Bulletin of the American Physical Society
16th APS Topical Conference on Shock Compression of Condensed Matter
Volume 54, Number 8
Sunday–Friday, June 28–July 3 2009; Nashville, Tennessee
Session F1: Poster Session I (6:00-8:00pm) |
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Room: Tennessee Ballroom D/E |
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F1.00001: BIOLOGICAL |
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F1.00002: The dynamic response of a viscoelastic biological tissue simulant Christopher Shepherd, Gareth Appleby-Thomas, Paul Hazell, Derek Allsop The development and optimisation of new projectiles requires comparative techniques to assess ballistic performance. Porcine gelatin has found a substantial niche in the ballistics community as a tissue mimic. Primarily due to its elasticity, gelatin has been shown to deform in a similar manner to biological tissues. Bullet impacts typically occur in the 350-850 m/s range and consequently, knowledge of the high strain rate dynamic properties of both the projectile constituents and target materials is desirable if simulations are to allow the optimisation of projectile design. A large body of knowledge exists on the dynamic properties of projectiles, however relatively little data exists in the literature on the dynamic response of flesh simulants. The Hugoniot for a 20 wt{\%} porcine gelatin, which exhibits a ballistic response similar to that of human tissues at room temperature, is determined in this paper using the plate impact technique. Up-Us and Up-P relationships are determined for impact velocities in the range of 200-900 m/s. Good agreement with the limited available data from the literature for similar concentrations is found and the dynamic response established at impact stresses up to 3 times higher than that observed elsewhere. Additionally, high frequency elastic properties are investigated using ultrasound and compared to those observed elsewhere. [Preview Abstract] |
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F1.00003: BALLISTIC STUDIES |
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F1.00004: Sand Penetration Experiments Stephan Bless, Don Berry, William Lawhorn In an experimental program, steel bullets and short cylinders, and tungsten alloy rods were shot into dry silica sand at 600 to 1100 m/s. The rods included finsets that were designed for aerodynamic stabilization. The fins also apparently provided trajectory stabilization within the sand as well. Time-of-arrival screens allowed measurement of velocity. Analysis of those data indicated that drag coefficients increased as projectiles slowed down. Comparison with previous data indicates there was a slight increase in drag coefficient of rods over expected values for unfinned rods; however, the net result was penetration normalized by length was as high as 40, depending on nose shape. It was found that when the velocity exceeded about 80 m/s (which is close to the speed of sound in sand) sand particles were broken down into their constituent grains, resulting in a decrease in size by about 1000. Normalized penetration is expected to scale as kinetic energy per unit area, and it was significantly higher for the rods than for the other projectiles. This is attributed to stabilization from interaction of the fins with the cavity wall. [Preview Abstract] |
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F1.00005: Calibrating the Johnson-Holmquist Ceramic Model for SiC using CTH James Cazamias The Johnson-Holmquist ceramic material model has been calibrated and successfully applied to numerically simulate ballistic events using the Lagrangian code EPIC. While the majority of the constants are ``physics'' based, two of the constants for the failed material response are calibrated using ballistic experiments conducted on a confined cylindrical ceramic target. The maximum strength of the failed ceramic is calibrated by matching the penetration velocity. The second refers to the equivalent plastic strain at failure under constant pressure and is calibrated using the dwell time. Use of these two constants in the CTH Eulerian hydrocode does not predict the ballistic response. This difference may be due to the phenomenological nature of the model and the different numerical schemes used by the codes. This paper determines the afore mentioned material constants for SiC suitable for simulating ballistic events using CTH. [Preview Abstract] |
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F1.00006: CONTINUUM AND MULTISCALE MODELING |
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F1.00007: Meso-Scale Computational Study of the Dynamic Behavior of Co-Rolled Ni-Al Laminates Paul Specht, Naresh Thadhani, Timothy Weihs Meso-scale computational analysis is used to study the shock-initiated reaction response of co-rolled Ni+Al laminates which provide an almost fully dense reactive system with continuous interparticle contacts. Laminates of composition $\sim$Al60Ni40 were prepared at Johns Hopkins University through rolling multiple Ni and Al foils with initial thicknesses of 127 $\mu$m and 178 $\mu$m, respectively, three times. The simulations are preformed using CTH on real, heterogeneous microstructures obtained through optical microscopy. The Baer-Nunziato nonequilbrium multiphase granular mixture model is utilized to model the reaction response of the materials during dynamic loading. Uniaxial strain experiments are also performed to validate the simulated responses so they can then be compared to previously obtained results for porous Ni-Al powder compacts. [Preview Abstract] |
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F1.00008: The effect of nano-particles on the one-dimensional shock compaction of Al-MnO$_{2}$-Epoxy mixtures Andrew Fraser, John Borg, Jennifer Jordan This work numerically explores the effect of nano-particles on the dynamic behavior of Al-MnO$_{2}$-Epoxy mixtures in a planar shock configuration. One-dimensional flyer plate experiments were conducted on the heterogenous mixture where stress wave signatures were measured with VISAR, manganin or PVDF gauges.~ Mesoscale simulations were carried out using the Eulerian hydrodynamic code CTH to simulate a planar shock wave propagating across the heterogeneous mixture; these simulations resolve the grain interactions, explore potential hot spot formations, and investigate the stress history.~Simulation results are compared to experimental data in order to verify the method, then the state space is explored with the addition of nano-particles of aluminum.~ Average longitudinal stress measurements obtained from the mesoscale simulations compare favorably with the stress measurements obtained from the experiments.~ [Preview Abstract] |
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F1.00009: Modeling Unit Cell interactions for the Microstructure of a Heterogeneous Explosive: Detonation Diffraction Past an Inert Sphere D. Scott Stewart, John B. Bdzil We describe an approach being used to model multi-phase blast explosive, that is mostly condensed explosive by volume with inert embedded particles. The asymptotic theory of detonation shock dynamics is used to describe the detonation shock propagation in the explosive. The shock motion rule in the explosive requires that the shock move at a normal speed that depends on the shock curvature. The angle that the shock makes with the particle boundary is also prescribed. We describe theory that can be used to predict the behavior of a collection of such detonation shock/particle interactions in the larger aggregate. A typical unit cell problem of a detonation shock diffraction over a sphere is analyzed by analytical and numerical means and the properties of an ensemble of such unit cell problems is discussed with implications for the macroscopic limiting behavior of the heterogeneous explosive. [Preview Abstract] |
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F1.00010: Modeling the Burning Rate Enhancement of a Propellant Containing Ultrafine Particles Clinton Richmond Burning laws for ultrafine particles have been used in previous work to develop models for the burning of single and agglomerated particles. These ultrafine particles are usually reactive metal particles. In a rocket propellant, aluminum particles are often added to other energetic materials to enhance the burning rate and increase the energy released. In this effort, the laws describing the burning of metal particles and those describing the burning of energetic materials will both be coupled into a model for deriving the surface regression rate of the burning rocket propellant. Also from this model, an enhancement factor will be derived for the increase in the burning rate of a propellant when the size of the metal particles is decreased. Examples are shown that illustrate how this concept conforms to experimental results. [Preview Abstract] |
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F1.00011: POLYMERS/COMPOSITES |
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F1.00012: The effect of particle reinforcement on the dynamic deformation of polymer-based composites Bradley W. White, Naresh N. Thadhani, Jennifer L. Jordan, Jonathan E. Spowart Multiphase composite materials consisting of one or more types of particle reinforcements in a polymer matrix are being studied to determine the effect of reinforcement on the dynamic yield strength and critical impact velocity for plastic deformation. Casting was used to prepare epoxy composites with varying particle loading fractions (10 -- 50 Vol{\%}), size (5 and 50 $\mu $m), and type (Al or Ni+Al). The cast samples were tested at strain rates in the range of 10$^{3}$ to 10$^{4}$ s$^{-1}$, using a 7.62 mm gas gun with a rod-on-anvil (Taylor) impact experimental setup. The recovered impacted specimens were analyzed to determine the dimensions of their deformed and undeformed regions. The yield strength and critical velocity for plastic deformation were evaluated using Hutching's analysis [J Mech Phys Solids, vol. 26, 1979] and correlated with quantitative characteristics of the size and distribution of the reinforcement phase(s). [Preview Abstract] |
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F1.00013: Constitutive modelling of shock response of PTFE Anatoly Resnyansky, Neil Bourne, Jeremy Millett, Eric Brown The PTFE (polytetrafluoroethylene) material is complex and attracts attention of the shock physics researchers because it has amorphous and crystalline components. In turn, the crystalline component has four known phases with the Phase II-to-III transition in shock waves. At the same time, as has been recently studied using spectrometry, the crystalline region is growing with load as well. Stress and velocity shock-wave profiles acquired recently with embedded gauges demonstrate features that may be related to impedance mis-matches between the regions subjected to some transitions resulting in density and modulus variations. We consider the above mentioned amorphous-to-crystalline transition and the high pressure Phase II-to-III transitions as possible candidates for the analysis. The present work utilizes a multi-phase rate sensitive model to describe shock response of the PTFE material. One-dimensional shock wave experimental profiles are compared with calculated profiles with the kinetics describing the transitions. The objective of this study is to understand the role of the various transitions in the shock response of PTFE. [Preview Abstract] |
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F1.00014: DETONATION AND SHOCK-INDUCED CHEMISTRY |
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F1.00015: Detonation waves parameters for FEFO/nitrobenzene solution Valentina Mochalova, Alexander Utkin, Victor Garanin, Sergey Torunov The dependence of detonation parameters for (bis-(2-fluoro-2,2-dinitroethyl) formal)/nitrobenzene solution (FEFO/NB) from NB concentration was defined. Velocity profiles of the boundary between HE and water window were recorded by laser interferometer VISAR. It was found that particle velocity in a pure FEFO was strongly oscillating with the oscillation amplitude $\sim $50 m/s. It means that detonation front is unstable and irregularity size is about 10 mkm. The average velocity profile corresponds to ZND model. The reaction time is equal to $\sim $ 400ns, C-J pressure and particle velocity are 24 GPa and 2.0 km/s respectively. For FEFO/NB solution it was found that at low NB concentrations (10-20{\%}) oscillations disappeared and detonation front was stable. When the NB concentration was increased up to 30 {\%} high-frequency oscillations appeared again. The measurements of reaction zone structure up to critical concentration were conducted, it was about 45{\%}. At average particle velocity profiles Von Neumann spike was distinctly registered. It was shown that in a pure FEFO and in solutions with NB concentration exceeding 30{\%} detonation front was unstable. [Preview Abstract] |
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F1.00016: Experimental Investigation of Shock Initiation in Mixtures of Manganese and Sulfur Francois-Xavier Jette, Sam Goroshin, Andrew Higgins Equimolar mixtures of manganese powder and sulfur at different initial densities were tested in two different types of steel recovery capsules in order to study the shock initiation phenomenon in SHS mixtures. This mixture composition was selected due to the large exothermic heat release of the manganese-sulfur reaction (214 kJ/mol), which causes the reaction to be self-sustaining once initiated. Two different sizes of Mn particles were used for these experiments, 1-5 $\mu $m and -325 mesh (44$\mu $m or less). The test samples were placed in planar recovery ampoules and a strong shock was delivered via the detonation of a charge of amine-sensitized nitromethane. Various shock strengths were achieved by placing different thicknesses of PMMA attenuator discs between the explosive charge and the ampoule. The results confirmed that shock-induced reactions can be produced in highly non-porous mixtures. It was also found that shock interactions with the side walls of the recovery capsule can play a significant role in the initiation, and that mixtures containing the larger Mn particles were very difficult to initiate in the absence of shock interactions with the capsule walls. [Preview Abstract] |
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F1.00017: Shock Chemistry of Organic Compounds Frozen in Ice Undergoing Impacts at 5 km s$^{-1}$ Mark Burchell, John Parnell, Stephen Bowden The development of complexity in organic compounds is a key step in the development of biological materials and the origin of life. Currently, great interest exists in the organic inventories of the icy satellites of outer planets. One source of increasing complexity in organic compounds on these icy bodies is impact driven processing. These impacts are high speed events which generate impact shocks in the many GPa range. To better understand this type of shock driven chemistry, we have undertaken a series of experiments using a two stage light gas gun to provide impacts at 5 km s$^{-1}$ of stainless steel projectiles onto ice targets doped with various organics. Three organics were used: $\beta $,$\beta $ carotene, stearic acid and anthracene. We have analysed the organic content of the ejecta from the impacts and shown that all three organics can be found, albeit with different ejection histories (i.e. the least thermally stable compounds were preferentially found at shallow angles of ejection). Samples of ice from the impact site itself are currently under analysis and the results of this will also be presented. [Preview Abstract] |
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F1.00018: The Future of Compression Science: Controlling Material Response David Funk, Cris Barnes, John Sarrao We are at a unique point in history for our scientific field, in that the experimental tools and computational powers have matured such that the direct comparison of timedependent properties and the connection of scales (atomistic to continuum) are within our reach. The realization of this intellectual goal and the resulting development of accurate physical models will enable an era in which we have moved from ``the science of observation'' to ``the science of control.'' To achieve this goal, we require exquisitely characterized materials, revolutionary time-dependent diagnostic tools, and unprecedented computational powers. This paper will examine the near-term experimental possibility of DC-CAT (within a few years; coupling synchrotron radiation with dynamic drivers); the mid-term possibilities of LCLS (and the future availability of x-ray FELs); and in the long term, the role of multiple simultaneous measurements (e.g. MaRIE and the ability to make multiple measurements in a time-resolved manner in a single shot) and how this data, when coupled with advanced physical models and computational powers, will enable an era in which we can ``Predict and Control Material Performance in the Extremes.'' [Preview Abstract] |
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F1.00019: PBX 9404 Cylinder Tests: A Comparison of New and Aged Material Robert Mier, Larry Hill, Matthew Briggs Standard 1-inch diameter copper cylinder tests were performed on aged PBX 9404 (94 wt{\%} HMX, 3 wt{\%} NC, 3 wt{\%} CEF) explosive. The material was about 35 years old at the time it was tested. The explosive was newly pressed from old molding powder that was stored in a magazine under nominal conditions during its entire history. The copper wall motion was measured using both streak camera and PDV. The two types of data are compared for consistency. We also compare the newly acquired data on old PBX 9404 with old data for new PBX 9404 (this is the best that can be done because no new PBX 9404 explosive exists) and compare the results. [Preview Abstract] |
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F1.00020: Shock Response of Bi-Metallic Layered Materials J.D. Molitoris, A.E. Gash, R.G. Garza, J.W. Tringe, J.D. Batteux, B.M. Wong Layered bi-metallic samples were placed in intimate contact with a high-explosive charge that was detonated to produce the transmitted shock. Using high-resolution radiography we obtained a set of images in time sequence detailing how the bi-metal responds. Fast optical imaging and pyrometry data were also taken. Complete data sets were obtained for Ni-Al and pure Al samples for direct comparison. As the experiments were designed for single-pass radiography, there are no interference effects. The data indicate that the shock promptly initiates the bi-metallic reaction and that the resulting alloy is not subsequently combusted. The experimental technique will be presented as well as results on Ni-Al and possibly other multi-layers. [Preview Abstract] |
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F1.00021: EXPERIMENTAL DEVELOPMENTS (DIAGNOSTICS - E.G. PDV; LOADING TECHNIQUES - E.G. ICE) |
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F1.00022: Integrated Multi-electrode Circuit for Velocity Measurement Ilan Be'ery, Gal Goldstein The accurate measurement of detonation and shock velocity is a common practice in shock physics. In many cases this is done using many shorting pins or electrodes. We present several techniques for the integration of up to 20 shorting electrodes into a single circuit with a single output channel. This integration simplifies the experimental assembly, increases accuracy, and saves space and cabling. We present the ``parallel'' and ``serial'' integrating circuits and discuss the relative benefits. Each of the two basic circuits can be equipped with additional components to monitor and validate the circuit's integrity. The realization of three shorting mechanism is demonstrated: direct contact, self shorting, and shock conduction of polymer. We bring several examples of experimental results which demonstrate an accuracy and repeatability better than 10-3 in velocity measurements. [Preview Abstract] |
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F1.00023: Computer Based Gas Gun Control Using National Instruments (NI) LabVIEW Development Environment R.A. Saavedra, P.A. Rigg, S. Dimarino, M.E. Byers, N.S. Khalsa, J. Maestas The high performance two-stage light gas gun located at Los Alamos National Laboratory has been in continuous operation since 1968 with the original remote control system largely intact. The primary goal of this project was to replace the existing 120VAC push button control system with a safer 24VDC system. This work involved using NI hardware and the LabVIEW programming language to implement the design of a computer based control system for the two-stage gun and a 40 mm powder gun located in the same facility. The control system is simple and easy to maintain, and the software based nature of the system makes it very easy to reconfigure and add components. Details of the control system will be presented and simple strategies to create a maintainable system using LabVIEW will be discussed. [Preview Abstract] |
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F1.00024: Accuracy of front Propagation speed determination Meir Werdiger, Lior Perelmutter, Shlomi Pistinner The utilization of front propagation velocity in bulk material to infer physical quantities at an arbitrary pressure is a widespread technique. Here we analyze the accuracy of inferring front propagation velocity from front arrival time at an arbitrary predetermined location in space. Thus we attempt to find out the optimum locations at which front arrival time should be measured. We generalize existing techniques previously used for front propagation determination, and formulate the general optimization problem. This generalization is used to demonstrate that any front velocity $u_w \hat {z}$, such that the front arrival time to an arbitrary location in space can be written in the following functional form: $t=\sum\nolimits_i {A_i g(x,y,z/u_w )} $, allows a predetermination of the accuracy by which $u_w$ can be obtained. Furthermore, it allows the analytical optimization of the locations at which the arrival time should be measured. [Preview Abstract] |
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F1.00025: Temperature measurements at material interfaces with thin-foil gauges Mike Morley, David Chapman, William Proud Measurements of shock heating are important in determining Equations of State that incorporate entropic effects. The use of thin-foil nickel gauges to measure shock heating in material was proposed by Rosenberg et al. in the 1980s. This research investigates the use of such commercial thin-foil gauges at interfaces between materials of different thermal and shock properties. The technique requires analysis of the resistance changes of the gauge which is a function of both temperature and stress. The response of manganin gauges to shock loading is well understood, and was used to calibrate for the piezoresistive effect in nickel. Results are presented for a variety of well-characterised materials and the applicability of the proposed method discussed. [Preview Abstract] |
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F1.00026: Calibration of Wire-Like Manganin Gauges for Use in Planar Shock-Wave Experiments David Chapman, William Proud Peizoresistive gauges have been used extensively for many decades as in-material stress transducers during shock wave experiments. Manganin demonstrates a high piezoresistive response which is relatively temperature independent. As such manganin gauges have been widely calibrated by many authors for use during shock-wave experiments. The precise calibration has been demonstrated to depend on both the chemical composition and mechanical history of the manganin, and on the geometry of the gauge. The research presented in this paper refers to the calibration of a commercially available manganin gauge, Micro-measurements J2M-SS-580SF-025, generally referred to as the T-gauge owing to its geometry. The T-gauge has seen widespread use as a pressure transducer to measure lateral stress during plate-impact experiments. It has been previously proposed that T-gauges have a similar response to the grid foil-like manganin gauges extensively calibrated by Rosenberg et. al.. However, recently it has been suggested that they in fact behave in a wire-like manner. The results presented here demonstrate that the gauges behaviour is wire-like when mounted to measure longitudinal stress. A modified calibration can be applied successfully to convert the relative resistance change to the stress normal to the gauge element. These results have important ramifications for the reduction of lateral stress measurements previously made using the T-gauge. [Preview Abstract] |
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F1.00027: Wide Angle X-ray Diffraction for Shocked Periclase Yoichiro Hironaka, Keisuke Shigemori, Toshihiko Kadono, Keisuke Fujioka, Minoru Tanabe, Akiyuki Shiroshita, Norimasa Ozaki, Kohei Miyanishi, Tadashi Kondo, Tasuhiro Sakaiya, Katsuya Shimizu, Kazuto Otani We performed wide angle X-ray diffraction for laser shocked single crystal to measure the perfect atomic uniaxial motion near the Hugoniot elastic limit Wide angle X-ray diffraction technique is enabled to identify the three dimensional lattice deformation under shocked crystal. We detected X-rays diffracted from multiple planes of MgO single crystal. [Preview Abstract] |
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F1.00028: Development of the large-bore powder gun for the Nevada Test Site James Esparza, Brian Jensen Past fundamental work at the Nevada Test Site (NTS) U1a complex has been performed using explosively-driven flyer plates which provide high-pressure loading at the expense of some shock. In contrast, plate-impact experiments on single stage guns provide very planar loading conditions suitable for studying complex phenomena such as phase transitions and material strength, and provide important data useful for constraining and validating predictive models. The objective of the current work was to develop a large-bore powder gun capable of accelerating projectiles to moderately high velocity for impact experiments at NTS. This gun will span a performance gap between existing gun facilities and provide a means of examining phenomena over a wide range of stresses and time-scales. Advantages of the large-bore gun include the capability to load multiple samples simultaneously, the use of large diameter samples that significantly extend the time duration of the experiment, and minimal tilt. This new capability required the development of a disposable confinement system that used an explosively driven closure method to prevent contamination from moving up into the gun system. Experimental results of the qualification testing of the large-bore gun, the confinement system, and the explosively driven valve will be presented. [Preview Abstract] |
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F1.00029: ENERGETIC MATERIALS |
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F1.00030: Cook-off violence mapping and pressure-volume relations with a scaled deflagration cylinder test Timothy Pierce, Daniel Hooks There have been significant advances in the scientific understanding of cook-off in explosives, which have led to a generalized mechanistic understanding of the processes involved for certain explosives. Several deflagration cylinder tests (DFCT) tests were recently fielded that alluded to regimes of outcomes depending on the history and state of the system. Importantly, a few of these tests also exhibited steady-wave combustion that enabled, using the method of G. I. Taylor, extraction of a pressure-volume relation for the conditions of the test. Such a relation, dubbed a ``pseudo-equation of state'' (pEOS), allows one to inform models to simulate the possible outcomes of violent reaction using hydrodynamic codes. Thus, this test was extremely valuable in that it demonstrated the possibility of both mapping outcomes based on system variables and external conditions and provides data to inform predictive models. We describe a scaled version of the DFCT. It delivers pEOS data when steady combustion is observed, and is inexpensive enough to map outcomes by fielding many tests. [Preview Abstract] |
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F1.00031: Shock Compression and Impact Response of Ta + Iron(III)Oxide Powder Mixtures D. Anthony Fredenburg, Naresh N. Thadhani The shock compression and impact response of equivolumetric Ta + Iron(III)Oxide thermite powder mixtures is investigated through instrumented parallel plate and rod-on-anvil impact experiments. Measurements of stress and shock velocity in the powder mixtures are made with PFDV stress gauges using a uniaxial strain configuration, allowing for determination of the materials' shock compressibility. Results reveal densification of the mixture at stresses up to the crush strength of $\sim $ 5.4 GPa. Densification trends are incorporated into existing compaction models to determine their applicability to the present metal + oxide powder mixture. At stresses above 5.4 GPa an expanded volume state is observed in the plane strain configuration, indicating possible reaction in the mixture. Reaction initiation conditions are also studied in the plane stress configuration, where powders pressed to $\sim $ 75 {\%} theoretical density are mounted on a rod and accelerated to impact an anvil over the velocity range 300-500 m/s. Initiation of reactive mixtures is observed through high-speed digital photography. Research funded by DTRA Grant {\#} HDTRA1-D7-1-0018. [Preview Abstract] |
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F1.00032: Femtosecond micromachining of internal voids in high explosive crystals for studies of hot spot initiation Shawn McGrane, Andrew Grieco, Kyle Ramos, Daniel Hooks, David Moore Femtosecond micromachining was used to produce controlled patterns of internal voids in high explosive single crystals of PETN, RDX, and HMX. Optical microscopy established that the voids generated near the threshold energy were localized to sub-micrometer diameters. Confocal Raman microscopy established that the defects generated were voids, with no chemical products observable and with diminished crystal spectral intensity. Increasing the micromachining energy above threshold led to microcracking along preferred crystalline planes. Consolidation of hundreds to thousands of individual voids allowed creation of defined two- and three- dimensional structures. [Preview Abstract] |
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F1.00033: Density-dependent Acoustic Properties of PBX 9502 Geoffrey Brown, Darla Thompson, Racci DeLuca The acoustic properties of a material can be used to tune models of the material's dynamic response since sound velocities and material density provide dynamic mechanical moduli. Ideally, density-dependent response is desired but often too little data exists to infer the relation between density and modulus. There is also no guarantee that a material's strength will be the same for a density obtained in different ways. In this work we explore the relation between density, acoustic properties, and moduli in PBX 9502, a plastic bonded explosive made of TATB (95{\%} by weight) in Kel-F binder (5{\%} by weight). Under thermal cycling, PBX 9502 undergoes irreversible volume expansion, called ``ratchet growth'', in which the density can drop by several percent. We have compared ratchet-grown parts to as-pressed parts of the same density and observe lower acoustic velocities in the ratchet-grown parts, implying lower moduli. This is consistent with our quasi-static testing results and implies a correlation between the material's void distribution and its mechanical properties. We will examine several scenarios that may account for decreased velocities. [Preview Abstract] |
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F1.00034: Effects of Damage on Non-Shock Initiation of HMX-Based High Explosives Daniel Preston, Paul Peterson, Kien-Yin Lee, David Chavez, Racci Deluca, Gabriel Avilucea, Stephanie Hagelberg Structural damage in energetic materials plays a significant role in the probability of non-shock initiation events. Damage may occur in the form of voids or cracks either within crystals or in binder-rich regions between crystals. These cracks affect whether hotspots generated by impact will quench or propagate. For this study, we have separately engineered intra-crystalline and inter-crystalline cracks into PBX 9501, an HMX-based explosive. Intra-crystalline cracks were created by subjecting HMX to forward and reverse solid-to-solid phase transformations prior to formulation. Inter-crystalline cracks were induced by compressing formulated samples of PBX 9501 to 1{\%} strain. Both sets of pre-damaged explosives were then impact tested using the LANL Type 12 Drop Weight-Impact Machine and their sensitivities compared to non-damaged PBX 9501. Results of these tests clearly show significant differences in impact sensitivity between damaged and non-damaged PBX 9501. [Preview Abstract] |
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F1.00035: The Energetic Metal Composite under High Strain Rate Yubin Shen, Naresh Thadhani, Fred Cook, Karl I. Jacob Composites with energetic materials like Titanium (Ti), Nickel (Ni), etc. could react upon high velocity impact to absorb some part of the kinetic energy. The impact induced transformation of the composite was characterized by a high-speed digital camera. Ti based composites were pressed and sintered into small rod which was attached to the front of copper rod for test. A series of Taylor impact tests have been carried out on in Ti composite at a velocity range from 118m/s to 308 m/s, and the visible light caused by the composite transformation was observed in all of the cases. The ignition time decreased with increasing impact velocity, but at a decreasing rate. During the impact process, Ti composites first deformed under the impact force, then the copper rod began punching into the sample until the diameter of the sample exceeded the diameter of the copper rod. Light was detected indicating transformation in the composite, at which point the axial strain was in the range of 50{\%} - 60{\%}, and the areal strain was in range of 140{\%} - 170{\%}. Smaller samples were also prepared for the Taylor impact test, and similar phenomenon was observed irrespective of the sample size. It is believed that the shear component of the impact stress played an important role in triggering the transformation of Ti composites. Several Taylor impact tests were also performed to characterize various Ti composite and the results will be presented in this talk. [Preview Abstract] |
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F1.00036: Remote liquid target loading system for LANL two-stage gas gun L.L. Gibson, B. Bartram, D.M. Dattelbaum, S.A. Sheffield, D.B. Stahl A Remote Liquid Loading System (RLLS) was designed to load high hazard liquid materials into targets for gas-gun driven impact experiments. These high hazard liquids tend to react with confining materials in a short period of time, degrading target assemblies and potentially building up pressure through the evolution of gas in the reactions. Therefore, the ability to load a gas gun target in place immediately prior to firing the gun, provides the most stable and reliable target fielding approach. We present the design and evaluation of a RLLS built for the LANL two-stage gas gun. Targets for the gun are made of PMMA and assembled to form a liquid containment cell with a volume of approximately 25 cc. The compatibility of materials was a major consideration in the design of the system, particularly for its use with highly concentrated hydrogen peroxide. Teflon and 304-stainless steel were the two most compatible materials with the materials to be tested. Teflon valves and tubing, as well as stainless steel tubing, were used to handle the liquid, along with a stainless steel reservoir. Preliminary testing was done to ensure proper flow rate and safety. The system has been used to successfully load 97.5 percent hydrogen peroxide into a target cell just prior to a successful multiple magnetic gauge experiment. TV cameras on the target verified the bubble-free filling operation. [Preview Abstract] |
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F1.00037: Gauge Run-To-Detonation Data and Failure/Dead Zone Modeling P. Clark Souers, Peter Vitello, Kevin S. Vandersall Previous shock initiation run-to-detonation experiments on energetic materials were plotted with distance and time to get a single distance/time to detonation. Modern shots utilize enough gauges so that the distance-time data can be differentiated, which shows not only the usual inflection pressure point before detonation, referred to here as P2, but also a second, low-pressure inflection, referred to here as P1, that marks rapid ramp-up of the initiation. An analysis of the TATB based LX-17 and PBX 9502 in addition to the LLM-105 based RX-55-AB data shows that both P1 and P2 increase linearly with the initiation pressure created by the sabot. This contradicts the current method in the Tarantula failure/dead zone model, which uses constant pressure boundaries between reaction regions. Modeling changes required by the new data will be considered. [Preview Abstract] |
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F1.00038: Low-pressure overdriven experiments on PBX 9502 Mark Byers, Brian Jensen Symmetric impact experiments were performed on PBX 9502 to obtain Hugoniot data in the low-pressure, overdriven regime. An explosive plane wave lens (P300 with comp-B booster) was used to launch an aluminum flyer plate (4 to 4.5 km/s) into an aluminum target backed by the PBX 9502 samples and a LiF window. Photonic Doppler velocimetry (PDV) and VISAR were used to obtain the shock transit time through the PBX 9502 samples and wave profile data at the PBX 9502/LiF interface. Past experimental result in the overdriven regime, utilizing a rotating mirror streak camera, revealed a well-defined high-pressure Hugoniot. In contrast, the low-pressure (overdriven) data exhibited significant scatter likely due to non-steady wave effects associated with the thin PBX 9502 samples (3-5 mm) used in the experiments. The objective of the current work was to obtain Hugoniot data in the low-pressure, overdriven regime for PBX 9502 using recently developed diagnostics along with thicker samples (5-10mm) to decrease the uncertainty and scatter in the Hugoniot data. Further results and implications are presented. [Preview Abstract] |
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F1.00039: Characterizing Detonating LX-17 Charges Crossing a Transverse Air Gap with Experiments and Modeling Lisa M. Lauderbach, P. Clark Souers, Frank Garcia, Peter Vitello, Kevin S. Vandersall Experiments were performed using detonating LX-17 (92.5{\%} TATB, 7.5{\%} Kel-f by weight) charges with various width transverse air gaps both with and without manganin peizoresistive in-situ gauges present. The experiments, performed with 25 mm diameter by 25 mm long LX-17 pellets with the transverse air gap in between, showed that transverse gaps up to about 3 mm could be present without causing the detonation wave to fail to continue as a detonation. A JWL++/Tarantula code was utilized to model the results and compare with the in-situ gauge records with reasonable agreement to the experimental data. This work will present the experimental details as well as comparison to the model results. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. [Preview Abstract] |
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F1.00040: EQUATION OF STATE |
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F1.00041: Measurement of thermal conductivity of sapphire at shock compression Xianming Zhou, Jun Li, Jiabo Li Measurement of thermal conductivity in materials at dynamic high pressure and temperature condition is a key step to the development of shock temperature measurement technique for opaque materials. Here, we present a recent progress in developing technique to measure thermal conductvity of a shocked window material. Our feature improvement over the previous method in the literature is that not only the thermal relaxation but also the optical extinction process was dectected in one shock compression experiment. Besides, the gap-flash effect has been controlled to an accepted extent by a separately vacuumed sample box and a numeric simulation method of the non-linear heat flow was introduced into the data analysis process. All these efforts provide additional information to correct the window extinction effect which was not taken into account in the original method. Primary result of heat conductivity $k_{w}\sim $3.54 W.m$^{-1}$ of sapphire at $\sim $115 GPa shock pressure was obtained, which is much lower than both theoretical prediction and the previous measurement in the literature at similar shock pressure and temperature. [Preview Abstract] |
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F1.00042: Comparison of Shock Loading traces obtained from PVDF stress gauges and VISAR Christopher Neel, Naresh Thadhani Parallel plate impact tests were performed on solid THV polymer (tetrafluoroethylene -- hexafluoropropylene -- vinylidene fluoride), as well as two well characterized polymers, PTFE and PMMA. Simultaneous time-resolved measurements at the interface between the polymer and fused silica were performed using PVDF stress gauges and VISAR probes. The effect of shielding to eliminate the effect of stress-induced polarization on the PVDF gauges is presented, and differences in the loading traces for the two measurement probes are discussed. [Preview Abstract] |
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F1.00043: EOS development and numerical modeling of CL-20 compaction Aaron Brundage, Marcia Cooper The response of low-density pressings (62-70{\%} theoretical maximum density) of CL-20 (Hexanitrohexaazaisowurtzitane) to shock impact has been investigated with numerical simulation using BN (Baer-Nunziato) multiphase modeling. Validation data for the modeling was acquired from wave profiles measured with VISAR from low-velocity impact gas-gun experiments. Previously unreported equation of state (EOS) data for CL-20 was determined to support the numerical modeling. A configurational stress relationship, which was needed for the multiphase modeling, was determined from the dynamic loading data. Additionally, a Mie-Gruniesen equation of state for crystalline CL-20 was constructed from previously reported diamond anvil cell (DAC) isothermal compression experiments. The predictions of the observed elastic wave precursors and compaction wave profiles were in good agreement with the data over the range of impact velocities reported herein. A multiphase model is needed to describe the deflagration-to-detonation transition (DDT) in porous CL-20 samples initiated by dynamic compaction. [Preview Abstract] |
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F1.00044: The equation of state of dense xenon at high temperature and high pressure Jun Zheng, Qifeng Chen, Yujun Gu The Hugoniot data of gaseous xenon under shock compression were measured in the pressure range 2.6$\sim $3.8Gpa, and the calculated temperature 42$\sim $50kKby means of a two-stage light-gas gun. Gaseous specimens were shocked from initial pressure 0.8Mpa at 293K. Time-resolved spectral radiation histories were recorded by using a six-wavelength channel pyrometer. Shock velocity was measured and particle velocity was determined by the impedance matching method. The data were discussed in terms of saha model with Debye-H\"uckel correction. [Preview Abstract] |
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F1.00045: 1D Gas-Dynamic Simulation of Shock-Wave Processes via Internet Pavel Levashov, Mikhail Povarnitsyn, Konstantin Khishchenko We present a web-interface, which allows one to perform a 1-dimensional gas-dynamic simulation of typical shock-wave processes via the Internet using the database on shock-wave experiments and equations of state. In this interface a user can supply initial conditions, control the process of simulation and make a treatment of the results. Up to seven objects can take part in the experiment; for every object a substance, its initial position and velocity, equation of state and destruction pressure should be defined. The simulation itself is based upon the Eulerian second order Godunov approach. To start computations, the user also has to set the final time, grid ``coarseness'' and the number of moments in which the output of necessary parameters will take place, including initial and final. Additionally, the user can define several Lagrangian markers to trace the state of matter at a given initial coordinate. At the end of simulation the user can analyze the profiles of different values at different times or at points with the specified coordinates of Lagrangian markers both as charts and in textual form. The main advantage of this system is the possibility to use in simulation all equations of state available in the database (more than 130). The system is available freely via addresses http://teos.ficp.ac.ru/rusbank/, http://www.ihed.ras.ru/rusbank/. [Preview Abstract] |
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F1.00046: GEOPHYSICS AND PLANETARY SCIENCE |
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F1.00047: Impact experiments with an impact velocity higher than 10 km/s T. Kadono, T. Sakaiya, Y. Hironaka, K. Otani, T. Sano, T. Fujiwara, T. Mochiyama, S. Fujioka, S. Sugita, Y. Sekine, A. Nakamura, M. Arakawa, K. Shigemori We accelerate glass and aluminum projectiles to a velocity higher than 10 km/s using a high power laser, GEKKO XII - HIPER at Institute of Laser Engineering, Osaka University. The velocity of the projectiles is estimated using high-speed streak and framing cameras. The projectiles collide with copper targets. The copper plates are recovered and craters are observed. Also, a tantalum plate as a witness plate is recovered and a large number of crates caused by ejecta impacts are observed. Thus, we can simulate the hypervelocity impacts with a velocity over 10 km/s in the laboratory. [Preview Abstract] |
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F1.00048: On the Source of Noise in Gauge Traces in Geological Materials C.H. Braithwaite, D.J. Chapman, J.E. Field, W.G. Proud It has been previously speculated that two distinct sources of noise in gauge traces in geological materials exist. These sources are straining of the gauge element through the non planarity of the shock front after it has passed through the polycrystalline material, and electromagnetic emission from piezoelectric minerals within the bulk material. Experiments have been conducted in materials of differing quartz content to show that the electromagnetic emission is indeed an issue. Further, mineral analysis data is presented to support the conclusion that gauge straining is also occurring. [Preview Abstract] |
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F1.00049: Conditions of Collapse of a Spherically Distributed Condensed Matter Dmitri Rabounski, Larissa Borissova Space-time inside a sphere of incompressible liquid is studied by the mathematical methods of chronometric invariants (physical observable quantities in General Relativity). We have obtained exact solutions to the field equations in the cases: 1) the sphere models planet or star; 2) the sphere is a cosmological model. Conditions of collapse have been obtained for both cases. It is shown that in the cosmological model the surface of a liquid universe (filled inside by an incompressible liquid consisting of galaxies and stars) is not coinciding with the surface of collapse calculated for the liquid sphere: a spherical liquid universe of a radius of 10$^{28}$ cm (size of the Metagalaxy we observe) is surrounded by a collapse surface whose radius is ten times bigger, 10$^{29}$ cm, while the large layer between the liquid sphere and the collapse surface is filled with only gravitational field (we refer to it as a galaxy-free and star-free layer). It is shown that in this model the four-dimensional curvature of space-time is positive, the three-dimensional curvature of space is negative, and Hubble redshift in three-dimensional (observable) space is proportional to the square of distance. [Preview Abstract] |
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F1.00050: Microstructural investigation of melting in laser-shocked recovered iron foils Guillaume Morard, Francois Guyot, Guillaume Fiquet, Alessandra Benuzzi-Mounaix, Erik Brambrink, Michel Koenig, Huigang Wei, Alexandra Diziere, Thibaut De Resseguier, Emilien Lescoute, Florent Occelli, Tommaso Vinci For a better characterization of the melting of shocked iron, we have carried out a study that combines a visual observation of recovered samples in the micrometer range along with in-situ time-resolved diagnostics. High-power laser shots were carried out at LULI 2000, France on 100 $\mu $m foils. A velocity interferometer system (VISAR) was used to measure the free surface velocity. Hydrodynamic simulations were performed. Then, the pressure and the temperature in solid iron were reconstructed through the iron foil using the Rankine-Hugoniot relations. These data were compared with Scanning Electron Microscope (SEM) analysis of recovered targets and ejecta that were collected on transparent polycarbonate plates placed on the opposite face. The evolution of the molten part of the target in relation with the analysis of the different categories of recovered ejecta gives useful indications on the potential of laser shock techniques for studying the melting of iron under planetary core conditions. [Preview Abstract] |
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F1.00051: The Laser-driven Flyer System for Space Debris Hypervelocity Impact Simulations Zizheng Gong, Fu Dai, Jiyun Yang, Mingqiang Hou, Jiandong Zheng, Jingyu Tong, Hewei Pang The Laser-driven flyer (LDF) technique is showing promiseful in simulating micro meteoroids and orbital debris (M/OD) hypervelocity impacting effects. LDF system with a single pulses from a $Q$-switched Nd: glass laser, of 15 ns duration and up to 20J energy, launched the aluminum films of 5 $\mu $m thickness up to 8.3km/s velocity was developed in \textit{Beijing Institute of Spacecrafts Environment Engineering(BISEE), CAST.} The quantitative relationships between the flyer velocity and the laser energy, the width of laser pulse, the diameter of laser focal spot, and the flyer thickness were analyzed, according to Lawrence-Gurney model, and compared with the experimental results. Some experimental aspects in our efforts on the space debris Hypervelocity impacts on the outer surfaces functional material, such as the thermal control material, window glass, and OSR etc., are reviewed. Though still developing, the Laser-driven flyer technique has been demonstrated promise in simulating micro M/OD hypervelocity impacting effects. [Preview Abstract] |
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F1.00052: HIGH ENERGY DENSITY PHYSICS / WARM DENSE MATTER |
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F1.00053: Self-similar compression flows in spherical geometry: numerical calculations and implementations Jean Gerin-Roze During the previous APS-SCCM meeting(2007) we exhibited a set of theoretical solutions for the implosion of a sphere initiated by a strong shock. We assumed that: 1. The sphere contains a perfect gas with a polytropic coefficient $\gamma $=5/3. 2. The shock follows the equation: r$_{s}$/r$_{0}$=(-t/t$_{foc})^{\alpha }$ where $\alpha $ is a positive constant and where --t$_{foc}<$t$<$0 The well known G.Guderley solution corresponds to $\alpha =\alpha _{ref}$= 0.6883 and we showed that one other self-similar solution exists for each value of $\alpha $ between 0 and $\alpha _{ref }$. In this paper, we continue this work by solving numerically two particular problems with shock parameter $\alpha $=1/2 and $\alpha $=2/3. The theoretical solutions are obtained with a very good accuracy. For example, the relative gap on the focalization time is less than 1/10000. Then, we use one of these implosions ($\alpha $=2/3) to generate thermonuclear neutrons in DT gas. These neutrons are obtained very early, before the focalization of the initial shock. [Preview Abstract] |
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F1.00054: Laser-Driven Ramp Compression of Pressure Standard Materials Kohei Miyanishi, Norimasa Ozaki, Ryosuke Brambrink, Erik Brambrink, Alessandra Benuzzi-Mounaix, Alessandra Ravasio, Alexandra Diziere, Huigang Wei, Michel Koenig, Tommaso Vinci Laser-driven ramp compression technique was used to shocklessly compress gold and plutinum targets. The equations of state (EOS) of these metals are of intrinsic importance to as pressure standard to determine the pressure under static compression. Our group has proposed to study EOS of pressure standards using the ramp compression technique as an approach different from shock Hugoniot-reduced isotherm. Experiments have been performed on LULI2000 facilities at the Ecole Polytechnique. Free-surface velocities of the metals with different thicknesses were measured with 2-channel velocity interferometer systems. [Preview Abstract] |
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F1.00055: Shock temperature measurements of pre-compressed water using two-color streaked optical pyrometer Tomoaki Kimura, Norimasa Ozaki, Tomoyuki Terai, Tomokazu Sano, Kohei Miyanishi, Takashi Endo, Tatsuya Jitsui, Akio Hirose, Tomoyuki Kakeshita, Ryosuke Kodama, Takuo Okuchi, Katsuya Shimizu, Takayoshi Sano, Youichi Sakawa, Masahiro Ikoma A coupling method of static pre-compression and laser-shock compression has been used to investigate off-Hugoniot states such as internal conditions of planets. This method has a possibility to generate lower temperature conditions than principal Hugoniot. In this work, shock temperature of a pre-compressed water has been experimentally obtained. We measured two-color emission from a shock wave driven into the pre-compressed water target using a streaked optical pyrometer. Using this method, it is possible to directly determine the shock temperature without any assumption of the emissivity of the shocked matter. [Preview Abstract] |
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F1.00056: INELASTIC DEFORMATION, FRACTURE AND SPALL |
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F1.00057: Deformation and fracture of bulk metallic glasses under shock loading Svetlana Atroshenko, Nikita Morozov, Jun Shen, Yuri Sudenkov, Natalia Naumova The dynamic behavior of Ti40Zr25Ni3Cu12Be20 ao.{\%} bulk metallic glasses is investigated using plane plates impact technique with duration of $\sim $ 0.5 $\mu $s on the base of electric explosive of conductors installation with following parameters: N=6 $\mu $f, U up to 50kV, {\AA} up to 7,5 eJ, short circuit duration T=11$\mu $s. Velocities of aluminum impactor were in the range of 250--750m/s and controlled using of differential laser interferometer. The elastic characteristics and elastic wave velocities were determined and elastic Young's modulus was calculated using developed optical-acoustic technique. The results show that after dynamic loading microstructure has a lot of shear bands in the form of tree. The grids of shear bands sometimes transform to spall cracks parallel each other. Fracture surface has ductile character with cups fracture. After dynamic loading microstructure has developed spall split. Spallation is realized mainly via rotational micromechanism of deformation and fracture. [Preview Abstract] |
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F1.00058: Turbulence and 3D-Dynamic Structures in Shock Deformed Copper Yury Meshcheryakov, Alexandre Divakov, Natalia Zhigacheva, Ivan Makarevich, Boris Barakhtin Shock loading of polycrystalline copper under uniaxial strain conditions at 6.2$\div$7.3 GPa results in nucleating 3D-dissipative structures of 5$\div$25 $\mu $m in diameter. Interior of structures is a network of microtwins of 100$\div$300 nm spacing. 3D-structures are thought to be a results of visualization of large-scale turbulence in the structure-unstable material. Nucleation of structures occurs at the impact velocity where particle velocity variation begins to grow faster than mean particle velocity or when local strain rate at the mesoscale becomes higher than macroscopic strain rate. Simultaneously, defect of particle velocity at the plateau of compressive pulse, hardness and spall-strength grow in the same manner. Repeated loading results in increase of Hugoniot elastic limit by 15$\div$20 times and decrease of plastic front slope. Physically, nucleation of dissipative structures is initiated under resonance conditions between period of polarized dislocation structure and plastic front rise-time. [Preview Abstract] |
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F1.00059: On the Compressive and Tensile Dynamic Strength of Magnesium Aluminate Spinel Shmuel Hayun, Vitaly Paris, Moshe Dariel, Eugene Zaretsky, Nahum Frage Polycrystalline transparent Magnesium Aluminate Spinel (MAS) is an attractive material for a wide range of optical, electronic, structural and armor applications. Transparent MAS samples of 20-30 mm diameter and 3-5 mm thickness has been successfully fabricated by means of Field Assisted Sintering Technology. The dynamic response of MAS was investigated by plate impact experiments. The values of the Hugoniot Elastic Limit (HEL) and the spall strength were derived from the VISAR records of the velocities of the free sample surface or of the sample/window (PMMA) interface. The dependence of the HEL and the spall strength on the impact stress, as well as, correlation between the spall strength and the width of the loading pulse are discussed. [Preview Abstract] |
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F1.00060: Dynamic fragmentation as a possible diagnostic for high pressure melting in laser shock-loaded iron Thibaut de Resseguier, Emilien Lescoute, Guillaume Morard, Francois Guyot High pressure melting of iron conditions the understanding of the Earth core constitution. For many years, shock compression has been used to complement the data obtained under quasi-static loading. However, shock-induced melting is uneasy to detect. Here, we investigate how dynamic fragmentation of laser shock- loaded iron is affected by melting. Thin iron samples are irradiated by a high power pulsed laser. The motion of the fragments ejected from the free surface is recorded using transverse shadowgraphy and soft recovery of the ejecta is performed in a low density gel. At low laser intensity, spalled layers can be seen in the shadowgraphs, and solid fragments of some tenths of mm are recovered. At higher intensity, a wide debris cloud is observed to expand from the free surface, and optical micrographs of the gel show some tiny spherical droplets of iron. This is consistent with the micro-spall process expected upon reflection of a triangular pressure pulse in a shock-melted metal. Hydrodynamic simulations accounting for laser-matter interaction, phase transformations and pulse decay during propagation are performed. The results are discussed to infer whether such experiments may provide data on melting of iron under high dynamic pressure loading. [Preview Abstract] |
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F1.00061: Modeling the Failure Wave in Polycrystalline Ceramics under Impact Loading based on the Mesodefaults Propagation Yao Guowen, Liu Zhanfang During these years, a failure wave has been observed propagating in impacted polycrystalline ceramics, such as alumina and silicon carbide. This dynamic inelastic deformation and failure process may be associated with the mesodefaults propagation and damage accumulation along crystal boundaries under impact loading. In this paper, the mesodefaults propagating model was proposed to describe the failure wave in ceramics based on their heterogeneous mesostructures. The interface force distribution in the crystal boundaries was statistically analyzed. The stress threshold for the failure wave formation was probed. Then the governing equation of the failure wave and the constitutive relation of the failed layer are proposed through the inelastic bulk strain characterized by mesodefaults propagation. Numerical simulation shows that the mesodefaults propagating model well describes the formation and propagation of the failure wave, and its interaction with the precursor and failed layer. [Preview Abstract] |
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F1.00062: Simulation of multiple shear-band formation in collapsing cylinder experiments Zev Lovinger, Yehuda Partom This work presents 2D numerical simulations of shear-band formation in collapsing Thick Walled Cylinder experiments with 304L stainless steel. We use a simple shear-failure model which incorporates a positive feedback mechanism. Both global behavior and shear band evolution are examined. The calculated global behavior compares well with the experimental results. The calculated shear-bands follow the patterns of self organization demonstrated in experiments, with a good quantitative agreement with the observed final spatial configuration. The calculations reveal a clear spacing between initiation sites at the inner surface of the cylinder. The evolving shear-bands, having a width of several mesh elements in which strength decreases to zero, develop outwards in spiral paths while maintaining an angle of 45 degrees to the radial direction. Interactions between shear-bands, either by direct contact or through relief waves, result in competitive growth, eventually leading to a typical distribution of lengths and spacing. The spacing at the initiation stage and at the matured developed stage is quantitatively compared with existing analytical models. [Preview Abstract] |
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F1.00063: Modeling Shock-Induced Ejecta Production using Large-Scale Molecular Dynamics Simulations T.C. Germann, M.B. Zellner, J. Quenneville, G. Dimonte, J.E. Hammerberg Large-scale classical molecular dynamics (MD) simulations with 10$^{6}$ to 10$^{9}$ atoms are being used to study shock ejection from a roughened surface. We employ an embedded atom method (EAM) model for copper, and are studying both single-mode and multi-mode sinusoidal surface finishes both below and above the Hugoniot melting transition. In addition, we are exploring the effect of loading conditions, utilizing both supported (infinite flyer thickness) and unsupported (thin flyer/HE) drives. Our MD results are in qualitative agreement with a similar series of LANL experiments on tin, and both simulations and experiments can be described by a model based on the Richtmyer-Meshkov fluid instability. [Preview Abstract] |
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F1.00064: Mechanical response of damaged explosive compositions Daniel Drodge, David Chapman, William Proud PBX materials often exhibit strain-softening as a consequence of increasing microstructural damage. Good mechanical models thus require an account of loading path dependence. For validation purposes, a series of experiments have been carried out on a PBX system, introducing damage through uniaxial compression to fixed strains, with accompanying X-ray microtomographic imaging to provide insight into the structural changes that occur. The resulting datasets should provide a thorough test of the various PBX models abounding in the literature. [Preview Abstract] |
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F1.00065: Experimental Study of Eject on Lead Surface under Varied Loading Rate and Amplitude Yongtao Chen, Xinzhu Li, Haibo Hu The eject phenomena of pure lead flyer under detonation loading of varied loading rate and amplitude were studied with the help of high speed photography, VISAR, the Asay foil and a special optical probe. The mass of eject material from the lead surface may change several times with the change of loading amplitude from 3GPa to5GPa and the change of corresponding loading rate. A layer of massive material flow, total mass of which can reach tens of times by compare to the traditional eject mass, was recorded after the traditional eject particles and tightly before the flyer surface when the loading amplitude exceeded some given threshold. Formation of such kind of dispersed material flow is surely related to the shock wave or release melting (partial melting) of lead, in which cavitation and fragmentation may take place very quickly under the tension state of release wave. The loading amplitude and loading rate were controlled by varying the gap or the thickness of a porous material between the rear surface of combined flyers and the front surface of high explosive in the range of sub-millimeter size. [Preview Abstract] |
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F1.00066: Ultrafast In-situ Small Angle X-ray scattering in a Shocked Solid James McNaney, Martin Butterfield, Bassem El-Dasher, Jan Hessler, Hector Lorenzana, Soenke Seifert, Tony Van Buuren When a shock wave reflects from a free surface a region of hydrostatic tension of sufficient magnitude may form causing voids to nucleate and grow which often leads to failure of the material (termed spall). We have conducted the first time resolved in-situ small angle x-ray scattering (SAXS) measurements of shock-loaded metal at the nanosecond timescale. The experiments utilized a Q-switched Nd:YAG laser to generate an ablatively driven shock wave while a custom x-ray detector in conjunction with a specialized synchrotron fill pattern was used to acquire the SAXS signal generated by a single photon bunch of less than 100 ps duration. A clear increase in scattering was observed over the timescale commensurate with the formation of a tensile loading wave as calculated from a one-dimensional hydrodynamic simulation of the experiment. This presentation will focus on the methodology and results of the first series of experiments, which were conducted on aluminum. [Preview Abstract] |
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F1.00067: Impact fragmentation and ballistics of pressed aluminum powder projectiles Sam Thuot, Joseph Hooper, Richard Lee, John Wilkinson, Joel Carney, Jim Lightstone The penetration and fragmentation characteristics of spheres made of pressed aluminum powder are studied via normal impact on thin steel plates at 0.6 to 2.5 km/s. Ultra-high speed photography and flash x-rays are used to monitor the formation and evolution of the debris cloud formed by impact. The mass distribution of debris fragments is measured directly via a soft-catch experiment. Experimental results are compared to simple analytic theories of brittle fragmentation and spall. Additional experiments in which the debris is allowed to strike a thick steel anvil result in significant energy release via particle combustion. This data aids in understanding the mechanical properties and potential energy release of porous reactive materials. [Preview Abstract] |
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F1.00068: FIRST-PRINCIPLES AND MOLECULAR DYNAMICS CALCULATIONS |
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F1.00069: Nuclear Quantum Vibrational Effects in Shock Hugoniot Temperatures Nir Goldman, Evan J. Reed, Laurence E. Fried We present a straightforward technique for the inclusion of nuclear quantum vibrational effects in molecular dynamics (MD) calculations of shock Hugoniot temperatures. Although \textit{ab initio} MD simulations accurately reproduce the high pressure-density equation of state for many materials, they have been shown to under-predict experimental Hugoniot temperatures by 20-30{\%}, partially due to the exclusion of nuclear quantum effects in standard MD simulations. Using a Gr\"{u}neisen equation of state and a quasi-harmonic approximation to the vibrational energies, we derive a simple, post-processing method for calculation of quantum corrected Hugoniot temperatures. We have used this technique to determine the quantum corrected temperatures for \textit{ab initio} MD simulations of shock compressed water, methane, and diamond. Our results indicate significantly closer agreement with all available experimental temperature data. This new technique and formalism can easily be applied to simulations of a number of different shock compressed systems, and has the potential to decrease the large uncertainties inherent in many experimental temperature measurements. [Preview Abstract] |
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F1.00070: Homogeneous nucleation during melting and spallation Sheng-Nian Luo, Qi An, Timothy Germann, Li-Bo Han Melt and void nucleation can be described with the classical nucleation theory in similar manners, and the critical nucleus size and steady state nucleation rate are key parameters. Numerical experiments such as molecular dynamics (MD) simulations yield atomistic scale details on nucleation, and different statistical methods are available to reduce MD simulations for extracting nucleation information. We conduct MD simulations of homogeneous nucleation of melt in single crystal Cu, and of void in liquid Cu and in single crystal Cu. The MD simulations are analyzed with two statistical methods and the results are compared. We also present a semi-empirical relation relating the critical tensile stress and strain rate based on the classical nucleation theory. [Preview Abstract] |
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F1.00071: The molecular dynamics simulation of the isothermal and elastic properties of HMX Fenglei Huang, Wei Yao The isotherms and elastic properties of \textit{$\beta $}-HMX crystals were calculated through molecular simulations in NPT ensemble using COMPASS force field. The pressure-induced changes of the lattice parameters showed the anisotropic compression of \textit{$\beta $}-HMX. The isotherm of \textit{$\beta $}-HMX was simulated and the bulk modulus $K_{0}$ and its pressure derivative $K_{0}^{'}$ were obtained by fitting the isotherms to different equations of state. However, the values of $K_{0 }$ and $K_{0}^{'}$ obtained from the isotherm are sensitive to the fitting form of equation of state. The elastic constants and modulus were calculated by statistic analysis mode at different pressures in the range of 0$\sim $27GPa. Cauchy pressure $C_{12}-C_{44}$ and $G/K$ ratios were also calculated which indicated that \textit{$\beta $}-HMX would become harder as the pressure increased, and as well the \textit{$\beta $}-HMX elastic property transformed from brittleness to ductibility. [Preview Abstract] |
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F1.00072: MATERIALS SCIENCE |
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F1.00073: Measurement of adhesion strength of solid-state diffusion bonding between nickel and copper by means of laser shock spallation method Manabu Satou, Hitoshi Akamatsu, Akira Hasegawa Coating and bonding techniques between different materials are essential to the field of technology. Bonding mechanism is of interest from scientific points of view. Several works concerning to the strength such bonding have been revealed that the strength depended on crystallographic orientations, differences of thermal expansion and chemical affinity and so on. The methods adopted for those measurements had uncertainties due to plastic deformation near the interface. A laser shock spallation method was utilized to measure adhesion strength of the bonding in this paper to minimize the deformation outside of the interface. A well-established method to make bonding between unalloyed nickel and copper was utilized, that was solid-state diffusion bonding at elevated temperatures. Irradiation by Nd:YAG laser with 7ns-pulse width created shock wave that caused tensile stress after reflection at free surface. The stress depended on laser power and was estimated by surface velocity profile measured by a laser interferometer. The adhesion strength was determined by the critical laser power that caused exfoliation of the bonding interface. [Preview Abstract] |
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F1.00074: Characterizing the Pore Structure and Effects of Ratchet Growth on PBX 9502 Darla Thompson, Geoff Brown, Joseph Mang, Brian Patterson, Richard Gustavsen, Salyer Terry, Racci DeLuca PBX 9502 is a plastic bonded explosive containing 95 wt{\%} TATB (2,4,6-trinintro-1,3,5-benzenetriamine). Pressed composites of TATB have long been known to undergo ``ratchet growth'' (irreversible volume change) when subjected to thermal cycling. This behavior relates to the unique graphitic structure of the TATB crystal and its strongly anisotropic coefficient of thermal expansion (CTE), however, the mechanism responsible for the behavior is not understood. In our present study, we have used micro x-ray computed tomography and ultra-small angle neutron scattering to characterize the micro-structure of ratchet grown PBX 9502 under various conditions. We have used these techniques to distinguish ratchet-grown and as-pressed specimens of equivalent density. Our results allow us to understand and interpret observed changes in engineering and sensitivity/performance metrics of the ratchet-grown PBX. [Preview Abstract] |
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F1.00075: Large-Scale Classical Molecular Dynamics Simulations of Shock-Induced Plasticity in bcc Niobium Timothy Germann Large-scale classical molecular dynamics simulations are used to study the response of bcc Nb to shock compression, for perfect crystals in the [100] and [110] orientations. An embedded atom method (EAM) potential due to Johnson and Oh is used to describe the interatomic forces. Both orientations appear to plastically deform primarily by twinning, and we observe a bcc-hcp phase transformation at shock pressures above $\sim $75 GPa. There is no experimental evidence for any such transformation in Nb, although a similar transformation occurs in Fe and other bcc metals, so it is likely that this is an artifact of the EAM potential. [Preview Abstract] |
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F1.00076: C$_{60}$ fullerene under high multi-shock pressures V. Avdonin, A. Molodets, A. Zhukov, J. Shulga, V. Fortov The present work is devoted to a versatile research of electrophysical and thermodynamical properties of C60 fullerene under a high multi-shock pressures. Our multi-shock experiments has shown that C60 fullerite is preserving its crystal structure and molecules under a dynamic loading up to 30 GPa unlike the high static pressure conditions. The measurements of an electroconductivity of C60 fullerene under these conditions was carried out. It is experimentally established that decreasing of a conductivity of C60 fullerene has been changed by a sudden increasing one under the pressure of multi-shock compression above 20 GPa. A semiempirical equation of the state of fcc C60 fullerite was constructed. The analysis of the thermodynamic fullerene conditions under the high multi-shock pressures was done with help of a present EOS. Thus, at the present work we found that the crystal and molecular structure of C60 fullerene demonstrates a stability under short (microsecond) high multi-shock loading. The data of crystal form properties of C60 fullerene under such extreme conditions unachievable under static loading has been obtained. The work is supported by the program of Presidium of Russian Academy of Sciences ``Investigations of a matter under extreme conditions.'' [Preview Abstract] |
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F1.00077: High pressure thermal conductivity of indium A. Golyshev, A. Molodets Results on electroconductivity and thermal conductivity of indium in a range of pressure to 27 GPa and temperatures to 1000 K are presented. Electroresistance of the indium samples at step shock compression was measured in this pressure range. The indium equation of state was constructed; on this basis indium thermodynamic parametres evolution was calculated for the shock wave experiments carried out and then the volume-temperature dependences specific electroresistance and thermal conductivity of indium were defined. It was shown that the thermal conductivity of indium does not depend on temperature, and its triple increase is caused by volume change only in the investigated pressure and temperature range. This work is partially supported by Presidium of the Russian Academy of Sciences program Thermophysics and mechanics of extreme energy effects and physics of high compressed matter. [Preview Abstract] |
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F1.00078: Growth and characterization of one-dimensional carbon composite structure consisting of carbon nanotubes and nanocones Hongxin Zhang, Peter Feng A simple approach is demonstrated for quickly growing a large-area aligned carbon composite nanostructure consisting of vertically aligned nanotubes and nanocones by the catalyst-assisted pulsed laser deposition techniques. The carbon nanocones were first grown on the molybdenum substrate with Ni catalysts. The carbon nanotubes grown on the nanocones have uniform shape and length, align vertically on carbon nanocones, and the average diameter is about 7 nm. The special carbon composite arrays present the turn-on field 0.19 V $\mu$m-1 in field emission, the lowest value reported so far. The long-term field emission current stability of the one-dimensioned carbon nanostructure has also been investigated. No current decay was observed after 10-day continuous experiment, indicating the super stability of the sample as cathode material. [Preview Abstract] |
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F1.00079: Molecular Dynamics Simulation of Dislocation Emission from Shocked Aluminum Grain Boundaries C. Pozzi, R.G. Hoagland, T.C. Germann A molecular dynamics (MD) simulation was performed to examine the behavior under shock loading conditions of the $\sum $11, $<$110$>$ {\{}252{\}}{\{}414{\}} asymmetric grain-boundary (GB) in Aluminum, with particular regard to the possibility of deformation twinning. Under different shock velocities, and with different embedded atom method (EAM) potentials, we observe the emission of both perfect and partial dislocations from the GB and, in some cases, the formation of nanotwins. These features and their nucleation mechanisms, as related to the shock velocity, the GB energy, and the size of the model (i.e. shock loading timescale), are discussed on the basis of our MD simulation results. [Preview Abstract] |
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F1.00080: PHYSICS AND CHEMISTRY AT HIGH PRESSURE - STATIC AND LOW RATE STUDIES |
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F1.00081: Compression and associated properties of boron carbide Jennifer Ciezak, Dattatraya Dandekar The observed loss of shear strength of boron carbide around 22 GPa has been attributed to presence of amorphous material in the shock recovered, and statically indented and pressurized boron carbide. The present work presents a more direct association of the observed loss of shear strength in boron carbide under plane shock wave compression to amorphization in boron carbide under triaxial stress compression. This evidence is obtained from in-situ measurement of Raman, and infrared vibrational spectra of boron carbide confined in a Diamond Anvil Cell (DAC) under hydrostatic and non-hydrostatic pressures. X-ray-diffraction measurements do show a shift in the compression of boron carbide around 27 GPa. However, X-ray diffraction measurements indicate that the amorphization does not extend to micron scale, as there is no evidence of a loss of crystallinity in the recorded diffraction pattern of boron carbide to 47 GPa. Our work shows that shear plays a very dominant role in the stress-induced amorphization of boron carbide. [Preview Abstract] |
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F1.00082: PARTICULATE / POROUS MATERIALS |
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F1.00083: Experimental Studies of Mitigation Materials for Blast Induced TBI Matthew Alley, Steven Son The objective of this experimental study is to compare the effects of various materials obstructing the flow of a blast wave and the ability of the given material to reduce the damage caused by the blast. Several methods of energy transfer in blast wave flows are known or expected including: material interfaces with impedance mismatches, density changes in a given material, internal shearing, and particle fracture. The theory applied to this research is that the greatest energy transfer within the obstructing material will yield the greatest mitigation effects to the blast. Sample configurations of foam were varied to introduce material interfaces and filler materials with varying densities and impedances (liquids and powders). The samples were loaded according to a small scale blast produced by an explosive driven shock tube housing gram-range charges. The transmitted blast profiles were analyzed for variations in impulse characteristics and frequency components as compared to standard free field profiles. The results showed a rounding effect of the transmitted blast profile for all samples with the effects of the low density fillers surpassing all others tested. [Preview Abstract] |
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F1.00084: PHASE TRANSITIONS |
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F1.00085: Study of Shock-Induced Phase Transformations in Silicon using Ultrafast Dynamic Ellipsometry Dan Eakins, Cindy Bolme, Shawn McGrane, David Moore The kinetics of shock-induced phase transformations are currently being investigated using ultrafast dynamic ellipsometry (UDE), which measures relative changes in optical phase and reflectivity. In this work, thin films (400 nm - 1.5 um) of crystalline and amorphous silicon are shock-compressed using a Ti-sapphire, shaped-pulse ultrafast laser system. UDE and an accompanying thin-film analysis are employed to track the motion of the shock-front, and provide evidence of structural phase transformations and/or metallization transitions in silicon. Results suggest a complex time-dependent change in the dielectric function within the 250 ps diagnostic lifetime, indicative of transformation kinetics. [Preview Abstract] |
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F1.00086: Mechanism and Diagnoses on Plasma Generated by Hypervelocity Impact Qingming Zhang, Enling Tang, Fenglei Huang Physical mechanism of plasma generated by hypervelocity impact is analyzed in the paper. The physical phenomenon and the critical condition of plasma for aluminum generated by hypervelocity impact are obtained with the help of the diagnostic system on the characteristic parameters of plasma. The features of plasma impact-generated are short lifespan, small scale in space and non-uniform distribution of particles and time-dependent disturbance, which make the experiment diagnoses very difficult. The sweep Langmuir probe diagnostic system of characteristic parameters of plasma and the magnetic probe diagnostic system for weak magnetic field are introduced. From them some typical results has gotten, correspondingly, the question and the developing trend are in discussion. [Preview Abstract] |
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F1.00087: SPECTROSCOPY AND OPTICAL STUDIES |
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F1.00088: Time-resolved Raman spectroscopy of shock compressed single crystal HMX R.J. Scharff, V.H. Whitley, D.B. Stahl, D.M. Dattelbaum Shock initiation of an energetic organic solid is generally considered to proceed via a mechanism through which low frequency acoustic phonons are upconverted to higher frequency bond stretching vibrations in the crystal. To elucidate changes in molecular structure under shock loading, a series of well defined gas gun driven plate impact experiments coupled to time-resolved Raman spectroscopy were performed on single crystal \textit{$\beta $}-HMX. We will also present progress in obtaining temperature measurements in the shocked material using a Stokes/anti-Stokes intensity ratio method. [Preview Abstract] |
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F1.00089: Thermal Decomposition Behavior of Poly(3-nitratooxetane) Brian Mason, Aliza Cruz, Chad Stoltz Poly(3-nitratooxetane), or PNO, is a new high-energy density polymer that is expected to increase formulation energy output without sacrificing binder stability. It is anticipated that using PNO in propellant formulations will be advantageous compared to other energetic binders such as its structural isomer poly(glycidyl nitrate) (PGN). In an effort to understand the combustion behavior of this new energetic polymer, thermal decomposition of PNO has been investigated. Differential scanning calorimetry coupled with thermal gravimetric analysis shows that this material is thermally stable to at least 150$^{\circ}$C and that exothermic decomposition peaks near 203$^{\circ}$C. T- Jump/FTIR was used under various conditions to identify gas- phase thermal decomposition products, including H2O, CH2O, CO2, CO, N2O, NO, NO2, and HONO (cis and trans). Additional time- resolved T-Jump/FTIR experiments suggest immediate dissociation of NO2 as the obvious first step in PNO decomposition, while previous work on the PGN polymer system suggests that the entire CH2ONO2 side chain breaks from the PGN backbone before dissociation. It is likely that different decomposition pathways are followed for each binder system due to location of available C-O and N-O moieties on each polymer. [Preview Abstract] |
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