Characterisation and modelling of a transversely isotropic melt-extruded low-density polyethylene closed cell foam under uniaxial compression

Abstract

This article describes uniaxial compression tests on a melt-extruded closed-cell low-density polyethylene foam. The stress–strain response shows that the mechanical behaviour of the foam is predominantly transversely isotropic viscoelastic and compressible. Image analysis is used to estimate the Poisson’s ratio under large strains. When the deformation is less than 5%, the compression kinematics and mechanical response of the polymer foam can be well described by a linear compressible transversely isotropic elastic model. For large strain, a simple method is proposed to estimate the uniaxial compression response of the foam at any arbitrary orientation by manipulating experimental data obtained from compression tests in the principal and transverse directions (stress vs. strain and Poisson’s ratio) and a simple shear test. An isotropic compressible hyperfoam model is then used to implement this behaviour in a finite element code.