Bulletin of the American Physical Society
17th Biennial International Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 56, Number 6
Sunday–Friday, June 26–July 1 2011; Chicago, Illinois
Session J2: Energetic Materials IV |
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Chair: Nathan Barton, Lawrence Livermore National Laboratory Room: Grand Ballroom IV-V |
Tuesday, June 28, 2011 11:00AM - 11:15AM |
J2.00001: Rankine-Hugoniot relationships for molecular crystal explosives calculated using density functional theory based molecular dynamics Ann E. Mattsson, Ryan R. Wixom, Thomas R. Mattsson Density Functional Theory (DFT) has become a crucial tool for understanding the behavior of matter. The ability to perform high-fidelity calculations is most important for cases where experiments are impossible, dangerous, and/or prohibitively expensive to perform. For molecular crystals, successful use of DFT has been hampered by an inability to correctly describe the van der Waals' dominated equilibrium state. We have explored a way of bypassing this problem by using the Armiento-Mattsson 2005 (AM05) exchange-correlation functional. This functional is highly accurate for a wide range of solids, in particular in compression. Another advantage is that AM05 does not include any van der Waals' attraction. We will demonstrate the method on the PETN Hugoniot, and discuss our confidence in the results and ongoing research aimed at improvement. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. [Preview Abstract] |
Tuesday, June 28, 2011 11:15AM - 11:30AM |
J2.00002: Equations of State of Hexanitrostilbene (HNS) Jared Gump, Chad Stoltz, Brian Mason, Emily Heim Hexanitrostilbene (HNS) is an energetic ingredient that is widely used in commercial and military explosives for its thermal stability. However, characterization of its thermodynamic parameters and phase stability is lacking. Crystalline properties, such as bulk modulus and thermal expansion, are necessary to accurately predict the behavior of shocked solids using hydrodynamic codes. In order to obtain these values, equations of state of fine-particle (type IV) HNS were investigated using synchrotron angle-dispersive x-ray diffraction experiments at static high-pressure and temperature. The samples were compressed and heated using diamond anvil cells. Pressure -- volume data for HNS at ambient temperature were fit to the Birch-Murnaghan and Vinet formalisms to obtain bulk modulus and its first pressure derivative. Temperature -- volume data at ambient pressure were fit to obtain the volume thermal expansion coefficient. [Preview Abstract] |
Tuesday, June 28, 2011 11:30AM - 11:45AM |
J2.00003: Unreacted Hugoniot and Shock Initiation Measurements in Diaminoazoxyfurazan (DAAF) John Morris, Kyle Ramos, Elizabeth Francois Gas gun-driven impact experiments have been performed using the embedded electromagnetic particle velocity gauge technique to measure the unreacted Hugoniot and the shock initiation behavior of diaminoazoxyfurazan (DAAF) formulated with 3 weight percent Kel-F 800. Previous sensitivity testing has shown that DAAF possesses a unique and unusual discrepancy between impact and shock sensitivity. The explosive is insensitive to impact under drop weight testing, with a drop weight impact height of greater than 320 cm, yet the shock sensitivity is similar to HMX. The extent difference in impact and shock sensitivity suggests changes in initiation behavior that need to be characterized and quantified. Understanding what physical characteristics lend insensitivity to DAAF could have significant implications for explosives in general and will allow it to be used more effectively (ie where does impact insensitivity transition to HMX-like shock sensitivity). Unreacted Hugoniot and shock initiation results will be presented and discussed. [Preview Abstract] |
Tuesday, June 28, 2011 11:45AM - 12:00PM |
J2.00004: Gas Gun Experiments to Measure the Shock Compression Behavior of an Ammonium-Perchlorate/Aluminum Based Propellant Nathaniel Sanchez, Richard Gustavsen, Lee Gibson, Daniel Hooks Gas-gun driven plate impact experiments were performed on High Performance Propellant (HPP) to measure the shock compression behavior and Hugoniot. HPP is a proprietary blend of ammonium-perchlorate, aluminum, and plastic binder. A small amount of FeO2 gives the propellant a rust color. The primary diagnostic was embedded magnetic particle velocity gauges. The Hugoniot was determined by performing multiple experiments using different impactors and a range of impact velocities. Impact stresses ranged from 0.3 GPa to 15 GPa. Even at the highest stress no reaction was observed; none was expected. At low stress HPP exhibits viscoelastic behavior with rounded wave profiles. Hugoniot data can be described using a model based on a Murnaghan isotherm with a small amount of porosity. [Preview Abstract] |
Tuesday, June 28, 2011 12:00PM - 12:15PM |
J2.00005: Hugoniot elastic limits in oriented cyclotrimethylene trinitramine (RDX) at low pressure Daniel Hooks, Marc Cawkwell, Kyle Ramos The Hugoniot elastic limit (HEL) of oriented samples of cyclotrimethylene trinitramine (RDX) was examined. For several years, the orientation dependent HEL response has been considered a marker of orientation-dependent initiation behavior. We have previously noted inconsistencies with this hypothesis in higher-pressure experiments and static determinations of elastic-plastic behavior. Here, we will present a data set for four orientations of RDX shock impacted to a peak pressure of about 1 GPa. The results will be compared with previous experiments at higher pressure. [Preview Abstract] |
Tuesday, June 28, 2011 12:15PM - 12:30PM |
J2.00006: Phase Diagram of RDX Crystals at High Pressures and Temperatures Zbigniew Dreger, Yogendra Gupta A knowledge of the RDX phase diagram is important for understanding shock-induced decomposition of RDX. Vibrational spectroscopy and optical imaging in a diamond anvil cell were used to examine the RDX behavior at high pressures and temperatures. Interplay between three solid ($\alpha $, $\gamma $, $\varepsilon )$, liquid, and decomposed phases was examined in experiments on single crystals at pressures up to 12.0 GPa and temperatures to 600 K. Several distinct pressure regions were found in the RDX response at elevated temperatures. The boundaries between the $\alpha $, $\gamma $, and $\varepsilon $ phases were determined with a triple point at 3.7 GPa and $\sim $ 466 K. The $\alpha -\gamma $ phase transition was confirmed to be reversible and to occur at the same pressure 3.7 GPa, regardless of temperature. The $\varepsilon $-phase was found to exist only in a narrow range of pressures, from 2.8 to 6.0 GPa. Below and above these pressures, $\alpha $- or $\gamma $-RDX crystals decompose or melt instead of transforming to $\varepsilon $-RDX. Both the $\alpha -\varepsilon $ and $\gamma -\varepsilon $ transitions were irreversible at the phase boundaries. Decomposition kinetics of both the $\varepsilon $ and $\gamma $ phases were found to have a positive volumes of activation. Work supported by ONR and DOE/NNSA. [Preview Abstract] |
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