Acoustic absorption mechanism and optimization of a rubber slab with cylindrical cavities

Abstract

The finite element method is introduced to investigate the absorption of a rubber slab (20 mm thick) with one layer of cylindrical cavities. It has a lower frequency absorption peak than that with spherical cavity in the same size, which is determined by the monopole resonance of cavities. Analysis of partial wave scattering verifies that the absorption peak is induced by the monopole resonance. Power dissipation density and displacement pattern of one unit cell is used to clarify intuitively the absorption mechanism of the cavity. Then the effect of damping of transverse modulus on the absorption is investigated under the condition of a steel backing. Both the physical and structural parameters of the rubber slab are optimized by a genetic algorithm for favorable absorption from 1.5 to 10 kHz.