Bulletin of the American Physical Society
20th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 62, Number 9
Sunday–Friday, July 9–14, 2017; St. Louis, Missouri
Session F9: Poster Session I (6:00-8:00pm)Poster
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Room: Regency Ballroom CD |
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F9.00001: EQUATIONS OF STATE |
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F9.00002: Preheating device for Isentropic Compression Experiments on GEPI Pierre-Yves Chanal, Gaetan Daulhac, Thierry D'almeida, Camille Chauvin GEPI is a 3 MA, 500 ns, high-pulsed power driver operated by the CEA and primarily used for launching ramp compression waves in planar loads with stress levels up to 100 GPa. In order to enhance the ability to explore metallic phase diagrams over a wide range of thermodynamic paths, we have recently developed a device capable of pre-heating samples up to 1200 K. This device is based on inductive heating under primary vacuum and ensures a temperature uniformity of \textpm 10K across the sample. The main features of this heating device are presented, along with the various technical solutions which significantly simplified its insertion in a robust and reliable experimental configuration. Several experiments, carried out to date on various materials including iron and copper ramp-compressed starting from different initial temperatures, are presented as illustration. [Preview Abstract] |
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F9.00003: Shock Recovery of the High Pressure Phase Bismuth III Zachary Fussell, Oliver Tschauner, Cameron Hawkins, Chi Ma, Jesse Smith Between 0 and 10 GPa there are five different bismuth phases. High-pressure bismuth (Bi) phases have been examined in static compression experiments; however, none could be recovered to ambient conditions. Here we report Bi-III recovery (stable above 3 GPa) to ambient conditions from a shock compression experiment to 5.7 GPa. Bi-III was identified by synchrotron micro-diffraction and backscatter electron imaging. Our work shows shock-compression provides a tool for recovering high-pressure phases that otherwise elude decompression. [Preview Abstract] |
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F9.00004: A High-Purity Alumina for Use in Studies of Shock Loaded Samples David Lacina, Christopher Neel We report the results of plate impact experiments on a potential new ``standard'' material, Coorstek Plasmapure-UC (99.9{\%} purity) polycrystalline alumina, for use in non-conduction, impact environment, shock loading studies. This work was motivated by a desire to find a 99.9{\%} purity alumina to replace the now unavailable Coors Vistal (99.9{\%}) alumina, as it was hoped the Hugoniot elastic limit (HEL) of the new standard would match the 9-11 GPa value of Vistal. Shock response data, including the HEL, Hugoniot particle velocities, Hugoniot shock velocities, stress vs volume, and release wave speeds, was obtained up to 14 GPa. This data will be compared with Hugoniot curve data for other high purity alumina to contrast differences in the shock response, and is intended to be useful in impedance matching calculations. We will show that the HEL of Plasmapure-UC alumina is 5.5 GPa and speculate on causes for this lower than expected value. We will also explore why the elastic-plastic response for Plasmapure-UC alumina differs from what has been observed from other high purity alumina. The final result of this work is to recommend a well-characterized, lower purity alumina (Coorstek AD-995) as a potential new ``standard'' material. [Preview Abstract] |
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F9.00005: ABSTRACT WITHDRAWN |
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F9.00006: Probing off-Hugoniot states of Lead at 85 GPa pressure Alexander Fedotov Gefen, Ella Moshe, Benny Glam, Elkana Porat, Yossef Horovitz, Avi Ravid, Arnon Yossef-Hai, Eitan Eidelstein, Gabriel Bialolenker, Daniela Kartoon The design and experimental results of probing the EOS of Pb in off-Hugoniot states are reported. A compression at two shock waves was generated by using double layer impactor. The experimental setup for measuring the second shock velocity is based on the ``overtake method". It includes two lead targets of different thicknesses whose back surface velocities were measured using an interferometry method. The pressures of the first and second shock waves were 60 GPa and 85 GPa, respectively. [Preview Abstract] |
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F9.00007: Optimization of the overtake method for sound velocity measurements in shock compressed Sn Eli Gudinetsky, Arnon Yosef-Hai, Eitan Eidelstein, Vitaly Paris, Gabi Bialolenker, Alex Fedotov-Gefen, Meir Werdiger, Yossef Horovitz, Avi Ravid Sound velocity measurements are useful for mapping the phase diagram of materials and for calibration of their EOS outside the principle Hugoniot. A common method is the overtake method, in which a flyer plate is accelerated towards two or more targets of different thickness. In the present work, detailed calculations were carried out in order to design optimal experiments in terms of expected uncertainties. These calculations took into account many factors: 2D effects such as edge rarefactions originating in the flyer plate, targets and the windows, EOS accuracy, thickness and diameters tolerances and error correlations. The experimental results were compared with these calculations to test the design of high accuracy experiments. The sound velocity measurements in Sn were compared to the literature. [Preview Abstract] |
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F9.00008: Comparison between two methods for measuring the sound velocity of shock compressed Al1100 Eli Gudinetsky, Arnon Yosef-Hai, Eitan Eidelstein, Gabi Bialolenker, Vitaly Paris, Alex Fedotov-Gefen, Meir Werdiger, Yossef Horovitz, Avi Ravid Sound velocity measurements are an important tool for investigating phase transitions and calibrating the EOS outside the principle Hugoniot. Two common methods are the overtake method and reverse-impact method. Although widely used, there is little discussion about the uncertainties of these methods. A comparison between the aforementioned methods for determining the sound velocity of shock compressed Al1100 is presented. The experiment consisted of an Al1100 flyer plate which was accelerated to velocity of 2.2 km/s towards two Al1100 targets of different thickness backed by a PMMA window and a third LiF target. This experiment was complimented by a second reverse-impact experiment in which an Al1100 flyer plate impacted a LiF target. The similarities of the shock impedance of LiF and Al1100 were used in order to achieve the same pressure in both of the experimental methods. The design of these experiments was led by detailed calculations in order to achieve minimal uncertainties in each experiment. These calculations took into account 2D effects such as edge rarefactions originating in the flyer plate, targets and windows. The uncertainty in the sound velocity is compared to our uncertainty estimate which was based on calculations. [Preview Abstract] |
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F9.00009: High accuracy hugoniot measurements of tin Arnon Yosef-Hai, Gabi Bialolenker, Eitan Eidelstein, Rafi Hevroni, Daniela Kartoon, Ela Moshe, Meir Werdiger, Yossef Horovitz, Moris Sudai, Lior Perlmuter, Elkana Porat The principal Hugoniot of tin was methodically investigated in more than 50 new plate impact experiments at pressures ranging from 18 GPa to 70 GPa. The aim of the research is to achieve a better empirically calibrated Hugoniot EOS for tin than currently available. Shock velocity was measured using an array of 19 electric pins pressed to the two surfaces of a top-hat shaped target [1], thus allowing to correct deviations from ideal planarity. Impact velocity was measured using a separate array of 6 electric pins aligned perpendicular to the impact axis. Different pressures in the tin targets were achieved using several impact velocities and a selection of standard materials used as impactors. The results are presented along with rigorous error calculations, and compared to previous data [2]. Careful attention has been given in order to identify possible effects of dynamic liquidation [3] along the shock Hugoniot. [1]A.C. Mitchel et al. JAP 52 3363 (1981) [2]T.J. Ahrens et al. A Handbook of Physical Constants, pp.143-183, Amer Geophysical Union (1995) [3]P.Song et al., JAP 120 195101 (2016) [Preview Abstract] |
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F9.00010: Machine-Learning based potential for Iron: plasticity and phase transition. jean-bernard Maillet, Christophe Denoual, Gabor Csanyi A classical interatomic potential is trained within the GAP framework with the goal of reproducing both plastic properties and phase transition for Iron. We first build a reference compact database based on tight-binding calculations of the magnetic bcc and non magnetic hcp phase, as well as the transition path between the two structures. We then show how the GAP formalism enables the reproduction of complex properties that include equation of state, elasticity, plasticity, and phase transition for this complex system. [Preview Abstract] |
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F9.00011: Approximating a Ti6Al4V alloy via a multiphase Ti equation of state and mixture model. Scott Crockett, Kevin Honnell We present a new multiphase equation of state (EOS) for titanium, describe the process involved in creating it, and present comparisons with relevant experimental data. We then use the new EOS as a foundation to then apply a simple additive volume mixture procedure. An EOS for the Ti-6-4 alloy EOS is generated by mixing the phases of Ti with corresponding Al and V EOSs. A comparison is made evaluating how well this simple mixing approach approximates the actual alloy behavior. [Preview Abstract] |
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F9.00012: Shock temperature determination for metals satisfying Rice-Walsh equation of state Kunihito Nagayama It is shown that the Rice-Walsh equation of state (EOS) can be used to describe shock compression of metals with the dimensionless material parameter $R$ introduced by Wu and Jing as a function of pressure alone. In this paper, two independent procedures of estimating shock temperature were proposed, which are; (i) the generalised function of specific heat at constant pressure as a function of $T/\Theta(p)$ is first derived from the measured temperature dependence of $C_p$ and it can be used to calculate shock temperature together with $R(p)$ function. Where $\Theta(p)$ is a function of $R(p)$. Alternative method is, (ii) residual volume isentropically released from shocked state is first calculated, and the residual temperature corresponding to this volume is calculated using temperature dependence of thermal expansion coefficient at zero-pressure. Shock temperature can then be calculated by the isentropic relationship to residual temperature. Estimated shock temperature by using two methods are compared. The results are also compared with the Gr\"{u}neisen EOS with $\rho\gamma=const$ plus Debye model. It is shown that the Gr\"{u}neisen EOS calculation was found to have apparent incompatibility with thermodynamic data at zero-pressure. [Preview Abstract] |
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F9.00013: Improvement of the Tin description: influence of the equation of state on phase change kinetics and damage modeling. Gregory Robert, Laurianne Pillon, Camille Chauvin When a solid material is undergoes to dynamic loading (HE, plate impacts \textellipsis ), a shock wave propagates from the impacted surface and reflects on a free surface. The behavior of this free surface depends on the local state of matter and its roughness: spall will appear in a solid material and the free surface remains undamaged, microspall will crumble in a particles cloud the free surface of a liquid or mixed solid/liquid material and microjetting will appear in addition on a rough surface. The description of these processes in hydrodynamic codes remains a challenge. Both the equation of state, phase change kinetics, elastoplasticity and damage modelling are involved in this full description. In order to improve our understanding of these mechanisms, we have initiated a working program on tin: it is based on atomistic calculations, experimental observations (plate impacts experiments involving fast XRD and PdV measurements) and comparisons with the description obtained by hydrocodes. In this presentation, we will focus on the consequences of the equation of state on phase change kinetics and micro-spalling description. [Preview Abstract] |
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F9.00014: EXPERIMENTAL DEVELOPMENTS, DIAGNOSTICS, AND LOADING TECHNIQUES |
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F9.00015: Explosive vessel for coupling dynamic experiments to the X-ray beam at the Advanced Photon Source Charles Owens, Nathaniel Sanchez, Christian Sorensen, Brian Jensen Recent experiments at the Advanced Photon Source have been successful in coupling gun systems to the synchrotron to take advantage of the advanced X-ray diagnostics available including X-ray diffraction and X-ray phase contrast imaging (PCI) to examine matter at extreme conditions. There are many experiments that require explosive loading capabilities, e.g. detonator and initiator dynamics, small angle X-ray scattering (SAXS), ejecta formation, and explosively driven flyer experiments. The current work highlights a new explosive vessel that was designed specifically for use at a synchrotron facility with requirements to confine up to 15 grams of explosives (TNT equivalent), couple the vessel to the X-ray beam line, and reliably position samples remotely. A description of the system and capability will be provided along with the results from qualification testing to bring the system into service (LA-UR-17-21381). [Preview Abstract] |
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F9.00016: Time-resolved X-ray diffraction for gas gun experiments. Camille Chauvin, Frederic Zucchini, Lea Travichon, Jacques Petit The beta-Sn$\leftrightarrow $gamma-Sn transformation has been investigated for a long time under dynamic loadings through usual macroscopic data (velocity and temperature measurements) revealing a kinetic effects in the phase transition mechanisms. We are improving the description of this process in our multiphase EOS with growth and nucleation mechanisms but the macroscopic data are not sufficient to provide the parameters. A direct insight about the crystallographic structure will bring essential informations of the beta-Sn$\leftrightarrow $gamma-Sn coexistence domain, of the completion of the transformation. In order to improve our understanding of these mechanisms, we are developing experiments with time-resolved X-ray diffraction in Bragg geometry on gas gun experiments. Experimental and analytical developments are described in this paper. Firstly, we have studied the behavior under shock-wave propagation of different orientations of single crystals Tin. Then, we have designed an experimental set-up to success in synchronizing our X-ray source with the shock propagation and to protect our image plate. Finally, work is also in progress to obtain an image of diffraction under shock. [Preview Abstract] |
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F9.00017: Synchronizing a 40-mm powder gun to an accelerator John Wright, Tim Tucker, Charles Owens, Brian Hollander, Brian Jensen Over the past decade, there have significant efforts to couple gun systems to beam lines such as at the Advanced Photon Source (APS) and the Los Alamos Neutron Science Center (LANSCE) to use advanced diagnostics to study the dynamic properties of materials. Synchronizing a gun system to these beam lines is challenging and requires improved characterization of their operation and a significant reduction in the uncertainty of the system time (propellant initiation to impact). In this work, data will be presented that describes the operation of a 40-mm bore powder gun (maximum velocity 2 km/s) including details of the projectile configuration and the propellant assembly that was designed specifically to reduce the jitter in the overall system time. Measurements of breech pressure, projectile velocity, and impact times were used to develop the gun performance curve (LA-UR-17-21403). [Preview Abstract] |
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F9.00018: High Precision Motion Control System for the Two-Stage Light Gas Gun at the Dynamic Compression Sector E. Zdanowicz, V. Guarino, C. Konrad, B. Williams, D. Capatina, K. D'Amico, N. Arganbright, K. Zimmerman, S. Turneaure, Y. M. Gupta The Dynamic Compression Sector (DCS) at the Advanced Photon Source (APS), located at Argonne National Laboratory (ANL), has a diverse set of dynamic compression drivers to obtain time resolved x-ray data in single event, dynamic compression experiments. Because the APS x-ray beam direction is fixed, each driver at DCS must have the capability to move through a large range of linear and angular motions with high precision to accommodate a wide variety of scientific needs. Particularly challenging was the design and implementation of the motion control system for the two-stage light gas gun, which rests on a 26' long structure and weighs over 2 tons. The target must be precisely positioned in the x-ray beam while remaining perpendicular to the gun barrel axis to ensure one-dimensional loading of samples. To accommodate these requirements, the entire structure can pivot through 60$^{\circ}$ of angular motion and move 10's of inches along four independent linear directions with 0.01$^{\circ}$ and 10$\mu$m resolution, respectively. This presentation will provide details of how this system was constructed, how it is controlled, and provide examples of the wide range of x-ray/sample geometries that can be accommodated. [Preview Abstract] |
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F9.00019: X-ray Instrumentation and Beam Characteristics at the Dynamic Compression Sector D. Capatina, K. D'Amico, T. Gog, P. Eng, T. Graber, J. Klug, D. Paskvan, N. Sinclair, Y. Li, P. A. Rigg, Y. M. Gupta The Dynamic Compression Sector (DCS) at the Advanced Photon Source at Argonne National Laboratory is a first-of-its-kind facility coupling a variety of high-precision, dynamic compression drivers with highly-tunable, high energy X-rays from a third generation synchrotron source. To meet the scientific needs of the DCS user community, precise control of the X-ray energy distribution, exposure, and spot size is of critical importance. This presentation will provide an overview of the X-ray beam conditioning optics and experimental shutters used at DCS to tailor the properties of the beam for the needs of each experiment. The full range of X-ray beam modes available at DCS will be described and the in-line X-ray diagnostic tools used to ensure a well-characterized source will be discussed. [Preview Abstract] |
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F9.00020: Laser-Driven Compression Experiments at the Dynamic Compression Sector Y. Toyoda, X. Wang, J. Sethian, J. Hawreliak, A. Schuman, B. Williams, D. Paskvan, J. Zhang, P. A. Rigg, Y. M. Gupta Proof of concept experiments have been carried out to ensure the capabilities of a 100J UV pulsed laser to generate compression waves in samples at the Dynamic Compression Sector (DCS) at the Advanced Photon Source (APS), Argonne National Laboratory. Velocity interferometry (PDV and VISAR) measurements were used to quantitatively determine the compression wave profile and uniformity across the sample back surface, when subjected to a variety of initial loading conditions. We will present the results obtained to date and discuss the potential of this system for future dynamic compression research at DCS. [Preview Abstract] |
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F9.00021: Configuring and Characterizing X-Rays for Laser-Driven Compression Experiments at the Dynamic Compression Sector Y. Li, D. Capatina, K. D'Amico, P. Eng, J. Hawreliak, T. Graber, D. Rickerson, J. Klug, P. A. Rigg, Y. M. Gupta Coupling laser-driven compression experiments to the x-ray beam at the Dynamic Compression Sector (DCS) at the Advanced Photon Source (APS) of Argonne National Laboratory requires state-of-the-art x-ray focusing, pulse isolation, and diagnostics capabilities. The 100J UV pulsed laser system can be fired once every 20 minutes so precise alignment and focusing of the x-rays on each new sample must be fast and reproducible. Multiple Kirkpatrick-Baez (KB) mirrors are used to achieve a focal spot size as small as 50$\mu$m at the target, while the strategic placement of scintillating screens, cameras, and detectors allows for fast diagnosis of the beam shape, intensity, and alignment of the sample to the x-ray beam. In addition, a series of x-ray choppers and shutters are used to ensure that the sample is exposed to only a single x-ray pulse ($\sim$80ps) during the dynamic compression event and require highly precise synchronization. Details of the technical requirements, layout, and performance of these instruments will be presented. [Preview Abstract] |
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F9.00022: Time-resolved Sensing of Meso-scale Shock Compression with Multilayer Photonic Crystal Structures David Scripka, Gyuhyon Lee, Christopher J. Summers, Naresh Thadhani Multilayer Photonic Crystal structures can provide spatially and temporally resolved data needed to validate theoretical and computational models relevant for understanding shock compression in heterogeneous materials. Two classes of 1-D photonic crystal multilayer structures were studied: optical microcavities (OMC) and distributed Bragg reflectors (DBR). These 0.5 to \textasciitilde 5 micron thick structures were composed of SiO2, Al2O3, Ag, and PMMA layers fabricated primarily via e-beam evaporation. The multilayers have unique spectral signatures inherently linked to their time-resolved physical states. By observing shock-induced changes in these signatures, an optically-based pressure sensor was developed. Results to date indicate that both OMCs and DBRs exhibit nanosecond-resolved spectral shifts of several to 10s of nanometers under laser-driven shock compression loads of 0-10 GPa, with the magnitude of the shift strongly correlating to the shock load magnitude. Additionally, spatially and temporally resolved spectral shifts under heterogeneous laser-driven shock compression created by partial beam blocking have been successfully demonstrated. These results illustrate the potential for multilayer structures to serve as meso-scale sensors, capturing temporal and spatial pressure profile evolutions in shock-compressed heterogeneous materials, and revealing meso-scale pressure distributions across a shocked surface. [Preview Abstract] |
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F9.00023: Analysis of Fiber Bragg Grating response to planar shocks Alexander Fedotov Gefen, Avi Ravid, Ehud Shafir, Shlomi Zilberman, Garry Berkovic, Yonatan Schweitzer Experimental and theoretical results of the response of 1 mm Fiber Bragg Gratings (FBGs) to planar 3-7 kbar shock waves are reported. The experimental setup includes two FBG sensors, inscribed on single mode fibers for ~1550 nm, embedded in different matrices. The sensors were oriented both in parallel and perpendicular directions with respect to the shock wave propagation. The research was aimed at quantitatively characterizing the FBG response to weak shocks. The experimental results show satisfactory match to analytical photo-elastic model. [Preview Abstract] |
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F9.00024: ABSTRACT WITHDRAWN |
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F9.00025: Analysis of Error Effects Broadband Laser Ranging Systems Michelle Rhodes, Brandon LaLone, Natalie Kostinski, Jared Catenacci, Patrick Younk, Corey Bennett Broadband laser ranging (BLR) is a recently developed measurement system that provides an attractive option for determining the position of shock-driven surfaces. Analysis of BLR signals typically assumes a linear relationship between relative delay and measured beat frequency. However, we show that the beat frequency deviates from a linear relationship at large relative delays. This is one of several consequences of using long fiber lengths to perform an imperfect dispersive Fourier transform. We discuss implications of the shape of the frequency versus distance curve for the calibration of BLR systems and the accuracy of ranging measurements. We also discuss other contributions to error in BLR measurements and how to mitigate them. [Preview Abstract] |
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F9.00026: Shockwave Interaction with a Cylindrical Structure Phillip Mulligan An increased understanding of the shockwave interaction with a cylindrical structure is the foundation for developing a method to explosively seal a pipe similar to the Deepwater Horizon accident in the Gulf of Mexico. Shockwave interactions with a cylindrical structure have been a reoccurring focus of energetics research. Some of the most notable contributions of non-destructive tests are described in ``The Effects of Nuclear Weapons'' (Glasstone, 1962). The work presented by Glasstone examines shockwave interaction from a 20-megaton bomb with a cylindrical structure. However, the data is limited to a peak overpressure of less than 25 psi, requiring several miles between the structure and the charge. The research presented in the following paper expands on the work Glasstone described by examining the shockwaves from 90, 180, and 270-gram C-4 charges interacting with a 6-inch diameter cylindrical structure positioned 52-inches from the center of the charge. The three charge weights that were tested in this research generated a peak overpressures of approximately 15, 25, and 40 psi, respectively. This research examines the peak pressure and total impulse from each charge acting on the cylindrical structure as well as the formation of vortices on the ``backside'' of the cylinder surface. This paper describes the methodology and findings of this study as well as examines the causality and implications of its results on our understanding of the shockwave interaction with a cylindrical structure. [Preview Abstract] |
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F9.00027: GEOPHYSICS AND PLANETARY SCIENCE |
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F9.00028: Gravitational Collapse and Shocks in Two-Phase Celestial Bodies Michael Greenfield The phenomenon of gravitational collapse (GC) is well-known in theoretical astro- and planetary physics. It occurs when the incompressibility of substances is unable to withstand the pressure due to gravitational forces in celestial bodies of sufficiently large mass. The GC never occurs in incompressible models -- homogeneous or layered. This situation changes dramatically when different incompressible layers appear to be different phases of the same chemical substance and the mass exchange between the phases can occur due to phase transformation. The possibility of destabilization in such system becomes realistic, as it was first discovered in the Ramsey static analysis [1,2]. We will present our generalization of the Ramsey's results using dynamic approach.\\ \\$[1]$W.H. Ramsey, ``On the instability of small planetary cores", Mon. Not. R. Astron. Soc. 110 (4), 325-338 (1950).\newline [2]H. Jeffreys, ``The Earth: Its Origin, History, and Physical Constitution". Cambridge University Press (1976). [Preview Abstract] |
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F9.00029: Magmas at extreme condition Toyohito Nishikawa, Yuhei Umeda, Norimasa Ozaki, Toshimori Sekine, Tomoko Sato, B. Albertazzi, A. Benuzzi-Mounaix, R. Bolis, M. Guaruaglini, M. Koeing, K. Miyanishi, A. Ravasio, Y. Sakawa, T. Sano, Ryousuke Kodama The system MgO-SiO$_{2}$ is one of the most important systems for understanding the formation process and dynamics of Earth-type planets as well as impact phenomena. Minerals in this system display various phase transformations, melt, and vaporize as a function of pressure and temperature. These phase changes depend on the stability of phases. We carried out laser shock experiments on enstatite at ILE, Osaka University. In these experiments, shock velocity was measured by VISAR and other shock states calculated by the impedance matching technique. The Hugoniot was measured around 300GPa and these data showed a continuous change. Even under decay shock compression, the states continuously changed. From the above, the liquid phase of enstatite is considered to be stable. We also discuss the optimum sample structure, based on the hydro simulation results. [Preview Abstract] |
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F9.00030: GRAIN-SCALE TO CONTINUUM MODELING |
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F9.00031: Simulation of shock and detonation waves with Smoothed Dissipative Particle Dynamics G\'er\^ome Faure, Jean-Bernard Maillet, Gabriel Stoltz Smoothed dissipative particle dynamics (SDPD) is a mesoscopic method that allows one to select the level of resolution at which a fluid is simulated. The consistency between these different resolutions has been shown in a previous work. While Molecular Dynamics (MD) is limited to time and length scales much smaller than the ones involved in experimental observations, SDPD enables us to simulate complex phenomena at much larger scales. We present here some applications of SDPD to non-equilibrium situations such as shock waves and micro-jetting. We also introduce a reactive mechanism in which chemical reactions are taken into account by means of a progress variable attached to each particle and allowing to change the equation of state as the reaction occurs. This allows us to handle exothermic chemical reactions and perform simulations of detonations waves. [Preview Abstract] |
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F9.00032: Effect of volume fraction on Hugoniot P-v curve of mixed aluminum (Al) and tungsten (W) materials. Hyoungjoon Kwon, Soonho Song, Jungsu Park, Kyungsun Chung Computational shock simulation is cost effective in understanding the contributions to Hugoniot behavior of solids. Mesoscale shock simulation is known to be effective method in studying bulk behavior of materials. In this study, the analyzation of Hugoniot behavior of three different solid mixtures (volume fraction of 30{\%}Al/70{\%}W, 50{\%}Al/50{\%}W, and 70{\%}Al/30{\%}W) were carried out by using this mesoscale shock simulation with the hydrocode AUTODYN$^{\mathrm{®}}$. Among three main factors that affect Hugoniot behavior (particle size, distribution and volume fraction of the mixture), this study was focused on the effect of volume fraction on Hugoniot behavior. Shock simulations were conducted under the particle velocity range from 0.5km/s to 5km/s, and consequently, dependence of volume fraction on Hugoniot P-v curve was proposed. [Preview Abstract] |
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F9.00033: Numerical simulation of the mechanical behavior of ultrafine-grained and coarse-grained Zr-Nb alloys over a wide range of strain rates Vladimir V. Skripnyak, Natalia V. Skripnyak, Irina K. Vaganova, Evgeniya G. Skripnyak, Vladimir A.. Skripnyak Multi-scale computational model is proposed for the investigation of deformation and fracture of ultrafine-grained and coarse grained Zr $-$ Nb alloy in a wide range of strain rate and temperature. The model takes into consideration the distribution of grain sizes. Model describes the shear stress relaxation under tension and compression at the homologous temperature below 0.5. The numerical results on dynamic and quasi-static deformation of Zr$-$1 vol. {\%} Nb alloy are good agreed with experimental data. Strain rate sensitivity of the yield stress of Zr--Nb alloys at fixed temperature depends on the concentration of Nb, and parameters of grain size distribution. It is shown that Zr--Nb alloys exhibit significant difference in the resistance to plastic deformation under compression and tension at high strain rates. [Preview Abstract] |
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F9.00034: Modeling of laser induced air plasma and shock wave dynamics using 2D-hydrodynamic simulations. Prem Kiran Paturi, Sai Shiva S, Leela Chelikani, Venkata Ramana Ikkurthi, Sijoy C. D., Shashank Chaturvedi The laser induced air plasma dynamics and the SW evolution modeled using the two dimensional hydrodynamic code by considering two different EOS: ideal gas EOS with charge state effects taken into consideration and Chemical Equilibrium applications (CEA) EOS considering the chemical kinetics of different species will be presented. The inverse bremsstrahlung absorption process due to electron-ion and electron-neutrals is considered for the laser-air interaction process for both the models. The numerical results obtained with the two models were compared with that of the experimental observations over the time scales of 200 -- 4000 ns at an input laser intensity of 2.3\texttimes 10$^{\mathrm{10}}$ W/cm$^{\mathrm{2}}$. The comparison shows that the plasma and shock dynamics differ significantly for two EOS considered. With the ideas gas EOS the asymmetric expansion and the subsequent plasma dynamics have been well reproduced as observed in the experiments, whereas with the CEA model these processes were not reproduced due to the laser energy absorption occurring mostly at the focal volume. [Preview Abstract] |
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F9.00035: Numerical Simulation of Laser Ablative Shock Waves From Aluminum in Presence of Helium Gas At Different Ambient Pressures Prem Kiran Paturi, P S L Kameswari Durvasula, Sai Shiva S A two dimensional comparative study of Laser Ablative Shock Wave into the Aluminum target in the presence of Helium gas at different ambient pressures over a range of 690 -- 10$^{\mathrm{5}}$ Pa performed using FLASH hydrodynamic codes will be presented. The irradiation of Aluminum target (thickness 2 mm and radius 3 mm) with a 7 ns laser pulse of energy 175 mJ, spot size of 150 \textmu m on the target surface at a wavelength of 532 nm at normal incidence is simulated. Helium gas enclosed in a chamber of height 3 mm and width 3 mm. The electron-ion inverse bremsstrahlung absorption coefficient is considered in the laser energy deposition process. The simulation was performed over a duration of 1 $\mu $s. It was observed that an ablative shock is launched into the Helium gas for the pressures of 0.5 atm and above. However, for pressure less than the 0.5 atm the plasma expanded into the He gas upto 12ns and after which due to pressure equilibration with the surroundings and plume splitting shock wave is launched in to Al. [Preview Abstract] |
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F9.00036: HIGH ENERGY DENSITY PHYSICS / WARM DENSE MATTER |
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F9.00037: Time-Resolved Spectroscopy Observation regarding Synthetic Uranus at High Pressure and Temperature Ryo Hazama, Norimasa Ozaki, Yohei Fujimoto, Mika Kita, Ryousuke Kodama, Masanori Fuyuki, Kosuke Kurosawa, Takuo Okuchi, Takayoshi Sano, Youichi Sakawa, Kohei Miyanishi, Michel Koenig, Alessandra Benuzzi-Mounaix, Alessandra Ravasio, Riccardo Bolis, Marco Guarduaglini, Patrice Barroso Icy giant planets, like Uranus and Neptune, are thought to consist of mixture of water, methane, and ammonia at high pressures and temperatures. In the 1980s the Voyager II mission revealed that both of Uranus and Neptune had unusual non-dipolar and non-axial magnetic fields. However, the cause of the magnetic fields is still a major unresolved issue in planetary science. It is necessary for solving this issue to better understand the behavior of the molecular mixture at the planetary interior conditions. We performed laser-shock experiments on molecular mixture samples to simulate the interior conditions of the planets in laboratory. The mixtures were shock-compressed up to \textasciitilde 80 GPa and 4500 K. We measured the self-emission spectra from the compressed samples. We here discuss the line spectra in the blue region by comparing the experiment with theory. [Preview Abstract] |
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F9.00038: Laser ablation of metal into liquid: near critical point phenomena and hydrodynamic instability Nail Inogamov, Vasily Zhakhovsky, Viktor Khokhlov Laser ablation of metal in contact with liquid differs much from ablation into vacuum. In spite of importance of this kind of laser-matter interaction (e.g., for nanoparticles production), the involved processes are still poorly understood. We show that to produce nanoparticles the laser absorbed energy should overcome the ablation threshold into vacuum by a few times. Thus the required temperatures in the heat-affected zone increase above a critical temperature. The flow of the substances, including propagation of a strong shock in liquid and a rarefaction wave inside the metal target, is analyzed. We demonstrate that the contact between metal and liquid, both being in their supercritical states, is hydrodynamically unstable. The instability is of the Rayleigh-Taylor type. Dynamics of the instability is important for separation of melt droplets which are frozen up to solid nanoparticles later. [Preview Abstract] |
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F9.00039: Warm dense matter in extremely small volume - hydrodynamics of nanofilms triggered by laser irradiation at diffraction limit Nail Inogamov, Vasily Zhakhovsky, Viktor Khokhlov Modern laser techniques combine sophisticated manipulations with photon bunch and refined target design together with ultrafast isochoric transfer of solid into WDM state. Photon bunch is just 10s micron long and one micron thick when it is focused in the diffraction limited regime onto a thin film of 10-100 nm thick. While the spherical or cylindrical lenses produces a hot spot with maximum in the central point, a spiral phase plate produces the illumination field with a hole in the center and also bears angular momentum to the target. To study the evolution of the targets a simulation package including two-temperature (immediately during and for some time after a fs pulse the electrons are much hotter than lattice) 2D hydrodynamics and MD code combined with Monte Carlo method for strong thermal conductivity in metal are utilized. The observed processes, including absorption, melting, capillary dynamics of hot melt and its freezing into solitary nanostructures, produced by such laser fields are discussed. [Preview Abstract] |
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F9.00040: INELASTIC DEFORMATIONS, FRACTURE AND SPALL |
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F9.00041: Experimental Investigation of the Shearing Resistance of Soda-Lime Glass at Pressures up to 9 GPa and Strain Rate of $10^{6}\,s^{-1}{\begin{array}{*{20}c} \hfill & \hfill \\ \end{array} }$ Tong Jiao, Christian Kettenbeil, Guruswami Ravichandran, Rodney Clifton Pressure-Shear Plate Impact (PSPI) experiments were conducted to measure the high-rate shearing resistance of soda-lime glass at pressures up to 9 GPa and at shearing rates of approximately$10^{6}\,s^{-1}$. Samples of soda lime glass, 5 $\mu m$ thick, were sandwiched between pure tungsten carbide (WC) plates and impacted by pure WC flyers. Normal stress and shearing resistance of the sample were calculated from measured free surface velocities using 1D elastic wave theory. The experimental results show that, at a pressure of 9 GPa, the shear stress increases almost linearly up to 1 GPa and then falls quickly to approximately 0.3 GPa --- after which it decreases slowly to approximately 0.17GPa. Comparisons with results of previous experiments on nominally identical samples, impacted to generate lower peak pressures, showed the peak shearing resistance to be proportionately higher at the higher pressures; however, the sharp fall in shearing resistance occurs at comparable shear strains (1.5-2). These pilot experiments are part of a larger collaborative effort to investigate shearing resistance and phase transformations in soda-lime glass at much higher pressures, say greater than 50 GPa. [Preview Abstract] |
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F9.00042: A micromechanical modeling approach to describe the dynamic spalling of ceramic materials Benjamin Erzar, Gael Le Blanc, Frederic Malaise, Eric Buzaud Subjected to a dynamic traction, a ceramic material will eventually fail as a consequence of the triggering, propagation and coalescence of a distribution of microcracks. The DFH (Denouald-Forquin-Hild) anisotropic damage model considered in this study is based on a description of three physical phenomena activated all along the fragmentation process occurring in brittle materials. The first one concerns the activation of the population of pre-existing defects distributed in the material, described by a Weibull law. The second one corresponds to the propagation of microcracks at a constant velocity. The last one is the so-called occultation phenomenon. It is based on the observation that in the vicinity of a crack, tensile stresses are relaxed, hence precluding the triggering of another crack in the same direction. The performance of DFH model has been assessed with the aim of improving the modeling of damage associated to spalling in ceramic materials. Dynamic tensile loadings have been performed in a range of high strain rates. The characteristics of resulting damage patterns observed experimentally have been accurately reproduced by means of three-dimensional Lagrangian calculations. [Preview Abstract] |
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F9.00043: Abstract Withdrawn
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F9.00044: Mode I Failure of Armor Ceramics: Experiments and Modeling Christopher Meredith, Brian Leavy The pre-notched edge on impact (EOI) experiment is a technique for benchmarking the damage and fracture of ceramics subjected to projectile impact. A cylindrical projectile impacts the edge of a thin rectangular plate with a pre-notch on the opposite edge. Tension is generated at the notch tip resulting in the initiation and propagation of a mode I crack back toward the impact edge. The crack can be quantitatively measured using an optical method called Digital Gradient Sensing, which measures the crack-tip deformation by simultaneously quantifying two orthogonal surface slopes via measuring small deflections of light rays from a specularly reflective surface around the crack. The deflections in ceramics are small so the high speed camera needs to have a very high pixel count. This work reports on the results from pre-crack EOI experiments of SiC and B$_{\mathrm{4}}$C plates. The experimental data are quantitatively compared to impact simulations using an advanced continuum damage model. The Kayenta ceramic model in Alegra will be used to compare fracture propagation speeds, bifurcations and inhomogeneous initiation of failure will be compared. This will provide insight into the driving mechanisms required for the macroscale failure modeling of ceramics. [Preview Abstract] |
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F9.00045: Investigation on Blast Resistance of Precast Reinforced Concrete Floor Slab Nicola Bonora, Domenico Gentile, Gianluca Iannitti, Andrew Ruggiero, Gabriel Testa, Manuele Bernabei, Luigi Cassioli, Silvana Grossi The knowledge of the effective blast resistance of civil infrastructures is a fundamental information for risk assessment and modelling consequences of terrorist attack in high population density urban environment. In this work, blast resistance of precast reinforced concrete floor slab, commonly used for commercial parking, was investigated performing blast tests, detonating bare explosive charge of RDX 80-20 in contact with the slab. The charge mass, and the stand-off distance, was varied in order to generate different damage extents, from visible to fully breached condition. Numerical simulations were performed considering all slab structural elements. Failure model for concrete was calibrated on breach size and shape observed in the experiments. The explosive and blast wave-structure interaction were simulated using arbitrary Lagrangian-Eulerian method (ALE) and particle blast method (PBM) for comparison. [Preview Abstract] |
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F9.00046: Impacting brittle materials using a designed fast indentation device W. Mirihanage, M. Olbinado, N.K. Bourne, C. Rau, A. Rack Material failure is determined by a suite of deformation mechanisms with differing kinetics operating together and presented an integrated response to an observer. To elucidate processes requires separating one from another in order to construct physically-based descriptions of behaviour. Observing a material where failure processes are controlled by a designed impulse and are at a suitable scale offers the possibility of separating operating mechanisms. A highly reproducible synchronised loading test frame has been developed by Diamond and Manchester. It has already been fielded at the ESRF and shown useful results using ultra-high speed single bunch image mode on simple test problems. Now that the device has been proven, we show studies on the compression and fracture of glass and quartz. The results indicate several modes of failure within the targets and emphasise the need for further fast radiography to elucidate failure mechanisms in solids. [Preview Abstract] |
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F9.00047: Dynamic strength and failure of 430F stainless steel determined by combined experimental-numerical method Vitaly Paris, Amitay Cohen, Elkana Porat, Pinhas Fridman, Zvi Harpenes, Arnon Yosef-Hai, David Levi-Hevroni Dynamic flow stress of metals is well known to depend significantly on the strain rate. Strain to failure behavior of ductile metals can be influenced by both the stress triaxiality and the strain rate. While either compressive or tensile Split Hopkinson Pressure Bar system (SHPB) are commonly used to obtain flow stress and failure data for metals, experimental methodologies to obtain such data under conditions of shear loading are less based. In the present study we have investigated the effect of strain rate on the flow stress and strain to failure of 430F stainless steel at strain rates ranging from 400 to 16000 1/sec using shear disc specimens (SDS) incorporated into standard SHPB system. The SDS sample is a disc having axisymmetric slits on its both flat faces which is sheared during the test by ring and cylinder-shaped adaptors mounted between the bars. The analysis of the data was performed by matching the experimental signals with results of numerical modeling of the tests. The obtained flow stress versus strain rate data were fitted with Cowper-Symonds model. The results indicate strong dependence of flow stress of 430F steel on strain rate in the investigated range of rates. The strain to failure data demonstrates a noticeable decrease with increase of the strain rate. [Preview Abstract] |
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F9.00048: Study of flow stress and spall strength of additively manufactured Ti-6-4 alloy Amitay Cohen, Vitaly Paris, Arnon Yosef-Hai, Eli Gudinetsky, Eitan Tiferet The use of additive manufacturing (AM) by Electron Beam Melting (EBM) or Selective Laser Melting (SLM) has extensively grown in the past few years. A major goal in AM is to manufacture materials with mechanical properties at least as good as traditionally manufactured materials. In this work we present results of planar impact tests and Split Hopkinson Pressure Bar tests (SHPB) on Ti-6-4 manufactured by EBM and SLM processes. Results of planar impact tests on SLM samples display slightly higher spall strength compared to EBM while the stress at Hugoniot elastic limit (HEL) is practically the same. Stress strain curves based on SHPB measurements at two different strain rates present similar plastic flow stresses for SLM and EBM processed Ti-6-4 alloy, while the flow stress is about 20\% higher than reported for commercial reference material. The strain to failure of both materials shows considerable strain rate sensitivity. The results of post-mortem analysis of spall fracture will also be presented. [Preview Abstract] |
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F9.00049: Modelling of Mechanical Behavior at High Strain Rate of Ti-6al-4v Manufactured By Means of Direct Metal Laser Sintering Technique Gianluca Iannitti, Nicola Bonora, Domenico Gentile, Andrew Ruggiero, Gabriel Testa, Simone Gubbioni In this work, the mechanical behavior of Ti-6Al-4V obtained by additive manufacturing technique was investigated, also considering the build direction. Dog-bone shaped specimens and Taylor cylinders were machined from rods manufactured by means of the EOSSINT M2 80 machine, based on Direct Metal Laser Sintering technique. Tensile tests were performed at strain rate ranging from 5E-4 s-1 to 1000 s-1 using an Instron electromechanical machine for quasistatic tests and a Direct-Tension Split Hopkinson Bar for dynamic tests. The mechanical strength of the material was described by a Johnson-Cook model modified to account for stress saturation occurring at high strain. Taylor cylinder tests and their corresponding numerical simulations were carried out in order to validate the constitutive model under a complex deformation path, high strain rates, and high temperatures. [Preview Abstract] |
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F9.00050: Prediction of fragmentation of an aluminum expanding ring Andrew Ruggiero, Nicola Bonora, Domenico Gentile, Gianluca Iannitti, Gabriel Testa, Roberto Di Stefano The fragmentation behavior of solid is important in a wide range of industrial and military applications. After Niordson, the electromagnetically launched expanding ring proved a useful technique for investigating tensile fracture and fragmentation at high strain rate and the method was largely exploited by many authors. Recently, Zhang and Ravi-Chandar reported the details of the experimental observations on Al 6061-O. In the present work, two approaches were used for predicting the fragmentation response in these tests. The first is an energy based fragmentation model derived from the Grady’s theory. The method, already applied to cold drawn pure copper, adopts the dynamic crack tip opening displacement as the fracture parameter that allows accounting for plastic strain occurring prior fracture. The second is a Continuum Damage Mechanics approach. Numerical simulations of the rings expansion were performed through finite element method taking care to apply proper boundary conditions. The Lorentz force was calculated by imposing the measured currents and providing the inductances values as a function of the ring geometry. To predict the material failure, the Bonora’s damage model was applied, considering a statistical variation of material parameters within the rings volume. [Preview Abstract] |
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F9.00051: Effect of Initial Grain Size on Ductile Damage of AA1100-O at High Strain Rate and Stress Triaxiality Gabriel Testa, Nicola Bonora, Andrew Ruggiero, Gianluca Iannitti, Domenico Gentile The effect of the initial grain size on ductile damage development in AA1100-O aluminum at high strain rate and severe stress triaxiality was investigated. Symmetric Taylor impact (rod-on-rod, RoR) specimens were machined from extruded bars and annealed at 350\,$^{\circ}$C for different times to obtain three grain sizes (147, 159 e 189\,$\mu$m). Numerical parametric investigation to assess the impact velocity for incipient damage development were made using a modified formulation of Rusinek-Klepaczko constitutive model and the Bonora damage model considering pressure effect and stochastic material variability on the damage parameters. Tests at estimated impact velocities, for incipient and fully developed damage condition, were performed. Soft recovered specimens were sectioned and polished to evaluate damage extension to compare with numerical simulation results. [Preview Abstract] |
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F9.00052: Computer modeling of dynamic necking in bars Yehuda Partom, Avishay Lindenfeld Necking of thin bodies (bars, plates, shells) is one form of strain localization in ductile materials that may lead to fracture. The phenomenon of necking has been studied extensively, initially for quasistatic loading and then also for dynamic loading. Nevertheless, many issues concerning necking are still unclear. Among these are: 1) is necking a random or deterministic process; 2) how does the specimen choose the final neck location; 3) to what extent do perturbations (material or geometrical) influence the neck forming process; and 4) how do various parameters (material, geometrical, loading) influence the neck forming process. Here we address these issues and others using computer simulations with a hydrocode. Among other things we find that: 1) neck formation is a deterministic process, and by changing one of the parameters influencing it monotonously, the final neck location moves monotonously as well; 2) the final neck location is sensitive to the radial velocity of the end boundaries, and as motion of these boundaries is not fully controlled in tests, this may be the reason why neck formation is sometimes regarded as a random process; and 3) neck formation is insensitive to small perturbations, which is probably why it is a deterministic process. [Preview Abstract] |
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F9.00053: In Situ Imaging during Compression of Plastic Bonded Explosives for Damage Modeling John Yeager, Virginia Manner, Brian Patterson, David Walters, Nikolaus Cordes, Kevin Henderson, Bryce Tappan, Darby Luscher The microstructure of plastic bonded explosives (PBXs) is known to influence behavior during insults such as deformation, heating or initiation to detonation. Obtaining three-dimensional microstructural data can be difficult due in part to fragility of the material and small feature size. X-ray computed tomography (CT) is an ideal characterization technique but the explosive crystals and binder in formulations such as PBX 9501 do not have sufficient x-ray contrast to differentiate between the components. Here, we have formulated several PBXs using octahydro-1,3,5,7-tetranitro-1,3,5,7- tetrazocine (HMX) crystals and low-density binder systems. The full three-dimensional microstructure of these samples has been characterized using microscale CT during uniaxial mechanical compression in an interrupted in situ modality. The rigidity of the binder was observed to significantly influence fracture, crystal-binder delamination, and material flow. Additionally, the segmented, 3D images were meshed for finite element simulation. Initial results of the mesoscale modeling exhibit qualitatively similar delamination. [Preview Abstract] |
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F9.00054: Experimental Study on Colliding Shock Waves and Mach Stem Formation in Metals. Haibo Hu, Chongyu Zhang, Xiang Wang, Yongtao Chen, Tiegang Tang The dynamic behavior of different metals under sliding detonation loading and head-on colliding shock waves is studied by using small spot multi-channel PDV. The free surface velocity data have shown different responses of Cu, Pb and W near the colliding surface including the regular reflection and the formation of Mach stem of two colliding shock waves when shock waves comes out from inside on free surface. These experimental data can be used to give more detailed interpretation of the phenomena recorded by high speed frame photography and radiography of the high speed mass spiking in the collision region of two shock waves. [Preview Abstract] |
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F9.00055: MATERIALS SCIENCE |
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F9.00056: Real-time observation of twinning in shocked and released c-axis Mg single crystals using synchrotron x-ray diffraction Y. M. Gupta, Stefan Turneaure, P. Renganathan, J. M. Winey Recent wave profile measurements on shocked and released c-axis Mg crystals exhibited an unusual feature during unloading; the complete loading/unloading wave profiles were matched using a phenomenological model with dislocation slip during compression and twinning during unloading [Winey et al., JAP 117, 105903 (2015)]. In this work, multi-frame Laue x-ray diffraction measurements were performed on shocked and released c-axis Mg crystals at the Dynamic Compression Sector to directly examine twinning in real-time. Pulsed broadband x-rays (153.4 ns between pulses) passed through a polycarbonate impactor and a c-axis Mg crystal. For x-ray diffraction images obtained during plastic shock wave propagation through the Mg crystal, the same Laue spots seen at ambient conditions were observed, but with significant broadening consistent with dislocation slip during shock compression. For x-ray diffraction images obtained after unloading onset, a number of new Laue spots were observed which are consistent with the expected twin variants for shocked/released c-axis Mg. Although crystal twinning has long been considered as a likely stress relaxation mechanism competing with dislocation slip in some classes of materials, direct real-time observation of twinning has been lacking. This work demonstrates that the new capabilities at the Dynamic Compression Sector provide direct observations of twinning evolution in dynamically compressed crystals. [Preview Abstract] |
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F9.00057: Laser Shock Compression Studies of Phase Changes in Ce$_{\mathrm{3}}$Al Metallic Glass Alex Bryant, Christopher Wehrenberg, Faisal Alamgir, Bruce Remington, Naresh Thadhani Laser shock-compression of Ce$_{\mathrm{3}}$Al metallic glass (MG) was performed to probe pressure-induced phase transitions. Ce$_{\mathrm{3}}$Al MG has been previously shown to crystallize into a single crystal FCC phase during static compression at 25 GPa. In the present work, experiments were performed using the 3J Nd:YAG pulse laser at Georgia Tech and the high energy laser at the OMEGA facility. Characterization of shock compressed samples recovered from the OMEGA laser experiments were performed using XRD and PDF measurements at the NSLS-2 synchrotron at Brookhaven National Lab. The results showed evidence of a permanent polyamorphous phase change at pressures \textgreater \textasciitilde 10 GPa and crystallization at pressures \textgreater \textasciitilde 75 GPa. Particle velocities were measured using VISAR in experiments performed at Georgia Tech and simulated using Hyades and Abaqus to create an empirical equation of state and correlate with results obtained from XRD and PDF characterization. The results attained to-date in terms of the evolution of the high pressure amorphous and crystalline phases and their correlations with the shock conditions will be presented. [Preview Abstract] |
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F9.00058: Shock recovery experiments on yttrium iron garnet (YIG) powder Hiroaki Kishimura, Hitoshi Matsumoto Shock recovery experiments on yttrium iron garnet (YIG) powder were carried out by the impact of a flyer plate accelerated by a single-stage powder-propellant gun. Sample was encapsulated in copper container at 64{\%} of the theoretical maximum density (TMD) of the powder. The recovered sample was characterized by X-ray diffraction (XRD) analysis and Raman spectroscopy. In contrast to hydrostatic high-pressure studies, where pressure-induced amorphization accompanied by demagnetization and metallization were observed at a pressure of around 50 GPa, YIG powders shocked at a pressure of 56 GPa were decomposed into hematite and YFeO$_{\mathrm{3}}$. Most of Raman spectra of sample shocked at a pressure of 24 GPa were corresponding to cubic YIG phase and some spectra obtained from the same sample were composed of peaks derived from YIG and hematite (iron oxide). The appearance of peaks originated from hematite indicated that YIG began to decompose at a pressure of 24 GPa. [Preview Abstract] |
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F9.00059: Thin film deposition using rarefied gas jet Dr. Sahadev Pradhan The rarefied gas jet of aluminium is studied at Mach number \textit{Ma }$=$\textit{ (U\textunderscore j / }$\backslash $\textit{sqrt\textbraceleft kb T\textunderscore j / m\textbraceright )}in the range \textit{.01 \textless Ma \textless 2}, and Knudsen number \textit{Kn }$=$\textit{ (1 / (}$\backslash $\textit{sqrt\textbraceleft 2\textbraceright }$\backslash $\textit{pi d\textasciicircum 2 n\textunderscore d H)} in the range \textit{.01 \textless Kn \textless 15}, using two-dimensional (2D) direct simulation Monte Carlo (DSMC) simulations, to understand the flow phenomena and deposition mechanisms in a physical vapor deposition (PVD) process for the development of the highly oriented pure metallic aluminum thin film with uniform thickness and strong adhesion on the surface of the substrate in the form of ionic plasma, so that the substrate can be protected from corrosion and oxidation and thereby enhance the lifetime and safety, and to introduce the desired surface properties for a given application. Here, $H$is the characteristic dimension, \textit{U\textunderscore j}and \textit{T\textunderscore j}are the jet velocity and temperature, \textit{n\textunderscore d}is the number density of the jet, $m$and $d$ are the molecular mass and diameter, and \textit{kb}is the Boltzmann constant. An important finding is that the capture width (cross-section of the gas jet deposited on the substrate) is symmetric around the centerline of the substrate, and decreases with increased Mach number due to an increase in the momentum of the gas molecules. DSMC simulation results reveals that at low Knudsen number \textit{((Kn }$=$\textit{ 0.01);}shorter mean free paths), the atoms experience more collisions, which direct them toward the substrate. However, the atoms also move with lower momentum at low Mach number$,$which allows scattering collisions to rapidly direct the atoms to the substrate. [Preview Abstract] |
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F9.00060: Thermal Cycling and Ratchet Growth of As-Pressed TATB Pellets Caitlin Woznick, Darla Graff Thompson, Racci DeLuca, Jamie Stull The explosive 2,4,6-triamino-1,3,5-trinitrobenzene (TATB) has unique crystals that impart a degree of texture to their compactions and to compactions of their formulated plastic bonded explosives (PBXs), thus inducing anisotropy to the mechanical and thermal properties of these materials. In addition, the plate-like TATB crystals possess very anisotropic coefficient of thermal expansion (CTE) values. The CTE in the through-plate direction is \textasciitilde 10 times greater than in the other two directions. Although the mechanism is not well-understood, in solid compactions of TATB and TATB-based PBXs, the highly-anisotropic CTE gives rise to an irreversible volume expansion that accompanies thermal cycling. This growth is believed to arise from internal stresses induced by thermal expansion. TATB was die-pressed into cylindrical pellets 5 mm long by 5 mm in diameter. These pellets were thermal cycled using thermal mechanical analysis (TMA) to measure the coefficient of CTE and specimen growth after thermal cycling to hot and cold temperatures. The results were compared to the ratchet growth response of PBX 9502, performed in a previous study, to highlight the role of the Kel-F binder in the ratchet growth phenomenon. The comparison is somewhat complicated by the effects of texture due to the difference in sample preparation (i.e. isostatically machined versus ``as-pressed'' parts), however, the detailed evaluation of porosity changes, before and after ratchet growth, is much easier in the absence of binder. [Preview Abstract] |
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F9.00061: Composite reinforced metallic cylinder for high speed rotation Dr. Sahadev Pradhan The objective of the present study is to design and development of the composite reinforced thin metallic cylinder to increase the peripheral speed significantly and thereby improve the separation performance in a centrifugal gas separation processes through proper optimization of the internal parameters. According to Dirac equation (Cohen (1951)), the maximum separative work for a centrifugal gas separation process increase with 4th power of the peripheral speed. Therefore, it has been intended to reinforce the metallic cylinder with composites (carbon fibers: T-700 and T- 1000 grade with suitable epoxy resin) to increase the stiffness and hoop stress so that the peripheral speed can be increased significantly, and thereby enhance the separative output. Here, we have developed the mathematical model to investigate the elastic stresses of a laminated cylinder subjected to mechanical, thermal and thermo-mechanical loading. A detailed analysis is carried out to underline the basic hypothesis of each formulation. Further, we evaluate the steady state creep response of the rotating cylinder and analyze the stresses and strain rates in the cylinder. [Preview Abstract] |
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F9.00062: On the dynamic response of additively manufactured 316L. Liam Smith, Daniel Eakins, David Chapman, Paul Hooper Understanding the dynamic performance of Additively Manufactured (AM) materials is important when designing components for real-world applications. A series of Taylor tests were carried out on AM and conventionally manufactured 316L Stainless Steel. AM specimens were produced with a Renishaw AM250 selective laser melting machine. Taylor tests were conducted in a reverse anvil-on-rod configuration with soft capture and post loading measurements used to corroborate high speed deformation imaging. The influence of microstructure orientation and surface roughness was investigated by manufacturing samples parallel and perpendicular to build direction and with both as-built and machined finishes. Results were compared with optimised Johnson-Cook and Zerilli-Armstrong constitutive models within AUTODYN FE software. [Preview Abstract] |
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F9.00063: Analysis of dynamic deformation behavior of AZ31 using Taylor Rod on Anvil Impact Tests. Maruwada Sukanya Sharma, Daniel Kirtley, Arun Gokhale, Naresh Thadhani The dynamic behavior and detailed microstructural characterization of rolled magnesium alloy AZ31 is described in this work. Magnesium alloys have gained considerable importance as they possess a high strength-to-weight ratio. The goal of the current work is to provide an insight on the dynamic deformation of AZ31 magnesium alloys.Taylor rod-on-anvil impact tests have been conducted at different velocities, on rods machined along the rolling and transverse directions of the as-rolled AZ31 plate, in order to capture the effects of anisotropy on the dynamic deformation behavior. The experiments used laser beam interruption to measure the impact velocity of the samples and high-speed digital imaging to capture transient deformation states. The impacted samples showed anisotropic deformation resulting in an elliptical impact surface foot print. Additionally, detailed orientation maps and micrographs revealed extensive twinning along with some cracks on the impact faces of the samples. Quantitative microscopy revealed that the surface area per unit volume of twins \textit{at least} tripled under all impact conditions. In this presentation evolution of microstructure and anisotropy in rolled AZ31 samples subjected to Taylor rod-on-anvil impact tests will be discussed. [Preview Abstract] |
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F9.00064: Study of dynamic properties of copper at high-strain rate using Proton Radiography to measure Rayleigh-Taylor instability Robert King, Guillermo Terrones, Russell Olson, Christopher Morris, Adam Montoya, Fesseha Mariam, Alexander Saunders, George Gray Our research focuses on the understanding of the dynamic behavior at high strain and strain-rates of copper. We have engineered an experimental package that allows systematic study of Rayleigh-Taylor (RT) instability using the Los Alamos National Laboratory Proton Radiography Facility. Polycrystalline grain-size, single-crystal orientation, and strain-hardening affect the yield strength at high strain-rates as assessed through measurements of the unstable RT perturbation growth through time-sequence radiographs and simulated using the PAGOSA hydrocode. Our measurements are being used to validate constitutive models that enable accurate predictions of dynamic deformation processes under high pressure. [Preview Abstract] |
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F9.00065: Simulation Twins Evolution of Polycrystalline Beryllium under Shock Wave Loading Hao Pan, Xiaomian Hu, Zihui Wu Beryllium is a metal with low density and high strength, so it has a wide use in the energy engineering and aeronautics. As a typical HCP material, twinning is another important mechanism for the plastic deformation of Be. On the basis of the thermo elastic – viscoplatic crystal plasticity model, we consider the twinning deformation. We suggest that the twin deformation does not always increase along with the shear stress. When the volume fraction of twinning reaches a certain level, the grain will be fragmented. Using this model, the twinning evolution of the Be material under shock compression and the followed releasing is numerically simulated. The calculation of the shock/releasing velocity profiles of Be are in agreement with the experimental data. Be begins to undergo twinning at a lower pressure. Texture evolution and shear stress is very sensitive to the evolution of twinning. In the releasing process, we find the volume fraction of the twins also has a certain degree of increase. [Preview Abstract] |
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F9.00066: PHASE TRANSITIONS |
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F9.00067: Shock induced phase transitions and current generation in ferroelectric ceramics Vinamra Agrawal, Kaushik Bhattacharya Ferroelectric materials are used as ferroelectric generators to obtain pulsed power by subjecting them to a shock loading. The impact induces a phase transition and at high impact speeds, dielectric breakdown. Depending on the loading conditions and the electromechanical boundary conditions, the current or voltage profiles obtained vary. We explore the phenomenon of large deformation dynamic behavior and the associated electro-thermo-mechanical coupling of ferroelectric materials in adiabatic environments. Using conservation laws, Maxwell's equations and second law of thermodynamics, we obtain a set of governing equations for the material and the driving force acting on the propagating phase boundary. We also account for the possibility of surface charges on the phase boundary in case of dielectric breakdown which introduces contribution of curvature of the phase boundary in the equations. Next, the governing equations are used to solve a plate impact problem. The Helmholtz energy of the material is chosen be a combination of piecewise quadratic potential in polarization and thermo-elastic material capable of undergoing phase transformation. We obtain current profiles for short circuit boundary conditions along with strain, particle velocity and temperature maps. [Preview Abstract] |
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F9.00068: Measurement of strength in shocked iron across the alpha-epsilon transition David Wood, Gareth Appleby-Thomas, Amer Hameed, Jonathan Painter, Neil Bourne, Jeremy Millett There has been a plethora of investigations concerning the martensitic phase transformation of BCC iron to its HCP polymorph at 13 GPa and the Hugoniot of iron has been measured many times illustrating this shock-induced phase transformation. However all previous work has been unable to assess the deviatoric (shear) stresses in either the mixed phase ($\alpha $ and $\varepsilon )$ region or the high pressure phase ($\varepsilon )$ as the transformation proceeds. This work has attempted to directly measure lateral stresses in one-dimensional shock loading of this material for the first time above and below the phase transition. Through knowledge of both longitudinal and lateral stresses, the shear strength can be deduced. Measurements have been taken both above and below the transformation stress and the results discussed. [Preview Abstract] |
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F9.00069: Forward Stimulated Raman Scattering of aqueous solution of Ammonium Nitrate Prem Kiran Paturi, Rakesh Kumar Vaddapally A great potential exists for stimulated Raman scattering (SRS) signals for the detection of energetic materials dissolved in liquids and laser generated shock pressure at the focal volume. When an intense picosecond laser pulse is focused into liquid medium there is generation of shock wave in the focal region. This shock wave while propagating into the medium varies the pressure and temperature of the liquid locally leading to the appearance of novel phases along with the regular Raman peaks. We present the phase changes of ammonium nitrate (AN) dissolved in water by studying the forward SRS (FSRS) signals due to propagation of 30 ps laser pulses. The dominant peak corresponding to the NO$_{\mathrm{3}}^{\mathrm{-}}$ symmetric stretching mode is observed with a Raman shift of 1045 cm$^{\mathrm{-1}}$ which represents phase IV of AN with an orthogonal crystalline structure. Apart from this peak, the dominant mode of liquid phase of water with a Raman shift of 3400 cm$^{\mathrm{-1}}$ and an ice VII peak at a Raman shift of 3050 cm$^{\mathrm{-1}}$ confirming the pressure of 10 GPa is observed. The effect of the concentration and input laser energy on the appearance of the phases will be presented. [Preview Abstract] |
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F9.00070: Novel Use of PVDF Gauges to Observe the Porosity Effects of PETN Kristina Parrack In order to better understand the performance of detonators and the effects of porosity in HE (high explosives) a single experiment utilizing a combination of diagnostics has been created. These diagnostics include the Rogowski coil and PVDF (polyvinylidene difluoride) gauges. This project focuses on the use of PVDF gauges not only as the traditional stress sensor but also to observe the electric effects of the reaction wave as it compresses HE crystals. These electric effects can be observed through the Hayes electric effect. The PVDF gauges were set up in a variety of orientations in order to determine the best set-up to obtain both the stress and electric effects of the explosive utilized throughout testing. The stress and electric effects are observed with the PVDF gauges and these data are correlated with the various HE porosities. [Preview Abstract] |
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F9.00071: Novel Uses of Detonator Diagnostics John Gibson A novel combination of diagnostics is being used to research the physics of detonator initiation. Rogowski coils are being used to obtain the time derivatives of electrical currents in the detonators in combination with polyvinylidene difluoride (PVDF) stress sensors to monitor shock propagation. PVDF is commonly used in contact with the detonator output to detect breakout time of the detonation wave; however, in this experiment PVDF foils are separated from the PETN and re-oriented to observe various shock events from the time of bridge burst until the breakout time of the detonation wave.~ The goal of these experiments is to use these diagnostics to study the response of detonators using specific explosive particle sizes. The new diagnostics were used to determine the timing of bridge burst, flyer impact, wave propagation and detonator breakout. Custom designed fixtures were loaded with the explosive PETN, which was pressed to a density of 1.55 g/cc. The results of testing various detonators with these new techniques will be presented. The data are compared to those of currently used diagnostics in order to validate the accuracy of these new methods. Future experiments will incorporate other methods of validation including dynamic radiography. [Preview Abstract] |
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F9.00072: The phase transition of RDX under hydrostatic and ramp compression Xianxu Zheng, Zhaohui Zhang, Jun Zhao, Daipeng Zeng, Yangyang Zeng, Xu Zhang The thermodynamic state of explosive was highly dependent on the phase transition structure and phase transition of explosive crystal. However, the phase transition details of explosive have never been characterized sufficiently under different compression conditions. In this study, both the hydrostatic and ramp compression were performed to examine the phase transition of RDX crystal. Based on our experimental results, we confirmed the $\alpha $-$\gamma $ phase transition onset around 4 GPa under hydrostatic compression, which agree with the published literature very well. In the ramp compression experiment, a \textasciitilde 260ns ramp compression up to 30 GPa was generated to compress the RDX single crystal along 020 crystal axis, the PDV signal indicated that the phase transition was induced around 2.8 GPa, and the phase transition induction time was about several tens nanoseconds. Our preliminary experiments suggest that the phase transition pressure of RDX have great relation with the compression history, that probably means the phase transition mechanism were quite different between the hydrostatic and ramp compression. [Preview Abstract] |
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F9.00073: The Microstructure Characteristics of RDX and their Effect on the Detonation Velocity Victor Bellitto, Mikhail Melnik, Mary Sherlock, Joseph Chang, John O’Connor, Joseph Mackey Numerous methods exist for the theoretical calculation of detonation parameters of explosives. However, thermodynamic-hydrodynamic based theoretical codes seldom take into account particle size as a basis for the computational analysis as they primarily focus on the equation of state of the detonation products, heat of formation and density of the explosive composition. This study utilized regression analysis to model the relationship between the microstructure characteristics and detonation velocity of a heterogeneous high-explosive composition containing RDX. The principal characteristics examined were the average particle size of RDX, impurity within the RDX particles, method of RDX manufacture, and compositional density. Statistical analysis demonstrated the relevancy of the microstructure influence on the detonation velocity of the developed experimental compositions of 73 wt. {\%} solids and 27 wt. {\%} polyurethane binder. The developed statistical model accurately predicts the detonation velocity of the heterogeneous composition used in our experiments. The model underscores the significance of the relationship between the average particle size and detonation velocity. The importance of using statistical models for selecting characteristics that result in optimum explosive performance are addressed. [Preview Abstract] |
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F9.00074: ABSTRACT WITHDRAWN |
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