Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session F2: Materials in Extremes IIIFocus
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Sponsoring Units: DCOMP DMP SHOCK Chair: Mitchell Wood, Sandia National Laboratories Room: 261 |
Tuesday, March 14, 2017 11:15AM - 11:51AM |
F2.00001: Hierarchical Multiscale Simulation: Scale-Bridging for Shock Response of Energetic Materials Invited Speaker: Brian Barnes As part of a multiscale modeling effort, we present progress on a challenge in continuum-scale modeling: the direct incorporation of complex molecular level processes in the constitutive evaluation. We use a concurrent scale-bridging approach, with a hierarchical multiscale framework running in parallel to couple a particle-based model (the “lower scale”) to the constitutive response in a finite-element multi-physics simulation (the “upper scale”). In this approach, many orders of magnitude in length scale separate the lower and upper scales, and the lower scale is able to be used in the constitutive model for all elements of the upper scale. Molecular level response includes the constitutive equation of state and non-equilibrium chemistry. Response dependent upon stochastic microstructure, such as porosity, and challenges for scale-bridging in time are also discussed. The lower scale simulations of hexahydro-1,3,5-trinitro-s-triazine (RDX) use a force-matched coarse-grain model and dissipative particle dynamics methods, and the upper scale simulates Taylor anvil and plate impact experiments. Results emphasize use of machine learning (via Gaussian process regression, or “kriging”) that accelerates time to solution, and its comparison to fully on-the-fly runs.\\ \\In collaboration with: Kenneth Leiter, Richard Becker, Jaroslaw Knap, John Brennan, US Army Research Laboratory. [Preview Abstract] |
Tuesday, March 14, 2017 11:51AM - 12:03PM |
F2.00002: Modeling of extended solids using DFT and evolutionary algorithms. Iskander G Batyrev We present overview of our recent results on simulation of poly-CO, mixtures of N2 and H2, and mixtures of N2 and CO gases in amorphous and crystalline phases under high pressure using density functional theory (DFT) and evolutionary algorithms. Structure of N-H extended network under high pressure was modelled using the evolutionary program USPEX based on plane wave DFT calculations with norm-conserving pseudopotentials. Range of the studied pressures was 10 -- 50 GPa on compression, and from 50 to 10 GPa on isotropic decompression of the extended network. Formation of an extended network with covalent bonds occurs between 30-50 GPa. Higher concentration of N requires higher pressure to form a covalent bond network. New structure of NH extended solids with high symmetry and covalent bonds are predicted: with C2M(C2H-3) symmetry group for 9:1 ratio, with PBAM (D2H$+$9) symmetry group for 4:1 ratio, and with P-1(CI-1) for 3:1 ratio of N$_{\mathrm{2}}$ to H$_{\mathrm{2}}$ gas. Modeling structure of N2-CO crystals using the same methods resulted in formation of crystals with covalent bonds and high symmetry: P41212 (D4$+$4) for 50{\%} of N2 and CO, CM (CS-3) for 80 N2 and 20{\%} CO, and R3 (C3-4) for 90{\%} N2 and 10{\%} CO at pressure of 50 GPa. We show that some of the structures, obtained at high pressures, may exist upon lowering of the pressures. [Preview Abstract] |
Tuesday, March 14, 2017 12:03PM - 12:15PM |
F2.00003: Multicale modeling of the detonation of aluminized explosives using SPH-MD-QM method Qing Peng, Guangyu Wang, Gui-Rong Liu, Suvranu De Aluminized explosives have been applied in military industry since decades ago. Compared with ideal explosives, aluminized explosives feature both fast detonation and slow metal combustion chemistry, generating a complex multi-phase reactive flow. Here, we introduce a sequential multiscale model of SPH-MD-QM to simulate the detonation behavior of aluminized explosives. At the bottom level, first-principles quantum mechanics (QM) calculations are employed to obtain the training sets for fitting the ReaxFF potentials, which are used in turn in the reactive molecular dynamics (MD) simulations in the middle level to obtain the chemical reaction rates and equations of states. At the up lever, a smooth particle hydrodynamics (SPH) method incorporated ignition and growth model and afterburning model has been used for the simulation of the detonation and combustion of the aluminized explosive. Simulation is compared with experiment and good agreement is observed. The proposed multiscale method of SPH-MD-QM could be used to optimize the performance of aluminized explosives. [Preview Abstract] |
Tuesday, March 14, 2017 12:15PM - 12:27PM |
F2.00004: Novel Rubidium Poly-Nitrogen Energetic Materials Ashley Huff, Brad Steele, Ivan Oleynik High-nitrogen content compounds are being actively explored with the goal of discovering new high-energy density materials with performance surpassing the conventional energetic materials such as HMX or RDX. Although pure polynitrogen compounds such as cg-N are predicted to deliver 10-fold increase in detonation pressure and detonation velocity of 30 km/s, their synthesis and recovery at ambient conditions is problematic. Doping polynitrogens with other elements is a viable route to promote metastability while reducing synthesis pressure. In this work, rubidium poly-nitrides are being investigated as candidates for high energy density materials. Using first principles evolutionary structure search methods performed at varying stoichiometries and several pressures ranging from 0 to 100 GPa, several new polynitrogen compounds have been discovered. The phase diagrams containing thermodynamically stable and lowest metastable phases are calculated and the dynamical stability of the promising materials is investigated at various pressures. Raman spectra and XRD patterns are also calculated to provide experimentally relevant information useful for identification of these compounds during their synthesis. [Preview Abstract] |
Tuesday, March 14, 2017 12:27PM - 12:39PM |
F2.00005: High fidelity probing of chemical moieties present in detonation plasmas Stephanie Johnson, Nick Glumac The intersection of multiple shock waves offers new extreme conditions of pressure, temperature, and shear flow that would not be seen under normal planar detonation conditions. A significant gap in knowledge exists between the computationally modeled and actual physicochemical cascades occurring in the initial stages of the conversion/coupling of energy released during detonation. Experimental results show intensified temperatures and pressures where multiple shocks merge and exhibit a reactive behavior varying from the classical detonation theory based on C-J or ZND models. A newly-developed technique enables the collection of simultaneous imaging and spectra as detonation evolves. The HSFC data is gated to timescales fast enough to avoid the obscuring carbon soot associated with the detonation fireball and maps UV/VIS/NIR emission spectra in a 50 ?m line across the surface. This technique is able to provide information on molecular species present in and the rotational and vibrational molecular energies occurring within the ionized plasma. Extensive studies have been done on plasmas from reacting energetic materials but their role in the formation and self-propagation of the shock waves is unclear. [Preview Abstract] |
Tuesday, March 14, 2017 12:39PM - 12:51PM |
F2.00006: Carbon Condensation during High Explosive Detonation with Time Resolved Small Angle X-ray Scattering Joshua Hammons, Michael Bagge-Hansen, Michael Nielsen, Lisa Lauderbach, Ralph Hodgin, Sorin Bastea, Larry Fried, Chadd May, Nicholas Sinclair, Brian Jensen, Rick Gustavsen, Dana Dattelbaum, Erik Watkins, Millicent Firestone, Jan Ilavsky, Tony Van Buuren, Trevor Willey Carbon condensation during high-energy detonations occurs under extreme conditions and on very short time scales. Understanding and manipulating soot formation, particularly detonation nanodiamond, has attracted the attention of military, academic and industrial research. An in-situ characterization of these nanoscale phases, during detonation, is highly sought after and presents a formidable challenge even with today's instruments. Using the high flux available with synchrotron X-rays, pink beam small angle X-ray scattering is able to observe the carbon phases during detonation. This experimental approach, though powerful, requires careful consideration and support from other techniques, such as post-mortem TEM, EELS and USAXS. We present a comparative survey of carbon condensation from different CHNO high explosives. [Preview Abstract] |
Tuesday, March 14, 2017 12:51PM - 1:03PM |
F2.00007: Synthesis, isolation, purification and characterization of nanocarbons derived from detonated high explosives Millicent Firestone, Bryan Ringstrand, Rachel Huber, David Podlesak, Kwyentero Kelso Products evolved during the detonation of high explosives are primarily a collection of molecular gases and solid carbon condensates. Examination of the post-detonation soot employing X-ray scattering, Raman spectroscopy, and electron microscopy has revealed a wide range of interesting nano-architectures that are not readily attainable through other synthetic strategies. Critical to understanding the mechanism of individual carbon particles during detonation requires their isolation and purification. To address this opportunity we are working to develop benign, low temperature and non-oxidizing multistep purification schemes for isolation of the carbons from residual metals and more importantly, separation of the various carbon phases based upon density differences. Room temperature aqueous phase extractions using sodium polytungstate, zinc chloride and tetrabromoethane have yielded the greatest success. This multistep separation procedure applied to Composition B recovered soot will be presented. It is envisioned that the recovered novel nanocarbons will be of significant value to both the shock physics and nanoscience communities. [Preview Abstract] |
Tuesday, March 14, 2017 1:03PM - 1:15PM |
F2.00008: Extended Solids of Carbon Monoxide formed from Re$_{\mathrm{2}}$(CO)$_{\mathrm{12}}$ Jennifer Ciezak-Jenkins Extended solids are formed from simple molecular gases under extreme P/T and are of considerable interest as high-energy-density materials. It has been postulated that a transformation from a single-bonded polymeric-like material back to the more stable triply-bonded diatomic phase would be a highly exothermic process yielding large amounts of energy. The extended polymeric solid of CO was first reported and recovered from high pressure conditions in 2005 [1]. Although the material was found to have potentially interesting energetic properties, it showed a number of stability issues, degrading into CO$_{\mathrm{2}}$ and graphitic carbon over 3 to 5 days. As such, our lab has been focused on the identification of methods to increase the metastability of the recovered solid. Metal carbonyls offer one such route for stabilization. In this talk, our progress in the study of the synthesis, characterization, and recovery of extended solids of CO starting from Re$_{\mathrm{2}}$(CO)$_{\mathrm{12\thinspace }}$to pressures near 50 GPa will be presented. I will discuss the analysis and the implications of these results. New opportunities and challenges that have arisen in the course of our studies that will be pursued in the future will also be presented. Ref [1] Lipp, M. J.; et al. Nat. Mater. 2005, 4 (3), 211-215. [Preview Abstract] |
Tuesday, March 14, 2017 1:15PM - 1:27PM |
F2.00009: Thermal stability and performance of oxadiazole based energetic materials Roman Tsyshevskiy, Phil Pagoria, Aleksandr Smirnov, Maija Kuklja Achievement of tailored properties of new energetic materials remains a great challenge. Among the most important and probably least understood criteria is sensitivity of energetic materials to detonation initiation. Thermal stability is a key factor that defines sensitivity. Because of the appealing properties including relatively low impact sensitivity, high decomposition temperature and low melting point, novel oxadiazole based energetic materials became attractive candidates for using as melt-castable explosives. We report results of our DFT modeling that reveals kinetically and energetically most favorable decomposition mechanisms, which govern thermal stability of the oxadiazole based materials. We show how reactivity and performance of the material depend on the chemical composition and molecular structure of the material. [Preview Abstract] |
Tuesday, March 14, 2017 1:27PM - 1:39PM |
F2.00010: Measurements of observables during detonator function Laura Smilowitz, Bryan Henson, Dennis Remelius Thermal explosion and detonation are two phenomena which can both occur as the response of explosives to thermal or mechanical insults. Thermal explosion is typically considered in the safety envelope and detonation is considered in the performance regime of explosive behavior. However, the two regimes are tied together by a phenomenon called deflagration to detonation transition (DDT). In this talk, I will discuss experiments on commercial detonators aimed at understanding the mechanism for energy release during detonator function. Diagnostic development towards measuring temperature, pressure, and density during the extreme conditions and time scales of detonation will be discussed. Our current ability to perform table-top dynamic radiography on functioning detonators will be described. Dynamic measurements of temperature, pressure, and density will be shown and discussion of the function of a detonator will be given in terms of our current understanding of deflagration, detonation, and the transition between the two. [Preview Abstract] |
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