Mechanical performance and cushioning energy absorption characteristics of rigid polyurethane foam at low and high strain rates

Abstract

This study elucidates the mechanical response of rigid polyurethane foam (RPUF) at different strain rates and densities. A series of quasi-static and dynamic loading tests on the RPUFs were performed to determine the deformation modes, stress-strain curves, and effects on density, strain rate, and energy absorbing performances. Consequently, the static compressive behavior of RPUF significantly depends on density and strain rate, while the dynamic compressive behavior of RPUF significantly depends on density. However, the effect of strain rate is not evident at high strain rates (500 s−1–2500 s−1). The elastic modulus, compressive strength, and yield stress of RPUF increase with a rise in density. The experimental results show that the compressive strength is enhanced at a high strain rate loading when compared with that at quasi-static loading. Based on the measured stress-strain curves, the variation in energy absorption and efficiency with respect to RPUF density was studied. The typical damage mechanism of RPUF with different densities was investigated via scanning electron microscopy. Cell wall buckling is the prominent failure mode in the high-density RPUF; however, the main failure modes of low-density RPUF are wrinkling and stretching of cell faces.