Bulletin of the American Physical Society
16th APS Topical Conference on Shock Compression of Condensed Matter
Volume 54, Number 8
Sunday–Friday, June 28–July 3 2009; Nashville, Tennessee
Session Z3: EOS-3: Equations of State |
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Chair: Carl Greff, Los Alamos National Laboratory Room: Hermitage C |
Friday, July 3, 2009 10:30AM - 10:45AM |
Z3.00001: Derivation of the constitutive model of high elastic limit window materials Ron Winter, Peter Keightley Transparent materials with a high Hugoniot Elastic Limit are often used as optical windows in shock experiments. Parameterised constitutive models for both compressibility and elastic distortion are needed to support the computer analysis of past experiments and to allow future experiments to be optimised.~ The AWE Heterodyne Velocity (Het-V) technique has been used to generate shock velocity versus particle velocity data for sapphire shocked within its elastic regime. The data is consistent with other workers findings. The elastic distortion of the sapphire was modelled by assuming that Poissons Ratio remains constant. This elastic model then allowed the fluid Hugoniot to be derived.~ The effect of taking account of the elastic contribution to the internal energy of the shocked material was assessed but this was found to have only a trivial effect on the derived fluid Hugoniot. Knowledge of the fluid Hugoniot allowed the compressibility of the sapphire to be described by a Mie-Gruneisen equation of state.~ Wave profiles computed using the derived constitutive model have been compared with experimentally measured profiles. [Preview Abstract] |
Friday, July 3, 2009 10:45AM - 11:00AM |
Z3.00002: Single shot ultrafast observation of 40 GPa shock waves in a diamond anvil cell Michael Armstrong, Jonathan Crowhurst, Joseph Zaug, Evan Reed, W. Michael Howard, Lawrence Fried We present the results of experiments using ultrafast laser excitation and detection of shock waves starting from high precompression (10s GPa) in a standard diamond anvil cell (DAC) attaining single shock pressures $>$ 40 GPa. Using single shot ultrafast interferometry, we directly detect surface motion with $\sim $nm spatial resolution and $\sim $ps time resolution. Ultrafast time resolution enables the observation of states where shock-induced chemistry and phase changes may occur on sub-nanosecond time scales. Furthermore, standard DACs can reach $\sim $100 GPa precompression and $>$1000 degrees, enabling the examination of thermodynamic states off the principle Hugoniot, starting from a wide range of thermodynamic initial conditions. In particular, precompression of soft materials significantly enhances impedance matching to metal ablators and reduces the temperature of the shocked state. Here, we present the results of shocking nitromethane and argon from precompressed states. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. [Preview Abstract] |
Friday, July 3, 2009 11:00AM - 11:15AM |
Z3.00003: Equation of state modeling improvements in the low pressure regime John Carpenter In an equation of state (EOS) the high pressure regime typically receives much attention so as to ensure good agreement with data, such as shock experiments. However, the low pressure regime is equally important. The liquid-vapor critical region as well as the tensile region both play important roles in a range of situations, from wire explosions to spalling. These two areas can be difficult to model in a wide-range EOS due to unsatisfactory models, unphysical states, or numerical issues. Recent improvements to models and tabulation techniques are presented which aim at reducing these difficulties so as to provide robust and highly accurate EOS tables for simulation codes. [Preview Abstract] |
Friday, July 3, 2009 11:15AM - 11:30AM |
Z3.00004: ABSTRACT WITHDRAWN |
Friday, July 3, 2009 11:30AM - 11:45AM |
Z3.00005: Isothermal Equations of State of LLM-105 Jared Gump, Chad Stoltz, Benjamin Freedman, Suhithi Peiris 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) is an energetic ingredient that has an impact sensitivity close to that of TATB, yet a calculated energy content close to HMX. Reported tests of formulated LLM-105 reveal that it is a good candidate for a new insensitive high-performance explosive. As use of LLM-105 increases, thermodynamic parameters and phase stability will need to be determined for accurate modeling. In order to accomplish this goal, isothermal equations of state of LLM-105 at static high pressure and temperature were investigated using synchrotron angle-dispersive x-ray diffraction experiments. The samples were compressed and heated using diamond anvil cells. Pressure - volume data for LLM-105 at ambient temperature and 100$^{\circ}$C were fit to the Birch-Murnaghan formalism to obtain isothermal equations of state. Temperature - volume data at ambient pressure were fit to obtain the volume thermal expansion coefficient. [Preview Abstract] |
Friday, July 3, 2009 11:45AM - 12:00PM |
Z3.00006: Hydrostatic equation of state and anisotropic Constitutive Relationships in 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) Mikalai Budzevich, Michael Conroy, Aaron Landerville, You Lin, Ivan Oleynik, Carter White TATB is an energetic molecular crystal which exhibits remarkable insensitivity to shock, heating and electrical sparks. Despite its high stability and relative safety, TATB is a highly powerful explosive which makes it an interesting target for both theoretical and experimental studies. We performed first-principles van-der-Waals Density Functional Theory (vdW-DFT) studies of the equilibrium properties and hydrostatic equation of state (EOS) for TATB and compared with experiment. The vdW-DFT showed better agreement with the experimentally determined hydrostatic EOS and unit cell parameters compared standard DFT, which suffers from the lack of proper description of long-range dispersive interactions. The anisotropic EOS as a function of uniaxial compression in the {\{}001{\}}, {\{}010{\}}, {\{}011{\}} , {\{}100{\}} , {\{}101{\}} , {\{}110{\}}, and {\{}111{\}} crystallographic directions was also studied. Calculated mechanical properties such as the principal and shear stresses, energy gap, and the energy per atom show a clear anisotropy in the TATB molecular crystal upon uniaxial compression. [Preview Abstract] |
Friday, July 3, 2009 12:00PM - 12:15PM |
Z3.00007: The use of the Grimme DFT potential for description of van der Waals bonded molecular crystals Warren Perger, Ken Flurchick A recent density-functional theory (DFT) potential by Grimme has been proposed for describing long-range dispersion corrections. This potential has been implemented into the CRYSTAL06 program and tested for a variety of molecular crystals including urea, pentaerythritol (PE) and pentaerythritol tetranitrate (PETN). Elastic constants, ambient volumes, and vibrational frequencies are calculated with this potential and compared with those calculated using other DFT potentials. [Preview Abstract] |
Friday, July 3, 2009 12:15PM - 12:30PM |
Z3.00008: Equation of state, initiation, and detonation of pure ammonium nitrate D.L. Robbins, S.A. Sheffield, D.M. Dattelbaum, N. Velisavljevic, D.B. Stahl Ammonium nitrate (AN) is a widely used fertilizer and mining explosive throughout the world. One of the more common explosives using AN is called ANFO, a mixture of AN prills and fuel oil in a 94:6 ratio by weight. The AN prills are specially made to absorb the fuel oil, forming a mixture that reacts under shock loading through a diffusion-controlled process, resulting in a non-ideal explosive with detonation velocities around 4 km/s. While there are a number of studies on ANFO, there are only a few studies relating to the equation of state (EOS) and detonation properties of pure AN - resulting mainly from studies of accidents that have occurred during transportation of large quantities of AN. We present the results of a series of gas gun-driven plate impact experiments on pressed AN ranging in density from 1.72 to 0.9 g/cm$^{3}$. Several of the high density experiments were performed in front surface impact geometry, in which pressed AN disks were built into the projectile front and impacted onto LiF windows. Additional experiments at low density have been done in ``half cell'' multiple magnetic gauge gun experiments. From this work a complete unreacted EOS has been developed, as well as some initiation and detonation information. Additional high pressure x-ray diffraction experiments in diamond anvil cells have provided a static isotherm for AN. [Preview Abstract] |
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