Experimental investigations on phenomenological constitutive model of closed-cell PVC foam considering the effects of density, strain rate and anisotropy

Abstract

The uniaxial compressive mechanical properties of PVC foams considering the effects of density ( ρ = 60 − 200 k g / m 3 ), strain rate ( ε ˙ = 0.001 − 721 / s ) and anisotropy ( R = 1 − 1.57 ) have been investigated by quasi-static and dynamic (Split Hopkinson Pressure Bar, SHPB) experiments. In order to verify the effectiveness of the experiments, a control group was set to eliminate the size effect, and to achieve the repeatability of the experiments. Besides, the stress equilibrium of the specimen in the SHPB experiment was examined by the polyvinylidene fluoride (PVDF) pressure sensors . The macroscopic deformation of the specimen during the whole loading process was recorded by the high-speed photography system. The microstructural failure morphology and mechanism were analyzed by combining the single loading control technique (SLCT) and scanning electron microscope (SEM). On this basis, an equation was proposed to predict the collapse stress of PVC foams considering the effects of density, strain rate and anisotropy. Moreover, a rigid-plastic hardening constitutive model (RP-H model) involving above three factors was summarized to characterize the uniaxial compressive mechanical properties of PVC foams. • The quantitative relationship between the chord length of PVC foams and loading angle (deviating from foam rise direction) is developed using the shape anisotropy-ratio R . • The stress equilibrium of PVC foam specimens was verified by polyvinylidene fluoride (PVDF) pressure sensors in dynamic SHPB tests. • The failure modes and mechanisms of specimens were analyzed combining the single loading control technique (SLCT) and the scanning electron microscope (SEM). • A phenomenological constitutive model (RP-H model) considering the effects of density, strain rate and anisotropy was proposed to characterize the uniaxial compressive mechanical properties of PVC foams.