Compression and spallation properties of polyethylene terephthalate under plate impact loading

Abstract

We conduct plate impact experiments to investigate shock compression and spallation properties of polyethylene terephthalate. The Hugoniot equation of state, the apparent velocity–particle velocity relation, and the indices of refraction are obtained from Hugoniot experiments. Spall strength, as well as tensile strain rate is deduced at shock pressures up to ∼2.4 GPa in spallation shots. At low shock pressures (<0.6 GPa), the spall strength increases slightly with increasing shock pressure, as a result of increasing tensile strain rate. Release melting is observed at high impact velocities (>816 m s−1). Via X-ray computed tomography, three-dimensional void and crack structures are revealed for shock-recovered specimens. Small voids appear thin and curved for low-speed impacts but become ellipsoidal for high-speed impacts. Such different void shapes may be attributed to the diverse damage mechanisms at different impact velocities.