assembly of different quarter-wavelength resonators. The metamaterial’s absorption coefficient is predicted using an efficient analytical model, that is based on an equivalent fluid description and accounts for the radiation impedance of the different resonators. The accuracy of this model is verified using a detailed Finite Element Analysis. Subsequently, the model is combined with a gradient-based optimization method to design a topology realizing a broadband high sound absorption in the low-frequency range between 500 Hz and 1000 Hz considering the volumetric constraints. To this purpose, the number of unique resonators is predefined whereas the porosity, channel length, width and thickness of each resonator type are optimized. Multiple samples of the resulting design are produced using additive manufacturing and tested in an in-house test rig to verify the reproducibility of the samples and to study the effect of production tolerances and the applied volumetric constraints on the acoustic performance of the absorber.