A metaporoelastic structure that overcomes the sound insulation weaknesses of single and double panel partitions

Abstract

Single and double panel partitions are well known for their sound transmission loss weaknesses in the vicinity of their structural resonances: the first mode of the finite size panel and the mass-spring-mass resonance of the double panel. In this paper, we investigate the use of a poroelastic based metamaterial to address this problem. The metamaterial is a network of poroelastic beams, the first bending mode of which is tuned at the targeted panel resonance. The porous nature of the resonators allows taking advantage of its dissipative properties stemming from the interaction between solid and fluid phases. For the double panel application, where a porous layer is generally present, the effectiveness of the poroelastic metamaterial relies on the design of its shape and mounting conditions. First, the sound transmission loss of a finite size single panel is studied experimentally in a rectangular duct under normal incidence. It is shown that the poroelastic metamaterial increases the transmission loss up to 12 dB at the first mode of the panel. Using resonators tuned at different frequencies makes it possible to spread this gain. The attenuation mechanisms are analyzed by simulation using a finite element model. Secondly, the double panel partition is investigated with a periodic finite element model using the Floquet-Bloch theorem. Finally, the impact of several parameters like airflow resistivity and filling fraction on the efficiency of the metaporoelastic structure is illustrated considering a diffuse field excitation.