Modeling and experimental validation of cellular porous material with large resonant inclusions

Abstract

Porousmaterials are widely used for improving sound absorption and sound transmission loss of vibrating structures. However, their efficiency is limited to medium and high frequencies. A common solution for improving their low frequency behavior while keeping an acceptable thickness is to embed resonant structures such as Helmholtz resonators. This work investigates the absorption and transmission acoustic performances of a cellular porous material with large resonatorinclusions. The homogenization theory cannot be appliedto cellular material made of suchlargeperiodic unit-cell (e.g., cubeof side L≈100 mm). A low frequency modelof a larger esonant unit-cell based on the Parallel Transfer Matrix Methodis proposedin this work.Theproposed model is validated by comparison with impedance tube measurements and finite element calculations. At the Helmholtzresonance frequency; (i) the transmission loss is greatly improved and (ii) the sound absorption of the host material isdecreasedif it is made of a highly sound absorbing material.