MICROMECHANICAL ANALYSIS OF DYNAMIC BEHAVIOR OF CONVENTIONAL AND NEGATIVE POISSONS RATIO FOAMS

Both conventional and negative Poisson's ratio foams exhibit dispersio n of acoustic waves, as well as cut-off frequencies, at which the grou p velocity tends to Zero. This macroscopic behavior is attributed to m icro-vibration of the foam cell ribs. The purpose of this article is t o develop a micromechanical model of the cut-off frequency. This model is based on the resonance of ribs which may be straight, curved or co nvoluted. 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 absorpt ion of sound.