Strain rate effects on sandwich core materials: An experimental and analytical investigation

Abstract Poly-vinyl chloride (PVC) based closed-cell foams were tested at different strain rate under compression loading ranging from 130s–1750 s−1 using a modified Split Hopkinson Pressure Bar (SHPB) apparatus, consisting of polycarbonate bars. Foams with different density and microstructure were examined. The attainment of stress equilibrium within the specimen at various strain rates was examined. It was found that the stress equilibrium was reached early at lower strain rate as compared to higher strain rate. Both the peak stress and absorbed energy were found to be dependent on foam density and strain rate, although foam density was found to be a more dominating factor. A model based on unit cell geometry of the closed-cell foam was also developed to predict the absorbed energy at high strain rate. The proposed model is found to be promising in predicting the energy absorption during high strain rate loading.