Effect of density, microstructure, and strain rate on compression behavior of polymeric foams

In this paper two types of polymeric foams, namely, cross-linked poly-vinyl chloride (PVC) and polyurethane (PUR) were examined under compression loading at different strain rates. Quasi-static compression tests were performed using a servo-hydraulic material testing system (MTS) at strain rate of 0.001, 0.01, and 0.1 s(-1). Higher strain rate compression tests were performed using a split Hopkinson pressure bar (SHPB) apparatus with polycarbonate bars at strain rate ranging from 130 to 1750 s(-1). PVC foams with three densities and two microstructures, and PUR foams with two densities were considered. All foam specimens were tested in the thickness (rise) direction and the stress-strain responses at different strain rate were established to determine the peak stress and energy absorption. Both peak stress and energy absorption were found to be dependent on foam density, foam microstructure, and strain rate. A power law relationship between the peak stress and foam density revealed that the constants were different at different strain rate. Microstructural examinations of the failed specimens showed that PUR foams disintegrated completely around 1600 s(-1) whereas PVC foams densified completely like a solid material. (c) 2005 Elsevier B.V. All rights reserved.