Investigation of the effects of the microstructure on the sound absorption performance of polymer foams using a computational homogenization approach

In this paper, a computational homogenization approach is exploited to study the effects of the microstructure of polymer foams on their acoustic properties. A Kelvin cell with partially-open thin membranes is adopted to represent the microstructure of the foam. By applying the homogenization approach, the effective material parameters are obtained based on a microscopic representative volume element (RVE) subjected to different loading conditions. Geometrical properties, including the opening and the thickness of the thin membranes and the cell size, are investigated. It is shown that when the opening of the membranes or the cell size are smaller, the sound absorption performance at low frequencies can be improved, at the expense of the mid-high frequency performance. Moreover, the optimal opening and optimal cell size for best sound absorption performance depend on the target frequency range. The effect of solid properties, including the stiffness and the loss factor, are also discussed. For low-stiffness materials, local resonance of the solid frame greatly affects the effective fluid density and the frame-borne wave, whereas global resonances can be utilized to improve the absorption performance in a specific frequency band.