Interpreting Experimental Results from Shock Impacts on Single Crystal PETN in the Context of Continuum Models

• Published in: Propellants, explosives, pyrotechnics explosives, pyrotechnics, 2019-11
• Main Authors: Luscher, Darby Jon, Cawkwell, Marc Jon, Ramos, Kyle J., Sandberg, R. L., Bolme, Cynthia Anne
• Format: Article
• Language: English
• Subjects: anisotropy; continuum model; impact; PETN; single crystal
• ISSN: 0721-3115; 1521-4087
• DOI: 10.1002/prep.201900228

Here, we interpret previous experimental measurements of impacts on single crystal PETN in the context of a simple continuum model. Hugoniot calculations using the simple model framework under various limiting assumptions envelope measured Hugoniot states reasonably well and suggest that non-negligible deviatoric elastic strains may exist in the shock compressed state for weak impacts. An accompanying simple kinematic model for lattice deformation was used to estimate the expected shifts in X-ray diffraction peaks for the (211) plane under impacts normal to (110) planes. The results suggest that negligible relaxation of the deviatoric lattice deformation occurs on the short (10–20 ns) time and wave propagation (40–80 m) scales of laser-driven shock experiments, and that the corresponding elastic strains may be large. Due to the potentially large deviatoric elastic strains, the specific finite deformation strain measure used within thermomechanical single crystal models is of significant consequence, which is explored numerically by the comparison of isothermal purely elastic responses under uniaxial and simple shear deformations.