Density, strain rate and strain effects on mechanical property evolution in polymeric foams

This paper presents a comprehensive experimental study of the evolution of Poisson's ratio and tangent modulus of polymeric foams during rate dependant uniaxial compression. In this study, polyurethane foams with densities of 195 kg/m(3), 244 kg/m(3), and 405 kg/m(3) obtained from PORON (XRD series) were examined under uniaxial compression loading at strain rates ranging from 0.001 s(-1) to 5000 s(-1). All compression experiments were coupled with a high-speed camera to enable Digital Image Correlation to measure and visualize deformation strains. These measurements enable us to study mechanical property evolution during compression and provide qualitative description of damage and failure in these materials. A non-linear evolution of Poisson's ratio is observed in-situ in these materials. The compressive stress-strain response is predicted through least square fitting using the Avalle model [1], and model coefficients are found to follow a power-law to scale across strain rates. The stress-strain curves, mechanical property evolution, and scaling coefficients are compared with microstructural parameters of interest such as pore size and wall thickness to inform on damage accumulation mechanisms in the material.