Membrane-Type Acoustic Metamaterials Carrying Asymmetric Arc/Platelet Masses for Sound Insulation

Objective: This study presents a novel membrane-type acoustic metamaterial (MAM) with loaded masses of asymmetric dimensions and arrangements. The transmission losses (TL) of the proposed structures were investigated theoretically. The two types of loaded ornaments investigated were arc masses and platelets. The dependence of TL characteristics on mass positions was also investigated. Method: An analytical model based on the Galerkin method was established to predict the TL behavior. Finite element (FE) simulations were conducted to verify the analytical results. Results and Conclusions: In comparison with traditional MAMs of symmetric loaded mass, asymmetric masses are more effective in increasing the number of TL peaks as well as reducing the overall weight of the structure. The TL peak frequency coincides with the frequency of the unbound mass and steep phase change. A good agreement between theoretical and FE results was observed.