Numerical and experimental investigation of the fracture behavior of shock loaded alumina

Plate impact expeiments are conducted to investigate the dynamic behavior of alumina by using one stage light gas gun. A velocity interferometer system for reflectors (VISAR) is used to obtain Hugoniot elastic limit and the free surface velocity profile, which consists of an elastic wave followed immediately by a dispersive inelastic wave. The stress histories under different impact velocities are measured by in-material manganin gauges. Based on the experimental data a Hugoniot curve is fitted, which shows the compressive characteristics that alumina changes typically from elastic to "plastic", and under higher pressure it will be transferred to similar-fluid state. The turning point of the Hugoniot curve from a high pressure region to a low pressure region is about 11.4 GPa. The fracture process of alumina is simulated by way of finite element code. After the analysis of the fracture mechanism, the numerical results show an important role played by the nucleation and the growth of the cracks in the macroscopic fracture of the alumina target. The numerical predictions of stress histories are compared with the experimental results, which indicates consistency between them.