High-fidelity Hugoniot analysis of porous materials

An experimental technique and analysis methodology for obtaining high-fidelity Hugoniot measurements with defined uncertainty bounds on powder compacts using optical velocimetry is presented. Impedance matching is used to calculate the shocked state in the powder from the measured initial compact density, ρ(00), impact velocity, V(Imp), and shock velocity, U(S). Detailed characterization of the powder thicknesses at precise locations results in improvements in characterization of the initial density state and accurate measurements of the powder thickness at locations corresponding to shock velocity measurements. These measurements result in high accuracies in the equilibrium Hugoniot state and reduced uncertainties in the measured and calculated Hugoniot parameters. Assumptions in this analysis include a constant and homogeneous initial porous density, and steady state wave propagation. The approach is applied to a system of CeO(2) powder pressed to 4.0 g/cm(3) (55% theoretical maximum density), and results indicate a complex dynamic response.