Poroelastic lamellar metamaterial for sound attenuation in a rectangular duct

The sound attenuation of a silencer consisting lamella network made with melamine foam inserted in rectangular duct is investigated numerically and experimentally. arrangement designed so that skeleton bending elastic resonances appear at low frequency. In addition to this phenomenon, viscothermal losses the porous material ensure broadband attenuation. provides natural sub-wavelength resonator, without any other kind inclusions, create an easy manufacture metamaterial high tunability efficiency. Experimental transmission compare well three dimensional finite element model obtained either on whole silencer, periodic cell. A parametric study conducted identify effect different geometrical parameters, like dimensions air gap, as physical flow resistivity, modulus loss factor poroelastic material, silencer.