Investigating the Performance of Strength Models for High Energy Density Applications

Laser-driven shock compression experiments on a nanosecond time scale were performed on Ag, Al, Be, and Cu samples using the Omega EP Laser System at the University of Rochester. The sample materials in this experiment are potential pushers for shock melt experiments, and thus one of the motivations for this experiment was to study the speed and amplitude of the elastic waves and hence investigate the conditions for these materials to transmit a clean shock. Radiation hydrodynamics simulations of these experiments using the Steinberg-Guinan yield stress model show significant disagreement from the experimental VISAR measurements, because of strain rate dependence and texture. An improved match was found using significantly modified values of the Steinberg-Guinan model parameters. Simulations were also performed using dislocation-based strength models, including a recently developed model for high energy density conditions (arXiv:2110.06345), which gave significantly closer agreement using parameters fitted to gas gun experiments.