Bulletin of the American Physical Society
15th APS Topical Conference on Shock Compression of Condensed Matter
Volume 52, Number 8
Sunday–Friday, June 24–29, 2007; Kohala Coast, Hawaii
Session C5: Equation of State I |
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Chair: Neal Chesnut, Los Alamos National Laboratory Room: Fairmont Orchid Hotel Plaza III |
Monday, June 25, 2007 1:45PM - 2:00PM |
C5.00001: Dynamic Properties of a Lead-Antimony Alloy Robert Hixson, Mark Byers, Darcie Dennis-Koller Several shock compression experiments have been done recently on a Lead-Antimony alloy. Data was collected using two experimental configurations. One configuration consisted of a forward impact experiment with a LiF window, and was designed to yield Hugoniot information, and information on strength in compression. Sound speed in the compressed state is also obtained, although with moderate uncertainty. The second experimental configuration was similar to the first, but with no window. The absence of a window will cause a large release wave to be generated at the back side of the sample. This wave is interacted with a similar wave from the back side of the flyer plate, and tension generated. This kind of experiment is intended to explore dynamic strength in tension. [Preview Abstract] |
Monday, June 25, 2007 2:00PM - 2:15PM |
C5.00002: Hugoniot measurement of gold in pressure range to 580 GPa Manabu Yokoo, Nobuaki Kawai, Kazutaka Nakamura, Ken-ichi Kondo Hugoniot for Au and Cu have been measured in the shock pressure range 170 - 580 GPa with a two-stage light gas gun. Impactor velocities were measured with accuracy of 0.2 {\%} by the Faraday-type electromagnetic sensors (FES) method. Shock velocities were measured with accuracy of 1 - 3 {\%} with the line reflection method (LRM) using a streak camera and Ar ion laser with a few nanosecond time resolution. Hugoniot measurement of Cu was performed for the demonstration of FES and LRM. For the relation between shock and particle velocities, the fractional standard deviations of the data from the fits range from 0.1 to 0.4 {\%} for copper, and that indicates excellent agreement between our data and the results of the previous studies. Symmetric impact experiment of Au was performed to qualify this material as a high-pressure standard for both dynamic and static experiments. Our data were obtained 0.8 to 3.0 {\%} upward from the previous ones for the relation between shock and particle velocities. [Preview Abstract] |
Monday, June 25, 2007 2:15PM - 2:30PM |
C5.00003: Equations of State of Selected Armor Ceramics by In-situ High-Pressure X-ray and Ultrasonic Techniques: Comparison with Shock Wave Data Murli Manghnani, George Amulele, Anwar Hushur Ultrasonic measurements of the sound velocity and elastic moduli, and their pressure derivatives for well prepared armor ceramics can provide accurate constraints for establishing their equations of state. Using in-situ high-pressure synchrotron X-ray diffraction and diamond anvil cell techniques at the Advanced Photon Source, we have investigated the compression behavior ($V$/$V_{o}$ vs $P)$ for $\alpha$- and $\beta$-SiC, TiB$_{2}$, B$_{4}$C, WC and WC-6{\%}Co to 65 GPa. Ultrasonic measurements of K$_{o}$ and K$_{o}\prime$ made to $\sim$15 GPa show excellent agreement with X-ray results. Together, these results are compared with published shock wave data in terms of U$_{s}$-U$_{p}$ slope, K$_{o}\prime $, compression behavior, elastic anisotropy, and material strength. No phase transition is found in these materials, except for B$_{4}$C, in which case some structural distortion is indicated. [Preview Abstract] |
Monday, June 25, 2007 2:30PM - 2:45PM |
C5.00004: Gruneisen Parameter of Teflon from Hugoniots Measured at Different Initial States Jerry Forbes, Paul Urtiew, Craig Tarver, Kevin Vandersall Abstract. The Gruneisen parameter for Teflon is calculated using measured Hugoniot states obtained by shocking Teflon initially at atmosphere pressure and an initial temperature of 200$^{\circ}$C. The Gruneisen equation of state is used with the reference state taken as the Teflon Hugoniot measured at atmospheric pressure and an initial temperature of 25$^{\circ}$C. An error analysis for Gruneisen parameter $\gamma $ yields large errors even for carefully done gas gun experiments using manganin gauges. Extremely accurate measurements of pressure, shock velocity, and particle velocity are required to reduce the error in g to approximately $\pm $ 10~{\%}. [Preview Abstract] |
Monday, June 25, 2007 2:45PM - 3:15PM |
C5.00005: Gr\"{u}neisen Equation of State for Condensed Media and Shock Thermodynamics Invited Speaker: Gr\"{u}neisen equation of state (EOS) for condensed media in terms of pressure, volume and internal energy is suitable for description of high pressure flow problems in condensed media including shock waves. It is shown that thermodynamically formulated Gr\"{u}neisen EOS can be regarded as a differential equation for internal energy along an isentrope. The differential equation has a formal but general solution for internal energy as a sum of cold part and thermal part. In this solution, the cold internal energy is given by a special solution of the differential equation, while the thermal part is a general solution represented as a product of a function of volume $\Theta $(v) and that of entropy C(S). The volume function can be regarded as a characteristic temperature, $\Theta $(v), whereas the entropy function C(S) is proved to be a conjugate variable of the volume function. The above mentioned formulation is possible under the assuption that the Gr\"{u}neisen parameter is a function only of volume. Heat added to the system quasi-statically represented as TdS can also be expressed as $\Theta $(v)dC(S), which means that the characteristic temperature plays a role of integrating denominator, while C(S) is a conjugate thermal variable with a new integrating denominator. Thermodynamic fomulation of the Gr\"{u}neisen EOS in terms of these new thermal variables has been given. Several examples of the applications of this formulation are also given including (i) compatibility of the formulation with Debye model for the specific heat, (ii) estimation of the variable C(S) along shock Hugoniot, (iii) shock temperature calculation, (iv) Gr\"{u}neisen parameter calculation by theoretical models, (v) extension to the formulation of anharmonic EOS, etc. [Preview Abstract] |
Monday, June 25, 2007 3:15PM - 3:30PM |
C5.00006: Modeling Dynamic Ductility: An Equation of State for Porous Metals Jeffrey Colvin Enhanced heating from shock compression of a porous material can potentially suppress or delay cracking of the material on subsequent expansion. In this presentation we quantify the expected enhanced heating in an experiment in which a sector of a thin cylindrical shell is driven from the inside surface by SEMTEX HE (peak pressure $\sim $21.5 GPa). We first show the derivation of an analytical equation of state (EOS) for porous metals, then discuss the coupling of this EOS with material elastic-plastic response in a 2D hydrocode, and then discuss the modeling of the HE experiment with both fully dense and 10{\%} porous Ta and a Bi/Ta composite. Finally, we compare our modeling with some recent experimental data. [Preview Abstract] |
Monday, June 25, 2007 3:30PM - 3:45PM |
C5.00007: Constitutive Modelling of Shock Compression of a Porous Copper Anatoly Resnyansky A substantial number of equations of state have been built up from the Hugoniot data obtained from laboratory and undeground nuclear tests. It is generally accepted that testing porous modifications of a material allows researchers to move into the high temperature area of material states. Therefore, the pressure-volume data restored from the porous Hugoniots are very valuable. However, a large amount of the Hugoniots have been obtained from the shock velocity data in a porous samples and in a standard. Primary experimental methods employed for such measurements are time-of-arrival methods, for instance, methods using the pin technique. The present work analyses the data for the material porosity m=4 using a constitutive two-phase rate-sensitive model that was used earlier for description of experimental stress profiles in dry and hydrated sand. The model employs conventional equations of states for the phases of porous copper and available compression curve obtained in independent gas gun experiments. The modelling results demonstrate a good description of the test data. [Preview Abstract] |
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