Study of the Constitutive Relationship of Rigid Polyurethane Foam Based on the Density and Strain Rate Effect

The rigid polyurethane foams (RPUFs) were subjected to a series of quasi-static and dynamic loading tests in order to determine their deformation modes, stress–strain curves, and the effects of density, strain rate, and energy absorption performance. Consequently, it is found that the static compressive behavior of the RPUF is significantly affected by both density and strain rate, whereas the dynamic compressive behavior depends primarily on density. At high strain rates the effect of the strain rate becomes less pronounced. A macroscopic constitutive model was developed for the RPUF and its parameters were fitted to the experimental data. By comparing with the experimental curves, it is observed that the results are in excellent agreement with the proposed constitutive model, thus demonstrating its ability to accurately describe the compressive deformation behavior of the RPUF.