Identification of acoustic properties of auxetic foams

This paper presents an experimental investigation on the acoustic properties of a novel concept of auxetic (Negative Poisson's ratio) open cell polyurethane gray foam for dynamic crash loading applications. The acoustic absorption coefficients and real and imaginary part of the specific acoustic impedance have been measured with an ASTM standard impedance tube using a transmissibility technique. The foam shows a significant increase of the absorption properties in the low frequency range compared to equivalent conventional open cell foams. The acoustic properties of the foams are identified using an empirical model to describe their structural characteristic.