Static and high constant strain rate loading on auxetic and conventional PU foam

A new type of auxetic (Negative Poisson's ratio) open cell polyurethane foam has been tested under static tensile tests and high constant strain rate loading to assess crashworthiness properties. The foam has been produced by transforming open cell rigid grey polyurethane foam with a manufacturing route similar to production processes published in open literature. Uniaxial tests in tension and compression have been performed on samples of conventional open cell grey PU foam and the corresponding transformed auxetic material, Constant strain rate loading (up to 54s(-1)) has been applied on the foam samples using a cam plastometer test machine. The experimental results quantified the mechanical properties of the auxetic foam and showed it to have a lower Young's modulus than the precursor foam in tension and a comparable value in compression, but with high elongation characteristics under tensile loading. The dynamic crush-loading tests showed that the rigid PU foam did not demonstrate any notable resilience under impact, while the auxetic foam showed stress-strain curves with low sensitivity to the constant strain rate