CONSTITUTIVE MODELLING OF POLYMER FOAMS USING AN ASYMMETRIC POISSON’S RATIO

Open-cell polymeric foams exhibit a pronounced asymmetry when subjected to uniaxial tension and compression: the axial stress–strain curves and the accompanying lateral (transverse) strains differ drastically. This behavior can be traced back to the nonlinearity of the polymer matrix material coupled with the complex geometry of the cellular microstructure. Hyperelastic constitutive models are the standard choice for modeling the elastic response of such materials. Yet a review of the literature reveals that even the most complex ones of the existing models invariably fail to reproduce the dual character of tension-compression characteristics, particularly the lateral strains. To overcome this limitation and capture the experimentally observed asymmetry we introduce a novel hyperelastic constitutive model asymmetric in Poisson’s ratio.