Bulletin of the American Physical Society
18th Biennial Intl. Conference of the APS Topical Group on Shock Compression of Condensed Matter held in conjunction with the 24th Biennial Intl. Conference of the Intl. Association for the Advancement of High Pressure Science and Technology (AIRAPT)
Volume 58, Number 7
Sunday–Friday, July 7–12, 2013; Seattle, Washington
Session Q7: Energetic Materials and Postdeadline |
Hide Abstracts |
Chair: Evan Reed, Stanford University Room: Grand Crescent |
Wednesday, July 10, 2013 1:45PM - 2:00PM |
Q7.00001: Jetting Formation of Explosive Dispersal of Hybrid Particles Kun Xue The explosive dispersal of granular matter is characterized by persistent ballistic conical jets with billowing wakes. This particle clustering or jet structures influence but only their dynamic trajectories but also the particle-fluid mixing and subsequent energy release if the particles are reactive. The explosive dispersal of hybrid sand with a range of saturation were observed to exhibit a postponed jetting onset and a significantly finer and more uniformed jet structure with increasing saturation. In order to predict the particle jetting formation, we proposed an instability criterion involving the opposing forces of stabilizing inertial pressures and destabilizing viscous resistance. Thus a kinetic breakup model was established. The predicted instability onsets of expanding sand shells agreed reasonably well with the experimental observations. The incorporation of a modified granular compaction model taking into account the lubrication effect of interstitial fluids in hybrid sand enables the breakup model to quantitatively describe the dependence of jetting onset on the saturation. A close inspection of dynamic fragmentation of sand subject to explosive loadings via a multi-material hydrodynamic modeling revealed a multiple necking mechanism underlying the jetting formation opposed to the surface instability mechanisms, such as Rayleigh-Taylor (RT), Richtmyer-Meshkov instabilities (RM). [Preview Abstract] |
Wednesday, July 10, 2013 2:00PM - 2:15PM |
Q7.00002: Modeling anisotropic sensitivity in pentaerythritol tetranitrate using strain rate dependent reactive flow model Kihong Kim, Laurence E. Fried, Jack J. Yoh Initiation of detonation in some high explosives has shown strong anisotropic sensitivity under mechanical impact. Preferred directions of crystal orientation on shock initiation have been experimentally observed in pentaerythritol tetranitrate (PETN), which resulted in dramatic difference in the detonation sensitivity upon shock compression in different directions. The ignition and growth model based on empirical observation on the pressure-dependent initiation of detonation has been widely used to date. Since the model is independent of direction of compression, it is impossible to address sensitivity associated with preferred crystal orientation for establishing the go/no-go criteria. In this paper, we have proposed a new reaction flow model that is consistent with avaialble PETN experiments and atomistic calculations. A general tensor notation is utilized to fully address three-dimensional effect of the strain rate dependence to anisotropic detonation of PETN. [Preview Abstract] |
Wednesday, July 10, 2013 2:15PM - 2:30PM |
Q7.00003: Quantum mechanical simulations of condensed-phase decomposition dynamics in molten RDX Igor Schweigert A reaction model for condensed-phase decomposition of RDX under pressures up to several GPa is needed to support mesoscale simulations of the energetic material's sensitivity to thermal and shock loading. A prerequisite to developing such a model is the identification of the chemical pathways that control the rate of the initial dissociation and the subsequent decomposition of molecular fragments. We use quantum mechanics based molecular dynamics simulations to follow the decomposition dynamics under high-pressure conditions and to identify the reaction mechanisms. This presentation will describe current applications to the liquid-phase decomposition of molten RDX. [Preview Abstract] |
Wednesday, July 10, 2013 2:30PM - 2:45PM |
Q7.00004: Time-Resolved K-shell Photoabsorption Edge Measurement in a Strongly Coupled Matter Driven by Laser-converted Radiation Yang Zhao, Jia-Min Yang, Ji-Yan Zhang, Guo-Hong Yang, Gang Xiong, Min-Xi Wei, Tian-Ming Song, Zhi-Yu Zhang A time-resolved K edge absorption measurement of warm dense KCl was performed on Shenguang II laser facility. The x-ray radiation driven shocks were adopted to take colliding shocks compression. By using Dog bone hohlraum the CH/KCl/CH sample was shielded from the laser hitting point to suppress the M band preheating and enhance the compressibility. Thus, an unexplored and extreme region of the plasma state with the maximum 5 times solid density and temperature lower than 3 eV (with coupling constant $\Gamma_{ii}$ around 100) was first obtained. The photoabsorption spectra of chlorine near the K-shell edge have been measured with a crystal spectrometer using a short x-ray backlighter. The K edge red shift up to 11.7eV and broadening of 15.2eV were obtained for the maximum compression. The electron temperature, inferred by Fermi-Dirac fit of the measured K-edge broadening, was consistent with the hydrodynamic predictions. The comparison of the K edge shift with a plasma model, in which the ionization effect, continuum lowering and partial degeneracy are considered, shows that more improvements are desired to describe in details the variation of K edge shift. This work might extend future study of WDM in extreme conditions of high compression. [Preview Abstract] |
Wednesday, July 10, 2013 2:45PM - 3:00PM |
Q7.00005: Enhanced sensitivity of explosives in the Condensed Phase: 2,4,6-trinitrotoluene as a model Yehuda Zeiri, David Furman, Faina Dubnikova, Naomi Rom, Barak Hirshberg, Sergey V. Zybin, William A, Goddard III, Ronnie Kosloff This study is based on the results of Molecular Dynamics (MD) employing a reactive force field (ReaxFF) and electronic structure (DFT) calculations of 2,4,6-trinitrotoluene (TNT) decomposition and high temperatures and pressures. The sensitivity to decomposition shows a marked increase for the condense phase as compared with single molecule. The simulations suggest that bimolecular processes dominate the initial stages of decomposition. The DFT calculations used to explore the role of bimolecular pathways. These pathways are responsible to the $\sim$23 kcal/mol reduction in the barrier height that lead to the enhanced sensitivity. These pathways involve (1) an H atom transfer between two neighboring TNT molecules in from the aromatic ring of one to one of the nitro groups of the other. The loss of the H atom promotes breaking the adjacent C-NO$_2$, and (2) the H atom transfer to the NO$_2$ leads subsequently to the formation of HONO and NO products. The thermal decomposition process was followed using the MD simulations for 400 ps to reach the final stable decomposition products. In addition to stable gas products, we obtained carbon clusters formed by the agglomeration of aromatic rings. The TNT decomposition mechanism is compared to that of other explosives. [Preview Abstract] |
Wednesday, July 10, 2013 3:00PM - 3:15PM |
Q7.00006: Measurements of Shaped Charge Jet Velocity Hongfa Huang Penetration depth is an important requirement in oil/gas well perforating jobs. The depth determines how far the wellbore can directly communicate with reservoir fluids. Deep perforation charges are widely used in oilfield industry and most of those are powder metal liner charge for no carrot-like slug left as solid liner does. Comprehensive measurements for the powder metal liner shaped charge jet characteristics, namely, the jet density and velocity, are needed to predict the shaped charge performance and to plan the perforating job. This paper focuses on an experimental work of jet velocity measurements. A medium size of powder metal liner charges (27 grams HMX) is used in the tests. The powder jet shoots through a stack of limestone blocks with shorting switch set in between. Half inch air-gap between two blocks is design to provide space for jet traveling in air to record free fly velocity, meanwhile the jet penetration velocity in the limestone is measured. Aluminum foil switches are used to record the jet Time of Arrival (TOA). The charged switch shorted by the metal jet when it arrives. The shorting signal is recorded. The two velocities can be used to estimate the jet penetration effectiveness. A series of TOA tests show that jet velocity along its length linearly decreases from jet tip to tail until the stagnation points referring to which jet material moves in opposite direction. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700