Complete acoustic bandgaps in a three-dimensional phononic metamaterial with simple cubic arrangement

In this work, a phononic metamaterial that could be a reliable solution for several sound attenuation applications is examined numerically and experimentally. The proposed structure consists of a spherical shell connected with cylindrical conduits in a simple cubic arrangement. Numerical calculations, using the finite element method, and experimental measurements of the sound transmission loss were performed, providing significant evidence of the applicability of the proposed metamaterial in sound attenuation applications. For the validation of the complete acoustic bandgaps by the structure, the research was expanded to the examination of all high symmetry spatial directions. The results for all the examined spatial directions provided wide acoustic bandgaps, thus validating the evidence of complete acoustic bandgaps by the structure over a wide frequency range of the audio spectrum. Furthermore, the contribution of each part of the structure was separately analyzed, providing the physical insight for a deeper understanding of the response of the structure and the principal mechanism of the bandgap formation. The findings of this research prove that the proposed metamaterial could be a functionable unit for efficient sound attenuation applications.