Response of a polystyrene foam subjected to large strains and high pressures

Abstract

This article presents experimental data, and their comprehensive analysis, for a polystyrene foam (with an initial density of 0.623 g/cm3) subjected to large strains and high pressures. The data were obtained from unconfined uniaxial stress tests in compression (at two different strain rates), confined compression tests with compressive strains to almost 50%, and a tension test. The confinement for the compression tests consists of a steel cylinder with external strain gages to monitor the hoop strains due to the radial stresses from the compressed foam. The procedure used to analyze the data allows for a continuous determination of axial, radial and hoop stresses, pressure, and von Mises equivalent stress. A parametric finite element analysis was used to provide for the determination of the stresses from small strains to large strains approaching 50%. There is excellent agreement between test results for similar conditions, as well as the results from data obtained from the confined experiments with two different wall thicknesses. The strength (von Mises equivalent stress) is highly dependent on the pressure, but not as dependent on the strain. The strain rate has a significant effect on strength for the uniaxial stress tests, but only limited data were obtained. Constants were obtained for an existing computational model, and there is good correlation between the experimental data and the model.