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

数值和实验研究了一种消音器的消声效果，该消声器由将三聚氰胺泡沫塑料制成的薄板网络插入矩形管中组成。薄片排列的设计使得骨架弯曲弹性共振在低频出现。除此现象外，多孔材料中的粘热损耗还确保宽带衰减。薄层网络提供了自然的亚波长谐振器，没有任何其他种类的夹杂物，并创建了易于制造的具有高可调性和宽带效率的超材料。实验的传输损耗与在整个消音器上，在周期单元上获得的三维有限元模型相比非常好。对周期模型进行了参数研究，以确定不同几何参数的影响，