Abstract: Rigid Polyurethane Foam is a material with cellular structure. It has excellent properties for cushioning and energy absorbing and is used in packaging and protective padding. So it is important to study its dynamic mechanical behaviour and to propose its constitutive relation including stress, strain, strain rate and density. In this paper, the high strain rate experiment of rigid polyurethane foam of four kinds of density by Split Hopkinson Pressure Bar was introduced, and the strain rate is 1 000/s, 1 5...