Sound insulation performance of cylindrical sandwich structure improved by membrane-type metamaterials

Cylindrical sandwich structure with excellent mechanical properties has attracted extensive attention from researchers and been applied in various fields. The cylindrical sandwich structure meets the mechanical requirements of the application and new requirements emerge at this time. The structure should have multifunctionality which can withstand multiple different loads simultaneously. To improve its sound insulation ability while maintaining its mechanical properties, membrane-type metamaterials are introduced into cylindrical sandwich structure in this article. A theoretical model according to the harmonic expansion method is established. Then, the sound transmission loss (STL) of the structure is predicted. Besides, the influence of boundary conditions on its STL is analyzed and the sound insulation mechanism of the structure is investigated by discussing various parameters effect on the STL curve.