Micromechanical Analysis of Dynamic Behavior of Conventional and Negative Poisson’s Ratio Foams

Both conventional and negative Poisson ’s ratio foams exhibit dispersion of acoustic waves, as well as cut-off frequencies, at which the group velocity tends to zero. This macroscopic behavior is attributed to micro-vibration of the foam cell ribs. The purpose of this article is to develop a micromechanical model of the cut-off frequency. This model is based on the resonance of ribs which may be straight, curved, or convoluted. As foam cell ribs become more curved, the cut-off frequency decreases. Therefore foams with curved or convoluted ribs are expected to provide superior performance in applications involving the absorption of sound.