On Characterizing Multiaxial Polymer Foam Properties in Sandwich Structures

Abstract

A pressure vessel experiment was developed to determine the triaxial, elastic-plastic and hysteresis behavior of Divinycell PVC H100 foam. Arcan butterfly and tensile dogbone specimens were encased in the air chamber of a cylindrical pressure vessel, which was designed to work within an MTS servohydraulic machine. Digital Image Correlation was used to measure strains in the specimen during the experiments. Material tests under cyclic loading of the foam under uniaxial compression and tension, shear, biaxial compression and shear, triaxial compression, triaxial compression-tension and triaxial compression and shear, were performed in both out-of-plane and in-plane directions. The foam, which was transversely isotropic, exhibited elastic-plastic response followed by damage and viscoelastic hysteresis. It was shown that only the Tsai-Wu quadratic failure criterion, with its 12 material constants, was able to predict the correct yield behavior under triaxial stress states. Tsai-Wu plasticity with anisotropic hardening was combined with a linear viscoelastic, damage mechanism to describe the elastic-plastic and hysteresis behavior of the foam. Good agreement was found between the proposed elastic-plastic-viscoelastic-damage constitutive model and experimental results.