Bulletin of the American Physical Society
21st Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 64, Number 8
Sunday–Friday, June 16–21, 2019; Portland, Oregon
Session Z4: MS: Shock Response of Metals |
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Chair: Ellen Cerreta, Los Alamos National Laboratory Room: Pavilion West |
Friday, June 21, 2019 11:00AM - 11:15AM |
Z4.00001: Constitutive Response of S65 Beryllium James Turner, Jeremy Millett, Carl Cady, Shuh-Rong Chen, Simon Case New data is presented on the constitutive response of S65 Be. Compressive strength tests and split-Hopkinson pressure bar testing were used to examine the response of the material at strain rates of 0.001, 1 and 10$^{\mathrm{3}}$ s$^{\mathrm{-1}}$ over the temperature range 20-400$^{\mathrm{o}}$C. The extent to which this low and intermediate strain-rate data can be captured using a simple rate-dependent strength model will be examined and possible extensions to the model calibration to capture higher rate data will also be discussed. [Preview Abstract] |
Friday, June 21, 2019 11:15AM - 11:30AM |
Z4.00002: Shock Compression of Iridium Christopher Seagle, William Reinhart, Scott Alexander, Justin Brown, Jean-Paul Davis Iridium is a non-reactive precious metal with one of the highest acoustic impedances of the elements making it an attractive impactor or pusher in dynamic compression experiments. The principal Hugoniot and shock release states of iridium have been investigated on a two-stage light gas gun in a symmetric impact configuration. High precision stress-density Hugoniot states were measured up to \textasciitilde 7.1 km/s impact or \textasciitilde 6.8 Mbar. Shocked iridium samples were released into lithium fluoride windows permitting a point on the release isentropes of iridium to be measured. This new data is compared to limited iridium compendium shock data and recent theoretical calculations. Experimental hints of a sub-solidus phase transition and melting on the Hugoniot will be discussed. [Preview Abstract] |
Friday, June 21, 2019 11:30AM - 11:45AM |
Z4.00003: Dynamic Behavior of Polycrystalline Metals Under Combined Compression and Shear Impact Loading at Elevated Temperatures Vikas Prakash, Bryan Zuanetti, Tianxue Wang In this paper, we will present results of a series of elevated temperature combined compression-and-shear plate impact experiments conducted on commercial purity polycrystalline aluminum (99.999{\%}) and magnesium (99.9{\%}) at test temperatures in the range from room to near melt. These experiments are designed primarily to study the effect of temperature on the shearing resistance of polycrystalline metals at ultra-high shear strain rates and high shear strains. In order to conduct these experiments, the single-stage gas-gun facility at Case Western Reserve University was modified to include a breech-end sabot heater system and a fully fiber-optics based combined normal and transverse displacement interferometer. The measured shear-stress versus shear-strain profiles in commercial purity aluminum and magnesium samples, as inferred from the transverse particle velocity record measured at the free surface of a fully elastic tungsten carbide target plate, reveal that the flow stress in both sample materials thermally soften when heated to approximately 50{\%} of their melt temperatures. The flow stress attained at higher temperatures up to melt will be discussed in the presentation. [Preview Abstract] |
Friday, June 21, 2019 11:45AM - 12:00PM |
Z4.00004: Scaling and characterization of steady waves in model Tungsten-Polymer Composites Roger Minich, David Bober, Mukul Kumar A large number of velocity time histories have recently been measured for steady waves generated in a model tungsten loaded composite ( \textit{Bober et. al. }\underline {\textit{Dynamic Behavior of Materials, Volume 1}}\textit{ pp 273-278 (2018) ).} The volume fraction of tungsten loaded in the model composite ranged in value from 0.0 to 0.6 . A steady wave was observed for each volume fraction at four different aluminum impact velocities. Each velocity time history may be characterized by two distinct features: i.) the particle velocity of the transmitted wave front and ii.) the relaxation time to the asymptotic particle velocity for a given pressure. A phenomenology is developed involving transmission and reflection of trapped waves due to the strong impedance contrast between the tungsten particles and polymer matrix. A characteristic scale length, inversely proportional to the volume fraction, plays the analogous role to a high impedance layer in layered composites. The scaling captures the observed trends in the data. Finally, the scaling is related to the effective viscosity model for composite materials originated by L. Barker. This work was performed under auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-769254 [Preview Abstract] |
Friday, June 21, 2019 12:00PM - 12:15PM |
Z4.00005: Shock Behavior of Galfenol James Cazamias, Brian Wilmer, Scott Turnage, Cyril Williams A series of shock loading experiments were conducted on Galfenol (Fe$_{\mathrm{81.6}}$Ga$_{\mathrm{18.4}})$, a magnetostrictive iron-gallium alloy developed by the NSWCCD. Flyer plate experiments were performed on the material to generate HEL and spall data via VISAR wave profiles. A larger diameter plate was added to the targets along with PDV diagnostics to determine impact times in order to come up with an estimate for the hugoniot. [Preview Abstract] |
Friday, June 21, 2019 12:15PM - 12:30PM |
Z4.00006: Anisotropic shock response of single-crystalline $\beta $-phase tin Robert Scharff, Gerald Stevens, Brandon La Lone, William Turley, Saryu Fensin, Darby Luscher Mesoscale simulations of the dynamic response of polycrystalline metals to shockwave compression can provide unique insight in to the nature of the various physical mechanisms responsible for material failure. This approach requires a constitutive description for individual grains and boundaries, including defects such as dislocations, within an explicit representation of the microstructure geometry and evolving deformation fields. Computational models of the single-crystal constituents cannot be unambiguously constrained by traditional measurements of the shock or stress-strain response of polycrystalline metals. Instead, these models require comprehensive measurements of the anisotropic shock response of single crystals for their calibration and validation. We present a coordinated experimental and simulation campaign on the shock response of single-crystalline $\beta $-phase tin demonstrating a remarkable anisotropic elastic-plastic response of the metal. This anisotropy will be explained with the help of molecular dynamics simulations that show preferred twinning in one orientation. [Preview Abstract] |
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