Unloading and reloading response of shocked aluminum single crystals: Time-dependent anisotropic material description

The measured unloading and reloading wave profiles in shocked metals have long been known to show deviations from the usual elastic-plastic response used to model shocked metals. To gain insight into inelastic deformation mechanisms during unloading and reloading from the shocked state and to avoid complexities associated with material heterogeneities present in polycrystalline metals, this work has focused on the shock wave response of single crystals. Here, we report on wave propagation simulations to examine the unloading and reloading response of aluminum single crystals shocked along [100], [110], and [111] orientations to 21 GPa peak stresses. The simulations utilized a dislocation dynamics based, time-dependent anisotropic material description to model shock-induced elastic-plastic deformation. The calculated profiles provide good overall agreement with measured unloading and reloading wave profiles [H. Huang and J. R. Asay, J. Appl. Phys. 101, 063550 (2007)] for all three crystal orientations and ...