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Sample records for hmx based high

  1. Deflagration of HMX-Based Explosives at High Temperatures and Pressures

    SciTech Connect

    Maienschein, J L; Wardell, J F; DeHaven, M R; Black, C K

    2004-05-12

    We measure the deflagration behavior of energetic materials at extreme conditions (up to 520K and 1 GPa) in the LLNL High Pressure Strand Burner, thereby obtaining reaction rate data for prediction of violence of thermal explosions. The apparatus provides both temporal pressure history and flame time-of-arrival information during deflagration, allowing direct calculation of deflagration rate as a function of pressure. Samples may be heated before testing. Here we report the deflagration behavior of several HMX-based explosives at pressures of 10-600 MPa and temperatures of 300-460 K. We find that formulation details are very important to overall deflagration behavior. Formulations with high binder content (>15 wt%) deflagrate smoothly over the entire pressure range regardless of particle size, with a larger particle size distribution leading to a slower reaction. The deflagration follows a power law function with the pressure exponent being unity. Formulations with lower binder content ({le} 10% or less by weight) show physical deconsolidation at pressures over 100-200 MPA, with transition to a rapid erratic deflagration 10-100 times faster. High temperatures have a relatively minor effect on the deflagration rate until the HMX {beta} {yields} {delta} phase transition occurs, after which the deflagration rate increases by more than a factor of 10.

  2. Deflagration Behavior of HMX-Based Explosives at High Temperatures and Pressures

    SciTech Connect

    Maienschein, J L; Wardell, J F

    2003-11-20

    We report the deflagration behavior of several HMX-based explosives at pressure from 10-600 MPa and temperatures from 20-180 C. We have made laminar burn rate measurements with the LLNL High Pressure Strand Burner, in which burn wires are used to record the time-of-arrival of the burn front in the cylindrical sample as a function of pressure. The explosive samples are 6.4 mm in diameter and 63 mm long, with ten burn wires embedded at different positions in the sample. Burning on the cylindrical surface is inhibited with an epoxy layer. With this direct measurement we do not have to account for product gas equation of state or heat losses in the system, and the burn wires allow detection of irregular burning. We find that formulation details are very important to overall deflagration behavior - the presence of 10% or less by weight of binder leads to physical deconsolidation and rapid deflagration at high pressures, and a larger particle size distribution leads to slower deflagration. High temperatures have a relatively minor effect on the deflagration rate until the beta-to-delta phase transition temperature is reached, beyond which the deflagration rate increases approximately 40-fold.

  3. Observation of sub-detonative responses in confined high density HMX-based PBXs

    NASA Astrophysics Data System (ADS)

    Cumming, Andrew; Wood, Andrew; Steward, Paul; Ottley, Philip; Gould, Peter; Lewtas, Ian

    2015-06-01

    This paper describes experiments and modelling aimed at understanding the behaviour of highly loaded (90%-95%) pressed HMX-based PBXs, when subjected to shock compression and ignition by means of distinct mechanical and thermal insults under confinement. In order to separate the role of the stimuli, a test has been designed where a metal impactor is propelled at test samples using a well characterised propellant over a range of velocities to produce various levels of mechanical damage. The impactor is then heated using a characterised pyrotechnic composition which ignites the mechanically damaged explosive. Tubes have been designed to examine the effect of confinement at burst pressures of 218.5MPa and 120MPa. The high confinement tubes employ polycarbonate windows and the low confinement tubes are manufactured from polycarbonate blocks to allow the reaction of the energetic material to be captured using high-speed video. Tests carried out using these tubes have given a good insight into the processes occurring. Modelling runs have predicted an oscillating compressive wave in the explosive and considerable damage at either end of the explosive column. The latter leads to potential deconsolidation once the donor charge has burnt out allowing increased burning and violence.

  4. Observation of sub-detonative responses in confined high density HMX-based PBXs

    NASA Astrophysics Data System (ADS)

    Cook, Malcolm; Wood, Andrew; Ottley, Philip; Cheese, Phil

    2013-06-01

    This paper describes experiments and modelling aimed at understanding the behaviour of highly loaded (90%-95%) pressed HMX-based PBX compositions, when subjected to shock compression and ignition, by means of a propellant donor charge, under confinement. Such tests are routinely carried out in the UK on new formulations to determine their burn to violent reaction characteristics. The Bullseye propellant donor charge has been characterised in terms of pressure and temperature output. A range of tubes have been designed to examine the contribution of tube material properties (steel versus aluminium, 218.5 MPa) and to examine the effect of reduced confinement (120 MPa). For the reduced confinement scenario polycarbonate as well as steel and aluminium vessels have been designed which allow the reaction of the energetic material to be captured using high-speed video. In particular, tests carried out in the polycarbonate tubes have given a good insight of the processes occurring. Preliminary hydrocode modelling runs predicted an oscillating compressive wave in the explosive and considerable damage at either end of the explosive column. The latter leads to potential deconsolidation once the donor charge has burnt out allowing increased burning and violence. This work was undertaken as part of the MOD funded UK-Energetics research programme.

  5. Observation of sub-detonation response in confined high density HMX based PBXs

    NASA Astrophysics Data System (ADS)

    Cook, M. D.; Wood, A. D.; Ottley, P. R.; Cheese, P. J.

    2014-05-01

    This paper describes experiments and modelling aimed at understanding the behaviour of highly loaded (90%-95%) pressed HMX-based PBX compositions, when subjected to shock compression and ignition, by means of a propellant donor charge, under confinement. Such tests are routinely carried out in the UK on new formulations to determine their burn to violent reaction characteristics. The Bullseye propellant donor charge has been characterised in terms of pressure and temperature output. A range of tubes have been designed to examine the contribution of tube material properties (steel versus aluminium, 218.5 MPa) and to examine the effect of reduced confinement (120 MPa). For the reduced confinement scenario polycarbonate as well as steel and aluminium vessels have been designed which allow the reaction of the energetic material to be captured using a Phantom high-speed camera. In particular, tests carried out in the polycarbonate tubes have given a good insight of the processes occurring. Preliminary hydrocode modelling runs predicted an oscillating compressive wave in the explosive and considerable damage at either end of the explosive column. The latter leads to potential deconsolidation once the donor charge has burnt out allowing increased burning and violence.

  6. Detonation wave profiles in HMX based explosives

    SciTech Connect

    Gustavsen, R.L.; Sheffield, S.A.; Alcon, R.R.

    1997-11-01

    Detonation wave profiles have been measured in several HMX based plastic bonded explosives including PBX9404, PBX9501, and EDC-37, as well as two HMX powders (coarse and fine) pressed to 65% of crystal density. The powders had 120 and 10 {micro}m average grain sizes, respectively. Planar detonations were produced by impacting the explosive with projectiles launched in a 72-mm bore gas gun. Impactors, impact velocity, and explosive thickness were chosen so that the run distance to detonation was always less than half the explosive thickness. For the high density plastic bonded explosives, particle velocity wave profiles were measured at an explosive/window interface using two VISAR interferometers. PMMA windows with vapor deposited aluminum mirrors were used for all experiments. Wave profiles for the powdered explosives were measured using magnetic particle velocity gauges. Estimates of the reaction zone parameters were obtained from the profiles using Hugoniots of the explosive and window.

  7. Shock-to-detonation transition of RDX, HMX and NTO based composite high explosives: experiments and modelling

    NASA Astrophysics Data System (ADS)

    Baudin, G.; Roudot, M.; Genetier, M.; Mateille, P.; Lefrançois, A.

    2014-05-01

    HMX, RDX and NTO based cast-cured plastic bounded explosive (PBX) are widely used in insensitive ammunitions. Designing modern warheads needs robust and reliable models to compute shock ignition and detonation propagation inside PBX. Comparing to a pressed PBX, a cast-cured PBX is not porous and the hot-spots are mainly located at the grain-binder interface leading to a different burning behavior during shock-to-detonation transition. Here, we review the shock-to-detonation transition (SDT) and its modeling for cast-cured PBX containing HMX, RDX and NTO. Future direction is given in conclusion.

  8. MESOSCALE MODELLING OF SHOCK INITIATION IN HMX-BASED EXPLOSIVES

    SciTech Connect

    Mulford, R. N. R.; Swift, D. C.

    2001-01-01

    Hydrocode calculations we used to simulate initiation in single- and double-shock experiments on several HMX-based explosives. Variations in the reactive behavior of theee materials reflects the differences between binders in the material, providing information regarding the sensitivity of the explosive to the mechanical properties of the constituents. Materials considered are EDC-37, with a soft binder, PBX-9601, with a relatively malleable binder, and PIBX-9404, with a stiff binder. Bulk reactive behavior of these materials is dominated by the HMX component and should be comparable, while the mechanical response varies. The reactive flow model is temperature-dependent, based on a modified Arrhenius rate. Some unreacted material is allowed to react at a rate given by the state of the hotspot rather than the bulk state of the unreacted explosive, according to a length scale reflecting the hotspot size, and a time scale for thermal equilibration. The Arrhenius rate for HMX is wsumed to be the same for all compositions. The initiation data for different HMX-bwd explosives axe modelled by choosing plausible parameters to describe the reactive and dissipative properties of the binder, and hence the behavior of the hotspots in each formulation.

  9. Thermal Cook-Off Experiments of the HMX Based High Explosive LX-04 to Characterize Violence with Varying Confinement

    NASA Astrophysics Data System (ADS)

    Garcia, Frank; Forbes, Jerry W.

    2005-07-01

    Thermal cook-off experiments were carried out using LX-04 explosive (85% HMX and 15% Viton by weight) with different levels of confinement to characterize the effect of confinement on the reaction violence. These experiments involved heating a porous LX-04 sample in a stainless steel container with varying container end plate thickness and assembly bolt diameter to control overall confinement. As expected, detonation did not occur and reducing the overall confinement lowered the reaction violence. Modeling was also performed using Ignition and Growth kinetics with reasonable agreement to the experiment. These results suggest that controlling the overall system confinement can modify the relative safety in a given scenario. This work was performed under the auspices of the U. S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

  10. Pressure Wave Measurements Resulting from Thermal Cook-Off of the HMX Based High Explosive LX-04

    NASA Astrophysics Data System (ADS)

    Garcia, Frank; Vandersall, Kevin S.; Forbes, Jerry W.; Tarver, Craig M.; Greenwood, Daniel

    2004-07-01

    Experiments that investigate thermal and nearby explosion scenarios are needed to provide essential data to models for accurate predictions. A porous LX-04 (85/15 wt% HMX/Viton) sample was heated in a heavily confined donor charge until it thermally exploded. The reaction accelerated a steel cover plate across a 10 cm gap into a preheated gauged acceptor cylinder (near its theoretical maximum density) of LX-04. The carbon resistor gauges in the acceptor measured the resulting multi-dimensional ramp wave as it propagated through the pre-heated LX-04. Detonation of the LX-04 acceptor does not occur. Results are compared to similar experiments with acceptors at room temperature.

  11. THERMAL COOK-OFF EXPERIMENTS OF THE HMX BASED HIGH EXPLOSIVE LX-04 TO CHARACTERIZE VIOLENCE WITH VARYING CONFINEMENT

    SciTech Connect

    Garcia, F; Vandersall, K S; Forbes, J W; Tarver, C M; Greenwood, D

    2005-07-25

    Thermal cook-off experiments were carried out using LX-04 explosive (85% HMX and 15% Viton by weight) with different levels of confinement to characterize the effect of confinement on the reaction violence. These experiments involved heating a porous LX-04 sample in a stainless steel container with varying container end plate thickness and assembly bolt diameter to control overall confinement. As expected, detonation did not occur and reducing the overall confinement lowered the reaction violence. This is consistent with modeling results that predict that a lower confinement will act to lower the cook-off pressure and thus the overall burn rate which lowers the overall violence. These results suggest that controlling the overall system confinement can modify the relative safety in a given scenario.

  12. The role and importance of porosity in the deflagration rates of HMX-based materials

    SciTech Connect

    Glascoe, E A; Hsu, P C; Springer, H K

    2011-03-15

    The deflagration behavior of thermally damaged HMX-based materials will be discussed. Strands of material were burned at pressures ranging from 10-300 MPa using the LLNL high pressure strand burner. Strands were heated in-situ and burned while still hot; temperatures range from 90-200 C and were chosen in order to allow for thermal damage of the material without significant decomposition of the HMX. The results indicate that multiple variables affect the burn rate but the most important are the polymorph of HMX and the nature and thermal stability of the non-HE portion of the material. Characterization of the strands indicate that the thermal soak produces significant porosity and permeability in the sample allowing for significantly faster burning due to the increased surface area and new pathways for flame spread into the material. Specifically, the deflagration rates of heated PBXN-9, LX-10, and PBX-9501 will be discussed and compared.

  13. Shockless Compression Studies of Hmx-Based Explosives

    NASA Astrophysics Data System (ADS)

    Baer, M. R.; Root, S.; Dattelbaum, D.; Hooks, D. E.; Gustavsen, R. L.; Orler, B.; Pierce, T.; Garcia, F.; Vandersall, K.; DeFisher, S.; Travers, B.

    2009-12-01

    Several HMX-based explosive samples were subjected to shockless compression using Sandia's Z magnetic compression accelerator. A multi-panel ICE configuration containing various thicknesses of energetic composites PBX9501, PBXN9, LX-10 was subjected to ramp loading up to 320 Kbar over 500 ns. A Velocity Interferometer System for Any Reflector (VISAR) was used to measure transmitted wave profile data of particle velocity and forward and backward procedures were used with an optimization method to determine appropriate EOS data.

  14. Chemical destruction of HMX-based explosives with ammonium hydroxide

    SciTech Connect

    Skidmore, C.; Dell`Orco, P.; Flesner, R.; Kramer, J.; Spontarelli, T.

    1995-09-01

    A series of experiments at Los Alamos National Laboratory explored the efficacy of ammonium hydroxide solutions in converting HMX (cyclotetramethylene-tetranitramine, or Octogen) and HMX-based explosives to nonenergetic, nonhazardous materials. When 80 g of explosive was converted in a reactor operating at 85 psig pressure at 140 C, the principal gaseous products were nitrous oxide (46% to 51%), nitrogen (22% to 32%), and ammonia (17% to 28%). Formate and hexamethylene-tetramine (hexamine) account for effectively 100% of the carbon-bearing aqueous species. Nitrate, nitrite, and acetate were present in the liquid in trace amounts. The process effectively treated molding powders of the plastic-bonded explosives PBX 9501 (2.5% estane), LX-04 (15% viton), and PBX 9404 (3% nitrocellulose). Results were compared with those achieved using sodium hydroxide solutions at 150 C in a pressurized reactor.

  15. SHOCK INITIATION EXPERIMENTS ON THE HMX BASED EXPLOSIVE LX-10 WITH ASSOCIATED IGNITION AND GROWTH MODELING

    SciTech Connect

    Vandersall, K S; Tarver, C M; Garcia, F; Urtiew, P A; Chidester, S K

    2007-06-15

    Shock initiation experiments on the HMX based explosives LX-10 (95% HMX, 5% Viton by weight) and LX-07 (90% HMX, 10% Viton by weight) were performed to obtain in-situ pressure gauge data, run-distance-to-detonation thresholds, and Ignition and Growth modeling parameters. A 101 mm diameter propellant driven gas gun was utilized to initiate the explosive samples with manganin piezoresistive pressure gauge packages placed between sample slices. The run-distance-to-detonation points on the Pop-plot for these experiments and prior experiments on another HMX based explosive LX LX-04 (85% HMX, 15% Viton by weight) will be shown, discussed, and compared as a function of the binder content. This parameter set will provide additional information to ensure accurate code predictions for safety scenarios involving HMX explosives with different percent binder content additions.

  16. Temperature Dependent Equations of State for HMX-based Composites

    NASA Astrophysics Data System (ADS)

    Baer, Melvin; Root, S.; Gustavsen, R.; Pierce, T.; Defisher, S.; Travers, B.; Sandia National Laboratories Collaboration; Los Alamos National Laboratory Collaboration; U. S. Army Ardec Collaboration

    2011-06-01

    In order to examine the temperature dependence of the equation of state (EOS) of two HMX-based explosives, PBX9501 and PBXN9, samples were subjected to shockless compression using the Sandia VELOCE magnetic compression system. Prior to compression, the energetic composites were heated to temperatures up to 155° C , just below the HMX β - δ phase transition at atmospheric pressure conditions. The phase transition is explored at higher stress conditions when subjected to near isentropic loading. A Velocity Interferometer System for Any Reflector (VISAR) was used to measure particle velocity of the transmitted compression wave. The velocity profile data was analyzed using forward/backward integration methods along with an optimization method to determine unreacted EOS parameters. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U. S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  17. The Evolution of Sensitivity in Hmx-Based Explosives during the Reversion from Delta to Beta Phase

    NASA Astrophysics Data System (ADS)

    Peterson, P. D.; Lee, K.-Y.; Moore, D. S.; Scharff, R. J.; Avilucea, G. R.

    2007-12-01

    In an effort to better understand the evolution of sensitivity in HMX-based explosives formulations during the reversion from the delta to the beta polymorph, we have performed friction and impact experiments on Class 1 (coarse) and Class 2 (fine) HMX [1]. Initial baselines for Type 12 drop weight impact and BAM friction sensitivities were obtained for the β-HMX starting material. The HMX was then heated at ˜184 °C for 14 h. Raman spectroscopy was used to confirm the conversion to delta-phase. Raman results show that the δ material remains δ for long periods when stored in a dessicator at room temperature (RT), converts to alpha when stored at RT and 20-40% relative humidity (RH) over a period of days, and reverts to beta over a period of days when stored at RT and 95-98% relative humidity (RH). Impact and friction tests were performed on the δ-HMX, converted α-HMX, and reverted β-HMX. The tests show similar sensitivities of the δ-HMX and converted α-HMX in both impact and friction, both of which are ˜10-20% more sensitive than the β-HMX and reverted beta depending on the particle size distribution. The α-HMX appears to be fairly stable over time (by Raman analysis) at ambient conditions, but fairly low humidity (20-40%), or in a dessicator.

  18. Reaction of Shocked but Undetonated HMX-Based Explosive

    NASA Astrophysics Data System (ADS)

    Taylor, P.; Salisbury, D. A.; Markland, L. S.; Winter, R. E.

    2001-06-01

    Cylindrical samples of the pressed plastic bonded HMX-based explosive EDC37, backed by metal discs, were shocked through a stainless steel attenuator by an explosive donor. Reaction of the EDC37 sample was diagnosed with embedded PVDF pressure gauges and a run distance to detonation for the geometry was determined. Sample length was then reduced to less than the observed run distance and laser interferometry was used to record the free surface velocity of the metal backing disc. The results provide data on the metal driving energy liberated by the explosive which is shocked and reacting but not detonated. The results are compared with Eulerian hydrocode calculations incorporating the three term Lee and Tarver reaction model with desensitisation. It is found that a parameter set for the reaction model which replicates the PVDF pressure profiles before reflection also gives good agreement to the metal disc velocity history at early times. The results show that an appreciable fraction of the metal driving potential of an explosive can be released without detonation being established.

  19. Experimental and numerical study of deformation modes of a pressed HMX-based explosive composition

    NASA Astrophysics Data System (ADS)

    Picart, Didier; Vial, Jerome; Bailly, Patrice

    Safety of industrial or military explosives is still studied to prevent inadvertent ignition of pressed HMX-based explosive compositions submitted to a low-velocity impact. Our aim is to determine the dissipative mechanisms leading to the local heating of the material. To observe the dissipative mechanisms, a reversed edge-on impact test has been developed. This test enables real-time observations of the microstructural scale. No friction is observed between the biggest HMX grains and the matrix (the smallest grains, the binder and the porosity). Plasticity of HMX grains is obtained as well as damage by micro-cracking. Meanwhile, a biphasic numerical representation (HMX grains and matrix) is used to mimic our material. A comparison between experimental observations and simulations is used to determine the yield stress of HMX. The behavior of the matrix has been determined to account for the effect of strain rate and damage. Lastly, a comparison between tests and simulations has highlighted (1) that heating should rather be located in the matrix than in the biggest HMX grains and (2) that the most likely heating mechanism is the friction of micro(or meso)-cracks lips.

  20. First Results of Reaction Propagation Rates in HMX at High Pressure

    SciTech Connect

    Farber, D L; Esposito, A; Zaug, J M; Aracne-Ruddle, C

    2001-06-15

    The authors have measured the reaction propagation rate (RPR) in weapons-grade, ultrafine octahydro-1,3,57-tetranitro-1,3,5,7-tetrazocine (HMX) powder in a diamond anvil cell over the pressure range 0.7-35 GPa. In order to have a cross-comparison of their experiments, they carried out a series of experiments on nitromethane (NM) up to 15 GPa. The results on NM are indistinguishable from previous measurements of Rice and Folz. In comparison to high-pressure, NM, the burn process for solid HMX is not spatially uniform.

  1. First Results of Reaction Propagation Rates in HMX at High Pressure

    SciTech Connect

    Farber, D L; Esposito, A; Zaug, J M; Aracne-Ruddle, C

    2001-06-15

    The authors have measured the reaction propagation rate (RPR) in weapons-grade, ultrafine octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) powder in a diamond anvil cell over the pressure range 0.7-35 GPa. In order to have a cross-comparison of their experiments, they carried out a series of experiments on nitromethane (NM) up to 15 GPa. The results on NM are indistinguishable from previous measurements of Rice and Folz. In comparison to high-pressure NM, the burn process for solid HMX is between 5-10 times faster at pressures above 10 GPa.

  2. Determination of sound velocities of "overcompressed" detonation in HMX-based explosive

    NASA Astrophysics Data System (ADS)

    Zhernokletov, Mikhail V.; Kovalev, Alexey E.; Bel'sky, Vladimir M.; Bogdanov, Evgeny N.

    2015-09-01

    The authors present results of determination of sound velocities in explosion products (EP) of HMX-based explosive overcompressed up to the pressures of 50-85 GPa by overtaking unloading method. The radiowave and optical methods are used to record the time when a front of overcompressed detonation wave in investigated sample of high explosive (HE) is overtaken by expansion wave, which propagates from the back surface of impactor with sound velocity. The data on sound velocities, which were independently obtained by two different methods, were in agreement. The methods with use of radiointerferometer and indicator liquid are rather effective for determination of sound velocities in overcompresed EP and for investigation of parameters at the Jouget point of various HEs, which are required for calibration of their equations of state (EOS).

  3. Temperature dependent equation of state for HMX-based composites

    NASA Astrophysics Data System (ADS)

    Baer, Melvin; Root, S.; Gustavsen, R. L.; Pierce, T.; DeFisher, S.; Travers, B.

    2012-03-01

    In order to examine the temperature dependence of the equation of state (EOS) of HMXbased explosives, two energetic composites, PBX9501 and PBXN9, were subjected to shockless compression using the Sandia VELOCE magnetic compression system. Prior to compression, the energetic samples were heated to temperatures up to 155°C, presumed to be below the HMX β - δ phase transition at atmospheric pressure conditions. A Velocity Interferometer System for Any Reflector (VISAR) was used to measure particle velocity of the transmitted compression wave. Temperature corrections in the drive plates and windows were estimated and velocity profile data was analyzed using forward/backward integration methods along with an optimization method to determine unreacted Mie-Grüneisen EOS parameters.

  4. Thermal explosion violence of HMX-based explosives -- effect of composition, confinement and phase transition using the scaled thermal explosion experiment

    SciTech Connect

    Maienschein, J L; Wardell, J F; Reaugh, J E

    2000-10-25

    We developed the Scaled Thermal Explosion Experiment (STEX) to provide a database of reaction violence from thermal explosion of explosives of interest. A cylinder of explosive, 1, 2 or 4 inches in diameter, is confined in a steel cylinder with heavy end caps, and heated under controlled conditions until it explodes. Reaction violence is quantified by micropower radar measurement of the cylinder wall velocity, and by strain gauge data at reaction onset. Here we describe the test concept and design, show that the conditions are well understood, and present initial data with HMX-based explosives. The HMX results show that an explosive with high binder content yields less-violent reactions that an explosive with low binder content, and that the HMX phase at the time of explosion plays a key role in reaction violence.

  5. Toward a Role of Light Absorption in Initiation Chemistry of Shocked HMX single Crystals and Crystalline High Explosives

    NASA Astrophysics Data System (ADS)

    Plaksin, Igor; Rodrigues, L.

    2013-06-01

    Question which mechanism is driving radiation-induced reactions, thermal or athermal becomes a subject of conflicting discussions. Major challenge of this work is to identify at micro- (sub-granular), meso- (grain level) and macro-scale roles of these two mechanisms in triggering initiation chemistry in HMX-based HEs. Four acceptor-patterns were tested at 20 GPa input pressure: single HMX crystal-in-water, HMX/water-slurry, PBX(HMX/HTPB) & inert PBX-simulant (HMX-particles replaced by crystalline sucrose). Scenario of reaction onset-localizations-dissipation was spatially resolved using Multi-Channel Optical Analyzer MCOA-UC (96 channels, 100um-spatial accuracy, 0.2ns-timeresolution, 450-850 nm-spectral range) through real-time panoramic recording emitted reaction light and shock field in standard optic monitor. Experiments reveal a dual nature of initiation chemistry: athermal and thermal. Single-crystal tests disclose origination of photo-induced reactions downstream of emitting reaction spot due to intensified radiation absorption in surface micro-defects. Polycrystalline samples reveal cyclic reproducibility of radiation-induced thermal precursors in which radiation absorption causes thermal expansion/phase-changes of HMX-grains resulting in oscillating detonation. Work was supported by the Office of Naval Research under the ONR and ONR Global Grants N00014-12-1-0477 and N62909-12-1-7131 with Drs. Cliff Bedford and Shawn Thorne Program Managers.

  6. Shock wave and detonation wave response of selected HMX based research explosives with HTPB binder systems

    NASA Astrophysics Data System (ADS)

    Sutherland, G. T.; Lemar, E. R.; Forbes, J. W.; Anderson, E.; Miller, P.; Ashwell, K. D.; Baker, R. N.; Liddiard, T. P.

    1994-07-01

    The sensitivity, detonation properties, and performance of selected HMX based explosives are compared. All explosives were manufactured using a hydroxyl-terminated polybutadiene (HTPB) binder system. IRX class explosives were manufactured to obtain explosives in which ingredients were systematically varied. The particle size range of the HMX particles was controlled by sieving. Sensitivity and performance experiments were conducted using the explosives IRX-1, and IRX-3A. These experiments measured: detonation pressure, detonation velocity, modified gap test shock sensitivity, and detonation wave curvature. Modified gap tests were also performed for SW-21 and PBXN-110. In addition, light gas gun experiments were performed in which reactive stress-time profiles were obtained for IRX-1 and PBXN-110.

  7. The Effect of Localised Short Duration Thermal Insults on HMX based Explosives

    NASA Astrophysics Data System (ADS)

    Wortley, Steve

    2011-06-01

    This paper describes some experiments undertaken to address a specific concern regarding the susceptibility of a bare HMX based explosive charge to an extremely hot source but with a short duration of application such as a metal spark arising from a cutting operation or a single drop of hot material. In a short series of experiments small pressed charges of HMX formulated with Viton where heated by the application of a pre-heated thermocouple. The temperature of the thermocouple and the duration of the contact were varied and the response of the explosive was observed. In general the explosive was remarkably tolerant of the thermal insult. However, at the highest test temperatures and at the longest durations ignitions leading to prolonged burning were observed. Although materials in these experiments were undamaged prior to application of the thermal insult this data may help to understand the likely response of explosives to bullets or fragments preheated by penetration of protective layers.

  8. Elastic properties of HMX.

    SciTech Connect

    Sewell, T. D.; Bedrov, D.; Menikoff, Ralph; Smith, G. D.

    2001-01-01

    Atomistic molecular dynamics simulations have been used to calculate isothermal elastic properties for {beta}-, {alpha}-, and {delta}-HMX. The complete elastic tensor for each polymorph was determined at room temperature and pressure via analysis of microscopic strain fluctuations using formalism due to Rahman and Parrinello [J. Chem. Phys. 76,2662 (1982)]. Additionally, the isothermal compression curve was computed for {beta}-HMX for 0 {le} p {le} 10.6 GPa; the bulk modulus K and its pressure derivative K{prime} were obtained from two fitting forms employed previously in experimental studies of the {beta}-HMX equation of state. Overall, the results indicate good agreement between the bulk modulus predicted from the measured and calculated compression curves. The bulk modulus determined directly from the elastic tensor of {beta}-HMX is in significant disagreement with the compression curve-based results. The explanation for this discrepancy is an area of current research.

  9. Violent cookoff reactions in HMX-based explosives in DDT tubes: Tracking luminous waves with streak imaging

    NASA Astrophysics Data System (ADS)

    Parker, Gary; Dickson, Peter; Asay, Blaine W.; Smilowitz, Laura; Henson, Bryan; McAfee, John

    2012-03-01

    Recent implementation of modern high-speed video cameras has permitted the experimental flexibility needed to revisit classic deflagration-to-detonation (DDT) tube experiments and capture novel and valuable results displaying the progression of luminous reaction from a cookoff event. The authors present select data from a series of experiments where the HMX-based high explosives PBX 9501 and LX-07 were heated above 180°C for various durations to impose damage (i.e. phase transitions and void generation) before being driven to cook off. These two explosives have different polymeric binders, HMX mass fractions and cook off responses and a comparison between the two offers mechanistic insights on how thermal explosions evolve. From this series, results will be displayed indicating a wide range of violence from somewhat mild pressure bursts, to intermediate power compressive burns, to high-violence DDT. Image data from high temperature DDT tube experiments, where the explosive was ignited on one end, were also collected and will be included for comparison.

  10. Shock Induced Shear Strength in Two HMX Based Polymer Bonded Explosives

    NASA Astrophysics Data System (ADS)

    Millett, Jeremy; Taylor, Peter; Appleby-Thomas, Gareth

    2015-06-01

    The response of energetic materials to shock loading has largely concentrated on their detonation behaviour. However, they can also be considered to be structural materials in their own right, and hence their response to a purely mechanical shock loading is also of interest. Therefore we present results from two HMX based polymer bonded explosives, EDC37 and EDC32, where we investigate the shock induced shear strength behind the shock front. Results are discussed in terms of microstructure and differences of the binder phases.

  11. One-dimensional plate impact experiments on the cyclotetramethylene tetranitramine (HMX) based explosive EDC32

    NASA Astrophysics Data System (ADS)

    Burns, Malcolm J.; Gustavsen, Richard L.; Bartram, Brian D.

    2012-09-01

    Eight one-dimensional plate impact experiments have been performed to study both the Shock to Detonation Transition and Hugoniot state in the cyclotetramethylene tetranitramine (HMX) based explosive EDC32. The experiments covered shock pressures ranging from 0.59 to 7.5 GPa with sustained shocks, double shocks, and short pulse shocks. Experiments were instrumented with embedded magnetic particle velocity gauges. Results include; (1) wave profiles of particle velocity vs. time vs. depth in the explosive, (2) time-distance coordinates for onset of detonation vs. initial shock pressure (aka the Pop-plot), (3) a reactants Hugoniot, and (4) measurement of the Hugoniot Elastic Limit of 0.22.GPa.

  12. Mesoscale modelling of shock initiation in HMX-based explosives

    SciTech Connect

    Swift, D. C.; Mulford, R. N. R.; Winter, R. E.; Taylor, P.; Salisbury, D. A.; Harris, E. J.

    2002-01-01

    Motivation: predictive capability Want to predict initiation, detonics and performance given: {sm_bullet} Variations in composition {sm_bullet} Variations in morphology {sm_bullet}Different loading conditions Previous work on PBX and ANFO: need physically-based model rather than just mechanical calibrations

  13. First Results of Reaction Propagation Rates in HMX at High Pressure

    NASA Astrophysics Data System (ADS)

    Farber, Daniel L.; Zaug, Joseph M.; Ruddle, Chantel

    2001-06-01

    We have measured the reaction propagation speed in weapons grade ultrafine HMX (lot B-881-wet) powder that contains less than 7% RDX in the pressure range 0.7 to 3.7 GPa. Our high-pressure cells consist of two counter opposed 0.25 carat diamonds, with a culet diameter range of 0.5-1.0mm. A 150-400 μm diameter metal gasket hole laterally confines the 100-150 μm thick samples. Ruby powder was placed on the rear diamond surface to permit determination of the initial pressure. Samples were ignited with a Q-switched Nd:YAG laser pulse, frequency doubled to 532 nm. Typical pulse energies were in the range of 10 * 1300 μJ focused to a 5 μm spot, with a pulse width of ~9 ns. At low (<0.5 GPa) pressures the highest energy pulse was insufficient to cause reliable ignition whereas at the highest pressures, the lowest energy densities caused accidental ignition during optical alignment. Light emission from the sample was magnified ( ~10x) and focused onto a 50 μm wide slit. The image of this slit was then magnified (9.5x) and focused onto the entrance slits of both the EG&G L-CA-20 electronic streak camera and a Kaiser Optics f1.8 spectrograph for ruby fluorescence pressure measurements. For all experiments the streak duration is 10s. In order to have a cross-comparison of our experiments, we carried out a series of experiments on Nitromethane (NM) up to 15 GPa. Our results on NM are indistinguishable from previous measurements of Rice and Foltz. In comparison to high-pressure NM, the burn process for solid HMX is not spatially uniform.

  14. Thermal Cook-off of an HMX Based Explosive: Pressure Gauge Experiments and Modeling

    SciTech Connect

    Urtiew, P A; Forbes, J W; Tarver, C M; Garcia, F; Greenwood, D W; Vandersall, K S

    2002-04-02

    Safety issues related to thermal cook-off are important for handling and storing explosive devices. Violence of event as a function of confinement is important for prediction of collateral events. There are major issues, which require an understanding of the following events: (1) transit to detonation of a pressure wave from a cook-off event, (2) sensitivity of HMX based explosives changes with thermally induced phase transitions and (3) the potential danger of neighboring explosive devices being affected by a cook-off reaction. Results of cook-off events of known size, confinement and thermal history allows for development and/or calibrating computer models for calculating events that are difficult to measure experimentally.

  15. Development of a portable non-contact optical diagnostic system for the detection of δ-HMX

    NASA Astrophysics Data System (ADS)

    Dale, Andrew J.; Wright, Mark W.; Hughes, Christopher T.; Bowden, Mike D.

    2007-09-01

    If a HMX-based explosive is subjected to an insult then there is a potential for the insulted β-HMX to undergo a phase change to the more sensitive δ form. AWE has an ongoing programme to develop a science-based model of the response of HMX-based explosives to potential insults. As part of this programme there is a need to identify whether δ-HMX has been formed, as this would subsequently affect the intrinsic safety properties of the formulation. δ-HMX, unlike the more stable β form, exhibits unusual optical properties for an explosive, as it acts as a frequency-doubling material. When illuminated by a high-energy laser pulse areas of the explosive charge that contain δ-HMX emit frequency doubled light. This non-linear optical phenomenon allows for a non-invasive diagnostic to be developed to study creation of the more sensitive δ phase within HMX based formulations. AWE has developed a portable diagnostic system based on this concept to investigate the behaviour of HMX-based explosives after low-speed impacts. The results of the commissioning trials are presented; using both an inert simulant, KDP, to align and prove the system and HMX samples from low-speed impact experiments. The results of these experiments are compared to initial calculations using the Hydrocode EDEN.

  16. Equation of state formulation for unreacted solid high explosives, PETN and HMX

    NASA Astrophysics Data System (ADS)

    Nagayama, Kunihito

    2015-06-01

    Equation of state (EOS) for unreacted explosives has been formulated thermodynamically aiming at using with numerical code of SDT processes. A generalized form of EOS is given in terms of p-v-E from the available static isothermal compression curve with non-constant specific heat, and arbitrary Grüneisen volume function. In this paper, a procedure of providing p-v-E EOS is developed based on the specific heat at constant volume as a function of entropy, Grüneisen volume function, together with Birch-Murnagan form of the isotherm. Material function of EOS and shock Hugoniot for PETN and HMX has been calculated, which is compared with the experimental data of shock-particle velocity Hugoniot. Dependence of shock pressure and temperature on the Grüneisen volume function is discussed. Insensitivity of the shock-particle velocity relationship to functional form of Grüneisen volume function is also shown. Second author: Dr. Shiro Kubota (AIST Japan).

  17. Dynamic compression of solid HMX-based explosives under ramp wave loading

    NASA Astrophysics Data System (ADS)

    Wang, G. J.; Cai, J. T.; Zhang, H. P.; Zhao, F.; Tan, F. L.; Wu, G.

    2012-11-01

    By means of the new techniques of magnetically driven quasi-isentropic compression based on compact capacitor bank facility CQ-1.5 developed by us, the dynamic compression of two mixed HMX-based plastic bonded explosives (PBX) explosives is researched under ramp wave loading. A pressure of 5-8 GPa over 600-800 ns is realized on explosive samples by optimizing loading electrodes and controlling charging voltages of CQ-1.5. And loading strain rates vary from 105 1/s to 106 1/s along the thickness of explosive samples. For experiments, the particle velocities of interface between explosive samples with different thicknesses and LiF windows are measured to determine material response by a displacement interferometry technique of Doppler pins system (DPS), and the experimental compression isentropes of researched explosives are obtained using the data processing method of backward integration and Lagrangian analysis for quasi-isentropic compression experiments, which are in agreement with the theoretical isentropes based on Mie-Grüneisen equation of state (EOS) and the results by Baer. For simulations, one-dimensional hydrodynamics code SSS is used to analyze the dynamic process, and the calculated results of particle velocity of interfaces are consistent with the experimental ones. Finally, one of the explosive constituents, the binder fluoride rubber F2311, is also investigated using this technique, and some properties under ramp wave loading are gained.

  18. Thermal Explosion Violence of HMX-Based and RDX-Based Explosives - Effects of Composition, Confinement, and Solid Phase Using the Scaled Thermal Explosion Experiment

    SciTech Connect

    Maienschein, J L; Wardell, J F

    2002-03-14

    The Scaled Thermal Explosion Experiment (STEX) has been developed to quantify the violence of thermal explosion under well defined and carefully controlled initial and boundary conditions. Here we present results with HMX-based explosives (LX-04 and PBX-9501) and with Composition B. Samples are 2 inches (50 mm) in diameter and 8 inches (200 mm) in length, under confinement of 7,500-30,000 psi (50-200 MPa), with heating rates of 1-3 C/hr. We quantify reaction violence by measuring the wall velocity in the ensuing thermal explosion, and relate the measured velocity to that expected from a detonation. Results with HMX-based explosives (LX-04 and PBX-9501) have shown the importance of confinement and HMX solid phase, with reaction violence ranging from mild pressure bursts to near detonations. By contrast, Composition B has shown very violent reactions over a wide range of conditions.

  19. Thermal Explosion Violence of HMX-Based and RDX-Based Explosives - Effects of Composition, Confinement, and Solid Phase Using the Scaled Thermal Explosion Experiment

    SciTech Connect

    Maienschein, J L; Wardell, J F

    2002-08-26

    The Scaled Thermal Explosion Experiment (STEX) has been developed to quantify the violence of thermal explosion under well defined and carefully controlled initial and boundary conditions. Here we present results with HMX-based explosives (LX-04 and PBX-9501) and with Composition B. Samples are 2 inches (50 mm) in diameter and 8 inches (200 mm) in length, under confinement of 7,500-30,000 psi (50-200 MPa), with heating rates of 1-3 C/hr. We quantify reaction violence by measuring the wall velocity in the ensuing thermal explosion, and relate the measured velocity to that expected from a detonation. Results with HMX-based explosives (LX-04 and PBX-9501) have shown the importance of confinement and HMX solid phase, with reaction violence ranging from mild pressure bursts to near detonations. By contrast, Composition B has shown very violent reactions over a wide range of conditions.

  20. Ignition Prediction of Pressed HMX based on Hotspot Analysis Under Shock Pulse Loading

    NASA Astrophysics Data System (ADS)

    Kim, Seokpum; Miller, Christopher; Horie, Yasuyuki; Molek, Christopher; Welle, Eric; Zhou, Min

    The ignition behavior of pressed HMX under shock pulse loading with a flyer is analyzed using a cohesive finite element method (CFEM) which accounts for large deformation, microcracking, frictional heating, and thermal conduction. The simulations account for the controlled loading of thin-flyer shock experiments with flyer velocities between 1.7 and 4.0 km/s. The study focuses on the computational prediction of ignition threshold using James criterion which involves loading intensity and energy imparted to the material. The predicted thresholds are in good agreement with measurements from shock experiments. In particular, it is found that grain size significantly affects the ignition sensitivity of the materials, with smaller sizes leading to lower energy thresholds required for ignition. In addition, significant stress attenuation is observed in high intensity pulse loading as compared to low intensity pulse loading, which affects density of hotspot distribution. The microstructure-performance relations obtained can be used to design explosives with tailored attributes and safety envelopes.

  1. Multi-physics Meso-scale Finite Element Simulation of HMX-based Solid Propellant Subjected to Thermal Insults

    NASA Astrophysics Data System (ADS)

    Srivastava, Gaurav; Matous, Karel

    2014-03-01

    A large strain chemo-thermo-mechanical numerical framework has been developed to model the coupled chemical, thermal and mechanical behavior of solid propellant at the meso-scale. The mechanical behavior is modeled using a hyperelastic material model with viscous damage and J2 plasticity. The model admits a general nonlinear coefficient of thermal expansion to capture the thermo-mechanical behavior. The chemical model considers a system of chemical reactions with the rate kinetics being governed by a modified Arrhenius law. The thermal model considers thermodynamically consistent energy contributions from the inelastic mechanical deformations and the chemical reactions. The finite element method has been employed to discretize the continuum equations. Some simulation results will be presented to demonstrate the use of the developed framework in modeling the behavior of HMX-based solid propellant under thermal loads. The developed framework captures the large volumetric strains that are a characteristic of the β- δ phase transition of the HMX crystals and is able to predict locations of potential cracks in the binder. Such a simulation tool may prove to be useful in determining optimal conditions for the safe storage of such materials. Indian Institute of Technology, Gandhinagar VGEC Complex, Chandkheda, Ahmedabad, Gujarat - 382424.

  2. Short Shock Experiments and Modeling of Initiation in the HMX Based Explosive PBX 9501

    NASA Astrophysics Data System (ADS)

    Gustavsen, Richard; Dattelbaum, Dana; Handley, Caroline; Johnson, Carl; Sheffield, Stephen; Gibson, Lee

    2011-06-01

    We present results from a series of gas-gun driven plate impact experiments designed to measure the initiation response of PBX 9501 (95 wt.% HMX, 2.5 wt.% estane and 2.5 wt.% nitroplasticizer) to short duration shocks. Embedded electromagnetic particle velocity gauges measured the reactive growth and initiation progress. Photonic Doppler Velocimetry (PDV) measured a particle velocity wave profile at the interface of the ~ 23 mm thick PBX 9501 sample and a Lithium Fluoride (LiF) window. Impact stress in all three experiments was 4.4 GPa. Pulse durations of 0.5, 0.36, and 0.25 μs were created using 1.0, 0.75, and 0.5 mm thick Kel-F81 flyers backed by syntactic foam. The 0.5 μs pulse transited to detonation at tD = 2.08 μs, xD = 9.32 mm, considerably beyond the coordinates of tD = 1.4 μs, xD = 6.2 mm, expected for a long pulse. The 0.25 μs pulse failed to transition to detonation while the 0.36 μs pulse transitioned to a detonation at a position slightly less than the sample thickness of 23 mm. These experiments provide a more stringent test for reactive burn models than do the long pulse experiments used to generate the Pop-plot.

  3. Threshold Studies of Heated HMX-Based Energetic Material Targets Using the Steven Impact Test

    SciTech Connect

    Switzer, L L; Vandersall, K S; Chidester, S K; Greenwood, D W; Tarver, C M

    2003-07-01

    Impact tests performed at low velocity on heated energetic material samples are of interest when considering the situation of energetic materials involved in a fire. To determine heated reaction thresholds, Steven Test targets containing PBX 9404 or LX-04 samples heated to the range of 150-170 C were impacted at velocities up to 150 m/s by two different projectile head geometries. Comparing these measured thresholds to ambient temperature thresholds revealed that the heated LX-04 thresholds were considerably higher than ambient, whereas the heated PBX 9404 thresholds were only slightly higher than the ambient temperature thresholds. The violence of reaction level of the PBX 9404 was considerably higher than that of the LX-04 as measured with four overpressure gauges. The varying results in these samples with different HMX/binder configurations indicate that friction plays a dominant role in reaction ignition during impact. This work outlines the experimental details, compares the thresholds and violence levels of the heated and ambient temperature experiments, and discusses the dominant mechanisms of the measured thresholds.

  4. Preparation and Properties of Surface-Coated HMX with Viton and Graphene Oxide

    NASA Astrophysics Data System (ADS)

    Wang, Jingyu; Ye, Baoyun; An, Chongwei; Wu, Bidong; Li, Hequn; Wei, Yanju

    2016-07-01

    To improve the safety performance of HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) particles, the new carbon material graphene oxide (GO) and Viton were used to coat HMX via a solvent-slurry process. For comparison, the HMX/Viton/graphite (HMX/Viton/G) and HMX/Viton composites were also prepared by the same process. Atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and differential scanning calorimetry (DSC) were employed to characterize the morphology, composition, and thermal decomposition of samples. The impact sensitivity and shock wave sensitivity of HMX-based composites were also measured and analyzed. The results of SEM, XRD, and XPS indicate that the cladding layer of HMX-based composites is successfully constructed. HMX/Viton/GO composites exhibit better thermal stability compared to HMX and HMX/Viton. The results show that both impact and shock wave sensitivities of HMX/Viton/GO composites are much lower than that of HMX/Viton. In addition, GO sheets exhibit a better desensitizing effect than G sheets. These combined properties suggest that nano-GO has good compatibility with explosives and can be utilized as a desensitizer in HMX particles.

  5. Mesoscale evolution of voids and microstructural changes in HMX-based explosives during heating through the β-δ phase transition

    NASA Astrophysics Data System (ADS)

    Willey, Trevor M.; Lauderbach, Lisa; Gagliardi, Franco; van Buuren, Tony; Glascoe, Elizabeth A.; Tringe, Joseph W.; Lee, Jonathan R. I.; Springer, H. Keo; Ilavsky, Jan

    2015-08-01

    HMX-based explosives LX-10 and PBX-9501 were heated through the β-δ phase transition. Ultra-small angle x-ray scattering (USAXS) and molecular diffraction were simultaneously recorded as the HMX was heated. Mesoscale voids and structure dramatically change promptly with the β-δ phase transition, rather than with other thermal effects. Also, x-ray induced damage, observed in the USAXS, occurs more readily at elevated temperatures; as such, the dose was reduced to mitigate this effect. Optical microscopy performed during a similar heating cycle gives an indication of changes on longer length scales, while x-ray microtomography, performed before and after heating, shows the character of extensive microstructural damage resulting from the temperature cycle and solid-state phase transition.

  6. Mesoscale evolution of voids and microstructural changes in HMX-based explosives during heating through the β-δ phase transition

    SciTech Connect

    Willey, Trevor M. Lauderbach, Lisa; Gagliardi, Franco; Buuren, Tony van; Glascoe, Elizabeth A.; Tringe, Joseph W.; Lee, Jonathan R. I.; Springer, H. Keo; Ilavsky, Jan

    2015-08-07

    HMX-based explosives LX-10 and PBX-9501 were heated through the β-δ phase transition. Ultra-small angle x-ray scattering (USAXS) and molecular diffraction were simultaneously recorded as the HMX was heated. Mesoscale voids and structure dramatically change promptly with the β-δ phase transition, rather than with other thermal effects. Also, x-ray induced damage, observed in the USAXS, occurs more readily at elevated temperatures; as such, the dose was reduced to mitigate this effect. Optical microscopy performed during a similar heating cycle gives an indication of changes on longer length scales, while x-ray microtomography, performed before and after heating, shows the character of extensive microstructural damage resulting from the temperature cycle and solid-state phase transition.

  7. The response of the HMX-based material PBXN-9 to thermal insults: thermal decomposition kinetics and morphological changes

    SciTech Connect

    Glascoe, E A; Hsu, P C; Springer, H K; DeHaven, M R; Tan, N; Turner, H C

    2010-12-10

    PBXN-9, an HMX-formulation, is thermally damaged and thermally decomposed in order to determine the morphological changes and decomposition kinetics that occur in the material after mild to moderate heating. The material and its constituents were decomposed using standard thermal analysis techniques (DSC and TGA) and the decomposition kinetics are reported using different kinetic models. Pressed parts and prill were thermally damaged, i.e. heated to temperatures that resulted in material changes but did not result in significant decomposition or explosion, and analyzed. In general, the thermally damaged samples showed a significant increase in porosity and decrease in density and a small amount of weight loss. These PBXN-9 samples appear to sustain more thermal damage than similar HMX-Viton A formulations and the most likely reasons are the decomposition/evaporation of a volatile plasticizer and a polymorphic transition of the HMX from {beta} to {delta} phase.

  8. Understanding and Predicting the Thermal Explosion Violence of HMX-Based and RDX-Based Explosives - Experimental Measurements of Material Properties and Reaction Violence

    SciTech Connect

    Maienschein, J L; Wardell, J F; Weese, R K; Cunningham, B J; Tran, T D

    2002-07-03

    The violence of thermal explosions with energetic materials is affected by many material properties, including mechanical and thermal properties, thermal ignition kinetics, and deflagration behavior. These properties must be characterized for heated samples as well as pristine materials. We present available data for these properties for two HMX-based formulations--LX-04 and PBX-9501, and two RDX-based formulations--Composition B and PBXN-109. We draw upon separately published data on the thermal explosion violence with these materials to compare the material properties with the observed violence. We have the most extensive data on deflagration behavior of these four formulations, and we discuss the correlation of the deflagration data with the violence results. The data reported here may also be used to develop models for application in simulation codes such as ALE3D to calculate and Dredict thermal explosion violence.

  9. Computer Simulations to Study the High-Pressure Deflagration of HMX

    SciTech Connect

    Reaugh, J E

    2003-07-11

    The accepted micro-mechanical picture of the build-up of detonation in solid explosives from a shock is that imperfections are a source of hot spots. The hot spots ignite and link up in the reaction zone by high-pressure deflagration. Although the deflagration is subsonic, there are so many ignition sites that the pressure build-up is rapid enough to strengthen the initial shock. Quantitative advances in this research require a detailed understanding of deflagration at the high pressure, 1 to 50 GPa, which is present in the reaction zone. We performed direct numerical simulations of high-pressure deflagrations using a simplified global (3-reaction) chemical kinetics scheme. We used ALE-3D to calculate coupled chemical reactions, heat transfer, and hydrodynamic flow for finite-difference zones comprising a mixture of reactants and products at pressure and temperature equilibrium. The speed of isobaric deflagrations depends on the pressure and initial temperature. We show how this dependence changes with kinetic parameters, including the order of the last reaction step and the heat of formation of the species formed, relative to the reactant.

  10. Binder/HMX Interaction in PBX9501 at Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Saw, Cheng K.; Tarver, Craig M.

    2004-07-01

    Plastic bonded explosives (PBX) generally consist of 85-95 % by weight energetic material, such as HMX, and 5-15 % polymeric binder. Understanding of the structure and morphology at elevated temperatures and pressures is important for predicting of PBX behavior in accident scenarios. The crystallographic behavior of pure HMX has been measured as functions of temperature and grain size. The investigation is extended to the high temperature behavior of PBX 9501 (95% HMX, 2.5 % Estane, 2.5 % BDNPA/F). The results show that the HMX β- to δ-phase transition in PBX 9501 is similar to that in neat HMX. However, in the presence of the PBX 9501 binder, δ-phase HMX readily converts back to β-phase during cooling. Using the same temperature profile, the conversion rate decreases for each subsequent heating and cooling cycle. As observed in earlier experiments, no reverse conversion is observed without the polymer binder. It is proposed that the reversion of δ-phase to β-phase is due to changes in the surface molecular potential caused by the influence of the polymer binder on the δ-phase. Upon thermal cycling, the polymer binder segregates from the HMX particles and thus reduces the influence of the binder on the surface molecules. This segregation increases the resistance for the δ-phase to β-phase transition, as demonstrated in an aged PBX 9501 material for which the reversion is not observed.

  11. Violent Reactions and DDT in Hot, Thermally Damaged HMX-Based PBXs

    SciTech Connect

    Parker, Gary R. Jr.; Holmes, Matthew D.; Dickson, Peter; Asay, Blaine W.; McAfee, John M.

    2012-07-03

    Conventional high explosives (e.g. PBX 9501, LX-07) have been observed to react violently following thermal insult: (1) Fast convective and compressive burns (HEVR); (2) Thermal explosions (HEVR); and (3) Deflagration-to-detonation transition (DDT). No models exist that sufficiently capture/predict these complex multiphase and multiscale behaviors. For now, research is focused on identifying vulnerabilities and factors that control this behavior.

  12. Pilot-scale pressurized base hydrolysis of HMX plastic-bonded explosives

    SciTech Connect

    Larson, S.A.; Brewer, G.R.; Harradine, D.M.; Polston, C.E.; Le, L.A.; Bishop, R.L.; Dell`Orco, P.C.; Flesner, R.L.

    1998-12-31

    A pilot-scale, pressurized, base hydrolysis reactor has been designed and its construction is nearly completed. Up to 120 L of 1--6 M NaOH aqueous solutions will convert as much as 25 kg of consolidated, explosive pieces to non-energetic compounds. Temperatures approaching 155 C in the pressurized unit will reduce reaction times significantly for the destruction of plastic-bonded explosives compared to previous atmospheric-pressure reactors. The hydrolysis effluent is then pumped into a holding tank where it is fed into a hydrothermal oxidation reactor for complete destruction to non-hazardous products. The hydrothermal unit operates at 480 C and 100 MPa and hydrogen peroxide fed into the reactor at two points will ensure complete destruction of all organic species and nitrogen-containing salts. The entire system is comprised of eight major components and is assembled on five separate and transportable skids. Following construction and preliminary testing at Los Alamos National Laboratory, the unit will be shipped to the Pantex Plant where it will be used for continuous demilitarization activities.

  13. Investigating short-pulse shock initiation in HMX-based explosives with reactive meso-scale simulations

    NASA Astrophysics Data System (ADS)

    Springer, H. K.; Tarver, C. M.; Reaugh, J. E.; May, C. M.

    2014-05-01

    We performed reactive meso-scale simulations of short-pulse experiments to study the influence of flyer velocity and pore structure on shock initiation of LX-10 (95wt% HMX, 5wt% Viton A). Our calculations show that the reaction evolution fit a power law relationship in time and increases with increasing porosity, decreasing pore size, and increasing flyer velocity. While heterogeneous shock initiation modes, dependent on hot spot mechanisms, are predicted at lower flyer velocities, mixed heterogeneous-homogeneous shock initiation modes, less dependent on hot spots, are predicted at higher velocities. These studies are important because they enable the development of predictive shock initiation models that incorporate complex microstructure and can be used to optimize performance-safety characteristics of explosives.

  14. Thermal reactive hazards of HMX with contaminants.

    PubMed

    Peng, Deng-Jr; Chang, Cheng-Ming; Chiu, Miin

    2004-10-18

    In the past, many unexpected runaway accidents occurred in manufacturing processes, involving volatile chemical and explosive storage and transportation. Incompatible product reactions of high explosives must be carefully considered using loss prevention strategies for thermal hazards risk analysis. High explosive reactions vary via environmental changes, contact materials, or process situations, such as onset temperature and shifts in reaction type when high explosives are in contact with contaminants. Therefore, the manufacture and handling of high explosives require the utmost in safety and loss prevention. HMX (cyclotetramethyene tetranitramine) is one kind of high explosive widely used around the world which is stable with high detonation strength properties. In this study, the influences of contaminants on HMX are investigated. The studied contaminants include ferrous chloride tetrahydrate, ferric chloride hexahydrate, acetone solution, acetic acid, and nitric acid. DSC thermal curves and incompatible reaction kinetic evaluations were preformed using iron, chlorine and acid. Organic acetone solution has lesser effects on HMX. Hopefully, this study will lead to improved thermal hazards risk analysis and reduce accidents. PMID:15511569

  15. Method for synthesizing HMX

    DOEpatents

    McGuire, Raymond R.; Coon, Clifford L.; Harrar, Jackson E.; Pearson, Richard K.

    1984-01-01

    A method and apparatus for electrochemically synthesizing N.sub.2 O.sub.5 cludes oxidizing a solution of N.sub.2 O.sub.4 /HNO.sub.3 at an anode, while maintaining a controlled potential between the N.sub.2 O.sub.4 /HNO.sub.3 solution and the anode. A potential of about 1.35 to 2.0 V vs. SCE is preferred, while a potential of about 1.80 V vs. SCE is most preferred. Thereafter, the N.sub.2 O.sub.5 is reacted with either 1.5-diacetyl-3,7-dinitro-1,3,5,7-tetraazacyclooctane (DADN) or 1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane (TAT) to form cyclotetramethylenetetraamine (HMX).

  16. Method for synthesizing HMX

    SciTech Connect

    McGuire, R.R.; Coon, C.L.; Harrar, J.E.; Pearson, R.K.

    1984-02-21

    A method and apparatus for electrochemically synthesizing N/sub 2/O/sub 5/ includes oxidizing a solution of N/sub 2/O/sub 4//HNO/sub 3/ at an anode, while maintaining a controlled potential between the N/sub 2/O/sub 4//HNO/sub 3/ solution and the anode. A potential of about 1.35 to 2.0 V vs. SCE is preferred, while a potential of about 1.80 V vs. SCE is most preferred. Thereafter, the N/sub 2/O/sub 5/ is reacted with either 1.5-diacetyl-3,7-dinitro-1,3,5,7-tetraazacyclooctane (DADN) or 1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane (TAT) to form cyclotetramethylenetetraamine (HMX).

  17. Effects of HMX-lead mixtures on reproduction of the earthworm Eisenia andrei.

    PubMed

    Savard, Kathleen; Berthelot, Yann; Auroy, Aurelie; Spear, Philip A; Trottier, Bertin; Robidoux, Pierre Yves

    2007-10-01

    High metal (e.g., Pb) concentrations are typically found in explosive-contaminated soil, and their presence may increase, decrease, or not influence toxicity predicted on the basis of one explosive alone (e.g., HMX). Nevertheless, few data are available in the scientific literature for this type of multiple exposure. Soil organisms, such as earthworms, are one of the first receptors affected by the contamination of soil. Therefore, a reproductive study was conducted using Eisenia andrei in a forest-type soil. Both HMX and Pb decreased reproduction parameters (number of total cocoons, hatched cocoons, and surviving juveniles) individually. Based on the total number of cocoons, HMX was more toxic in a forest soil than Pb, with EC(50) of 31 mg kg(-1), and 1068 mg kg(-1), respectively. The slope of the concentration-response curve was significantly greater in the case of Pb, which is consistent with the possibility that the two compounds do not act on the same target site. The response-addition model was used to predict the response of earthworms and to test for interaction between the two contaminants. The predicted toxicity was not significantly different than the observed toxicity, implying that Pb and HMX were considered noninteractive compounds. The combined action of Pb-HMX may be described, therefore, as dissimilar-noninteractive joint action in a forest soil. The results illustrate the relevance of considering the presence of metals in the risk assessment of explosive-contaminated sites because metals can add their toxicity to explosives. Extension of this study to other types of soil and other metals would improve the understanding of toxicity at these sites. PMID:17690834

  18. A comparative study of 1,3,5-Trinitroperhydro-1,3,5-triazine (RDX) and Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) under high pressures using Raman spectroscopy and DFT calculations

    NASA Astrophysics Data System (ADS)

    Zeng, Yangyang; Song, Yunfei; Yu, Guoyang; Zheng, Xianxu; Guo, Wencan; Zhao, Jun; Yang, Yanqiang

    2016-09-01

    High pressure Raman experiment was performed to compare RDX and HMX crystals. Ab initio calculations using B3LYP Density Functional Theory method with Sadlej's medium-sized polarized basis set (SadlejpVTZ) were carried out for Caae RDX and 1,5-diaxial-3,7-diequatorial chair HMX molecules. Our calculations and measured Raman vibrational spectra reveal both molecules have similarities on bonding and vibrational properties at ambient pressure. However, high pressure responses for both molecules aren't the same. For RDX, at pressure near 4 GPa, a number of changes become apparent in the Raman spectra, such as modes splitting, intensity modification, and discontinuity of pressure-dependence of frequency shifts, which are consistent with previous experiment and believed to associate with α-γ phase transition. For HMX, only slight conformational deformation involving NO2 group was observed, and was considered as an onset of β-ε phase transition. It is proposed that the markedly different behavior under high pressure for these two molecules results from different molecular packing in unit cell.

  19. An Analytic Tool to Investigate the Effect of Binder on the Sensitivity of HMX-Based Plastic Bonded Explosives in the Skid Test

    SciTech Connect

    D.W. Hayden

    2005-02-01

    This project will develop an analytical tool to calculate performance of HMX based PBXs in the skid test. The skid-test is used as a means to measure sensitivity for large charges in handling situations. Each series of skid tests requires dozens of drops of large billets. It is proposed that the reaction (or lack of one) of PBXs in the skid test is governed by the mechanical properties of the binder. If true, one might be able to develop an analytical tool to estimate skid test behavior for new PBX formulations. Others over the past 50 years have tried to develop similar models. This project will research and summarize the works of others and couple the work of 3 into an analytical tool that can be run on a PC to calculate drop height of HMX based PBXs. Detonation due to dropping a billet is argued to be a dynamic thermal event. To avoid detonation, the heat created due to friction at impact, must be conducted into the charge or the target faster than the chemical kinetics can create additional energy. The methodology will involve numerically solving the Frank-Kamenetskii equation in one dimension. The analytical problem needs to be bounded in terms of how much heat is introduced to the billet and for how long. Assuming an inelastic collision with no rebound, the billet will be in contact with the target for a short duration determined by the equations of motion. For the purposes of the calculations, it will be assumed that if a detonation is to occur, it will transpire within that time. The surface temperature will be raised according to the friction created using the equations of motion of dropping the billet on a rigid surface. The study will connect the works of Charles Anderson, Alan Randolph, Larry Hatler, Alfonse Popolato, and Charles Mader into a single PC based analytic tool. Anderson's equations of motion will be used to calculate the temperature rise upon impact, the time this temperature is maintained (contact time) will be obtained from the work of

  20. Surface-Accelerated Decomposition of δ-HMX.

    PubMed

    Sharia, Onise; Tsyshevsky, Roman; Kuklja, Maija M

    2013-03-01

    Despite extensive efforts to study the explosive decomposition of HMX, a cyclic nitramine widely used as a solid fuel, explosive, and propellant, an understanding of the physicochemical processes, governing the sensitivity of condensed HMX to detonation initiation is not yet achieved. Experimental and theoretical explorations of the initiation of chemistry are equally challenging because of many complex parallel processes, including the β-δ phase transition and the decomposition from both phases. Among four known polymorphs, HMX is produced in the most stable β-phase, which transforms into the most reactive δ-phase under heat or pressure. In this study, the homolytic NO2 loss and HONO elimination precursor reactions of the gas-phase, ideal crystal, and the (100) surface of δ-HMX are explored by first principles modeling. Our calculations revealed that the high sensitivity of δ-HMX is attributed to interactions of surfaces and molecular dipole moments. While both decomposition reactions coexist, the exothermic HONO-isomer formation catalyzes the N-NO2 homolysis, leading to fast violent explosions. PMID:26281926

  1. Chemical Kinetic Modeling of HMX and TATB Laser Ignition Tests

    SciTech Connect

    Tarver, C M

    2004-03-02

    Recent laser ignition experiments on octahydro-1,3,5,7-tetranitro-1,3,5,7-terrazocine (HMX) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) subjected to laser fluxes ranging from 10 to 800 W/cm{sup 2} produced ignition times from seconds to milliseconds. Global chemical kinetic thermal decomposition models for HMX and TATB have been developed to calculate times to thermal explosion for experiments in the seconds to days time frame. These models are applied to the laser ignition experimental data in this paper. Excellent agreement was obtained for TATB, while the calculated ignition times were longer than experiment for HMX at lower laser fluxes. At the temperatures produced in the laser experiments, HMX melts. Melting generally increases condensed phase reaction rates so faster rates were used for three of the HMX reaction rates. This improved agreement with experiments at the lower laser fluxes but yielded very fast ignition at high fluxes. The calculated times to ignition are in reasonable agreement with the laser ignition experiments, and this justifies the use of these models for estimating reaction times at impact and shock ''hot spot'' temperatures.

  2. Burning rate for steel-cased, pressed binderless HMX

    NASA Technical Reports Server (NTRS)

    Fifer, R. A.; Cole, J. E.

    1980-01-01

    The burning behavior of pressed binderless HMX laterally confined in 6.4 mm i.d. steel cases was measured over the pressure range 1.45 to 338 MPa in a constant pressure strand burner. The measured regression rates are compared to those reported previously for unconfined samples. It is shown that lateral confinement results in a several-fold decrease in the regression rate for the coarse particle size HMX above the transition to super fast regression. For class E samples, confinement shifts the transition to super fast regression from low pressure to high pressure. These results are interpreted in terms of the previously proposed progressive deconsolidation mechanism. Preliminary holographic photography and closed bomb tests are also described. Theoretical one dimensional modeling calculations were carried out to predict the expected flame height (particle burn out distance) as a function of particle size and pressure for binderless HMX burning by a progressive deconsolidation mechanism.

  3. Chemical-decomposition models for the thermal explosion of confined HMX, TATB, RDX, and TNT explosives

    SciTech Connect

    McGuire, R.R.; Tarver, C.M.

    1981-03-26

    Chemical decomposition models have been deduced from the available chemical kinetic data on the thermal decomposition of HMX, TATB, RDX, and TNT. A thermal conduction model is used in which the thermal conductivity of the reacting explosive decreases linearly with the mass fraction reacted to that of the gaseous products. These reactive heat flow models are used to predict the time to explosion versus reciprocal temperature curves from several heavily confined explosive tests. Good agreement is obtained between experimental and calculated explosion times for the pure explosives HMX, TATB, RDX, and TNT, mixtures such as RX-26-AF (HMX/TATB), Octol (HMX/TNT), and Comp B (RDX/TNT), and for PBX 9404, an HMX-based explosive containing an energetic nitrocellulose binder.

  4. Ignition and Growth Modeling of Detonation Reaction Zone Experiments on Single Crystals of PETN and HMX

    NASA Astrophysics Data System (ADS)

    White, Bradley; Tarver, Craig

    2015-06-01

    Fedorov et al. reported nanosecond time resolved interface particle velocity records for detonation reaction zone profiles of single crystals of PETN and HMX with adjoining LiF windows. Von Neumann spike and Chapman-Jouguet pressures were measured, and reaction zone lengths and times wereinferred. The single crystal detonation velocities and von Neumann spike pressures are higher than those measured for heterogeneous PETN and HMX-based explosives pressed to 98-99% theoretical maximum density. Due to the absence of voids, the single crystal detonation reaction zone lengths and times for both PETN and HMX were longer than those for their heterogeneous explosives. Ignition and Growth modeling results are compared to the single crystal PETN and HMX measurements and to previous experimental results for pressed PETN and HMX charges. This work was performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  5. Picosecond Dynamics of Shock Compressed and Flash-Heated Nanometer Thick Films of HMX

    NASA Astrophysics Data System (ADS)

    Berg, Christopher; Dlott, Dana

    2013-06-01

    New results are described for probing molecular dynamics of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) subjected to shock compression to a few GPa and/or temperature excursions exceeding thermal decomposition values (T > 500 K). 5-10 nm thick films of δ-HMX were grown on metallic substrates coated with monolayers of 4-nitrothiophenol. Due to shock velocities of a few nm/ps, nanometer thick films allowed picosecond time resolution of shock loading. A plastic polymer layer a few microns in thickness was spin-coated on top of HMX for shock confinement purposes. Both the monolayer and explosive layer were probed utilizing an ultrafast nonlinear coherent vibrational spectroscopy, vibrational sum-frequency generation. Shock compression pressures were estimated via comparison of the monolayer nitro transition frequency shift with static high pressure measurements in a diamond anvil cell. Temperature determinations were based on thermoreflectance measurements of the metallic substrate. Supported by the Stewardship Sciences Academic Alliance Program from the Carnegie-DOE Alliance Center under grant number DOE CIW 4-3253-13 and the US Air Force Office of Scientific Research under award number FAA9550-09-1-0163.

  6. Finite element code development for modeling detonation of HMX composites

    NASA Astrophysics Data System (ADS)

    Duran, Adam; Sundararaghavan, Veera

    2015-06-01

    In this talk, we present a hydrodynamics code for modeling shock and detonation waves in HMX. A stable efficient solution strategy based on a Taylor-Galerkin finite element (FE) discretization was developed to solve the reactive Euler equations. In our code, well calibrated equations of state for the solid unreacted material and gaseous reaction products have been implemented, along with a chemical reaction scheme and a mixing rule to define the properties of partially reacted states. A linear Gruneisen equation of state was employed for the unreacted HMX calibrated from experiments. The JWL form was used to model the EOS of gaseous reaction products. It is assumed that the unreacted explosive and reaction products are in both pressure and temperature equilibrium. The overall specific volume and internal energy was computed using the rule of mixtures. Arrhenius kinetics scheme was integrated to model the chemical reactions. A locally controlled dissipation was introduced that induces a non-oscillatory stabilized scheme for the shock front. The FE model was validated using analytical solutions for sod shock and ZND strong detonation models and then used to perform 2D and 3D shock simulations. We will present benchmark problems for geometries in which a single HMX crystal is subjected to a shock condition. Our current progress towards developing microstructural models of HMX/binder composite will also be discussed.

  7. Compaction Waves in Granular HMX

    SciTech Connect

    E. Kober; R. Menikoff

    1999-01-01

    Piston driven compaction waves in granular HMX are simulated with a two-dimensional continuum mechanics code in which individual grains are resolved. The constitutive properties of the grains are modeled with a hydrostatic pressure and a simple elastic-plastic model for the shear stress. Parameters are chosen to correspond to inert HMX. For a tightly packed random grain distribution (with initial porosity of 19%) we varied the piston velocity to obtain weak partly compacted waves and stronger fully compacted waves. The average stress and wave speed are compatible with the porous Hugoniot locus for uni- axial strain. However, the heterogeneities give rise to stress concentrations, which lead to localized plastic flow. For weak waves, plastic deformation is the dominant dissipative mechanism and leads to dispersed waves that spread out in time. In addition to dispersion, the granular heterogeneities give rise to subgrain spatial variation in the thermodynamic variables. The peaks in the temperature fluctuations, known as hot spots, are in the range such that they are the critical factor for initiation sensitivity.

  8. Ignition and Growth Reactive Flow Modeling of Recent HMX/TATB Detonation Experiments

    NASA Astrophysics Data System (ADS)

    Tarver, Craig

    2015-06-01

    Ignition and Growth model parameters for detonating PBX 9501 (95%HMX, 2.5 %Estane, 2.5%BDNPAF) and PBX 9502 (95%TATB, 5%Kel-F800) are used to simulate two experiments in which detonating HMX-based PBX's accelerate slower detonating TATB PBX's. The measured HMX and TATB detonation velocities, the angles produced in the detonating TATB charges by the leading HMX detonation waves, the arrival times of the complex detonation wave front, and the PDV records measured at several positions along the interfaces between the two explosives and LiF windows are accurately calculated. This work was performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  9. Kinetics of HMX and Phase Transitions: Effects of Grain Size at Elevated Temperature

    SciTech Connect

    Saw, C K

    2002-06-13

    To date a global kinetic rate law has not been written to accurately describe solid-solid phase transformations of HMX and TATB where contributions from grain size effects, binder contents, and impurity levels are explicitly defined. Our recent work presented at the 2001 SCCM topical APS meeting, Atlanta, GA, demonstrated one can not confidently use the second harmonic generation (SHG) diagnostic to study energetic material phase transitions where non-uniform grain size distributions are present. For example, in HMX, the early arrival of SHG before the XRD in the SHG/XRD simultaneous high temperature experiment clearly indicates the partial molecular conversion from centrosymmetric to non-centrosymmetric without any structural changes as exhibit by the XRD pattern. This conversion is attributed to the changes of the surface molecules due to the differences in potential between the surface and the bulk. The present paper reports on accurate XRD measurements following changes of {beta}-HMX to {delta}-HMX at elevated temperature. The results are compared for sample with 2 different grain sizes for HMX. We report accurate temperature dependent lattice parameters and hence volume and linear thermal expansion coefficients along each crystallographic axis. We have also conducted kinetic studies of the behavior of 2 grain-sizes of HMX and concluded that their kinetics, are drastically different.

  10. A theoretical study of wave dispersion and thermal conduction for HMX/additive interfaces

    NASA Astrophysics Data System (ADS)

    Long, Yao; Chen, Jun

    2014-04-01

    The wave dispersion rule for non-uniform material is useful for ultrasonic inspection and engine life prediction, and also is key in achieving an understanding of the energy dissipation and thermal conduction properties of solid material. On the basis of linear response theory and molecular dynamics, we derive a set of formulas for calculating the wave dispersion rate of interface systems, and study four kinds of interfaces inside plastic bonded explosives: HMX/{HMX, TATB, F2312, F2313}. (HMX: octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine; TATB: 1,3,5-triamino-2,4,6-trinitrobenzene; F2312, F2313: fluoropolymers). The wave dispersion rate is obtained over a wide frequency range from kHz to PHz. We find that at low frequency, the rate is proportional to the square of the frequency, and at high frequency, the rate couples with the molecular vibration modes at the interface. By using the results, the thermal conductivities of HMX/additive interfaces are derived, and a physical model is built for describing the total thermal conductivity of mixture explosives, including HMX multi-particle systems and {TATB, F2312, F2313}-coated HMX.

  11. Ignition Chemistry in HMX from Thermal Explosion to Detonation

    NASA Astrophysics Data System (ADS)

    Henson, Bryan F.; Asay, Blaine W.; Smilowitz, Laura B.; Dickson, Peter M.

    2002-07-01

    We present a global chemical decomposition model for HMX based materials. The model contains three component processes, the initial beta to delta phase transition, solid to gas decomposition and gas phase ignition, for which all kinetic and thermodynamic parameters are fixed by independent measurement. We present an isothermal ignition calculation over the range of temperatures from thermal explosion to detonation. The calculation is performed for a sphere of material and the critical diameter and time for ignition are determined. The sample diameter, and thus the balance of heat generation and dissipation, is the only degree of freedom in the calculation. The results of the calculation are in good agreement with data with respect to both the ignition times and length scales over the full temperature range of energetic response in HMX.

  12. Ignition chemistry in HMX from thermal explosion to detonation

    NASA Astrophysics Data System (ADS)

    Henson, Bryan; Smilowitz, Laura; Asay, Blaine; Dickson, Peter

    2001-06-01

    We present a global chemical decomposition model for HMX based materials. The model contains three component processes, the initial beta to delta phase transition, solid to gas decomposition and gas phase ignition, for which all kinetic and thermodynamic parameters are fixed by independent measurement. We present isothermal ignition calculations over the range of temperatures from thermal explosion to detonation. The calculation is performed for a sphere of material and the critical diameter and time for ignition are determined. The sample diameter, and thus the balance of heat generation and dissipation, is the only degree of freedom in the calculation. The results of the calculation are in good agreement with data with respect to both the ignition times and length scales over the full temperature range of energetic response in HMX.

  13. Treatment of HMX and RDX contamination

    SciTech Connect

    Card, R.E. Jr.; Autenrieth, R.

    1998-03-01

    HMX and RDX are often found in the soil, groundwater, and surface waters at facilities where they are manufactured as the result of negligent disposal methods. The toxicity of these compounds and their degradation products has led to concern about their fate in the environment and the potential for human exposure. HMX and RDX are recalcitrant in the environment with low rates of biodegradation and photolysis. Several methods of treating contaminated soils and waters have been developed and studied. Many of these technologies (i.e., carbon adsorption, oxidation, and chemical treatment) have been developed to treat munition plant wastewaters that are contaminated with explosives. These methods need to be adapted to remediate contaminated water. Other technologies such as bioremediation and composting are being developed as methods of remediating HMX and RDX contamination in a solid matrix. This report describes and evaluates each of these technologies. This report also describes the processes which affect HMX and RDX in the environment. The major transformation processes of RDX and HMX in the environment are biodegradation and photolysis. A major factor affecting the transport and treatment of RDX and HMX in soil-water environments is their sorption and desorption to soil particles. Finally, this report draws conclusions as to which treatment methods are currently most suitable for the remediation of contaminated soils and waters.

  14. Pressure wave measurements from thermal cook-off of an HMX based high explosive

    SciTech Connect

    Forbes, J W; Tarver, C M; Urtiew, P A; Garcia, F; Greenwood, D W; Vandersall, K S

    2000-10-10

    A better understanding of thermal cook-off is important for safe handling and storing explosive devices. A number of safety issues exist about what occurs when a cased explosive thermally cooks off. For example, violence of the events as a function of confinement are important for predictions of collateral damage. This paper demonstrates how adjacent materials can be gauged to measure the resulting pressure wave and how this wave propagates in this adjacent material. The output pulse from the thermal cook-off explosive containing fixture is of obvious interest for assessing many scenarios.

  15. Pressure Wave Measurements from Thermal Cook-Off of an HMX Based High Explosive PBX 9501

    SciTech Connect

    Garcia, F; Forbes, J W; Tarver, C M; Urtiew, P A; Greenwood, D W; Vandersall, K S

    2001-05-31

    A better understanding of thermal cook-off is important for safe handling and storing explosive devices. A number of safety issues exist about what occurs when a cased explosive thermally cooks off. For example, violence of the events as a function of confinement are important for predictions of collateral damage. This paper demonstrates how adjacent materials can be gauged to measure the resulting pressure wave and how this wave propagates in this adjacent material. The output pulse from the thermal cook-off explosive containing fixture is of obvious interest for assessing many scenarios.

  16. Deflagration-to-detonation transition in granular HMX

    NASA Technical Reports Server (NTRS)

    Campbell, A. W.

    1980-01-01

    Granular HMX of three degrees of fineness was packed into heavy-walled steel tubes closed at both ends. Ignition was obtained at one end using an intimate mixture of finely divided titanium and boron as an igniter that produced heat with little gas. The distance to detonation was determined by examination of the resulting tube fragments. By inserting tightly-fitted neoprene diaphragms periodically into the HMX column, it was shown that the role of convective combustion was limited to the initial stage of the deflagration to detonation (DDT) process. Experiments in which various combinations of two of the three types of HMX were loaded into the same tube showed that heating by adiabatic shear of explosive grains was an essential factor in the final buildup to detonation. A description of the DDT process is developed in which conductive burning is followed in turn by convective burning, bed collapse with plug formation, onset of accelerated burning at the front of the plug through heating by intercrystalline friction and adiabatic shear, and intense shock formation resulting in high-order detonation.

  17. Thermal Decomposition Kinetics of HMX

    SciTech Connect

    Burnham, A K; Weese, R K

    2004-05-05

    Nucleation-growth kinetic expressions are derived for thermal decomposition of HMX from a variety of types of data, including mass loss for isothermal and constant rate heating in an open pan, and heat flow for isothermal and constant rate heating in open and closed pans. Conditions are identified in which thermal runaway is small to nonexistent, which typically means temperatures less than 255 C and heating rates less than 1 C/min. Activation energies are typically in the 140 to 150 kJ/mol regime for open pan experiments and about 160 kJ/mol for sealed pan experiments. Our activation energies are about 10% lower than those derived from data supplied by the University of Utah, which we consider the best previous work. The reaction clearly displays more than one process, and most likely three processes, which are most clearly evident in open pan experiments. The reaction is accelerated for closed pan experiments, and one global reaction appears to fit the data well.

  18. Thermal Decomposition Kinetics of HMX

    SciTech Connect

    Burnham, A K; Weese, R K

    2005-03-17

    Nucleation-growth kinetic expressions are derived for thermal decomposition of HMX from a variety of types of data, including mass loss for isothermal and constant rate heating in an open pan, and heat flow for isothermal and constant rate heating in open and closed pans. Conditions are identified in which thermal runaway is small to nonexistent, which typically means temperatures less than 255 C and heating rates less than 1 C/min. Activation energies are typically in the 140 to 165 kJ/mol regime for open pan experiments and about 150-165 kJ/mol for sealed-pan experiments. The reaction clearly displays more than one process, and most likely three processes, which are most clearly evident in open pan experiments. The reaction is accelerated for closed pan experiments, and one global reaction fits the data fairly well. Our A-E values lie in the middle of the values given in a compensation-law plot by Brill et al. (1994). Comparison with additional open and closed low temperature pyrolysis experiments support an activation energy of 165 kJ/mol at 10% conversion.

  19. Thermal Decomposition Kinetics of HMX

    SciTech Connect

    Burnham, A K; Weese, R K

    2004-11-18

    Nucleation-growth kinetic expressions are derived for thermal decomposition of HMX from a variety of thermal analysis data types, including mass loss for isothermal and constant rate heating in an open pan and heat flow for isothermal and constant rate heating in open and closed pans. Conditions are identified in which thermal runaway is small to nonexistent, which typically means temperatures less than 255 C and heating rates less than 1 C/min. Activation energies are typically in the 140 to 165 kJ/mol range for open pan experiments and about 150 to 165 kJ/mol for sealed pan experiments. Our activation energies tend to be slightly lower than those derived from data supplied by the University of Utah, which we consider the best previous thermal analysis work. The reaction clearly displays more than one process, and most likely three processes, which are most clearly evident in open pan experiments. The reaction is accelerated in closed pan experiments, and one global reaction appears to fit the data well. Comparison of our rate measurements with additional literature sources for open and closed low temperature pyrolysis from Sandia gives a likely activation energy of 165 kJ/mol at 10% conversion.

  20. Damaging HMX/HTPB formulations: In-situ compression imaging using X-ray micro computed tomography

    SciTech Connect

    Patterson, Brian M.; Cordes, Nikolaus Lynn; Tappan, Bryce C.; Thompson, Darla Graff; Manner, Virginia Warren

    2015-04-17

    HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) is a powerful high explosive that is routinely used in formulations such as PBX 9501. Much remains to be learned about the performance and mechanical properties of HMX formulations such as these, particularly after dynamic damage has occurred. We have prepared formulations with HMX using hydroxyl terminated polybutadiene (HTPB) binder in order to form an explosive that is relatively insensitive to mild stimuli, analogous to PBXB-110 (different only is substitution of dioctyladipate (DO) for isodecyl pelargonate).

  1. Complete equation of state for [beta]-HMX and implications for initiation

    SciTech Connect

    Sewell, T. D.; Menikoff, Ralph

    2003-01-01

    A thermodynamically consistent equation of state for {beta}-HMX, the stable ambient polymorph of HMX, is developed that fits isothermal compression data and the temperature dependence of the specific heat computed from molecular dynamics. The equation of state is used to assess hot-spot conditions that would result from hydrodynamic pore collapse in a shock-to-detonation transition. The hot-spot temperature is determined as a function of shock strength by solving two Riemann problems in sequence: first for the velocity and density of the jet formed when the shock overtakes the pore, and second for the stagnation state when the jet impacts the far side of the pore. For a shock pressure below 5 GPa, the stagnation temperature from the jet is below the melt temperature at ambient pressure and hence insufficient for rapid reaction. Consequently for weak shocks a dissipation mechanism in addition to shock heating is needed to generate hot spots. When the stagnation temperature is sufficiently high for rapid reaction, the shock emanating from the hot spot is computed, assuming aconstant volume burn. For initial shocks below 20 GPa, the temperature behind the second shock is below 1000K and would not propagate a detonation wave. This analysis, based solely on the equation of state of the explosive, can serve as a check on mesoscale simulations of initiation in a plastic-bonded explosive.

  2. Synthesis and First Principles Investigation of HMX/NMP Cocrystal Explosive

    NASA Astrophysics Data System (ADS)

    Lin, He; Zhu, Shun-Guan; Zhang, Lin; Peng, Xin-Hua; LI, Hong-Zhen

    2013-10-01

    1,3,5,7-Tetranitro-l,3,5,7-tetrazocine (HMX)/N-methyl-2-pyrrolidone (NMP) cocrystal explosive was prepared by a solution evaporation method. This cocrystal explosive crystallized in the trigonal system (space group ? ), with cell parameters a = 16.605(8) Å and c = 31.496(4) Å. Theoretical investigations of the formation mechanism of HMX/NMP cocrystal were carried out in Cambridge serial total energy package (CASTEP) based on dispersion-corrected density functional theory (DFT-D) with a plane wave scheme. The exchange-correlation potential was treated with the Perdew-Burke-Ernzerhof function of generalized gradient approximation, and dispersion force was correlated using Grimme's method. The band structure, density of states, projected density of states, and Mulliken populations were calculated at the generalized gradient approximation level. The results showed that the main host-guest interactions in HMX/NMP cocrystal were hydrogen bonds and stacking interactions, which were the same as those analyzed using X-ray diffraction. Theoretical investigations of HMX/NMP cocrystal explosive may provide the basis for the preparation of cocrystal explosive composed of HMX and energetic materials.

  3. A Molecular Dynamics simulation of Hugoniot curves of HMX using ReaxFF and its application in SPH modeling of macroscale terminal effects

    NASA Astrophysics Data System (ADS)

    Liu, Gui-Rong; Wang, Gangyu; Peng, Qing; de, Suvranu

    2015-06-01

    HMX is a widely used high explosive. Hugoniot curve is a valuable tool for analyzing the equations of state, and is of importance for all energetic materials including HMX. The Hugoniot curves serve as one of the key character in continuum modeling of high explosives. It can be obtained from experimental measurements, and recently also from computational studies. In this study, the Hugoniot curve of HMX is calculated using a multi-scale shock technique via Molecular Dynamics (MD) simulations, where the reactive force field ReaxFF is obtained from Quantum Mechanics calculations and tailored for HMX. It is found that our MD Hugoniot curve of HMX from the optimized ReaxFF potential agree well with experiments. The MD Hugoniot curve of HMX is also incorporated in our in-house Smoothed Particle Hydrodynamics (SPH) code for the modeling of the macro-scale explosive behaviors of HMX explosives and HMX cased in a 3D cylinder. The authors would like to acknowledge the generous financial support from the Defense Threat Reduction Agency (DTRA) Grant HDTRA1-13-1-0025.

  4. Pressure Dependent Decomposition Kinetics of the Energetic Material HMX up to 3.6 GPa

    SciTech Connect

    Glascoe, E A; Zaug, J M; Burnham, A K

    2009-05-29

    The effect of pressure on the thermal decomposition rate of the energetic material HMX was studied. HMX was precompressed in a diamond anvil cell (DAC) and heated at various rates. The parent species population was monitored as a function of time and temperature using Fourier transform infrared (FTIR) spectroscopy. Decomposition rates were determined by fitting the fraction reacted to the extended-Prout-Tompkins nucleation-growth model and the Friedman isoconversional method. The results of these experiments and analysis indicate that pressure accelerates the decomposition at low to moderate pressures (i.e. between ambient pressure and 1 GPa) and decelerates the decomposition at higher pressures. The decomposition acceleration is attributed to pressure enhanced autocatalysis whereas the deceleration at high pressures is attributed pressure inhibiting bond homolysis step(s), which would result in an increase in volume. These results indicate that both {beta} and {delta} phase HMX are sensitive to pressure in the thermally induced decomposition kinetics.

  5. Understanding metastable phase transformation during crystallization of RDX, HMX and CL-20: experimental and DFT studies.

    PubMed

    Ghosh, Mrinal; Banerjee, Shaibal; Shafeeuulla Khan, Md Abdul; Sikder, Nirmala; Sikder, Arun Kanti

    2016-09-14

    Multiphase growth during crystallization severely affects deliverable output of explosive materials. Appearance and incomplete transformation of metastable phases are a major source of polymorphic impurities. This article presents a methodical and molecular level understanding of the metastable phase transformation mechanism during crystallization of cyclic nitramine explosives, viz. RDX, HMX and CL-20. Instantaneous reverse precipitation yielded metastable γ-HMX and β-CL-20 which undergo solution mediated transformation to the respective thermodynamic forms, β-HMX and ε-CL-20, following 'Ostwald's rule of stages'. However, no metastable phase, anticipated as β-RDX, was evidenced during precipitation of RDX, which rather directly yielded the thermodynamically stable α-phase. The γ→β-HMX and β→ε-CL-20 transformations took 20 and 60 minutes respectively, whereas formation of α-RDX was instantaneous. Density functional calculations were employed to identify the possible transition state conformations and to obtain activation barriers for transformations at wB97XD/6-311++G(d,p)(IEFPCM)//B3LYP/6-311G(d,p) level of theory. The computed activation barriers and lattice energies responsible for transformation of RDX, HMX and CL-20 metastable phases to thermodynamic ones conspicuously supported the experimentally observed order of phase stability. This precise result facilitated an understanding of the occurrence of a relatively more sensitive and less dense β-CL-20 phase in TNT based melt-cast explosive compositions, a persistent and critical problem unanswered in the literature. The crystalline material recovered from such compositions revealed a mixture of β- and ε-CL-20. However, similar compositions of RDX and HMX never showed any metastable phase. The relatively long stability with the highest activation barrier is believed to restrict complete β→ε-CL-20 transformation during processing. Therefore a method is suggested to overcome this issue. PMID

  6. A theoretical study of the stress relaxation in HMX on the picosecond time scale

    NASA Astrophysics Data System (ADS)

    Long, Yao; Chen, Jun

    2015-12-01

    The stress relaxation model of β-HMX on the picosecond time scale is studied by a theoretical approach. The relaxation of normal stress is contributed by lattice vibration, and the relaxation of shear stress is contributed by molecular rotation. Based on this model, the energy dissipation rule of the elastic wave and the profile of the shock wave are investigated. We find at low frequency the dissipation rate of the elastic wave is proportional to the power function of frequency, and under high speed shock loading the width of the stress relaxation zone is less than 0.3 μm there is a pressure peak with a height of 14 GPa near the wave front.

  7. Shock Sensitivity of LX-04 Containing Delta Phase HMX at Elevated Temperatures

    SciTech Connect

    Urtiew, P A; Forbes, J W; Tarver, C M; Vandersall, K S; Garcia, F; Greenwood, D W; Hsu, P C; Maienschein, J L

    2003-07-11

    LX-04 is a widely used HMX-based plastic bonded explosive, which contains 85 weight % HMX and 15 weight % Viton binder. The sensitivity of LX-04 to a single stimulus such as heat, impact, and shock has been previously studied. However, hazard scenarios can involve multiple stimuli, such as heating to temperatures close to thermal explosion conditions followed by fragment impact, producing a shock in the hot explosive. The sensitivity of HMX at elevated temperatures is further complicated by the beta to delta solid-state phase transition, which occurs at approximately 165 C. This paper presents the results of shock initiation experiments conducted with LX-04 preheated to 190 C, as well as density measurements and small scale safety test results of the {delta} phase HMX at room temperature. This work shows that LX-04 at 190 C is more shock sensitive than LX-04 at 150 C or 170 C due to the volume increase during the {beta} to {delta} solid phase transition, which creates more hot spots, and the faster growth of reaction during shock compression.

  8. Human health risks from TNT, RDX, and HMX in environmental media and consideration of the US Regulatory Environment

    SciTech Connect

    Daniels, J.I.; Knezovich, J.P.

    1994-12-01

    Although the most economical method for disposing of unwanted energetic high explosives [HEs; e.g., 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-triazine (RDX, also known as Cyclonite), and octahydro-1,3,5,7-tetrazocine (HMX, also known as Octogen)] involves open burning and open or underground detonation [OB/O(U)D]; federal, state, and even local government agencies in the United States (U.S.) are implementing stricter environmental regulations that eventually may prevent such activities. These stricter regulations will promote alternative technologies that are designed to be environmentally benign. However, past HE-waste disposal practices at manufacturing and fabrication facilities in the U.S. have included uncontrolled OB/O(U)D, as well as direct surface discharge of HE-contaminated waste water, resulting in contaminated environmental media (e.g., ground water, soil, and perhaps even edible vegetation) near residential areas. Using TNT, RDX, and HMX as examples, this paper describes how risk-based standards for HEs can be derived that account for potential multimedia exposures (associated with contaminated air, water, food, and soil) by individuals near a contaminated site, and used to (1) protect public health and safety; (2)prevent limited resources from being dedicated to unnecessary cleanup activities; and (3) identify the most cost-effective, practical, and environmentally benign technologies suitable for integrating with the handling of the large quantity of high explosives scheduled for demilitarization.

  9. Accumulation and effects of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) exposure in the green anole (Anolis carolinensis).

    PubMed

    McMurry, S T; Jones, L E; Smith, P N; Cobb, G P; Anderson, T A; Lovern, M B; Cox, S; Pan, X

    2012-03-01

    Environmental contamination by energetic compounds is an increasing international concern, although little is known of their accumulation in and affect on wildlife. Reptiles are often good models for contaminants studies due to natural history traits that increase their potential for exposure. We report a study to assess accumulation and effects of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX, High Melting Explosive) in green anoles (Anolis carolinensis). Acute oral toxicity (LD(50)) was estimated to exceed 2000 mg/kg body weight in adult male and female anoles using a standard up-and-down method. Accumulation of HMX was assessed in adult females via dietary exposure and into eggs by two routes (directly from the soil and via maternal transfer). HMX readily accumulated into adult females in a dose-dependent manner and into eggs following both exposure pathways. However, total HMX in soil-exposed eggs was up to 40-times greater than those exposed via maternal transfer. Although there was a suggestion of an HMX-induced reduction in body weight in adult females, overall there were no effects observed over the 12 week exposure period. The only significant effect on eggs was a 50% reduction in hatching success for eggs exposed to 2000 mg/kg HMX in the soil during incubation. Growth and survival of hatchlings was not affected by HMX exposure. Our results demonstrate that HMX accumulates through the food chain and into eggs from the soil, but likely poses minimal threat to lizards except to hatching success in eggs incubated in soils with HMX levels near maximum environmental concentrations. PMID:21947615

  10. Synthesis, thermolysis, and sensitivities of HMX/NC energetic nanocomposites.

    PubMed

    Wang, Yi; Song, Xiaolan; Song, Dan; Liang, Li; An, Chongwei; Wang, Jingyu

    2016-07-15

    1,3,5,7-Tetranittro-1,3,5,7-tetrazocane/nitrocellulose (HMX/NC) nanocomposites were successfully synthesized by an improved sol-gel-supercritical method. NC nanoparticles with a size of ∼30nm were cross-linked to form a network structure, and HMX nanoparticles were imbedded in the nano-NC matrix. The key factors, i.e., the selection of catalyst and solvent, were probed. No phase transformation of the HMX occurred before or after fabrication, and the molecular structures of the HMX and NC did not change. Thermal analyses were performed, and the kinetic and thermodynamic parameters, such as activation energy (EK), per-exponent factor (lnAK), rate constant (k), activation heat (ΔH(≠)), activation free energy (ΔG(≠)), activation entropy (ΔS(≠)), critical temperature of thermal explosion (Tb), and critical heating rate of thermal explosion (dT/dt)Tb, were calculated. The results indicate that HMX/NC presented a much lower activation energy (165.03kJ/mol) than raw HMX (282.5kJ/mol) or raw NC (175.51kJ/mol). The chemical potential (ΔG(≠)) for the thermal decomposition of HMX/NC has a positive value, which means that the activation of the molecules would not proceed spontaneously. The significantly lower ΔH(≠) value of HMX/NC, which represents the heat needed to be absorbed by an explosive molecule to change it from its initial state to an activated state, implies that the molecules of HMX/NC are much easier to be activated than those of raw HMX. Similarly, the HMX/NC presented a much lower Tb (168.2°C) than raw HMX (283.2°C). From the results of the sensitivity tests, the impact and friction sensitivities of HMX/NC were significantly decreased compared with those of raw HMX, but the thermal sensitivity was distinctly higher. The activation of the particles under external stimulation was simulated, and the mechanism was found to be crucial. Combining the thermodynamic parameters, the mechanism as determined from the results of the sensitivity tests was

  11. Kinetics of (beta)(right arrow)(delta) Solid-Solid Phase Transition of HMX

    SciTech Connect

    Weese, R K

    2000-09-01

    In order to calculate the kinetic parameters from DSC data, we have used the generally accepted methods of Bershtein [13]. We have calculated the rate constants for 4 temperatures and the activation energy based on the shift in the transition temperature, {beta} {yields} {delta} for HMX. The values of E{sub a} from this work is 402 kJ/mol compared to previous results by Brill [9] of 204 kJ/mol. Brill and associates measured the phase transition of HMX using FTIR, sodium chloride plates and silicon oil. Given the differences in technique between FTIR and DSC the results found in this work are reasonable. In this investigation a large sample set (16) proved to be statistically valid for the determinations of k. Linear regressions were performed, observed and good fits were obtained, for each temperature. The enthalpy determination of {Delta}H{sub o}, for the {beta} {yields} {delta} phase transition was reproducible with in 3 parts in 100 over the range of this experiment. Thus, the data derived from this experiment k, E{sub a}, and {Delta}H{sub o} are valid parameters for the solid-solid phase transition. Obtaining pure {beta} phase HMX was very important for this investigation. Related to the phase change is the particle size distribution and is presented in Figure 3. Compared to previous work on HMX, this study utilized very pure {beta} phase material. In addition, the particle size was controlled more rigorously at about 160 {micro}m, giving a more consistent result for {alpha}. Thus, these kinetic results should have less scatter than results with less control of HMX purity and particle size. The kinetic basis of the polymorphic conversion is due to the cohesive forces in the HMX crystal lattice [21]. The energy required to bring about change from chair to chair-chair conformation has been reported by Brill [21] as ring torsion and is essentially a normal mode of the molecule that requires about 4 kJ mol{sup -1}. For the purpose of this investigation the energy

  12. Modeling compaction-induced energy dissipation of granular HMX

    SciTech Connect

    Gonthier, K.A.; Menikoff, R.; Son, S.F.; Asay, B.W.

    1998-12-31

    A thermodynamically consistent model is developed for the compaction of granular solids. The model is an extension of the single phase limit of two-phase continuum models used to describe Deflagration-to-Detonation Transition (DDT) experiments. The focus is on the energetics and dissipation of the compaction process. Changes in volume fraction are partitioned into reversible and irreversible components. Unlike conventional DDT models, the model is applicable from the quasi-static to dynamic compaction regimes for elastic, plastic, or brittle materials. When applied to the compaction of granular HMX (a brittle material), the model predicts results commensurate with experiments including stress relaxation, hysteresis, and energy dissipation. The model provides a suitable starting point for the development of thermal energy localization sub-scale models based on compaction-induced dissipation.

  13. High dynamic range emission measurements of shocked energetic materials: Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)

    NASA Astrophysics Data System (ADS)

    Bassett, Will P.; Dlott, Dana D.

    2016-06-01

    A new emission apparatus with high time resolution and high dynamic range was used to study shock-induced ignition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine in the form of ultrafine powder (4 ± 3 μm particle size), over a range of impact velocities (0.8-4.3 km s-1) and impact durations (2.5-16 ns). A graybody model was used to extract graybody emissivities and time-dependent temperatures from a few ns to 100 μs. The emission transients consisted of three parts: a 6700 K nanosecond burst during the shocks, a 4000-4500 K temperature spike near 0.3 μs followed by a ˜3300 K tail extending out to ˜100 μs. These temperatures varied remarkably little with impact velocity and duration, while the emission intensities and emissivities changed by over an order of magnitude. The emissivity changes were interpreted with a hot spot model, where hot spot temperatures reached a maximum of 6700 K and the hot spot volume fractions increased from 5% to 100% as impact velocity increased from 1 to 3 km s-1. Changing shock durations in the 2.5-16 ns range had noticeable effects on the microsecond emission. The 0.3 μs temperature spike was much smaller or absent with 2.5 ns shocks, but prominent with longer durations. An explanation for these effects was put forth that invoked the formation of carbon-rich clusters during the shock. In this view, cluster formation was minimal with 2.5 ns shocks, but longer-duration shocks produced increasingly larger clusters, and the 0.3 μs temperature spikes represented cluster ignition.

  14. How does low temperature coupled with different pressures affect initiation mechanisms and subsequent decompositions in nitramine explosive HMX?

    PubMed

    Wu, Qiong; Xiong, Guolin; Zhu, Weihua; Xiao, Heming

    2015-09-21

    We have performed ab initio molecular dynamics simulations to study coupling effects of temperature (534-873 K) and pressure (1-20 GPa) on the initiation mechanisms and subsequent chemical decompositions of nitramine explosive 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX). A new initiation decomposition mechanism of HMX was found to be the unimolecular C-H bond breaking, and this mechanism was independent of the coupling effects of different temperatures and pressures. The formed hydrogen radicals could promote subsequent decompositions of HMX. Subsequent decompositions were very sensitive to the pressure at low temperatures (534 and 608 K), while the temperature became the foremost factor that affected the decomposition at a high temperature (873 K) instead of the pressure. Our study may provide a new insight into understanding the coupling effects of the temperature and pressure on the initiation decomposition mechanisms of nitramine explosives. PMID:26264421

  15. The fate and transport of RDX, HMX, TNT and DNT in the volcanic soils of Hawaii: a laboratory and modeling study.

    PubMed

    Alavi, Ghasem; Chung, Mel; Lichwa, Joseph; D'Alessio, Matteo; Ray, Chittaranjan

    2011-01-30

    The adsorption and degradation behavior of RDX, HMX, TNT and DNT and the impact of pH, ionic strength and dissolved organic matter on sorption were examined for two volcanic soils of a former military training area on Hawaii Island, Hawaii, USA. The transport of these chemicals in the soil was also studied in small packed columns and simulated using a water-flow and solute-transport model, HYDRUS_1D. The results show that HMX and RDX are both significantly more mobile than TNT and DNT. The adsorbability of the four chemicals was ranked as: RDX<HMXHMX>RDX>DNT>TNT. No significant trend was observed for the effect of ionic strength, pH and dissolved organic carbon (DOC) on the adsorption of explosive compounds within the concentrations and pH ranges evaluated. The simulation results show that TNT and DNT would not leach beyond a depth of 30cm soil profile whereas a significant amount of HMX and RDX would pass the 30cm depth. It seems that the risk for contamination of groundwater is much higher for both HMX and RDX than for DNT and TNT as the substratum in this area consists of highly permeable lavas. PMID:21087822

  16. A direct method to calculate thermal conductivity and its application in solid HMX.

    PubMed

    Long, Y; Chen, J; Liu, Y G; Nie, F D; Sun, J S

    2010-05-12

    The calculation of thermal conductivity for complex material systems is a challenging problem in computational materials science. Its key point is to calculate heat flux. In this work, we derive a concise formula for this purpose based on the equation of motion and then use it to study the thermal conduction properties of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), which is a widely used plastic-bonded explosive (PBX). The results are in fair agreement with experiments and show a distinct thermal conduction anisotropy for HMX single crystals. Then we investigate some key issues of thermal conductivity, such as its temperature-dependence and composition-dependence. A series of interesting results are obtained. PMID:21393685

  17. Porous HMX initiation studies -- Sugar as an inert simulant

    SciTech Connect

    Sheffield, S.A.; Gustavsen, R.L.; Alcon, R.R.

    1997-11-01

    For several years the authors have been using magnetic particle velocity gauges to study the shock loading of porous HMX (65 and 73% TMD) of different particle sizes to determine their compaction and initiation characteristics. Because it has been difficult to separate the effects of compaction and reaction, an inert simulant was needed with properties similar to HMX. Sugar was selected as the simulant for several reasons: (1) the particle size distribution of C and H granulated sugar is similar to the coarse HMX the authors have been using (120 {micro}m average size), (2) the particle size of C and H confectioners (powdered) sugar is similar to the fine HMX in the studies (10 {micro}m average size), (3) it is an organic material, and (4) sugar was readily available. Because the densities of HMX and sugar are somewhat different, the authors chose to do the experiments on sugar compacts at 65 and 73% TMD. As expected, no reaction was observed in the sugar experiments. Compaction wave profiles were similar to those measured earlier for the HMX, i.e., the compaction waves in the coarse sugar were quite disperse while those in the fine sugar were much sharper. This indicates that the compaction wave profiles are controlled by particle size and not reaction. Also, the coarse sugar gauge signals exhibited a great deal of noise, thought to the be result of fracto-emission.

  18. Trace Detection of RDX, HMX and PETN Explosives Using a Fluorescence Spot Sensor

    NASA Astrophysics Data System (ADS)

    Wang, Chen; Huang, Helin; Bunes, Benjamin R.; Wu, Na; Xu, Miao; Yang, Xiaomei; Yu, Li; Zang, Ling

    2016-05-01

    1,3,5-trinitroperhydro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and pentaerythritol tetranitrate (PETN), the major components in plastic explosives, pose a significant threat to public safety. A quick, sensitive, and low-cost detection method for these non-volatile explosives is eagerly demanded. Here we present a fluo-spot approach, which can be employed for in situ detection of trace amount of explosives. The sensor molecule is a charge-transfer fluorophore, DCM, which is strongly fluorescent in its pristine state, but non-fluorescent after the quick reaction with NO2· (or NO2+) generated from the UV photolysis of RDX, HMX (or PETN). When fabricated within silica gel TLC plate, the fluo-spot sensor features high sensitivity owing to the large surface area and porous structure of the substrate. The sensor reaction mechanism was verified by various experimental characterizations, including chromatography, UV-Vis absorption and fluorescence spectroscopy, MS and 1H NMR spectrometry. The fluo-spot also demonstrated high selectivity towards RDX, HMX and PETN, as no significant fluorescence quenching was observed for other chemical compounds including common nitro-aromatic explosives and inorganic oxidative compounds. The DCM sensor can also be used as an economical spray kit to directly spot the explosives by naked eyes, implying great potential for quick, low-cost trace explosives detection.

  19. Trace Detection of RDX, HMX and PETN Explosives Using a Fluorescence Spot Sensor.

    PubMed

    Wang, Chen; Huang, Helin; Bunes, Benjamin R; Wu, Na; Xu, Miao; Yang, Xiaomei; Yu, Li; Zang, Ling

    2016-01-01

    1,3,5-trinitroperhydro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and pentaerythritol tetranitrate (PETN), the major components in plastic explosives, pose a significant threat to public safety. A quick, sensitive, and low-cost detection method for these non-volatile explosives is eagerly demanded. Here we present a fluo-spot approach, which can be employed for in situ detection of trace amount of explosives. The sensor molecule is a charge-transfer fluorophore, DCM, which is strongly fluorescent in its pristine state, but non-fluorescent after the quick reaction with NO2· (or NO2(+)) generated from the UV photolysis of RDX, HMX (or PETN). When fabricated within silica gel TLC plate, the fluo-spot sensor features high sensitivity owing to the large surface area and porous structure of the substrate. The sensor reaction mechanism was verified by various experimental characterizations, including chromatography, UV-Vis absorption and fluorescence spectroscopy, MS and (1)H NMR spectrometry. The fluo-spot also demonstrated high selectivity towards RDX, HMX and PETN, as no significant fluorescence quenching was observed for other chemical compounds including common nitro-aromatic explosives and inorganic oxidative compounds. The DCM sensor can also be used as an economical spray kit to directly spot the explosives by naked eyes, implying great potential for quick, low-cost trace explosives detection. PMID:27146290

  20. Trace Detection of RDX, HMX and PETN Explosives Using a Fluorescence Spot Sensor

    PubMed Central

    Wang, Chen; Huang, Helin; Bunes, Benjamin R.; Wu, Na; Xu, Miao; Yang, Xiaomei; Yu, Li; Zang, Ling

    2016-01-01

    1,3,5-trinitroperhydro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and pentaerythritol tetranitrate (PETN), the major components in plastic explosives, pose a significant threat to public safety. A quick, sensitive, and low-cost detection method for these non-volatile explosives is eagerly demanded. Here we present a fluo-spot approach, which can be employed for in situ detection of trace amount of explosives. The sensor molecule is a charge-transfer fluorophore, DCM, which is strongly fluorescent in its pristine state, but non-fluorescent after the quick reaction with NO2· (or NO2+) generated from the UV photolysis of RDX, HMX (or PETN). When fabricated within silica gel TLC plate, the fluo-spot sensor features high sensitivity owing to the large surface area and porous structure of the substrate. The sensor reaction mechanism was verified by various experimental characterizations, including chromatography, UV-Vis absorption and fluorescence spectroscopy, MS and 1H NMR spectrometry. The fluo-spot also demonstrated high selectivity towards RDX, HMX and PETN, as no significant fluorescence quenching was observed for other chemical compounds including common nitro-aromatic explosives and inorganic oxidative compounds. The DCM sensor can also be used as an economical spray kit to directly spot the explosives by naked eyes, implying great potential for quick, low-cost trace explosives detection. PMID:27146290

  1. Kinetics of HMX and CP Decomposition and Their Extrapolation for Lifetime Assessment

    SciTech Connect

    Burnham, A K; Weese, R K; Andrzejewski, W J

    2005-03-10

    Decomposition kinetics are determined for HMX (nitramine octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) and CP (2-(5-cyanotetrazalato) pentaammine cobalt (III) perchlorate) separately and together. For high levels of thermal stress, the two materials decompose faster as a mixture than individually. This effect is observed both in high-temperature thermal analysis experiments and in long-term thermal aging experiments. An Arrhenius plot of the 10% level of HMX decomposition by itself from a diverse set of experiments is linear from 120 to 260 C, with an apparent activation energy of 165 kJ/mol. Similar but less extensive thermal analysis data for the mixture suggests a slightly lower activation energy for the mixture, and an analogous extrapolation is consistent with the amount of gas observed in the long-term detonator aging experiments, which is about 30 times greater than expected from HMX by itself for 50 months at 100 C. Even with this acceleration, however, it would take {approx}10,000 years to achieve 10% decomposition at {approx}30 C. Correspondingly, negligible decomposition is predicted by this kinetic model for a few decades aging at temperatures slightly above ambient. This prediction is consistent with additional sealed-tube aging experiments at 100-120 C, which are estimated to have an effective thermal dose greater than that from decades of exposure to temperatures slightly above ambient.

  2. The Anisotropic Dynamic Response of Ultrafast Shocked Single Crystal PETN and Beta-HMX

    NASA Astrophysics Data System (ADS)

    Zaug, Joseph; Armstrong, Michael; Crowhurst, Jonathan; Austin, Ryan; Ferranti, Louis; Fried, Laurence; Bastea, Sorin

    2015-06-01

    We report results from ultrafast shockwave experiments conducted on single crystal high explosives. Experimental results consist of 12 picosecond time-resolved dynamic response wave profile data, (ultrafast time-domain interferometry-TDI), which are used to validate calculations of anisotropic stress-strain behavior of shocked loaded energetic materials. In addition, here we present unreacted equations of state data from PETN and beta-HMX up to higher pressures than previously reported, which are used to extend the predictive confidence of hydrodynamic simulations. Our previous results derived from a 360 ps drive duration yielded anisotropic elastic wave response in single crystal beta-HMX ((110) and (010) impact planes). Here we provide results using a 3x longer drive duration to probe the plastic response regime of these materials. We compare our ultrafast time domain interferometry (TDI) results with previous gun platform results. Ultrafast time scale resolution TDI measurements further guide the development of continuum models aimed to study pore collapse and energy localization in shock-compressed crystals of beta-HMX. This work was performed under the auspices of the U.S. Department of Energy jointly by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  3. Deflagration to detonation experiments in granular HMX

    SciTech Connect

    Burnside, N.J.; Son, S.F.; Asay, B.W.; Dickson, P.M.

    1998-03-01

    In this paper the authors report on continuing work involving a series of deflagration-to-detonation transition (DDT) experiments in which they study the piston-initiated DDT of heavily confined granular cyclotetramethylenetetranitramine (HMX). These experiments were designed to he useful in model development and evaluation. A main focus of these experiments is the effect of density on the DDT event. Particle size distribution and morphology are carefully characterized. In this paper they present recent surface area analysis. Earlier studies demonstrated extensive fracturing and agglomeration in samples at densities as low as 75% TMD as evidenced by dramatic decreases in particle size distribution due to mild stimulus. This is qualitatively confirmed with SEM images and quantitatively studied with gas absorption surface area analysis. Also, in this paper they present initial results using a microwave interferometer technique. Dynamic calibration of the technique was performed, a 35 GHz signal is used to increase resolution, and the system has been designed to be inexpensive for repeated experiments. The distance to where deformation of the inner wall begins for various densities is reported. This result is compared with the microwave interferometer measurements.

  4. Modeling pore collapse and chemical reactions in shock-loaded HMX crystals

    NASA Astrophysics Data System (ADS)

    Austin, Ryan; Barton, Nathan; Howard, William; Fried, Laurence

    2013-06-01

    The collapse of micron-sized pores in crystalline high explosives is the primary route to initiating thermal decomposition reactions under shock wave loading. Given the difficulty of resolving such processes in experiments, it is useful to study pore collapse using numerical simulation. A significant challenge that is encountered in such calculations is accounting for anisotropic mechanical responses and the effects of highly exothermic chemical reactions. In this work, we focus on simulating the shock-wave-induced collapse of a single pore in crystalline HMX using a multiphysics finite element code (ALE3D). The constitutive model set includes a crystal-mechanics-based model of thermoelasto-viscoplasticity and a single-step decomposition reaction with empirically determined kinetics. The model is exercised for shock stresses up to ~10 GPa to study the localization of energy about the collapsing pore and the early stages of reaction initiation. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 (LLNL-ABS-618941).

  5. Photoexcitation, Reaction Localization and Energy Dissipation in Single beta-HMX Crystals subjected to 20 GPa Shock and PBX Detonation

    NASA Astrophysics Data System (ADS)

    Plaksin, Igor; Rodrigues, L.; Plaksin, S.; Mendes, R.; Campos, J.; Simoes, P.

    2011-06-01

    We present experimentally revealed highly anisotropic dynamics of the detonation conversion occurring in beta-HMX crystals. Panoramic observation of 1-mm single b-HMX crystal surrounded by different binder materials (HTPB, GAP, water) and by fine-grained PBX (HMX 85/15 GAP as a dirty binder) performed by mean of Multi-Channel Optical Analyzer (96 optical fibers) provided spatially resolved measurements of reaction spots onset/growth and a post-detonation ejecta of reaction products via the radiance registration carried out with 100 μm-spatial and 0.2 ns-temporal accuracy in a spectral range 450-850 nm. Experimental evidences obtained in more than 20 tests with b-HMX crystals subjected to a 20 GPa shock and to the PBX detonation (51 GPa-VN spike at entering to a crystal and 21.5 GPa-CJ pressure), demonstrate that independently on orientation crystal vs. input front, a major reaction spots are localized in crystal vertexes/edges and the emitted reaction radiance induces photoexcitation in the crystal bulk causing a radiation-induced precursor of the major reaction front. Further reaction spots dissipation is attended by origination of the reaction products' longitudinal/transversal ejecta moving behind the leading front with the 20-30 micron/ns speed. This work was funded by the Office of Naval Research under the Grant No 0014-08-1-0096 with Dr. Clifford Bedford as Program Manager.

  6. DMSO/base hydrolysis method for the disposal of high explosives and related energetic materials

    DOEpatents

    Desmare, Gabriel W.; Cates, Dillard M.

    2002-05-14

    High explosives and related energetic materials are treated via a DMSO/base hydrolysis method which renders them non-explosive and/or non-energetic. For example, high explosives such as 1,3,5,7-tetraaza-1,3,5,7-tetranitrocyclooctane (HMX), 1,3,5-triaza-1,3,5-trinitrocyclohexane (RDX), 2,4,6-trinitrotoluene (TNT), or mixtures thereof, may be dissolved in a polar, aprotic solvent and subsequently hydrolyzed by adding the explosive-containing solution to concentrated aqueous base. Major hydrolysis products typically include nitrite, formate, and nitrous oxide.

  7. Thermal Decomposition Behaviors and Burning Characteristics of AN/Nitramine-Based Composite Propellant

    NASA Astrophysics Data System (ADS)

    Naya, Tomoki; Kohga, Makoto

    2015-04-01

    Ammonium nitrate (AN) has attracted much attention due to its clean burning nature as an oxidizer. However, an AN-based composite propellant has the disadvantages of low burning rate and poor ignitability. In this study, we added nitramine of cyclotrimethylene trinitramine (RDX) or cyclotetramethylene tetranitramine (HMX) as a high-energy material to AN propellants to overcome these disadvantages. The thermal decomposition and burning rate characteristics of the prepared propellants were examined as the ratio of AN and nitramine was varied. In the thermal decomposition process, AN/RDX propellants showed unique mass loss peaks in the lower temperature range that were not observed for AN or RDX propellants alone. AN and RDX decomposed continuously as an almost single oxidizer in the AN/RDX propellant. In contrast, AN/HMX propellants exhibited thermal decomposition characteristics similar to those of AN and HMX, which decomposed almost separately in the thermal decomposition of the AN/HMX propellant. The ignitability was improved and the burning rate increased by the addition of nitramine for both AN/RDX and AN/HMX propellants. The increased burning rates of AN/RDX propellants were greater than those of AN/HMX. The difference in the thermal decomposition and burning characteristics was caused by the interaction between AN and RDX.

  8. Vibron dynamics in RDX, β-HMX and Tetryl crystals

    NASA Astrophysics Data System (ADS)

    Ye, Shuji; Tonokura, Kenichi; Koshi, Mitsuo

    2003-08-01

    The Raman line widths of 16 vibron modes in RDX, β-HMX and Tetryl crystals have been measured at the temperature ranging from 3.6 to 300.0 K. The experimental line shapes were deconvoluted to extract inhomogeneous contribution to the line broadening due to probably crystal defects. The inhomogeneous line width is independent of temperature for most measured modes. The homogeneous line width is interpreted on the basis of elementary relaxation mechanisms. Three-phonon and dephasing processes are dominant relaxation processes for most of the vibrons of RDX, β-HMX and Tetryl. In particular, for Tetryl crystal, the vibrational relaxation is dominated by three-phonon down processes. For RDX and β-HMX crystals, vibrational relaxation is dominated by three-phonon down processes at lower temperature, three-phonon up or dephasing mechanisms generally contribute to the vibron dynamics while above 60 K. The lifetimes of some vibrons in the frequency range of 200-900 cm -1 in RDX, 200-1450 cm -1 in β-HMX and 200-1100 cm -1 in Tetryl crystal were calculated in term of the line widths at low temperature. The lifetimes of the measured vibrons fall in the range of 2.5-11 ps.

  9. The deflagration-to-detonation transition in granular HMX

    SciTech Connect

    McAfee, J.M.; Asay, B.; Campbell, A.W.; Ramsay, J.B.

    1991-01-01

    The transition from deflagration to detonation in porous beds of explosive and propellant has received considerable attention both experimentally and theoretically. In many cases, the use of a hot-gas-producing igniter complicates the interpretation and subsequent modeling of experiments because considerable effort is required to account for the effect of the igniter gases on the granular bed. Hot-wire ignition is less intrusive; however, the ignition front is not planar. Thus the early events in these experiments cannot be approximated as one-dimensional. We have studied the deflagration-to-detonation behavior of granular HMX confined in steel tubes with x-radiography, light emission, stress gauges, and various pin techniques. Simplification and consistency of results were obtained by igniting the HMX with a piston (initially at rest and in contact with the HMX) driven into the bed. A gasless igniter is used to stare the burning of the piston propellant (low-density HMX) providing the piston with a smooth initial motion. Analysis of the data gives a detailed picture of the DDT process under these conditions. The qualitative and quantitative experimental results show the transition from the burning to detonation is discontinuous. The results are discussed in terms of a descriptive model.

  10. Ignition dynamics of high explosives

    SciTech Connect

    Ali, A.N.; Son, S.F.; Sander, R.K.; Asay, B.W.

    1998-12-31

    Mechanical insults of granular high explosives (HE) can result in localized areas of elevated temperature, or hot spots. The evolution of these hot spots is a central issue of HE science. Because of the complexity involved, it is worthwhile to study mechanical and reaction processes in isolation. Mechanical processes are isolated and studied using inert materials or weak insults where reaction may be minimal. Likewise, purely thermal processes can be considered to isolate HE reaction response. In this work the authors study the radiant ignition of various HEs of interest, including HMX (C{sub 4}H{sub 8}N{sub 8}O{sub 8}), PBX 9501 (95% HMX, 2.5% Estane, 2.5% BDNPA/BDNPF), RDX (C{sub 3}H{sub 6}N{sub 6}O{sub 6}), TATB (C{sub 6}H{sub 6}N{sub 6}O{sub 6}), and PBX 9502 (95% TATB, 5% Kel-F) and aged PBX 9502. Initial work has included unconfined samples at ambient pressure in air. Diagnostics have included photodiodes to record first light emission, high speed photography, microthermocouple and IR emission measurement to obtain surface temperature, IR emission of gases above the pellet, and a novel nonlinear optical technique to characterize the dynamic {beta}-{delta} solid phase transformation and the formation of a liquid layer. The authors find that ignition delays at various power levels is very similar for HMX and RDX; except that the minimum radiant flux needed for RDX ignition is higher. The addition of only 5% binder (PBX 9501) causes significantly longer ignition delays at lower heat fluxes compared with HMX alone. TATB and TATB-based explosives exhibit much longer ignition delays than HMX. In contrast to HMX, however, no measurable difference is observed in TATB by the addition of a binder (PBX 9502, aged or pristine).

  11. Theoretical study of β-HMX decomposition mechanism of the solid phase under shock loadings

    NASA Astrophysics Data System (ADS)

    Ji, Guangfu; Ge, Nina; Chen, Xiangrong

    2015-06-01

    Study material properties under extreme conditions is a fundamental problem in the field of condensed matter physics. The decomposition mechanisms of energetic materials under the shock wave become a hot topic in recent years. In this paper, molecular dynamics simulations combined with multi-scale shock technology (MSST) are used to study the decomposition mechanism, shock sensitivity and electronic structure of β-HMX. First, the decomposition mechanism of β-HMX perfect crystal were studied at different shock speeds. We found that when the shock wave at a speed 8 km / s is loaded, the decomposition reaction start at N-NO2 bond breakage; when the shock wave at a speed of 10 km / s and 11 km / s is loaded, the the first decomposition reaction is CH bond breaking, and accompanied by the formation of five-membered ring and transfer of hydrogen ions. The simulation results also show that when the shock wave velocity is increased, the higher the pressure generated in the high-pressure N-NO2 bond cleavage was inhibited significantly. Secondly, the impact of its initial chemical reaction process along different crystal axis directions were studied, the results showed that along the a-axis and c-axis shock sensitivity is higher, and along the b-axis sensitivity is lower. We believe that the system of all sensitivity of direction is due to the rotation of the friction between the slip plane of crystals and molecules. Finally, we discussed the solid phase β-HMX electronic properties change under the shock wave loadings. We found that in the 11 km/s under the impact load, when the pressure reaches 130 GPa, zero bandgap is reached.

  12. Shock-to-detonation transition of RDX and NTO based composite high explosives: experiments and modeling

    NASA Astrophysics Data System (ADS)

    Baudin, Gerard; Roudot, Marie; Genetier, Marc

    2013-06-01

    Composite HMX and NTO based high explosives (HE) are widely used in ammunitions. Designing modern warheads needs robust and reliable models to compute shock ignition and detonation propagation inside HE. Comparing to a pressed HE, a composite HE is not porous and the hot-spots are mainly located at the grain - binder interface leading to a different behavior during shock-to-detonation transition. An investigation of how shock-to-detonation transition occurs inside composite HE containing RDX and NTO is proposed in this lecture. Two composite HE have been studied. The first one is HMX - HTPB 82:18. The second one is HMX - NTO - HTPB 12:72:16. These HE have been submitted to plane sustained shock waves at different pressure levels using a laboratory powder gun. Pressure signals are measured using manganin gauges inserted at several distances inside HE. The corresponding run-distances to detonation are determined using wedge test experiments where the plate impact is performed using a powder gun. Both HE exhibit a single detonation buildup curve in the distance - time diagram of shock-to-detonation transition. This feature seems a common shock-to-detonation behavior for composite HE without porosity. This behavior is also confirmed for a RDX - HTPB 85:15 based composite HE. Such a behavior is exploited to determine the heterogeneous reaction rate versus the shock pressure using a method based on the Cauchy-Riemann problem inversion. The reaction rate laws obtained allow to compute both run-distance to detonation and pressure signals.

  13. One dimensional time-to-explode (ODTX) in HMX spheres

    SciTech Connect

    Breshears, D.

    1997-06-02

    In a series of papers researchers at Lawrence Livermore National Laboratory (LLNL) have reported measurements of the time to explosion in spheres of various high explosives following a rapid, uniform increase in the surface temperature of the sphere. Due to the spherical symmetry, the time-dependent properties of the explosive (temperature, chemical composition, etc.) are functions of the radial spatial coordinate only; thus the name one-dimensional time-to-explosion (ODTX). The LLNL researchers also report an evolving series of computational modeling results for the ODTX experiments, culminating in those obtained using a sophisticated heat transfer code incorporating accurate descriptions of chemical reaction. Although the chemical reaction mechanism used to describe HMX decomposition is quite simple, the computational results agree very well with the experimental data. In addition to reproducing the magnitude and temperature dependence of the measured times to explosion, the computational results also agree with the results of post reaction visual inspection. The ODTX experiments offer a near-ideal example of a transport process (heat transfer in this case) tightly coupled with chemical reaction. The LLNL computational model clearly captures the important features of the ODTX experiments. An obvious question of interest is to what extent the model and/or its individual components (specifically the chemical reaction mechanism) are applicable to other experimental scenarios. Valid exploration of this question requires accurate understanding of (1) the experimental scenario addressed by the LLNL model and (2) details of the application of the model. The author reports here recent work addressing points (1) and (2).

  14. The evolution of microstructural changes in pressed HMX explosives

    SciTech Connect

    Skidmore, C.B.; Phillips, D.S.; Howe, P.M.; Mang, J.T.; Romero, J.A.

    1998-12-31

    Recently developed techniques for investigating the microstructure of plastic-bonded explosives have been applied to HMX explosives pressed to various levels of porosity. Microstructural changes in PBX 9501 area followed from the early stages of prill consolidation through typical density to very low porosity (0.6%). As porosity is reduced, the following sequence is observed. Large inter- and intra-prill voids are eliminated with first damage to HMX crystals occurring at prill boundaries. This is followed by increased incidence of crystal twinning and cracking. At the lowest porosities, spall pullout artifacts are observed, cracks associated with particle contact points are more obvious, and the results of intercrystalline indentation or intergrowth migration processes are apparent. A comparison is made, at lowest porosities achieved, with PX 9404 and X-0242 (a formulation like PBX 9501 with higher binder volume). Possible implications on porosity trends in shock sensitivity data are discussed.

  15. Observation and modeling of deflagration-to-detonation (DDT) transition in low-density HMX

    NASA Astrophysics Data System (ADS)

    Tringe, Joseph; Vandersall, Kevin; Reaugh, Jack; Levie, Harold; Henson, Bryan; Smilowitz, Laura; Parker, Gary

    2015-06-01

    We employ simultaneous flash x-ray radiography and streak imaging, together with a multi-phase finite element model, to understand deflagration-to-detonation transition (DDT) phenomena in low-density (~ 1.2 gm/cm3) powder of the explosive cyclotetramethylene-tetranitramine (HMX). HMX powder was lightly hand-tamped in a 12.7 mm diameter column, relatively lightly-confined in an optically-transparent polycarbonate cylinder with wall thickness 25.4 mm. We observe apparent compaction of the powder in advance of the detonation transition, both by x-ray contrast and by the motion of small steel spheres pre-emplaced throughout the length of explosive. High-speed imaging along the explosive cylinder length provides a temporally continuous record of the transition that is correlated with the high-resolution x-ray image record. Preliminary simulation of these experiments with the HERMES model implemented in the ALE3D code enables improved understanding of the explosive particle burning, compaction and detonation phenomena which are implied by the observed reaction rate and transition location within the cylinder. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  16. Effect of HMX on the combustion response function

    NASA Technical Reports Server (NTRS)

    Strand, L. D.; Cohen, N. S.

    1980-01-01

    Over a pressure range of 3.5-7 MPa and a frequency range of 500-2000 Hz and compared to propellants having equivalent energy and burn rate, HMX produces less pressure-coupled acoustic driving than AP and is equivalent to NC/TMETN. Formation of carbonaceous combustion products indicates that binder decomposition does not follow equilibrium thermochemistry, and that this is aggravated by fuel richness or the absence of AP.

  17. Pressing Induced Polymorphic Phase Transition in Submicron-Sized Gamma-Hmx

    NASA Astrophysics Data System (ADS)

    Lee, K.-Y.; Moore, D. S.

    2007-12-01

    Using Raman spectroscopy, a novel submicron-sized HMX (sm-HMX) was determined to be both the gamma polymorph and stable with respect to conversion to beta-HMX under ambient conditions for at least a year. Pressing of sm-HMX powder in a small diameter pellet press at pressures from 10,000 psi to 31,000 psi and 1 to 5 minute hold times was found to promote the gamma to beta polymorphic phase transition. The fraction converted and rate of conversion versus time after pellet removal from the press, measured using Raman spectroscopy, fit a sigmoidal curve, indicating nucleation and growth as a possible polymorphic transition mechanism.

  18. Phytoremediation of explosives (TNT, RDX, HMX) by wild-type and transgenic plants.

    PubMed

    Panz, Katarzyna; Miksch, Korneliusz

    2012-12-30

    The large-scale production and processing of munitions has led to vast environmental pollution by the compounds TNT(2,4,6-trinitrotoluene), RDX(hexahydro-1,3,5-trinitro-1,3,5-triazine) and HMX(octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine). Explosives contain these toxic and mutagenic xenobiotics, which are stable in the environment and recalcitrant to remediation. Certain technologies used thus far (incineration, adsorption, advanced oxidations processes, chemical reduction etc.) have not only been very expensive but also caused additional environmental problems. During recent decades, the most popular technologies have been biotechnological methods, such as phytoremediation, which is relatively cheap, environmentally friendly, and a highly accepted solution by society. The most promising of these technologies is the usage of genetically modified plants, which combines the ability of bacterial genes to detoxify compounds with the phytoremediation benefits of plants. This paper is a review related to the latest and most important achievements in the field of phytoremediation of water and soil contaminated with TNT, RDX and HMX. PMID:22996005

  19. Application of a four-step HMX kinetic model to an impact-induced fraction ignition problems

    SciTech Connect

    Perry, William L; Gunderson, Jake A; Dickson, Peter M

    2010-01-01

    There has been a long history of interest in the decomposition kinetics of HMX and HMX-based formulations due to the widespread use of this explosive in high performance systems. The kinetics allow us to predict, or attempt to predict, the behavior of the explosive when subjected to thermal hazard scenarios that lead to ignition via impact, spark, friction or external heat. The latter, commonly referred to as 'cook off', has been widely studied and contemporary kinetic and transport models accurately predict time and location of ignition for simple geometries. However, there has been relatively little attention given to the problem of localized ignition that results from the first three ignition sources of impact, spark and friction. The use of a zero-order single-rate expression describing the exothermic decomposition of explosives dates to the early work of Frank-Kamanetskii in the late 1930s and continued through the 60's and 70's. This expression provides very general qualitative insight, but cannot provide accurate spatial or timing details of slow cook off ignition. In the 70s, Catalano, et al., noted that single step kinetics would not accurately predict time to ignition in the one-dimensional time to explosion apparatus (ODTX). In the early 80s, Tarver and McGuire published their well-known three step kinetic expression that included an endothermic decomposition step. This scheme significantly improved the accuracy of ignition time prediction for the ODTX. However, the Tarver/McGuire model could not produce the internal temperature profiles observed in the small-scale radial experiments nor could it accurately predict the location of ignition. Those factors are suspected to significantly affect the post-ignition behavior and better models were needed. Brill, et al. noted that the enthalpy change due to the beta-delta crystal phase transition was similar to the assumed endothermic decomposition step in the Tarver/McGuire model. Henson, et al., deduced the

  20. Hmx1 is required for the normal development of somatosensory neurons in the geniculate ganglion.

    PubMed

    Quina, Lely A; Tempest, Lynne; Hsu, Yun-Wei A; Cox, Timothy C; Turner, Eric E

    2012-05-01

    Hmx1 is a variant homeodomain transcription factor expressed in the developing sensory nervous system, retina, and craniofacial mesenchyme. Recently, mutations at the Hmx1 locus have been linked to craniofacial defects in humans, rats, and mice, but its role in nervous system development is largely unknown. Here we show that Hmx1 is expressed in a subset of sensory neurons in the cranial and dorsal root ganglia which does not correspond to any specific sensory modality. Sensory neurons in the dorsal root and trigeminal ganglia of Hmx1dm/dm mouse embryos have no detectable Hmx1 protein, yet they undergo neurogenesis and express sensory subtype markers normally, demonstrating that Hmx1 is not globally required for the specification of sensory neurons from neural crest precursors. Loss of Hmx1 expression has no obvious effect on the early development of the trigeminal (V), superior (IX/X), or dorsal root ganglia neurons in which it is expressed, but results in marked defects in the geniculate (VII) ganglion. Hmx1dm/dm mouse embryos possess only a vestigial posterior auricular nerve, and general somatosensory neurons in the geniculate ganglion are greatly reduced by mid-gestation. Although Hmx1 is expressed in geniculate neurons prior to cell cycle exit, it does not appear to be required for neurogenesis, and the loss of geniculate neurons is likely to be the result of increased cell death. Fate mapping of neural crest-derived tissues indicates that Hmx1-expressing somatosensory neurons at different axial levels may be derived from either the neural crest or the neurogenic placodes. PMID:22586713

  1. Theoretical insight into the binding energy and detonation performance of ε-, γ-, β-CL-20 cocrystals with β-HMX, FOX-7, and DMF in different molar ratios, as well as electrostatic potential.

    PubMed

    Feng, Rui-Zhi; Zhang, Shu-Hai; Ren, Fu-de; Gou, Rui-Jun; Gao, Li

    2016-06-01

    Molecular dynamics method was employed to study the binding energies on the selected crystal planes of the ε-, γ-, β-conformation 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (ε-, γ-, β-CL-20) cocrystal explosives with 1,1-diamino-2,2-dinitroethylene (FOX-7), 1,3,5,7-tetranitro- 1,3,5,7-tetrazacyclooctane with β-conformation (β-HMX) and N,N-dimethylformamide (DMF) in different molar ratios. The oxygen balance, density, detonation velocity, detonation pressure, and surface electrostatic potential were analyzed. The results indicate that the binding energies E b (*) and stabilities are in the order of 1:1 > 2:1 > 3:1 > 5:1 > 8:1 (CL-20:FOX-7/β-HMX/DMF). The values of E b (*) and stabilities of the energetic-nonenergetic CL-20/DMF cocrystals are far larger than those of the energetic-energetic CL-20/FOX-7 and CL-20/β-HMX, and those of CL-20/β-HMX are the smallest. For CL-20/FOX-7 and CL-20/β-HMX, the largest E b (*) appears in the cocrystals with the 1:1, 1:2 or 1:3 molar ratio, and the stabilities of the cocrystals with the excess ratio of CL-20 are weaker than those in the cocrystals with the excess ratio of FOX-7 or β-HMX. In CL-20/FOX-7, CL-20 prefers adopting the γ-form, and ε-CL-20 is the preference in CL-20/β-HMX, and ε-CL-20 and β-CL-20 can be found in CL-20/DMF. The CL-20/FOX-7 and CL-20/β-HMX cocrystals with low molar ratios can meet the requirements of low sensitive high energetic materials. Surface electrostatic potential reveals the nature of the sensitivity change upon the cocrystal formation. Graphical Abstract MD method was employed to study the binding energies on the selected crystal planes in the ε-, γ-, β-CL-20 cocrystals with FOX-7, β-HMX and DMF in different molar ratios. Surface electrostatic potential reveals the nature of the sensitivity change in cocrystals. PMID:27168198

  2. The Application of Global Kinetic Models to HMX Beta-Delta Transition and Cookoff Processes

    SciTech Connect

    Wemhoff, A P; Burnham, A K; Nichols III, A L

    2006-12-07

    The reduction of the number of reactions in kinetic models for both the HMX beta-delta phase transition and thermal cookoff provides an attractive alternative to traditional multi-stage kinetic models due to reduced calibration effort requirements. In this study, we use the LLNL code ALE3D to provide calibrated kinetic parameters for a two-reaction bidirectional beta-delta HMX phase transition model based on Sandia Instrumented Thermal Ignition (SITI) and Scaled Thermal Explosion (STEX) temperature history curves, and a Prout-Tompkins cookoff model based on One-Dimensional Time to Explosion (ODTX) data. Results show that the two-reaction bidirectional beta-delta transition model presented here agrees as well with STEX and SITI temperature history curves as a reversible four-reaction Arrhenius model, yet requires an order of magnitude less computational effort. In addition, a single-reaction Prout-Tompkins model calibrated to ODTX data provides better agreement with ODTX data than a traditional multi-step Arrhenius model, and can contain up to 90% less chemistry-limited time steps for low-temperature ODTX simulations. Manual calibration methods for the Prout-Tompkins kinetics provide much better agreement with ODTX experimental data than parameters derived from Differential Scanning Calorimetry (DSC) measurements at atmospheric pressure. The predicted surface temperature at explosion for STEX cookoff simulations is a weak function of the cookoff model used, and a reduction of up to 15% of chemistry-limited time steps can be achieved by neglecting the beta-delta transition for this type of simulation. Finally, the inclusion of the beta-delta transition model in the overall kinetics model can affect the predicted time to explosion by 1% for the traditional multi-step Arrhenius approach, while up to 11% using a Prout-Tompkins cookoff model.

  3. LDRD final report : raman spectroscopic measurements to monitor the HMX beta-delta phase transition.

    SciTech Connect

    Renlund, Anita Mariana; Tappan, Alexander Smith; Miller, Jill C.

    2000-11-01

    The HMX {beta}-{delta} solid-solid phase transition, which occurs as HMX is heated near 170 C, is linked to increased reactivity and sensitivity to initiation. Thermally damaged energetic materials (EMs) containing HMX therefore may present a safety concern. Information about the phase transition is vital to predictive safety models for HMX and HMX-containing EMs. We report work on monitoring the phase transition with real-time Raman spectroscopy aimed towards obtaining a better understanding of physical properties of HMX through the phase transition. HMX samples were confined in a cell of minimal free volume in a displacement-controlled or load-controlled arrangement. The cell was heated and then cooled at controlled rates while real-time Raman spectroscopic measurements were performed. Raman spectroscopy provides a clear distinction between the phases of HMX because the vibrational transitions of the molecule change with conformational changes associated with the phase transition. Temperature of phase transition versus load data are presented for both the heating and cooling cycles in the load-controlled apparatus, and general trends are discussed. A weak dependence of the temperature of phase transition on load was discovered during the heating cycle, with higher loads causing the phase transition to occur at a higher temperature. This was especially true in the temperature of completion of phase transition data as opposed to the temperature of onset of phase transition data. A stronger dependence on load was observed in the cooling cycle, with higher loads causing the reverse phase transitions to occur at a higher cooling temperature. Also, higher loads tended to cause the phase transition to occur over a longer period of time in the heating cycle and over a shorter period of time in the cooling cycle. All three of the pure HMX phases ({alpha}, {beta} and {delta}) were detected on cooling of the heated samples, either in pure form or as a mixture.

  4. Decomposition Kinetics for Mass Loss and Heat Released for HMX

    SciTech Connect

    Weese, R K; Burnham, A K

    2004-07-27

    Nucleation-growth kinetic expressions are derived for thermal decomposition of HMX from a variety of types of data, including mass loss for isothermal and constant rate heating in an open pan, and heat flow for isothermal and constant rate heating in open and closed pans. Conditions are identified in which thermal runaway is small to nonexistent, which typically means temperatures less than 255 C and heating rates less than 1 C/min. Activation energies are typically in the 140 to 150 kJ/mol regime for open pan experiments and about 160 kJ/mol for sealed pan experiments. The reaction clearly displays more than one process, and most likely three processes, which are most clearly evident in open pan experiments. The reaction is accelerated for closed pan experiments, and one global reaction appears to fit the data well.

  5. Pressing induced polymorphic phase transition in submicron-sized gamma-HMX

    NASA Astrophysics Data System (ADS)

    Moore, David; Lee, Kien-Yin

    2007-06-01

    Submicron HMX has been produced and characterized to be less sensitive than impact standard HMX in small-scale sensitivity tests. The sm-HMX was found to be the gamma polymorph and to be stable under ambient conditions for at least a year. Pressing of sm-HMX in a small diameter pellet press at pressures from 10 000 psi to 31 000 psi and 1 to 5 minute hold times was found to promote the gamma to beta polymorphic phase transition. The fraction converted and rate of conversion versus time after pellet removal from the press were found to fit a sigmoidal curve, indicating nucleation and growth as a possible polymorphic transition mechanism.

  6. Equation of state of unreacted high explosives at high pressures

    SciTech Connect

    Yoo, C-S

    1998-08-14

    Isotherms of unreacted high explosives (HMX, RDX, and PETN) have been determined to quasi-hydrostatic high pressures below 45 GPa, by using a diamond-anvil cell angle-resolved synchrotron x-ray diffraction method. The equation-of-state parameters (bulk modulus Bo, and its derivatives B' ) are presented for the 3rd-order Birch-Murnaghan formula based on the measured isotherms. The results are also used to retrieve unreacted Hugoniots in these high explosives and to develop the equations of state and kinetic models for composite high explolsivcs such as XTX-8003 and LX-04. The evidence of shear-induced chemistry of HMX in non-hydrostatic conditions is also presented.

  7. Raman Spectroscopic and Ultrasonic Measurements to Monitor the HMX ( ) Phase Transition

    SciTech Connect

    GIESKE,JOHN H.; MILLER,JILL C.; RENLUND,ANITA M.; TAPPAN,ALEXANDER S.

    1999-10-14

    The HMX {beta}-{delta} solid-solid phase transition, which occurs as HMX is heated near 170 C, is clearly linked to increased reactivity and sensitivity to initiation. Thermally damaged energetic materials (EMs) containing HMX therefore may present a safety concern. Information about the phase transition is vital to a predictive safety model for HMX and HMX-containing EMs. We report work in progress on monitoring the phase transition with real-time Raman spectroscopy and ultrasonic measurements aimed towards a better understanding of physical properties through the phase transition. HMX samples were confined with minimal free volume.in a cell with constant volume. The cell was heated at a controlled rate and real-time Raman spectroscopic or ultrasonic measurements were performed. Raman spectroscopy provides a clear distinction between the two phases because the vibrational transitions of the molecule change with confirmational changes associated with the phase transition. Ultrasonic time-of-flight measurements provide an additional method of distinguishing the two phases because the sound speed through the material changes with the phase transition. Ultrasonic attenuation measurements also provide information about microstructural changes such as increased porosity due to evolution of gaseous decomposition products.

  8. Pilot-scale in situ bioremediation of HMX and RDX in soil pore water in Hawaii.

    PubMed

    Payne, Zachary M; Lamichhane, Krishna M; Babcock, Roger W; Turnbull, Stephen J

    2013-10-01

    A nine-month in situ bioremediation study was conducted in Makua Military Reservation (MMR) in Oahu, Hawaii (USA) to evaluate the potential of molasses to enhance biodegradation of royal demolition explosive (RDX) and high-melting explosive (HMX) contaminated soil below the root zone. MMR has been in operation since the 1940's resulting in subsurface contamination that in some locations exceeds USEPA preliminary remediation goals for these chemicals. A molasses-water mixture (1 : 40 dilution) was applied to a treatment plot and clean water was applied to a control plot via seven flood irrigation events. Pore water samples were collected from 12 lysimeters installed at different depths in 3 boreholes in each test plot. The difference in mean concentrations of RDX in pore water samples from the two test plots was very highly significant (p < 0.001). The concentrations differences with depth were also very highly significant (p < 0.001) and degradation was greatly enhanced at depths from 5 to 13.5 ft. biodegradation was modeled as first order and the rate constant was 0.063 per day at 5 ft and decreased to 0.023 per day at 11 ft to 13.5 ft depth. Enhanced biodegradation of HMX was also observed in molasses treated plot samples but only at a depth of 5 ft. The difference in mean TOC concentration (surrogate for molasses) was highly significant with depth (p = 0.003) and very highly significant with treatment (p < 0.001). Mean total nitrogen concentrations also differed significantly with treatment (p < 0.001) and depth (p = 0.059). The molasses water mixture had a similar infiltration rate to that of plain water (average 4.12 ft per day) and reached the deepest sensor (31 ft) within 5 days of application. Most of the molasses was consumed by soil microorganisms by about 13.5 feet below ground surface and treatment of deeper depths may require greater molasses concentrations and/or more frequent flood irrigation. Use of the bioremediation method described herein

  9. Recent developments in formulating model descriptors for subsurface transformation and sorption of TNT, RDX, and HMX. Final report

    SciTech Connect

    Townsend, D.M.; Myers, T.E.

    1996-02-01

    Subsurface contamination with 2,4,6-trinitrotoluene (TNT), 2,3,5-trinitro-1,3,5-triazine (RDX), and oxyhydro-1,3,5,7-tetranitro- 1,3,5,7-tetrazocine (HMX) is a problem at military installations where these explosives were manufactured or used in loading munitions. Recent laboratory batch and column studies conducted to identify processes affecting subsurface transport of TNT, RDX, and HMX provide new information on the relative significance of transformation and sorption for these explosives and yield estimates of key process descriptors. This report assesses the current state of knowledge regarding subsurface transformation and sorption of TNT, RDX, and HMX, provides estimates for subsurface transport descriptors, and recommends further research. Transformation and sorption are important processes in the subsurface transport of TNT, RDX, and HMX. Measurement of transformation products has provided unequivocal evidence of TNT transformation. Research has also indicated that RDX and HMX are affected by subsurface transformations, but RDX and HMX transformation products have not been measured due to lack of chemical analytical capability. The order to magnitude of transformation is TNT >> RDX approx equal to HMX, and the order of magnitude of sorption in TNT > HMX > RDX.

  10. Surface Polarity Of Beta-hmx Crystal And The Related Adhesive Forces With Estane Binder

    SciTech Connect

    Yang, Lu; Hanson, David E

    2008-01-01

    Here we present the results on the study of surface properties of {beta}-HMX crystal utilizing molecular simulations. The surface polarity of three principal crystal surfaces are investigated by measuring the water contact angles. The calculated contact angles agree excellently with the values measured by experiment and show that the surface polarity of three crystal surfaces are different. The free energies and forces of detaching an Estane chain with and without nitroplasticizer from the three principal crystal surfaces were calculated using umbrella sampling technique. We find that the detaching free energy/force increases with the increasing HMX surface polarity. In addition, our results also show that nitroplasticizer plays an important role in the adhesion forces between Estane and HMX surfaces.

  11. Compressible Heating in the Condense Phase due to Pore Collapse in HMX

    NASA Astrophysics Data System (ADS)

    Zhang, Ju; Jackson, Thomas

    Axisymmetric pore collapse in HMX is studied numerically by solving multi-phase reactive Euler equations. The generation of hot spots in the condense phase due to compressible heating is examined. The motivation is to improve the understanding of the role of embedded cavities in the initiation of reaction in explosives, and to investigate the effect of hot spots in the condense phase due to compressible heating alone, complementing previous study on hot spots due to the reaction in the gas phase and at the interface. It is found that the shock-cavity interaction results in pressures and thus temperatures that are substantially higher than the post-shock values in the condense phase. However, these hot spots in the condense phase due to compressible heating alone do not seem to be sufficiently hot to lead to ignition at shock pressures of 1-3 GPa. Thus, compressible heating in the condense phase may be excluded as a mechanism for initiation of explosives. It should be pointed out that the ignition threshold for the temperature, the so-called ``switch-on'' temperature, of hot spots depend on chemistry kinetics parameters. Switch-on temperature is lower for faster reaction rate. The current chemistry kinetics parameters are based on previous experimental work. This work was supported in part by the Defense Threat Reduction Agency and by the U.S. Department of Energy.

  12. Examining the effects of microstructure and loading on the shock initiation of HMX with mesoscale simulations

    NASA Astrophysics Data System (ADS)

    Springer, H. Keo; Tarver, Craig; Bastea, Sorin

    2015-06-01

    We perform reactive mesoscale simulations to study shock initiation in HMX over a range of pore morphologies and sizes, porosities, and loading conditions in order to improve our understanding of structure-performance relationships. These relationships are important because they guide the development of advanced macroscale models incorporating hot spot mechanisms and the optimization of novel energetic material microstructures. Mesoscale simulations are performed using the multiphysics hydrocode, ALE3D. Spherical, elliptical, polygonal, and crack-like pore geometries 0.1, 1, 10, and 100 microns in size and 2, 5, 10, and 14% porosity are explored. Loading conditions are realized with shock pressures of 6, 10, 20, 38, and 50 GPa. A Cheetah-based tabular model, including temperature-dependent heat capacity, is used for the unreacted and the product equation-of-state. Also, in-line Cheetah is used to probe chemical species evolution. The influence of microstructure and shock loading on shock-to-detonation-transition run distance, reaction rate and product gas species evolution are discussed. This work performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344. This work is funded by the Joint DoD-DOE Munitions Program.

  13. Critical analysis of nitramine decomposition data: Activation energies and frequency factors for HMX and RDX decomposition

    NASA Technical Reports Server (NTRS)

    Schroeder, M. A.

    1980-01-01

    A summary of a literature review on thermal decomposition of HMX and RDX is presented. The decomposition apparently fits first order kinetics. Recommended values for Arrhenius parameters for HMX and RDX decomposition in the gaseous and liquid phases and for decomposition of RDX in solution in TNT are given. The apparent importance of autocatalysis is pointed out, as are some possible complications that may be encountered in interpreting extending or extrapolating kinetic data for these compounds from measurements carried out below their melting points to the higher temperatures and pressure characteristic of combustion.

  14. Role of soil organic carbon and colloids in fate of TNT, RDX and HMX in training range soils.

    SciTech Connect

    Sharma, Prasesh; Mayes, Melanie; Tang, Guoping

    2013-01-01

    Contamination of soils/groundwater by munition compounds (TNT, RDX, HMX) is of significant concern at many U.S. Department of Defense sites. We collected soils from operational ranges in Maryland (APG), Massachusetts (MMR-B and MMR-E) and Washington (JBLM) and conducted sorption/transport studies to investigate effects of soil organic carbon (OC) and clay content on fate of dissolved munition compounds (MCs). Sorption experiments showed higher sorption coefficients [TNT:42-68 kg/L, RDX:6.9-8.7 Kg/L and HMX:2.6-3.1 Kg/L] in OC rich soils (JBLM, MMR-E) compared to clay rich soils MMR-B and APG [TNT:19-21 Kg/L, RDX:2.5-3.4 Kg/L, HMX:0.9-1.2 Kg/L]. In column experiments, breakthrough of MCs was mostly quicker in MMR-B and APG soil filled columns compared to MMR-E and JBLM. Between TNT, RDX and HMX, breakthrough was fastest for RDX followed by HMX and TNT for all soil columns. Separation of effluents into dissolved (<3 kDa) vs unfiltered (total) fractions in effluents showed 30-50% of TNT in the fraction >3kDa (colloidal fraction). HMX and RDX were completely associated with dissolved fraction. Results demonstrate that OC rich soils may enhance sorption and delay transport of TNT, RDX and HMX. Furthermore, colloids could contribute to transport of dissolved TNT to a significant amount.

  15. Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)

    Integrated Risk Information System (IRIS)

    Octahydro - 1,3,5,7 - tetranitro - 1,3,5,7 - tetr . . . ( HMX ) ; CASRN 2691 - 41 - 0 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I

  16. Nonideal detonation and initiation behavior of a composite solid rocket propellant. [HMX/AP/Al

    SciTech Connect

    Dick, J.J.

    1981-01-01

    Shock initiation and detonation behavior of an HMX/AP/Al rocket propellant were studied for nonideal character. Low detonation velocities and unusual shock initiation behavior were observed. Failure to propagate steady detonation in cylinders of the propellant was also noted.

  17. 4-Aminothiophenol functionalized gold nanoparticle-based colorimetric sensor for the determination of nitramine energetic materials.

    PubMed

    Üzer, Ayşem; Can, Ziya; Akın, Ilknur; Erçağ, Erol; Apak, Reşat

    2014-01-01

    The heterocyclic nitramine compounds, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), are two most important military-purpose high explosives. Differentiation of RDX and HMX with colorimetric methods of determination has not yet been made because of their similar chemical structures. In this study, a sensitive colorimetric method for the determination of RDX and HMX was proposed on the basis of differential kinetics in the hydrolysis of the two compounds (yielding nitrite as a product) followed by their colorimetric determination using 4-aminothiophenol (4-ATP) modified gold nanoparticles (AuNPs) and naphthylethylene diamine (NED) as coupling agent for azo-dye formation, abbreviated as "4-ATP-AuNP+NED" colorimetric method. After alkaline hydrolysis in a 1 M Na2CO3 + 0.04 M NaOH mixture solution at room temperature, only RDX (but not HMX) was hydrolyzed to give a sufficient colorimetric response in neutralized solution, the molar absorptivity (ε) at 565 nm and the limit of detection (LOD) for RDX being (17.6 ± 1.3) × 10(3) L mol(-1) cm(-1) and 0.55 μg mL(-1), respectively. On the other hand, hot water bath (at 60 °C) hydrolysis enabled both nitramines, RDX and HMX, to give substantial colorimetric responses; i.e., ε and LOD for RDX were (32.8 ± 0.5) × 10(3) L mol(-1)cm(-1) and 0.20 μg mL(-1) and for HMX were (37.1 ± 2.8) × 10(3) L mol(-1)cm(-1) and 0.24 μg mL(-1), respectively. Unlike other AuNP-based nitrite sensors in the literature showing absorbance quenching within a relatively narrow concentration range, the developed sensor operated with an absorbance increase over a wide range of nitrite. Synthetic mixtures of (RDX + HMX) gave additive responses, and the proposed method was statistically validated against HPLC using nitramine mixtures. PMID:24299426

  18. Stand-off detection of HMX traces by active spectral imaging with a tunable CO{sub 2} laser

    SciTech Connect

    Pavlenko, A A; Maksimenko, E V; Chernyshova, L V

    2014-04-28

    Experimental results on stand-off detection of HMX traces at various surfaces using the method of active spectral imaging in the IR region are reported. (laser applications and other topics in quantum electronics)

  19. Isentropic Compression Loading of HMX and the Pressure-induced Phase Transition at 27 GPa

    SciTech Connect

    Hare, D E; Reisman, D B; Dick, J J; Forbes, J W

    2004-02-25

    The 27 GPa pressure-induced epsilon-phi phase transition in HMX is explored using the Isentropic Compression Experiment (ICE) technique at the Sandia National Laboratories Z-machine facility. Our data indicate that this phase transition is sluggish and if it does occur to any extent under the time scales (200-500 ns) and strain rates (5 x 10{sup 5}) typical of ICE loading conditions, the amount of conversion is small.

  20. Direct numerical simulation of shear localization and decomposition reactions in shock-loaded HMX crystal

    SciTech Connect

    Austin, Ryan A.; Barton, Nathan R.; Reaugh, John E.; Fried, Laurence E.

    2015-05-14

    A numerical model is developed to study the shock wave ignition of HMX crystal. The model accounts for the coupling between crystal thermal/mechanical responses and chemical reactions that are driven by the temperature field. This allows for the direct numerical simulation of decomposition reactions in the hot spots formed by shock/impact loading. The model is used to simulate intragranular pore collapse under shock wave loading. In a reference case: (i) shear-enabled micro-jetting is responsible for a modest extent of reaction in the pore collapse region, and (ii) shear banding is found to be an important mode of localization. The shear bands, which are filled with molten HMX, grow out of the pore collapse region and serve as potential ignition sites. The model predictions of shear banding and reactivity are found to be quite sensitive to the respective flow strengths of the solid and liquid phases. In this regard, it is shown that reasonable assumptions of liquid-HMX viscosity can lead to chemical reactions within the shear bands on a nanosecond time scale.

  1. Compaction of granular HMX: P-α porosity model in CTH hydrocode

    NASA Astrophysics Data System (ADS)

    Mahon, K. S.; Lee, T.-W.

    2015-12-01

    Compaction waves traveling through porous cyclotetramethylene-tetranitramine (HMX) are computationally modeled using the Eulerian hydrocode CTH and validated with gas gun experimental data. The method employed use of a newly generated set of P-α parameters for granular HMX in a Mie-Gruneisen equation of state. The P-α model adds a separate parameter to differentiate between the volume changes of a solid material due to compression from the volume change due to compaction, void collapse in a granular material. Computational results are compared via five validation schema for two different initial-porosity experiments. These schema include stress measurements, velocity rise times and arrival times, elastic sound speeds though the material and final compaction densities for a series of two different percent Theoretical Maximum Density (TMD) HMX sets of experimental data. There is a good agreement between the simulations and the experimental gas gun data with the largest source of error being an 11% overestimate of the peak stress which may be due to impedance mismatch on the experimental gauge interface. Determination of these P-α parameters are important as they enable modeling of porosity and are a vital first step in modeling of precursory hotspots, caused by hydrodynamic collapse of void regions or grain interactions, prior to deflagration to detonation transition of granular explosives.

  2. Coefficient of Thermal Expansion of the Beta and Delta Polymorphs of HMX

    SciTech Connect

    Weese, R K; Burnham, A K

    2005-01-11

    Dimensional changes related to temperature cycling of the {beta} and {delta} polymorphs of HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) are important for a variety of applications. The coefficient of thermal expansion (CTE) of the {beta} and {delta} phases are measured over a temperature range of -20 C to 215 C by thermo-mechanical analysis (TMA). Dimensional changes associated with the phase transition were also measured, and the time-temperature dependence of the dimensional change is consistent with phase transition kinetics measured earlier by differential scanning calorimetry (DSC). One HMX sample measured by TMA during its initial heating and again three days later during a second heating showed the {beta}-to-{delta} phase transition a second time, thereby indicating back conversion from {delta}-to-{beta} phase HMX during those three days. DSC was used to measure kinetics of the {delta}-to-{beta} back conversion. The most successful approach was to first heat the material to create the {delta} phase, then after a given period at room temperature, measure the heat absorbed during a second pass through the {beta}-to-{delta} phase transition. Back conversion at room temperature follows nucleation-growth kinetics.

  3. Direct numerical simulation of shear localization and decomposition reactions in shock-loaded HMX crystal

    DOE PAGESBeta

    Austin, Ryan A.; Barton, Nathan R.; Reaugh, John E.; Fried, Laurence E.

    2015-05-14

    A numerical model is developed to study the shock wave ignition of HMX crystal. The model accounts for the coupling between crystal thermal/mechanical responses and chemical reactions that are driven by the temperature field. This allows for the direct numerical simulation of decomposition reactions in the hot spots formed by shock/impact loading. The model is used to simulate intragranular pore collapse under shock wave loading. In a reference case: (i) shear-enabled micro-jetting is responsible for a modest extent of reaction in the pore collapse region, and (ii) shear banding is found to be an important mode of localization. The shearmore » bands, which are filled with molten HMX, grow out of the pore collapse region and serve as potential ignition sites. The model predictions of shear banding and reactivity are found to be quite sensitive to the respective flow strengths of the solid and liquid phases. In this regard, it is shown that reasonable assumptions of liquid-HMX viscosity can lead to chemical reactions within the shear bands on a nanosecond time scale.« less

  4. Carbon and nitrogen isotope ratios of factory-produced RDX and HMX.

    PubMed

    Howa, John D; Lott, Michael J; Chesson, Lesley A; Ehleringer, James R

    2014-07-01

    RDX and HMX are explosive compounds commonly used by the military and also occasionally associated with acts of terrorism. The isotopic characterization of an explosive can be a powerful approach to link evidence to an event or an explosives cache. We sampled explosive products and their reactants from commercial RDX manufacturers that used the direct nitration and/or the Bachmann synthesis process, and then analyzed these materials for carbon and nitrogen isotope ratios. For manufacturers using the Bachmann process, RDX (13)C enrichment relative to the hexamine substrate was small (+0.9‰) compared to RDX produced using the direct nitration process (+8.2‰ to +12.0‰). RDX (15)N depletion relative to the nitrogen-containing substrates (-3.6‰) was smaller in the Bachmann process than in the direct nitration process (-12.6‰ to -10.6‰). The sign and scale of these differences agree with theorized mechanisms of mass-dependent fractionation. We also examined the isotopic relationship between RDX and HMX isolated from explosive samples. The δ(13)C and δ(15)N values of RDX generally matched those of the HMX with few exceptions, most notably from a manufacturer known to make RDX using two different synthesis processes. The range in δ(13)C values of RDX in a survey of 100 samples from 12 manufacturers spanned 33‰ while the range spanned by δ(15)N values was 26‰; these ranges were much greater than any previously published observations. Understanding the relationship between products and reactants further explains the observed variation in industrially manufactured RDX and can be used as a diagnostic tool to analyze explosives found at a crime scene. PMID:24814332

  5. Monte Carlo calculations of the physical properties of RDX, {beta}-HMX, and TATB

    SciTech Connect

    Sewell, T.D.

    1998-07-01

    Atomistic Monte Carlo simulations in the {ital NpT} ensemble are used to calculate the physical properties of crystalline RDX, {beta}-HMX, and TATB. Among the issues being considered are the effects of various treatments of the intermolecular potential, inclusion of intramolecular flexibility, and simulation size dependence of the results. Calculations of the density, lattice energy, and lattice parameters are made over a wide domain of pressures; thereby allowing for predictions of the bulk and linear coefficients of isothermal expansion of the crystals. Comparison with experiment is made where possible. {copyright} {ital 1998 American Institute of Physics.}

  6. Deflagration-to-detonation in granular HMX: Ignition, kinetics, and shock formation

    SciTech Connect

    McAfee, J.M.; Asay, B.W.; Bdzil, J.B.

    1993-06-01

    Experimental studies and analysis of the deflagration-to detonation transition (DDT) in granular HMX are continued. Experiments performed using a direct-gasless igniter exhibit the same phenomenology as those ignited with a piston. Simple kinetics and mechanics describe the formation of the {approximately}100% TMD plug in terms of competing pressurization processes. A mass-conservation analysis of the experimentally observed structures shows how the low velocities characteristic of convective burning are amplified to shock-wave velocities through non-convective processes.

  7. HMX and HNS Shock Sensitivity Correlation with Specific Heat and Reactive Temperature Magnitudes

    NASA Astrophysics Data System (ADS)

    Billingsley, J. P.

    1999-06-01

    A paper in the 1995 SCCM Conference Proceedings(pages 429-432) documents that shock sensitivity of five explosives(TETRYL, PETN,TNT, RDX, and TATB) could be correlated with their specific heats and reactive temperature magnitudes. In fact, it was demonstrated that the shock sensitivity of these explosives was basically related to their reactive temperatures such as T(melt), T(phase change), and T(explode). Two additional explosives(HMX and HNS) have also been investigated and similar results are documented in this article. Thus, this concept has been affirmatively demonstrated via comparisons with experimental results for seven important explosive chemical compounds.

  8. Analysis of Compaction Shock Interactions During DDT of Low Density HMX

    NASA Astrophysics Data System (ADS)

    Rao, Pratap; Gonthier, Keith

    2015-06-01

    Deflagration-to-Detonation Transition (DDT) within low density HMX often occurs by a complex mechanism that involves compaction shock interactions. Piston driven DDT experiments indicate that detonation can be abruptly triggered by the interaction of a strong combustion driven shock and a lead piston supported shock, where the nature of the interaction depends on initial density and lead shock strength. These shocks induce dissipation and thermomechanical fluctuations at the meso-scale due to pore collapse resulting in hot-spots. Inert meso-scale simulations of successive shock loading of low density HMX are performed to examine how dissipation and hot-spot formation are affected by initial density, and lead and trailing shock strength. Emphasis is placed on interpreting solutions in a phase space expressed in terms of effective pressure and dissipative work because of their relevance to hot-spot formation. Meso-scale predictions are shown to compare favorably to those given by a macro-scale theory. This information is being used to formulate a dissipation-dependent reactive burn model to describe shock desensitization and DDT. Preliminary redictions will be presented that illustrate how initial density and input shock strength can affect the transition mechanism. This research is supported by the Defense Threat Reduction Agency (DTRA) under sponsor Award Number HDTRA1-10-1-0018, and the Air Force Research Laboratory (AFRL-RWME) under sponsor Award Number FA8651-09-0021.

  9. Time-resolved spectroscopic studies of detonating heterogeneous explosives. [HMX and HNS

    SciTech Connect

    Trott, W.M.; Renlund, A.M.

    1985-01-01

    Emission spectroscopy and pulsed-laser-excited Raman scattering methods have been applied to the study of detonating heterogeneous explosives, including PETN, HMX and HNS. Time-resolved spectra of emission from detonating HNS show the evolution of features due to electronically-excited radical species. For HNS, the CN(B-X) system near 388 nm has been studied at a wavelength resolution of 0.5 A. Boltzmann vibrational temperatures have been calculated by comparing the experimental data with computer-simulated spectra. These temperatures are consistent with the expected trend of detonation temperature as a function of charge density. Using 532-nm laser excitation, single-pulse Raman scattering measurements have been made at the free surface of detonating HMX and PETN samples. Monotonic attenuation of Raman scattering intensity over a 100-ns interval is observed after detonation front arrival at the free surface. Depletion of the Raman signal occurs prior to significant loss of the scattered laser light. The significance of the Raman measurements as a possible probe of reaction zone length in detonating explosives is discussed. 21 refs., 11 figs.

  10. Shock initiation studies of low density HMX using electromagnetic particle velocity and PVDF stress gauges

    SciTech Connect

    Sheffield, S.A.; Gustavsen, R.L.; Alcon, R.R.; Graham, R.A.; Anderson, M.U.

    1993-09-01

    Magnetic particle velocity and PVDF stress rate gauges have been used to measure the shock response of low density octotetramethylene tetranitramine (HMX) (1.24 &/cm{sup 3}). In experiments done at LANL, magnetic particle velocity gauges were located on both sides of the explosive. In nearly identical experiments done at SNL, PVDF stress rate gauges were located at the same positions so both particle velocity and stress histories were obtained for a particular experimental condition. Unreacted Hugoniot data were obtained and an EOS was developed by combining methods used by Hayes, Sheffield and Mitchell (for describing the Hugoniot of HNS at various densities) with Hermann`s P-{alpha} model. Using this technique, it is only necessary to know some thermodynamic constants or the Hugoniot of the initially solid material and the porous material sound speed to obtain accurate unreacted Hugoniots for the porous explosive. Loading and reaction paths were established in the stress-particle velocity plane for some experimental conditions. This information was used to determine a global reaction rate of {approx} 0.13 {mu}s{sup {minus}1} for porous HMX shocked to 0.8 GPa. At low input stresses the transmitted wave profiles had long rise times (up to 1 {mu}s) due to the compaction processes.

  11. Predicting Elastic Properties of β-HMX from First-principles Calculations

    NASA Astrophysics Data System (ADS)

    Peng, Qing; Rahul, -; Wang, Guangyu; Liu, Gui-Rong; Grimme, Stefan; de, Suvranu

    2015-03-01

    We investigate the performance of the van der Waals (vdW) functions in predicting the elastic constants of the β-polymorph of cyclotetramethylene tetranitramine (HMX) energetic molecular crystal using density functional theory (DFT) calculations. We confirm that the accuracy of the elastic constants is significantly improved using the vdW corrections with environment dependent C6 together with PBE and revised PBE exchange-correlation functionals. The elastic constants obtained using PBE-D3(0) calculations yield the most accurate mechanical response of β-HMX, with compared to the experimental stress-strain data. The PBEsol without vdW corrections can also predict the elastic constants well. Our results suggest that PBE-D3 calculations are reliable in predicting the elastic constants of this material. The authors would like to acknowledge the generous financial support from the Defense Threat Reduction Agency (DTRA) Grant # HDTRA1-13-1-0025, and the Office of Naval Research grants ONR Award # N00014-08-1-0462 and # N00014-12-1-0527.

  12. Anaerobic transformation of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) by ovine rumen microorganisms.

    PubMed

    Perumbakkam, Sudeep; Craig, A M

    2012-01-01

    Explosives such as octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) provide a challenge in terms of bioremediation. In the present study, sheep rumen was studied for its potential to detoxify HMX using analytical chemistry and molecular microbial ecology tools. Results indicated significant loss (p < 0.05) of HMX at 8 h post-incubation and complete disappearance of the parent molecule after 16 h. Qualitative LC-MS/MS analysis provided evidence for the formation of 1-NO-HMX and MEDINA metabolites. A total of 1006 16S rRNA-V3 clones were sequenced and the Classifier tool of the RDPII database was used to sort the sequences at their phylum level. Most sequences were associated with either the phylum Bacteroidetes or Firmicutes. Significant differences at the phylum level (p < 0.001) were found between 0 h and 8 h HMX treatments. Using LibCompare analysis, 8 h HMX treatment showed enrichment of clones (p < 0.01) belonging to the genus Prevotella. From these results, it could be concluded that members of the genus Prevotella are enriched in the rumen and are capable of detoxifying HMX. PMID:22903090

  13. A distal 594 bp ECR specifies Hmx1 expression in pinna and lateral facial morphogenesis and is regulated by the Hox-Pbx-Meis complex.

    PubMed

    Rosin, Jessica M; Li, Wenjie; Cox, Liza L; Rolfe, Sara M; Latorre, Victor; Akiyama, Jennifer A; Visel, Axel; Kuramoto, Takashi; Bobola, Nicoletta; Turner, Eric E; Cox, Timothy C

    2016-07-15

    Hmx1 encodes a homeodomain transcription factor expressed in the developing lateral craniofacial mesenchyme, retina and sensory ganglia. Mutation or mis-regulation of Hmx1 underlies malformations of the eye and external ear in multiple species. Deletion or insertional duplication of an evolutionarily conserved region (ECR) downstream of Hmx1 has recently been described in rat and cow, respectively. Here, we demonstrate that the impact of Hmx1 loss is greater than previously appreciated, with a variety of lateral cranioskeletal defects, auriculofacial nerve deficits, and duplication of the caudal region of the external ear. Using a transgenic approach, we demonstrate that a 594 bp sequence encompassing the ECR recapitulates specific aspects of the endogenous Hmx1 lateral facial expression pattern. Moreover, we show that Hoxa2, Meis and Pbx proteins act cooperatively on the ECR, via a core 32 bp sequence, to regulate Hmx1 expression. These studies highlight the conserved role for Hmx1 in BA2-derived tissues and provide an entry point for improved understanding of the causes of the frequent lateral facial birth defects in humans. PMID:27287804

  14. A comparative study of chemical kinetics models for HMX in mesoscale simulations of shock initiation due to void collapse

    NASA Astrophysics Data System (ADS)

    Rai, Nirmal; Schweigert, Igor; Udaykumar, H. S.

    2015-06-01

    The development of chemical kinetics schemes for use in modeling the reactive mechanics of energetic materials such as HMX has been an active area of research. Decomposition, deflagration and detonation models need to predict time to ignition and locations of onset of chemical reaction in energetic materials when used in meso- and macro-scale simulations. Modeling the chemical processes and development of appropriate kinetic law is challenging work because of lack of experimental data. However, significant work has been done in this area. Multistep kinetic models by Tarver and Tran, Henson and Smilowitz have provided plausible chemical kinetic rate laws for HMX. These models vary in the way they model the details of the decomposition process. Hence, a comparative study of different models will provide an understanding of the uncertainties involved in predicting ignition in HMX. In the current work, hot-spot ignition due to void collapse in shock compressed HMX has been analyzed using several reaction rate models, including the Tarver-Tran 4-equation model, the Henson-Smilowitz 7-equation model, and a new rate model that combines the condensed-phase decomposition rates measured by Brill et al and the detailed mechanism of nitramine flame chemistry due to Yetter et al. The chemical models have been incorporated in a massively parallel Eulerian code SCIMITAR3D. The variations in the predicted thresholds due to differences in the rate models will be discussed.

  15. A Non-Coding Genomic Duplication at the HMX1 Locus Is Associated with Crop Ears in Highland Cattle

    PubMed Central

    Koch, Caroline Tina; Bruggmann, Rémy; Tetens, Jens; Drögemüller, Cord

    2013-01-01

    Highland cattle with congenital crop ears have notches of variable size on the tips of both ears. In some cases, cartilage deformation can be seen and occasionally the external ears are shortened. We collected 40 cases and 80 controls across Switzerland. Pedigree data analysis confirmed a monogenic autosomal dominant mode of inheritance with variable expressivity. All affected animals could be traced back to a single common ancestor. A genome-wide association study was performed and the causative mutation was mapped to a 4 Mb interval on bovine chromosome 6. The H6 family homeobox 1 (HMX1) gene was selected as a positional and functional candidate gene. By whole genome re-sequencing of an affected Highland cattle, we detected 6 non-synonymous coding sequence variants and two variants in an ultra-conserved element at the HMX1 locus with respect to the reference genome. Of these 8 variants, only a non-coding 76 bp genomic duplication (g.106720058_106720133dup) located in the conserved region was perfectly associated with crop ears. The identified copy number variation probably results in HMX1 misregulation and possible gain-of-function. Our findings confirm the role of HMX1 during the development of the external ear. As it is sometimes difficult to phenotypically diagnose Highland cattle with slight ear notches, genetic testing can now be used to improve selection against this undesired trait. PMID:24194898

  16. Hot spot formation and chemical reaction initiation in shocked HMX crystals with nanovoids: a large-scale reactive molecular dynamics study.

    PubMed

    Zhou, Tingting; Lou, Jianfeng; Zhang, Yangeng; Song, Huajie; Huang, Fenglei

    2016-07-14

    We report million-atom reactive molecular dynamic simulations of shock initiation of β-cyclotetramethylene tetranitramine (β-HMX) single crystals containing nanometer-scale spherical voids. Shock induced void collapse and subsequent hot spot formation as well as chemical reaction initiation are observed which depend on the void size and impact strength. For an impact velocity of 1 km s(-1) and a void radius of 4 nm, the void collapse process includes three stages; the dominant mechanism is the convergence of upstream molecules toward the centerline and the downstream surface of the void forming flowing molecules. Hot spot formation also undergoes three stages, and the principal mechanism is kinetic energy transforming to thermal energy due to the collision of flowing molecules on the downstream surface. The high temperature of the hot spot initiates a local chemical reaction, and the breakage of the N-NO2 bond plays the key role in the initial reaction mechanism. The impact strength and void size have noticeable effects on the shock dynamical process, resulting in a variation of the predominant mechanisms leading to void collapse and hot spot formation. Larger voids or stronger shocks result in more intense hot spots and, thus, more violent chemical reactions, promoting more reaction channels and generating more reaction products in a shorter duration. The reaction products are mainly concentrated in the developed hot spot, indicating that the chemical reactivity of the hmx crystal is greatly enhanced by void collapse. The detailed information derived from this study can aid a thorough understanding of the role of void collapse in hot spot formation and the chemical reaction initiation of explosives. PMID:27307079

  17. Modeling energy dissipation induced by quasi-static compaction of granular HMX

    SciTech Connect

    Gonthier, K.A.; Menikoff, R.; Son, S.F.; Asay, B.W.

    1998-07-01

    A simple extension of a conventional two-phase continuum model of Deflagration-to-Detonation Transition (DDT) in energetic granular material is given to account for energy dissipation induced by quasi-static compaction. To this end, the conventional model equations are supplemented by a relaxation equation that accounts for irreversible changes in solid volume fraction due to intergranular friction, plastic deformation of granules, and granule fracture. The proposed model, which is consistent with the Second Law of Thermodynamics for a two-phase mixture, is demonstrated by applying it to the quasi-static compaction of granular HMX. The model predicts results commensurate with experimental data including stress relaxation and substantial dissipation; such phenomena have not been previously accounted for by two-phase DDT models. {copyright} {ital 1998 American Institute of Physics.}

  18. Vibrational and Thermal Properties of β-HMX and TATB from Dispersion Corrected Density Functional Theory

    NASA Astrophysics Data System (ADS)

    Landerville, Aaron; Oleynik, Ivan

    2015-06-01

    Dispersion Corrected Density Functional Theory (DFT+vdW) calculations are performed to predict vibrational and thermal properties of the bulk energetic materials (EMs) β-octahydrocyclotetramethylene-tetranitramine (β-HMX) and triaminotrinitrobenzene (TATB). DFT+vdW calculations of optimized unit cells along the hydrostatic equation of state are followed by frozen-phonon calculations of their respective vibration spectra. These are then used under the quasi-harmonic approximation to obtain zero-point and thermal free energy contributions to the pressure, resulting in PVT equations of state for each material that is in excellent agreement with experiment. Further, heat capacities, thermal expansion coefficients, and Gruneissen parameters as functions of temperature are calculated and compared with experiment. The vibrational properties, including phonon densities of states and pressure dependencies of individual modes, are also analyzed and compared with experiment.

  19. Mesodermal expression of the C. elegans HMX homolog mls-2 requires the PBC homolog CEH-20

    PubMed Central

    Jiang, Yuan; Shi, Herong; Amin, Nirav M.; Sultan, Ibrahim; Liu, Jun

    2008-01-01

    Metazoan development proceeds primarily through the regulated expression of genes encoding transcription factors and components of cell signaling pathways. One way to decipher the complex developmental programs is to assemble the underlying gene regulatory networks by dissecting the cis-regulatory modules that direct temporal-spatial expression of developmental genes and identify corresponding trans-regulatory factors. Here, we focus on the regulation of a HMX homoebox gene called mls-2, which functions at the intersection of a network that regulates cleavage orientation, cell proliferation and fate specification in the C. elegans postembryonic mesoderm. In addition to its transient expression in the postembryonic mesodermal lineage, the M lineage, mls-2 expression is detected in a subset of embryonic cells, in three pairs of head neurons and transiently in the somatic gonad. Through mutational analysis of the mls-2 promoter, we identified two elements (E1 and E2) involved in regulating the temporal-spatial expression of mls-2. In particular, we showed that one of the elements (E1) required for mls-2 expression in the M lineage contains two critical putative PBC-Hox binding sites that are evolutionarily conserved in C. briggsae and C. remanei. Furthermore, the C. elegans PBC homolog CEH-20 is required for mls-2 expression in the M lineage. Our data suggests that mls-2 might be a direct target of CEH-20 in the M lineage and that the regulation of CEH-20 on mls-2 is likely Hox-independent. PMID:18316179

  20. Modeling the material strength and equations of state of beta-HMX from both first-principles calculations and molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Peng, Qing; Wang, Guangyu; Liu, G. R.; de, Suvranu

    2015-06-01

    We investigate the elastic constants and equations of state (EOS) of the β-polymorph of cyclotetramethylene tetranitramine (HMX) energetic molecular crystal using density functional theory (DFT) calculations. The combination of vdW-DF2 van der Waals functionals and PBE exchange-correlation functionals gives optimized results. The DFT results are used to optimize the Reactive Force Field (ReaxFF). The material strength and EOS of beta-HMX at finite temperatures are then predicted from ReaxFF molecular dynamics simulations. Our results suggest that the optimized ReaxFF predicts the mechanics and EOS of beta-HMX well. The authors would like to acknowledge the generous financial support from the Defense Threat Reduction Agency (DTRA) Grant # HDTRA1-13-1-0025.

  1. FPGA Based High Performance Computing

    SciTech Connect

    Bennett, Dave; Mason, Jeff; Sundararajan, Prasanna; Dellinger, Erik; Putnam, Andrew; Storaasli, Olaf O

    2008-01-01

    Current high performance computing (HPC) applications are found in many consumer, industrial and research fields. From web searches to auto crash simulations to weather predictions, these applications require large amounts of power by the compute farms and supercomputers required to run them. The demand for more and faster computation continues to increase along with an even sharper increase in the cost of the power required to operate and cool these installations. The ability of standard processor based systems to address these needs has declined in both speed of computation and in power consumption over the past few years. This paper presents a new method of computation based upon programmable logic as represented by Field Programmable Gate Arrays (FPGAs) that addresses these needs in a manner requiring only minimal changes to the current software design environment.

  2. Thermal decomposition of HMX: Low temperature reaction kinetics and their use for assessing response in abnormal thermal environments and implications for long-term aging

    SciTech Connect

    Behrens, R.; Bulusu, S.

    1995-12-01

    The thermal decomposition of HMX between 175 and 200{degree}C has been studied using the simultaneous thermogravimetric modulated beam mass spectrometer (STMBMS) apparatus with a focus on the initial stages of the decomposition. The identity of thermal decomposition products is the same as that measured in previous higher temperature experiments. The initial stages of the decomposition are characterized by an induction period followed by two acceleratory periods. The Arrhenius parameters for the induction and two acceleratory periods are (Log(A) = 18.2 {plus_minus} 0.8, Ea = 48.2 {plus_minus} 1.8 kcal/mole), (Log(A) = 17.15 {plus_minus} 1.5 and Ea = 48.9 {plus_minus} 3.2 kcal/mole), (Log A) = 19.1 {plus_minus} 3.0 and Ea = 52.1 {plus_minus} 6.3 kcal/mole), respectively. This data can be used to calculate the time and temperature required to decompose a desired fraction of a sample that is being prepared to test the effect of thermal degradation on its sensitivity or burn rates. It can also be used to estimate the extent of decomposition that may be expected under normal storage conditions for munitions containing HMX. This data, along with previous mechanistic studies conducted at higher temperatures, suggest that the process that controls the early stages of decomposition of HMX in the solid phase is scission of the N-NO{sub 2} bond, reaction of the N0{sub 2} within a ``lattice cage`` to form the mononitroso analogue of HMX and decomposition of the mononitroso HMX within the HMX lattice to form gaseous products that are retained in bubbles or diffuse into the surrounding lattice.

  3. Pressure Wave Measurements from Thermal Cook-off of an HMX Based Explosive

    SciTech Connect

    Forbes, J W; Tarver, C M; Urtiew, P A; Garcia, F; Greenwood, D W; Vandersall, K S

    2001-05-09

    A better understanding of thermal cook-off is important for safe handling and storing explosive devices. A number of safety issues exist about what occurs when a cased explosive thermally cooks off. For example, violence of the events as a function of confinement are important for predictions of collateral damage. This paper demonstrates how adjacent materials can be gauged to measure the resulting pressure wave and how this wave propagates in this adjacent material. The output pulse from the thermal cook-off explosive containing fixture is of obvious interest for assessing many scenarios.

  4. Energetic Salts Based on 3,5-Bis(dinitromethyl)-1,2,4-triazole Monoanion and Dianion: Controllable Preparation, Characterization, and High Performance.

    PubMed

    Zhang, Jiaheng; Dharavath, Srinivas; Mitchell, Lauren A; Parrish, Damon A; Shreeve, Jean'ne M

    2016-06-22

    Molecular modification of known explosives is considered to be an efficient route to design new energetic materials. A new family of energetic salts based on the 3,5-bis(dinitromethyl)-1,2,4-triazole monoanion and dianion were controllably synthesized by using 1-diamino-2,2-dinitroethene as a precursor. X-ray structure determination of monohydrazinium 3,5-bis(dinitromethyl)-1,2,4-triazolate (5) and monoammonium (6) and diammonium 3,5-bis(dinitromethyl)-1,2,4-triazolate hydrate (8·H2O) further confirmed the structures of these anions. In addition, as supported by X-ray data, in the monoanion system, the roving proton on the ring nitrogen rather than on the gem-dinitro carbon results in extensive hydrogen-bonding interactions and higher packing coefficients. Interestingly, 5 and 6 possess the highest calculated crystal densities, 1.965 and 1.957 g cm(-3) at 150 K, for hydrazinium and ammonium energetic salts, respectively. Energetic evaluation indicates that 5 (detonation velocity vD = 9086 m s(-1); detonation pressure P = 38.7 GPa) and 6 (vD, 9271 m s(-1); P = 41.0 GPa) exhibit great detonation properties, superior to those of current highly explosive benchmarks, such as 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). PMID:27267735

  5. Comparison of the thermal decompositions of HMX and 2,4-DNI for evaluation of slow cookoff response and long-term stability

    SciTech Connect

    Minier, L.; Behrens, R.; Bulusu, S.

    1995-12-01

    Thermal decomposition of HMX between 175C and 200C was studied using the simultaneous thermogravimetric modulated beam mass spectrometer with focus on initial stages of the decomposition. Thermal decomposition products are the same as in previous higher temperature experiments. The initial stages of the decomposition have an induction period followed by two acceleratory periods. Arrhenius parameters for the induction and two acceleratory periods are (Log(A)= 18.2 {plus_minus} 0.8, Ea = 48.2 {plus_minus} 1.8 kcal/mole), (Log (A) = 17.15 {plus_minus} 1.5 and Ea = 48.9 {plus_minus} 3.2 kcal/mole), (Log (A) = 19.1 {plus_minus} 3.0 and Ea = 52.1 {plus_minus} 6.3 kcal/mole). This data can be used to calculate the time and temperature required to decompose a desired fraction of a test sample testing the effect of thermal degradation on sensitivity or bum rates. It can also be used to estimate the extent of decomposition expected under normal storage conditions for munitions containing HMX. This data, along with previous mechanistic studies conducted at higher temperatures, suggest that the process that controls the early stages of decomposition of HMX in the solid phase is scission of the N-NO{sub 2} bond, reaction of the N0{sub 2} within a lattice cage to form the mononitroso analogue of HMX and decomposition of the mononitroso HMX within the HMX lattice to form gaseous products that are retained in bubbles or diffuse into the surrounding lattice. These methods evaluating HMX can be used to evaluate new energetic materials such as 2,4-DNI. The early 2,4-DNI thermal decomposition is characterized by an initial decomposition, an apparent induction period, then an initial acceleratory period. The main gaseous products are NO, C0{sub 2}, HNCO, H{sub 2}0, N{sub 2}, CO, HCN and C{sub 2}N{sub 2}. The presence of adsorbed and occluded H{sub 2}0 is the major cause of the early decomposition.

  6. Burning mechanism and regression rate of RX-35-AU and RX-35-AV as a function of HMX particle size measured by the hybrid closed bomb-strand burner

    SciTech Connect

    Tao, W.C.; Costantino, M.S.; Ornellas, D.L.

    1990-04-01

    In this study, the average surface regression rate of two HMX-based cast explosives, RX-35-AU and RX-35-AV, is measured to pressures above 750 MPa using a hybrid closed bomb-strand burner. The hybrid design allows the simultaneous measurement of pressure and regression rate over a large range of pressures in each experiment. Nitroglycerin/Triacetin (75/25) and polyethylene glycol (PEG) are used as the energetic plasticizer and polymeric binder, respectively, in both formulations. The HMX solids loading in each formulation is 50 wt %, consisting of a narrow particle size distribution of 6--8 {mu}m for RX-35-AU and 150--177 {mu}m for RX-35-AV. Of special interest are the regression rate and burning mechanism as a function of the initial particle size distribution and the mechanical properties fo the cast explosives. In general, the regression rate for the larger particle size formulation, RX-35-AV, is two to three times faster compared to that for RX-35-AU. Up to 750 MPa and independent of the initial confinement pressure, RX-35-AU exhibits a planar burning mechanism with the regression rate obeying the classical aP{sup n} formalism. For RX-35-AV, however, the burning behavior is erratic for samples ignited at 200 MPa confinement pressure. At confinement pressures above 400 MPa, the regression exhibits more of a planar burning mechanism. The unstable combustion behavior for RX-35-AV at lower confinement pressures is related to several mechanisms: (1) an abrupt increase in surface area due to particle fracture and subsequent translation and rotation, resulting in debonding and creating porosity, (2) thixotropic'' separation of the binder and nitramine, causing the significantly greater fracture damage to the nitramine during the loading cycle, (3) microscopic damage to the nitramine crystals that increase its intrinsic burning rate. 12 refs., 8 figs., 2 tabs.

  7. Characterization of layers of Tetryl, TNB, and HMX on metal surfaces using fiber optics coupled grazing angle-FTIR

    NASA Astrophysics Data System (ADS)

    Pacheco-Londoño, Leonardo; Santiago, Angel; Pujols, Jackson; Primera-Pedrozo, Oliva M.; Mattei, Alessandra; Ortiz, William; Ruiz, Orlando; Ramirez, Michael; Hernández-Rivera, Samuel P.

    2007-04-01

    Fiber optics coupled-grazing angle probe Fourier transform infrared (FTIR) spectroscopy and infrared microspectroscopy have been used for characterization of the distribution and form of layers of some explosives deposited on stainless steel sheets. Among the explosives tested were trinitrobenzene, HMX and Tetryl. Various solvents were used to deposit the films on stainless steel slides. Isopropyl alcohol was the preferred solvent because it produced more homogeneous mass distributions of target explosives on the substrates. The film thickness, analyte distribution and the relation of thickness to infrared absorption/reflection response of these explosives were compared with those previously reported for TNT, 2,4-DNT and RDX. This comparison was used for described the general optical behavior of the explosives studied.

  8. Method and apparatus for synthesizing HMX and N/sub 2/O/sub 5/. [Patent application; cyclotetramethylenetetraamine

    DOEpatents

    McGuire, R.R.; Coon, C.L.; Harrar, J.E.; Pearson, R.K.

    1982-07-20

    A method and apparatus for electrochemically synthesizing N/sub 2/O/sub 5/ includes oxidizing a solution of N/sub 2/O/sub 4//HNO/sub 3/ at an anode, while maintaining a controlled potential between the N/sub 2/O/sub 4//HNO/sub 3/ solution and the anode. A potential of about 1.35 to 2.0V vs. SCE is preferred, while a potential of about 1.80V vs. SCE is most preferred. Thereafter, the N/sub 2/O/sub 5/ is reacted with either 1.5-diacetyl-3,7-dinitro-1,3,5,7-tetraazacyclooctane (DADN) or 1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane (TAT) to form cyclotetramethylenetetraamine (HMX).

  9. Investigating the fate of nitroaromatic (TNT) and nitramine (RDX and HMX) explosives in fractured and pristine soils.

    PubMed

    Douglas, Thomas A; Walsh, Marianne E; McGrath, Christian J; Weiss, Charles A

    2009-01-01

    Explosives compounds, known toxins, are loaded to soils on military training ranges predominantly during explosives detonation events that likely fracture soil particles. This study was conducted to investigate the fate of explosives compounds in aqueous slurries containing fractured and pristine soil particles. Three soils were crushed with a piston to emulate detonation-induced fracturing. X-ray diffraction, energy-dispersive X-ray spectrometry, gas adsorption surface area measurements, and scanning electron microscopy were used to quantify and image pristine and fractured soil particles. Aqueous batches were prepared by spiking soils with solutions containing 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro 1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and 2,4-dinitrotoluene (2,4-DNT). Samples were collected over 92 d and the concentrations of the spiked explosives compounds and TNT transformation products 2-amino-4,6-dinitrotoluene (2ADNT) and 4-amino-2,6-dinitrotoluene (4ADNT) were measured. Our results suggest soil mineralogical and geochemical compositions were not changed during piston-induced fracturing but morphological differences were evident with fractured soils exhibiting more angular surfaces, more fine grained particles, and some microfracturing that is not visible in the pristine samples. TNT, 2,4-DNT, RDX, and HMX exhibited greater analyte loss over time in batch solutions containing fractured soil particles compared to their pristine counterparts. 2ADNT and 4ADNT exhibited greater concentrations in slurries containing pristine soils than in slurries containing fractured soils. Explosives compound transformation is greater in the presence of fractured soil particles than in the presence of pristine soil particles. Our results imply fractured soil particles promote explosive compound transformation and/or explosives compounds have a greater affinity for adsorption to fractured soil particle surfaces. PMID

  10. Small Scale Characterization of the Presence of the Explosive Octahydro-1,3,5,7-tetranitro- 1,3,5,7 tetrazocine (HMX) Near Former Naval Sites on Vieques Island, Puerto Rico

    NASA Astrophysics Data System (ADS)

    Simmons, C. C.; Carvalho-Knighton, K. M.; Pyrtle, A. J.

    2007-12-01

    Octahydro-1,3,5,7-tetranitro-1,3,5,7 tetrazocine (HMX) is a synthetic energetic compounds that has been commonly used in military munitions. The presence and movement of HMX through the environment is of growing concern because of potential civilian exposure and impacts on human health. HMX remains in the environment unreactive with little degradation. It can be transported great distances in water thus having the possibility for migrating into groundwater. The former naval sites in Vieques were used for weapons training and housed several disposal sites. Previous studies around these sites indicate the presence of radioactive materials produced through thermal fission, such as Cs-137. Since HMX was primarily used to implode fissionable materials in nuclear devices, evaluating the release of HMX and consequent movement through the environment at these sites is essential. Surface water and soil samples as well as core and pore water samples were collected from two sites in Vieques; Kiani Lagoon and Mosquito Bay. All samples were extracted using EPA method 8330 and analyzed using RP-HPLC analysis with a C-18 column. HMX was undetected in samples collected from both Kiani Lagoon and Mosquito Bay. The development of a model that studies the flow rates and fate of water runoff in these areas of interest, coupled with data on groundwater testing inside the actual former naval facilities, is being explored for further sample collection and analysis.

  11. High strength forgeable tantalum base alloy

    NASA Technical Reports Server (NTRS)

    Buckman, R. W., Jr.

    1975-01-01

    Increasing tungsten content of tantalum base alloy to 12-15% level will improve high temperature creep properties of existing tantalum base alloys while retaining their excellent fabrication and welding characteristics.

  12. Low amplitude impact testing and analysis of pristine and aged solid high explosives

    SciTech Connect

    Chidester, S K; Garza, R; Tarver, C M

    1998-08-17

    The critical impact velocities of 60.1 mm diameter blunt steel projectiles required for ignition of exothermic chemical reaction were determined for heavily confined charges of new and aged (15-30 years) solid HMX-based high explosives. The explosives in order of decreasing impact sensitivity were: PBX 9404; LX-lo; LX-14; PBX 9501; and LX-04. Embedded pressure gauges measured the interior pressure histories. Stockpile aged LX-04 and PBX 9501 from dismantled units were tested and compared to freshly pressed charges. The understanding of explosive aging on impact ignition and other hazards must improve as systems are being deployed longer than their initial estimated lifetimes. The charges that did not react on the first impact were subjected to multiple impacts. While the violence of reaction increased with impact velocity, it remained much lower than that produced by an intentional detonation. Ignition and Growth reactive flow models were developed to predict HMX-based explosive impact sensitivity in other geometries and scenarios.

  13. Ab initio studies of 1,3,5,7-tetranitro-1,3,5,7-tetrazocine/1,3-dimethyl-2-imidazolidinone cocrystal under high pressure using dispersion corrected density functional theory

    SciTech Connect

    Gu, Bang-Ming; Lin, He; Zhu, Shun-Guan

    2014-04-14

    A detailed study of structural, electronic, and thermodynamic properties of 1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)/1,3-dimethyl-2-imidazolidinone (DMI) cocrystal under the hydrostatic pressure of 0–100 GPa was performed by using dispersion-corrected density functional theory (DFT-D) method. The calculated crystal structure is in reasonable agreement with the experimental data at the ambient pressure. Based on the analysis of lattice constants, bond lengths, bond angles, and dihedral angles under compression, it is found that HMX molecules in HMX/DMI cocrystal are seriously distorted. In addition, as the pressure increases, the band gap decreases gradually, which suggests that HMX/DMI cocrystal is becoming more metallic. Some important intermolecular interactions between HMX and DMI are also observed in the density of states spectrum. Finally, its thermodynamic properties were characterized, and the results show that HMX/DMI cocrystal is more easily formed in the low pressure.

  14. Simulating Thermal Explosion of Octahydrotetranitrotetrazine-based explosives: Model Comparison with Experiment

    SciTech Connect

    Yoh, J J; McClelland, M A; Maienschein, J L; Nichols, A L; Tarver, C M

    2006-02-07

    The authors compare two-dimensional model results with measurements for the thermal, chemical and mechanical behavior in a thermal explosion experiment. Confined high explosives are heated at a rate of 1 C per hour until an explosion is observed. The heating, ignition, and deflagration phases are modeled using an Arbitrarily Lagrangian-Eulerian code (ALE3D) that can handle a wide range of time scales that vary from a structural to a dynamic hydro time scale. During the pre-ignition phase, quasi-static mechanics and diffusive thermal transfer from a heat source to the HE are coupled with the finite chemical reactions that include both endothermic and exothermic processes. Once the HE ignites, a hydro dynamic calculation is performed as a burn front propagates through the HE. Two octahydrotetranitrotetrazine (HMX)-based explosives, LX-04 and LX-10, are considered, whose chemical-thermal-mechanical models are constructed based on measurements of thermal and mechanical properties along with small scale thermal explosion measurements. The present HMX modeling work shows very first violence calculations with thermal predictions associated with a confined thermal explosion test. The simulated dynamic response of HE confinement during the explosive phase is compared to measurements in larger scale thermal explosion tests. The explosion temperatures for both HE's are predicted to within 1 C. Calculated and measured wall strains provide an indication of vessel pressurization during the heating phase and violence during the explosive phase.

  15. Behavior of Plastic Bonded Composite Explosives During High Acceleration

    NASA Astrophysics Data System (ADS)

    Lanzerotti, Y.

    1998-03-01

    The mechanical behavior of plastic bonded composite explosives has been studied during high acceleration in an ultracentrifuge. The pressed explosives studied include LX-14 [95% HMX (cyclotetramethylene- tetranitramine), 5% Estane], Composition A3 type II [91% RDX (cyclotrimethylene-trinitramine), 99% BDNPF (bis-dinitropropyl acetal formal), 6% CAB (cellulose acetate butyrate)], and PAX-3 (85% HMX, 9% BDNPF, 6% CAB/25% Aluminum). The fracture strength of LX-14 is greater than all pressed explosives studied to date. The fracture strength of Composition A3 type II is smaller than all pressed explosives studied to date.

  16. High performance pitch-based carbon fiber

    SciTech Connect

    Tadokoro, Hiroyuki; Tsuji, Nobuyuki; Shibata, Hirotaka; Furuyama, Masatoshi

    1996-12-31

    The high performance pitch-based carbon fiber with smaller diameter, six micro in developed by Nippon Graphite Fiber Corporation. This fiber possesses high tensile modulus, high tensile strength, excellent yarn handle ability, low thermal expansion coefficient, and high thermal conductivity which make it an ideal material for space applications such as artificial satellites. Performance of this fiber as a reinforcement of composites was sufficient. With these characteristics, this pitch-based carbon fiber is expected to find wide variety of possible applications in space structures, industrial field, sporting goods and civil infrastructures.

  17. Project Surveys Community Based Organizations High Schools

    ERIC Educational Resources Information Center

    Black Issues in Higher Education, 2004

    2004-01-01

    A new report aims to promote awareness at the state level of the importance of Community Based Organizations (CBO) high schools, highlighting the promising lessons these schools hold for improving the educational outcomes of youth at risk of school failure or dropping out. This document briefly analyzes the report, "CBO High Schools: Their Value…

  18. High sensitivity cymbal-based accelerometer

    SciTech Connect

    Sun Chengliang; Lam, K.H.; Choy, S.H.; Chan, H.L. W.; Zhao, X.-Z.; Choy, C.L.

    2006-03-15

    A high sensitivity piezoelectric accelerometer has been developed by replacing the conventional piezoelectric rings with a cymbal transducer. The sensitivity of the cymbal-based accelerometers containing cymbal transducers with different endcap thicknesses and different seismic masses has been measured as a function of driving frequency. Due to the high d{sub 33}{sup '} coefficient of the cymbal transducers, the cymbal-based accelerometers have a high sensitivity of {approx}97 pC/ms{sup -2} with the amplitude rise of 2.85% (<1 dB) at one-third of the mounted resonance frequency (3.38 kHz). The effect of the seismic mass, the resonance frequency, and d{sub 33}{sup '} coefficient of the cymbal transducers on the sensitivity and the frequency range of the cymbal-based accelerometers are reported.

  19. Intermetallic-Based High-Temperature Materials

    SciTech Connect

    Sikka, V.K.

    1999-04-25

    The intermetallic-based alloys for high-temperature applications are introduced. General characteristics of intermetallics are followed by identification of nickel and iron aluminides as the most practical alloys for commercial applications. An overview of the alloy compositions, melting processes, and mechanical properties for nickel and iron aluminizes are presented. The current applications and commercial producers of nickel and iron aluminizes are given. A brief description of the future prospects of intermetallic-based alloys is also given.

  20. Electronic structure of transition metal dichalcogenides monolayers 1H-MX2 (M = Mo, W; X = S, Se, Te) from ab-initio theory: new direct band gap semiconductors

    NASA Astrophysics Data System (ADS)

    Kumar, A.; Ahluwalia, P. K.

    2012-06-01

    We report first principles calculations of the electronic structure of monolayer 1H-MX2 (M = Mo, W; X = S, Se, Te), using the pseudopotential and numerical atomic orbital basis sets based methods within the local density approximation. Electronic band structure and density of states calculations found that the states around the Fermi energy are mainly due to metal d states. From partial density of states we find a strong hybridisation between metal d and chalcogen p states below the Fermi energy. All studied compounds in this work have emerged as new direct band gap semiconductors. The electronic band gap is found to decrease as one goes from sulphides to the tellurides of both Mo and W. Reducing the slab thickness systematically from bulk to monolayers causes a blue shift in the band gap energies, resulting in tunability of the electronic band gap. The magnitudes of the blue shift in the band gap energies are found to be 1.14 eV, 1.16 eV, 0.78 eV, 0.64, 0.57 eV and 0.37 eV for MoS2, WS2, MoSe2, WSe2, MoTe2 and WTe2, respectively, as we go from bulk phase (indirect band gap) to monolayer limit (direct band gap). This tunability in the electronic band gap and transitions from indirect to direct band make these materials potential candidates for the fabrication of optoelectronic devices.

  1. Phosphonate Based High Nuclearity Magnetic Cages.

    PubMed

    Sheikh, Javeed Ahmad; Jena, Himanshu Sekhar; Clearfield, Abraham; Konar, Sanjit

    2016-06-21

    Transition metal based high nuclearity molecular magnetic cages are a very important class of compounds owing to their potential applications in fabricating new generation molecular magnets such as single molecular magnets, magnetic refrigerants, etc. Most of the reported polynuclear cages contain carboxylates or alkoxides as ligands. However, the binding ability of phosphonates with transition metal ions is stronger than the carboxylates or alkoxides. The presence of three oxygen donor sites enables phosphonates to bridge up to nine metal centers simultaneously. But very few phosphonate based transition metal cages were reported in the literature until recently, mainly because of synthetic difficulties, propensity to result in layered compounds, and also their poor crystalline properties. Accordingly, various synthetic strategies have been followed by several groups in order to overcome such synthetic difficulties. These strategies mainly include use of small preformed metal precursors, proper choice of coligands along with the phosphonate ligands, and use of sterically hindered bulky phosphonate ligands. Currently, the phosphonate system offers a library of high nuclearity transition metal and mixed metal (3d-4f) cages with aesthetically pleasing structures and interesting magnetic properties. This Account is in the form of a research landscape on our efforts to synthesize and characterize new types of phosphonate based high nuclearity paramagnetic transition metal cages. We quite often experienced synthetic difficulties with such versatile systems in assembling high nuclearity metal cages. Few methods have been emphasized for the self-assembly of phosphonate systems with suitable transition metal ions in achieving high nuclearity. We highlighted our journey from 2005 until today for phosphonate based high nuclearity transition metal cages with V(IV/V), Mn(II/III), Fe(III), Co(II), Ni(II), and Cu(II) metal ions and their magnetic properties. We observed that

  2. Deflagration Rate Measurements of Three Insensitive High Explosives: LLM-105, TATB, and DAAF

    SciTech Connect

    Glascoe, E A; Maienschein, J L; Lorenz, K T; Tan, N; Koerner, J G

    2010-03-08

    The pressure dependent deflagration rates of LLM-105, DAAF and TATB based formulations were measured in the LLNL high pressure strand burner. The role of binder amount, explosive type, and thermal damage and their effects on the deflagration rate will be discussed. One DAAF formulation, two different formulations of LLM-105, and four formulations of TATB were studied; results indicate that binder amount and type play a minor role in the deflagration behavior. This is in sharp contrast to the HMX based formulations which strongly depend on binder amount and type. The effect of preheating these samples was considerably more dramatic. In the case of LLM-105, preheating the sample appears to have little effect on the deflagration rate. In contrast, preheating DAAF and TATB formulations causes the deflagration rate to accelerate. The thermal and mechanical properties of these formulations will be discussed in the context of their pressure and temperature dependent deflagration rates.

  3. Single and multiple impact ignition of new and aged high explosives in the Steven Impact Test

    SciTech Connect

    Chidester, S K; DePiero, A H; Garza, R G; Tarver, C M

    1999-06-01

    Threshold impact velocities for ignition of exothermic reaction were determined for several new and aged HMX-based solid high explosives using three types of projectiles in the Steven Test. Multiple impact threshold velocities were found to be approximately 10% lower in damaged charges that did not react in one or more prior impacts. Projectiles with protrusions that concentrate the friction work in a small volume of explosive reduced the threshold velocities by approximately 30%. Flat projectiles required nearly twice as high velocities for ignition as rounded projectiles. Blast overpressure gauges were used for both pristine and damaged charges to quantitatively measure reaction violence. Reactive flow calculations of single and multiple impacts with various projectiles suggest that the ignition rates double in damaged charges.

  4. Small-angle X-ray analysis of the effect of grain size on the thermal damage of octahydro-1, 3, 5, 7-tetranitro-1, 3, 5, 7 tetrazocine-based plastic-bounded expolsives

    NASA Astrophysics Data System (ADS)

    Yan, Guan-Yun; Tian, Qiang; Liu, Jia-Hui; Chen, Bo; Sun, Guang-Ai; Huang, Ming; Li, Xiu-Hong

    2014-07-01

    The microstructure evolution of plastic-bonded explosives (PBXs) after thermal stimulus plays a key role in PBX performance. In this paper, the nanoscale pores of thermal-treated octahydro-1,3,5,7-tetranitro-1,3,5,7 tetrazocine (HMX)-based PBXs with different HMX particle sizes [approximately 40 (FHP) and 100 μm (LHP)] were measured using small-angle X-ray scattering (SAXS). No obvious pore variations were found in the LHP samples heated at 160 °C for 6 h, whereas the amount of pores of FHP decreased when subjected to 160 °C for 6 h. At 180 °C, the average pore radii of FHP and LHP decreased from approximately 45 nm to 25 nm, and the total pore volume increased distinctively because of phase transformation. The LHP sample reached a high level of pore content after being held at 180 °C for 1 h, whereas FHP required 3 h. Both FHP and LHP had relatively high pore volumes when subjected to 200 °C for 1 and 3 h.

  5. Elastic constants of B-HMX and tantalum, equations of state of supercritical fluids and fluid mixtures and thermal transport determinations

    SciTech Connect

    Zaug, J M

    1998-08-21

    Ultrasonic sound speed measurements via Impulsive Stimulated Light Scattering (ISLS) were made in single crystals of b-HMX and tantalum over an extended range of temperatures. Elastic constants are consequently determined for b-HMX. Sound speeds are calculated for tantalum, from known elastic constants, and compare favorably with the results presented here. ISLS time-domain fits of tantalum records allowed for thermal diffusion determinations and, correspondingly, thermal conductivity. Measurements of the speed of sound and of the thermal diffusivities of fluid oxygen up to pressures of 13 GPa and at several temperatures are presented. Between 0.1 and 13 GPa the fluid's density increases by a factor of three. Thermal diffusivities rise slowly over this range, and are substantially smaller than those previously measured for the solid b-phase. Additional sound speed measurements were made along the 250 C isotherm in a 1:1 molar ratio mixture of liquid oxygen and nitrogen. These experiments demonstrate the versatility and potential application of a new laboratory within the U. S. DOD and DOE complex. 1

  6. A High Performance COTS Based Computer Architecture

    NASA Astrophysics Data System (ADS)

    Patte, Mathieu; Grimoldi, Raoul; Trautner, Roland

    2014-08-01

    Using Commercial Off The Shelf (COTS) electronic components for space applications is a long standing idea. Indeed the difference in processing performance and energy efficiency between radiation hardened components and COTS components is so important that COTS components are very attractive for use in mass and power constrained systems. However using COTS components in space is not straightforward as one must account with the effects of the space environment on the COTS components behavior. In the frame of the ESA funded activity called High Performance COTS Based Computer, Airbus Defense and Space and its subcontractor OHB CGS have developed and prototyped a versatile COTS based architecture for high performance processing. The rest of the paper is organized as follows: in a first section we will start by recapitulating the interests and constraints of using COTS components for space applications; then we will briefly describe existing fault mitigation architectures and present our solution for fault mitigation based on a component called the SmartIO; in the last part of the paper we will describe the prototyping activities executed during the HiP CBC project.

  7. Sensitivity of once-shocked, weathered high explosives

    SciTech Connect

    Williams, K.L.; Harris, B.W.

    1998-07-01

    Effects caused by stimulating once-shocked, weathered high explosives (OSW-HE) are investigated. The sensitivity of OSW-HE to mechanical stimuli was determined using standard industry tests. Some initial results are given. Pieces of OSW-HE were collected from active and inactive firing sites and from an area surrounding a drop tower at Los Alamos where skid and spigot tests were done. Samples evaluated were cast explosives or plastic bonded explosive (PBX) formulations containing cyclotrimethylenetrinitramine (RDX), cyclotetramethylene tetranitramine (HMX), 2,4,6-trinitrotoluene (TNT), mock or inert HE [tris(beta-chloroethyl)phosphate (CEF)], barium nitrate, cyanuric acid, talc, and Kel-F. Once-shocked, weathered LX-10 Livermore explosive [HMX/Viton A, (95/5 wt %)], PBX 9011 [HMX/Estane, (90/10 wt %)], PBX 9404 [HMX/nitrocellulose, tris(beta-chloroethyl) phosphate, (94/3/3 wt %)], Composition B or cyclotol (TNT/RDX explosives), and PBX 9007 (90% RDX, 9.1% styrene, 0.5% dioctyl phthalate, and 0.45 resin) were subjected to the hammer test, the drop-weight impact sensitivity test, differential thermal analysis (DTA), the spark test, the Henkin`s critical temperature test, and the flame test. Samples were subjected to remote, wet cutting and drilling; remote, liquid-nitrogen-cooled grinding and crushing; and scanning electron microscope (SEM) surface analyses for morphological changes.

  8. Tapered fiber based high power random laser.

    PubMed

    Zhang, Hanwei; Du, Xueyuan; Zhou, Pu; Wang, Xiaolin; Xu, Xiaojun

    2016-04-18

    We propose a novel high power random fiber laser (RFL) based on tapered fiber. It can overcome the power scaling limitation of RFL while maintaining good beam quality to a certain extent. An output power of 26.5 W has been achieved in a half-open cavity with one kilometer long tapered fiber whose core diameter gradually changes from 8 μm to 20 μm. The steady-state light propagation equations have been modified by taking into account the effective core area to demonstrate the tapered RFL through numerical calculations. The numerical model effectively describes the power characteristics of the tapered fiber based RFL, and both the calculating and experimental results show higher power exporting potential compared with the conventional single mode RFL. PMID:27137338

  9. Highly stretchable nanoalginate based polyurethane elastomers.

    PubMed

    Daemi, Hamed; Barikani, Mehdi; Barmar, Mohammad

    2013-06-20

    Highly stretchable elastomeric samples based on cationic polyurethane dispersions-sodium alginate nanoparticles (CPUD/SA) were prepared by the solution blending of sodium alginate and aqueous polyurethane dispersions. CPUDs were synthesized by step growth polymerization technique using N-methyldiethanolamine (MDEA) as a source of cationic emulsifier. The chemical structure and thermal-mechanical properties of these systems were characterized using FTIR and DMTA, respectively. The presence of nanoalginate particles including nanobead and nanorod particles were proved by SEM and EDX. It was observed that thermal properties of composites increased with increasing SA content. All prepared samples were known as thermoplastic-elastomers with high percentages of elongation. Excellent compatibility of prepared nanocomposites was proved by the DMTA data. PMID:23648022

  10. High Performance Oxides-Based Thermoelectric Materials

    NASA Astrophysics Data System (ADS)

    Ren, Guangkun; Lan, Jinle; Zeng, Chengcheng; Liu, Yaochun; Zhan, Bin; Butt, Sajid; Lin, Yuan-Hua; Nan, Ce-Wen

    2015-01-01

    Thermoelectric materials have attracted much attention due to their applications in waste-heat recovery, power generation, and solid state cooling. In comparison with thermoelectric alloys, oxide semiconductors, which are thermally and chemically stable in air at high temperature, are regarded as the candidates for high-temperature thermoelectric applications. However, their figure-of-merit ZT value has remained low, around 0.1-0.4 for more than 20 years. The poor performance in oxides is ascribed to the low electrical conductivity and high thermal conductivity. Since the electrical transport properties in these thermoelectric oxides are strongly correlated, it is difficult to improve both the thermoelectric power and electrical conductivity simultaneously by conventional methods. This review summarizes recent progresses on high-performance oxide-based thermoelectric bulk-materials including n-type ZnO, SrTiO3, and In2O3, and p-type Ca3Co4O9, BiCuSeO, and NiO, enhanced by heavy-element doping, band engineering and nanostructuring.

  11. PRESSURE AND TEMPERATURE DEPENDENT DEFLAGRATION RATE MEASUREMENTS OF LLM-105 AND TATB BASED EXPLOSIVES

    SciTech Connect

    Glascoe, E A; Tan, N; Koerner, J; Lorenz, K T; Maienschein, J L

    2009-11-10

    The pressure dependent deflagration rates of LLM-105 and TATB based formulations were measured in the LLNL high pressure strand burner. The role of binder amount, explosive type, and thermal damage and their effects on the deflagration rate will be discussed. Two different formulations of LLM-105 and three formulations of TATB were studied and results indicate that binder amount and type play a minor role in the deflagration behavior. This is in sharp contrast to the HMX based formulations which strongly depend on binder amount and type. The effect of preheating these samples was considerably more dramatic. In the case of LLM-105, preheating the sample appears to have little effect on the deflagration rate. In contrast, preheating TATB formulations causes the deflagration rate to accelerate and become erratic. The thermal and mechanical properties of these formulations will be discussed in the context of their pressure and temperature dependent deflagration rates.

  12. Detonation Characteristics of Plastic Explosives Based on Attractive Nitramines with Polyisobutylene and Poly(methyl methacrylate) Binders

    NASA Astrophysics Data System (ADS)

    Elbeih, Ahmed; Pachman, Jiri; Zeman, Svatopluk; Vávra, Pavel; Trzciński, Waldemar A.; Akštein, zbyněk

    2012-10-01

    Four highly brisant nitramines, RDX (1,3,5-trinitro-1,3,5-triazinane), HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane), BCHMX (cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d]imidazole), and ɛ-HNIW (ɛ-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane), were studied as extruded plastic explosives bonded by two plastic matrices based on polyisobutylene (C4 matrix) and poly-methylmethacrylate (plasticized by dioctyl-adipate) binders. The detonation velocities, D, were measured experimentally. Detonation parameters were also calculated by means of the Kamlet and Jacobs method and CHEETAH and EXPLO5 codes. These detonation parameters showed that plastic-bonded explosives (PBXs) based on BCHMX are more powerful explosives than those based on RDX. The Urizar coefficient for poly(methyl methacrylate) binder was also calculated.

  13. Spectral signatures for RDX-based explosives in the 3 micron region

    NASA Astrophysics Data System (ADS)

    Osborn, Tabetha; Kaimal, Sindhu; Reeve, Scott W.; Burns, William

    2008-04-01

    Explosive compounds such as RDX, and HMX present significant challenges to optically based sensors. This difficulty is due in part to the low vapor pressures these compounds possess. One approach for sensing explosives that circumvents the low explosive vapor pressure problem, involves focusing on the trace amounts of relatively high vapor pressure impurities that will be present in the vapor signature. In order to effectively detect these volatile impurities, the spectral signature databases must be readily available. One of our goals therefore, is the generation of a database of high resolution spectral signatures for these volatile organic impurities. Some rather formidable spectroscopic measurement challenges have been encountered while working to extend the spectral signature effort to the 3 micron region. Here we will outline progress to date, with a focus on the volatile organic compounds formaldehyde, acetaldehyde, nitromethane, acetone, isobutene, and cyclohexanone.

  14. Reactive Force Fields Based on Quantum Mechanics for Applications to Materials at Extreme Conditions

    NASA Astrophysics Data System (ADS)

    van Duin, Adri C. T.; Zybin, Sergey V.; Chenoweth, Kimberley; Zhang, Luzheng; Han, Si-Ping; Strachan, Alejandro; Goddard, William A.

    2006-07-01

    Understanding the response of energetic materials (EM) to thermal or shock loading at the atomistic level demands a highly accurate description of the reaction dynamics of multimillion-atom systems to capture the complex chemical and mechanical behavior involved: nonequilibrium energy/mass transfer, molecule excitation and decomposition under high strain/heat rates, formation of defects, plastic flow, and phase transitions. To enable such simulations, we developed the ReaxFF reactive force fields based on quantum mechanics (QM) calculations of reactants, products, high-energy intermediates and transition states, but using functional forms suitable for large-scale molecular dynamics simulations of chemical reactions under extreme conditions. The elements of ReaxFF are: - charge distributions change instantaneously as atomic coordinates change, - all valence interactions use bond orders derived uniquely from the bond distances which in turn describe uniquely the energies and forces, - three body (angle) and four body (torsion and inversion) terms are allowed but not required, - a general "van der Waals" term describes short range Pauli repulsion and long range dispersion interactions, which with Coulomb terms are included between all pairs of atoms (no bond or angle exclusions), - no environmental distinctions are made of atoms involving the same element; thus every carbon has the same parameters whether in diamond, graphite, benzene, porphyrin, allyl radical, HMX or TATP. ReaxFF uses the same functional form and parameters for reactive simulations in hydrocarbons, polymers, metal oxides, and metal alloys, allowing mixtures of all these systems into one simulation. We will present an overview of recent progress in ReaxFF developments, including the extension of ReaxFF to nitramine-based (nitromethane, HMX) and peroxide-based (TATP) explosives. To demonstrate the versatility and transferability of ReaxFF, we also present applications to silicone polymer poly

  15. High weldability nickel-base superalloy

    DOEpatents

    Gibson, Robert C.; Korenko, Michael K.

    1980-01-01

    This is a nickel-base superalloy with excellent weldability and high strength. Its composition consists essentially of, by weight percent, 10-20 iron, 57-63 nickel, 7-18 chromium, 4-6 molybdenum, 1-2 niobium, 0.2-0.8 silicon, 0.01-0.05 zirconium, 1.0-2.5 titanium, 1.0-2.5 aluminum, 0.02-0.06 carbon, and 0.002-0.015 boron. The weldability and strength of this alloy give it a variety of applications. The long-time structural stability of this alloy together with its low swelling under nuclear radiation conditions, make it especially suitable for use as a duct material and controlling element cladding for sodium-cooled nuclear reactors.

  16. Diaphragm based high sensitive FBG pressure sensor

    NASA Astrophysics Data System (ADS)

    Vengal Rao, P.; Srimannarayana, K.; Sai Shankar, M.; Kishore, P.

    2013-06-01

    A high sensitive pressure sensor based on Fiber Bragg grating (FBG) integrated with a thin metal diaphragm was designed and demonstrated. To enhance the pressure sensitivity FBG is firmly glued across the diameter of the diaphragm. Under pressure, the diaphragm deforms and produces an induced strain along the length of the fiber causes shift in Bragg wavelength of the FBG. Pressure measurement is made by measuring the Bragg wavelength shift against change in pressure. The sensor was tested up to the maximum pressure of 140 psi and the corresponding pressure sensitivity was found to be 0.0204 nm/psi, which is approximately 970 times higher than that can be achieved with a bare FBG. The experimental results show good agreement with the theoretical results and possess good linearity and repeatability. This sensor can be used for the measurement of medium pressure, liquid level and depth of underwater.

  17. Bis(4-nitraminofurazanyl-3-azoxy)azofurazan and Derivatives: 1,2,5-Oxadiazole Structures and High-Performance Energetic Materials.

    PubMed

    Liu, Yuji; Zhang, Jiaheng; Wang, Kangcai; Li, Jinshan; Zhang, Qinghua; Shreeve, Jean'ne M

    2016-09-12

    Bis(4-nitraminofurazanyl-3-azoxy)azofurazan (1) and ten of its energetic salts were prepared and fully characterized. Computational analysis based on isochemical shielding surface and trigger bond dissociation enthalpy provide a better understanding of the thermal stabilities for nitramine-furazans. These energetic compounds exhibit good densities, high heats of formation, and excellent detonation velocity and pressure. Some representative compounds, for example, 1 (vD : 9541 m s(-1) ; P: 40.5 GPa), and 4 (vD : 9256 m s(-1) ; P: 38.0 GPa) exhibit excellent detonation performances, which are comparable with current high explosives such as RDX (vD : 8724 m s(-1) ; P: 35.2 GPa) and HMX (vD : 9059 m s(-1) ; P: 39.2 GPa). PMID:27511132

  18. A thermodynamically based definition of fast verses slow heating in secondary explosives

    NASA Astrophysics Data System (ADS)

    Henson, Bryan; Smilowitz, Laura

    2013-06-01

    The thermal response of energetic materials is often categorized according to the rate of heating as either fast or slow, e.g. slow cook-off. Such categorizations have most often followed some operational rationale, without a material based definition. We have spent several years demonstrating that for the energetic material octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) a single mechanism of thermal response reproduces times to ignition independent of rate or means of heating over the entire range of thermal response. HMX is unique in that bulk melting is rarely observed in either thermal ignition or combustion. We have recently discovered a means of expressing this mechanism for HMX in a reduced form applicable to many secondary explosives. We will show that with this mechanism a natural definition of fast versus slow rates of heating emerges, related to the rate of melting, and we use this to illustrate why HMX does not exhibit melting, and why a number of other secondary explosives do, and require the two separate categories.

  19. Proposal for superstructure based high efficiency photovoltaics

    NASA Technical Reports Server (NTRS)

    Wagner, M.; Leburton, J. P.

    1986-01-01

    A novel class of cascade structures is proposed which features multijunction upper subcells, referred to as superstructure high-efficiency photovoltaics (SHEPs). The additional junctions enhance spectral response and improve radiation tolerance by reducing bulk recombination losses. This is important because ternary III-V alloys, which tend to have short minority-carrier diffusion lengths, are the only viable materials for the high-bandgap upper subcells required for cascade solar cells. Realistic simulations of AlGaAs SHEPs show that one-sun AM0 efficiencies in excess of 26 percent are possible.

  20. Network based high performance concurrent computing

    SciTech Connect

    Sunderam, V.S.

    1991-01-01

    The overall objectives of this project are to investigate research issues pertaining to programming tools and efficiency issues in network based concurrent computing systems. The basis for these efforts is the PVM project that evolved during my visits to Oak Ridge Laboratories under the DOE Faculty Research Participation program; I continue to collaborate with researchers at Oak Ridge on some portions of the project.

  1. Nano copper based high temperature solder alternative

    NASA Astrophysics Data System (ADS)

    Sharma, Akshay

    Nano Cu an alternative to high temperature solder is developed by the Advance Technological Center at the Lockheed Martin Corporation. A printable paste of Cu nano particles is developed with an ability to fuse at 200°C in reflow oven. After reflow the deposited material has nano crystalline and nano porous structure which affects its properties. Accelerated test are performed on nano Cu deposition having nano porous and nano crystalline structure for assessment and prediction of reliability. Nano Cu assemblies with different bond layer thickness are sheared to calculate the strength of the material and are correlated with the porous and crystalline structure of nano Cu. Thermal and isothermal fatigue test are performed on nano Cu to see the dependency of life on stress and further surface of failed assemblies were observed to determine the type of failure. Creep test at RT are performed to find the type of creep mechanism and how they are affected when subjected to high temperature. TEM, SEM, X-ray, C-SAM and optical microscopy is done on the nano Cu sample for structure and surface analysis.

  2. High Frequency Laser-Based Ultrasound

    SciTech Connect

    Huber, R; Chinn, D; Balogun, O; Murray, T

    2005-09-12

    To obtain micrometer resolution of materials using acoustics requires frequencies around 1 GHz. Attenuation of such frequencies is high, limiting the thickness of the parts that can be characterized. Although acoustic microscopes can operate up to several GHz in frequency, they are used primarily as a surface characterization tool. The use of a pulsed laser for acoustic generation allows generation directly in the part, eliminating the loss of energy associated with coupling the energy from a piezoelectric transducer to the part of interest. The use of pulsed laser acoustic generation in combination with optical detection is investigated for the non-contact characterization of materials with features that must be characterized to micrometer resolution.

  3. Limits of simulation based high resolution EBSD.

    PubMed

    Alkorta, Jon

    2013-08-01

    High resolution electron backscattered diffraction (HREBSD) is a novel technique for a relative determination of both orientation and stress state in crystals through digital image correlation techniques. Recent works have tried to use simulated EBSD patterns as reference patterns to achieve the absolute orientation and stress state of crystals. However, a precise calibration of the pattern centre location is needed to avoid the occurrence of phantom stresses. A careful analysis of the projective transformation involved in the formation of EBSD patterns has permitted to understand these phantom stresses. This geometrical analysis has been confirmed by numerical simulations. The results indicate that certain combinations of crystal strain states and sample locations (pattern centre locations) lead to virtually identical EBSD patterns. This ambiguity makes the problem of solving the absolute stress state of a crystal unfeasible in a single-detector configuration. PMID:23676453

  4. PETN, RDX, HMX, TATB: band gap dependence on pressure under hydrostatic compression from DFT with GW and vdW corrections

    NASA Astrophysics Data System (ADS)

    Mukhanov, Andrei; Yanilkin, Alexei

    2014-03-01

    In the middle of 1990s Gilman (Gilman J. J. 1995 Phil. Mag. B, 71:6, 1057) proposed the idea that explosives transit from insulator to conductor state with following adiabatic expansion of free electrons in shockwave. One of the reasons of such a behavior of electrons is narrowing or disappearing of the fundamental band gap in explosive single crystal. It is well known that similar behavior can be simulated by DFT. But there is a severe problem of lowering the value of gap by DFT. So for quantitative prediction of narrowing of gap under pressure it is necessary to use more complicated methods like GW. From first principle calculations we determined elastic moduli for ideal crystals of PETN, RDX, HMX, and TATB. Accounting for those moduli we simulated the 0 K isotherms for hydrostatic compression of single crystal. Due to the essential role of van der Waals interaction in such materials the vdW corrections to DFT in Grimme's form was used. We obtained the dependencies for band gap on pressure under hydrostatic compression. Our preliminary results on GW calculations show that for TATB at initial uncompressed volume we have the value of gap twice a bigger in GW than in DFT.

  5. Influence of Small Change of Porosity on Shock Initiation of an HMX/TATB/Viton Explosive and Ignition and Growth Modeling

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Hussain, Tariq; Huang, Fenglei; Duan, Zhuoping

    2016-07-01

    All solid explosives in practical use are more or less porous. Although it is known that the change in porosity affects the shock sensitivity of solid explosives, the effect of small changes in porosity on the sensitivity needs to be determined for safe and efficient use of explosive materials. In this study, the influence of a small change in porosity on shock initiation and the subsequent detonation growth process of a plastic-bonded explosive PBXC03, composed of 87% cyclotetramethylene-tetranitramine (HMX), 7% triaminotrinitrobenzene (TATB), and 6% Viton by weight, are investigated by shock to detonation transition experiments. Two explosive formulations of PBXC03 having the same initial grain sizes pressed to 98 and 99% of theoretical mass density (1.873 g/cm3) respectively are tested using the in situ manganin piezoresistive pressure gauge technique. Numerical modeling of the experiments is performed using an ignition and growth reactive flow model. Reasonable agreement with the experimental results is obtained by increasing the growth term coefficient in the Lee-Tarver ignition and growth model with porosity. Combining the experimental and simulation results shows that the shock sensitivity increases with porosity for PBXC03 having the same explosive initial grain sizes for the pressures (about 3.1 GPa) applied in the experiments.

  6. A high throughput droplet based electroporation system

    NASA Astrophysics Data System (ADS)

    Yoo, Byeongsun; Ahn, Myungmo; Im, Dojin; Kang, Inseok

    2014-11-01

    Delivery of exogenous genetic materials across the cell membrane is a powerful and popular research tool for bioengineering. Among conventional non-viral DNA delivery methods, electroporation (EP) is one of the most widely used technologies and is a standard lab procedure in molecular biology. We developed a novel digital microfluidic electroporation system which has higher efficiency of transgene expression and better cell viability than that of conventional EP techniques. We present the successful performance of digital EP system for transformation of various cell lines by investigating effects of the EP conditions such as electric pulse voltage, number, and duration on the cell viability and transfection efficiency in comparison with a conventional bulk EP system. Through the numerical analysis, we have also calculated the electric field distribution around the cells precisely to verify the effect of the electric field on the high efficiency of the digital EP system. Furthermore, the parallelization of the EP processes has been developed to increase the transformation productivity. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (Grant Number: 2013R1A1A2011956).

  7. High Performance Graphene Oxide Based Rubber Composites

    NASA Astrophysics Data System (ADS)

    Mao, Yingyan; Wen, Shipeng; Chen, Yulong; Zhang, Fazhong; Panine, Pierre; Chan, Tung W.; Zhang, Liqun; Liang, Yongri; Liu, Li

    2013-08-01

    In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications.

  8. High Performance Graphene Oxide Based Rubber Composites

    PubMed Central

    Mao, Yingyan; Wen, Shipeng; Chen, Yulong; Zhang, Fazhong; Panine, Pierre; Chan, Tung W.; Zhang, Liqun; Liang, Yongri; Liu, Li

    2013-01-01

    In this paper, graphene oxide/styrene-butadiene rubber (GO/SBR) composites with complete exfoliation of GO sheets were prepared by aqueous-phase mixing of GO colloid with SBR latex and a small loading of butadiene-styrene-vinyl-pyridine rubber (VPR) latex, followed by their co-coagulation. During co-coagulation, VPR not only plays a key role in the prevention of aggregation of GO sheets but also acts as an interface-bridge between GO and SBR. The results demonstrated that the mechanical properties of the GO/SBR composite with 2.0 vol.% GO is comparable with those of the SBR composite reinforced with 13.1 vol.% of carbon black (CB), with a low mass density and a good gas barrier ability to boot. The present work also showed that GO-silica/SBR composite exhibited outstanding wear resistance and low-rolling resistance which make GO-silica/SBR very competitive for the green tire application, opening up enormous opportunities to prepare high performance rubber composites for future engineering applications. PMID:23974435

  9. Characteristics Data Base: Programmer's guide to the High-Level Waste Data Base

    SciTech Connect

    Jones, K.E. ); Salmon, R. )

    1990-08-01

    The High-Level Waste Data Base is a menu-driven PC data base developed as part of OCRWM's technical data base on the characteristics of potential repository wastes, which also includes spent fuel and other materials. This programmer's guide completes the documentation for the High-Level Waste Data Base, the user's guide having been published previously. 3 figs.

  10. 26. "AIR INSTALLATIONS; EDWARDS AIR FORCE BASE, CALIFORNIA; HIGH SPEED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. "AIR INSTALLATIONS; EDWARDS AIR FORCE BASE, CALIFORNIA; HIGH SPEED TEST TRACK." Drawing No. 10-259. One inch to 400 feet plan of original 10,000-foot sled track. No date. No D.O. series number. No headings as above. - Edwards Air Force Base, South Base Sled Track, Edwards Air Force Base, North of Avenue B, between 100th & 140th Streets East, Lancaster, Los Angeles County, CA

  11. High Brightness GaN-Based Light-Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Lee, Ya-Ju; Lu, Tien-Chang; Kuo, Hao-Chung; Wang, Shing-Chung

    2007-06-01

    This paper reviews our recent progress of GaN-based high brightness light-emitting diodes (LEDs). Firstly, by adopting chemical wet etching patterned sapphire substrates in GaN-based LEDs, not only could increase the extraction quantum efficiency, but also improve the internal quantum efficiency. Secondly, we present a high light-extraction 465-nm GaN-based vertical light-emitting diode structure with double diffuse surfaces. The external quantum efficiency was demonstrated to be about 40%. The high performance LED was achieved mainly due to the strong guided-light scattering efficiency while employing double diffuse surfaces.

  12. High-energy attosecond nanoplasmonic-based electron gun

    NASA Astrophysics Data System (ADS)

    Greig, S. R.; Elezzabi, A. Y.

    2016-03-01

    We present the design of an ultrafast conical lens based nanoplasmonic electron gun. Through excitation with a radially polarized laser pulse, and a combination of magnetostatic and spatial filtering, high energy electron packets with attosecond durations can be achieved.

  13. Molecular design and property prediction of high density polynitro[3.3.3]-propellane-derivatized frameworks as potential high explosives.

    PubMed

    Zhang, Qinghua; Zhang, Jiaheng; Qi, Xiujuan; Shreeve, Jean'ne M

    2014-11-13

    Research in energetic materials is now heavily focused on the design and synthesis of novel insensitive high explosives (IHEs) for specialized applications. As an effective and time-saving tool for screening potential explosive structures, computer simulation has been widely used for the prediction of detonation properties of energetic molecules with relatively high precision. In this work, a series of new polynitrotetraoxopentaaza[3.3.3]-propellane molecules with tricyclic structures were designed. Their properties as potential high explosives including density, heats of formation, detonation properties, impact sensitivity, etc., have been extensively evaluated using volume-based thermodynamic calculations and density functional theory (DFT).These new energetic molecules exhibit high densities of >1.82 g cm(-3), in which 1 gives the highest density of 2.04 g cm(-3). Moreover, most new materials show good detonation properties and acceptable impact sensitivities, in which 5 displays much higher detonation velocity (9482 m s(-1)) and pressure (43.9 GPa) than HMX and has a h50 value of 11 cm. These results are expected to facilitate the experimental synthesis of new-generation nitramine-based high explosives. PMID:25325391

  14. Competency-Based Adult High School Curriculum Project.

    ERIC Educational Resources Information Center

    Singer, Elizabeth

    This compilation of program materials serves as an introduction to and overview of Florida's Brevard Community College's (BCC's) Competency-Based Adult High School Completion Project, which was conducted to teach administrators, counselors, and teachers how to organize and implement a competency-based adult education (CBAE) program; to critique…

  15. Hershey Montessori Farm School: Place-Based High School Biology.

    ERIC Educational Resources Information Center

    Venaleck, Judy; McDonald, Pete

    2001-01-01

    Describes how the Hershey Montessori Farm School in Huntsburg, Ohio, developed an advanced biology course, which begins with an experience-based, task-oriented approach within different biomes of the surrounding environs while incorporating high school content and scientific method. Concludes that integrating place-based and contextual inquiries…

  16. High School Students' Concepts of Acids and Bases.

    ERIC Educational Resources Information Center

    Ross, Bertram H. B.

    An investigation of Ontario high school students' understanding of acids and bases with quantitative and qualitative methods revealed misconceptions. A concept map, based on the objectives of the Chemistry Curriculum Guideline, generated multiple-choice items and interview questions. The multiple-choice test was administered to 34 grade 12…

  17. Effects of Problem Based Economics on High School Economics Instruction

    ERIC Educational Resources Information Center

    Finkelstein, Neal; Hanson, Thomas

    2011-01-01

    The primary purpose of this study is to assess student-level impacts of a problem-based instructional approach to high school economics. The curriculum approach examined here was designed to increase class participation and content knowledge for high school students who are learning economics. This study tests the effectiveness of Problem Based…

  18. Research On Bi-Based High-Temperature Superconductors

    NASA Technical Reports Server (NTRS)

    Banks, Curtis; Doane, George B., III; Golben, John

    1993-01-01

    Brief report describes effects of melt sintering on Bi-based high-temperature superconductor system, as well as use of vibrating-sample magnetometer to determine hysteresis curves at 77 K for partially melt-sintered samples. Also discussed is production of high-temperature superconducting thin films by laser ablation: such films potentially useful in detection of signals of very low power.

  19. High harmonic generation by novel fiber amplifier based sources.

    PubMed

    Hädrich, S; Rothhardt, J; Krebs, M; Tavella, F; Willner, A; Limpert, J; Tünnermann, A

    2010-09-13

    Significant progress in high repetition rate ultrashort pulse sources based on fiber technology is presented. These systems enable operation at a high repetition rate of up to 500 kHz and high average power in the extreme ultraviolet wavelength range via high harmonic generation in a gas jet. High average power few-cycle pulses of a fiber amplifier pumped optical parametric chirped pulse amplifier are used to produce µW level average power for the strongest harmonic at 42.9 nm at a repetition rate of 96 kHz. PMID:20940915

  20. Investigation into low-temperatures influence on high explosive compounds sensitivity to shock-wave impacts

    SciTech Connect

    Averin, A.N.; Alekseev, A.V.; Batalov, S.V.; Loboiko, B.G.; Litvinov, B.V.; Sumin, V.D.; Filin, V.P.; Yagnakov, A.N.

    1996-05-01

    Study of shock-wave sensitivity of explosives under various temperatures is of great significance for correct analysis of safe application of different industrial processes, technologies, as well as for correct understanding of explosion initiation mechanism in (explosives). Currently, the influence of low, ({minus}100{degree}C{hor_ellipsis}{minus}200{degree}C) temperatures on explosive sensitivity to weak shock waves is poorly studied. This paper gives experimental results on the influence of low temperatures on the sensitivity of HMX{emdash}based explosives to weak shock-waves. In the present paper an attempt is made to experimentally determine dependence of HMX{emdash}based explosive sensitivity to weak shock waves on temperatures. The original technique of the experiment is presented in the report. {copyright} {ital 1996 American Institute of Physics.}

  1. Looking for high energy density compounds among polynitraminecubanes.

    PubMed

    Chi, Wei-Jie; Li, Lu-Lin; Li, Bu-Tong; Wu, Hai-Shun

    2013-02-01

    Based on fully optimized geometric structures at DFT-B3LYP/6-311G** level, we calculated electronic structures, heats of formation, strain energies, bond dissociation energies and detonation performance (detonation velocity and detonation pressure) for a series of polynitraminecubanes. Our results have shown that energy gaps of cubane derivatives are much higher than that of triaminotrinitrobenzene (TATB), which means that cubane derivatives may be more sensitive than TATB. Polynitraminecubanes have high and positive heats of formation, and a good linear relationship between heats of formation and nitramine group numbers was presented. As the number of nitramine groups in the molecule increases, the enthalpies of combustion values are increasingly negative, but the specific enthalpy of combustion values decreases. It is found that all cubane derivatives have high strain energies, which are affected by the number and position of nitramine group. The calculated bond dissociation energies of C-NHNO(2) and C-C bond show that the C-C bond should be the trigger bond in the pyrolysis process. It is found that detonation velocity (D), detonation pressure (P) and molecule density (ρ) have good linear relationship with substituented group numbers. Heptanitraminecubane and octanitraminecubane have good detonation performance over 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), and they can be regarded as potential candidates of high energy density compounds (HEDCs). The results have not only shown that these compounds may be used as HEDCs, but also provide some useful information for further investigation. PMID:22961623

  2. Highly charged ion based time of flight emission microscope

    DOEpatents

    Barnes, Alan V.; Schenkel, Thomas; Hamza, Alex V.; Schneider, Dieter H.; Doyle, Barney

    2001-01-01

    A highly charged ion based time-of-flight emission microscope has been designed, which improves the surface sensitivity of static SIMS measurements because of the higher ionization probability of highly charged ions. Slow, highly charged ions are produced in an electron beam ion trap and are directed to the sample surface. The sputtered secondary ions and electrons pass through a specially designed objective lens to a microchannel plate detector. This new instrument permits high surface sensitivity (10.sup.10 atoms/cm.sup.2), high spatial resolution (100 nm), and chemical structural information due to the high molecular ion yields. The high secondary ion yield permits coincidence counting, which can be used to enhance determination of chemical and topological structure and to correlate specific molecular species.

  3. Visible light metasurfaces based on gallium nitride high contrast gratings

    NASA Astrophysics Data System (ADS)

    Wang, Zhenhai; He, Shumin; Liu, Qifa; Wang, Wei

    2016-05-01

    We propose visible-light metasurfaces (VLMs) capable of serving as lens and beam deflecting element based on gallium nitride (GaN) high contrast gratings (HCGs). By precisely manipulating the wavefront of the transmitted light, we theoretically demonstrate an HCG focusing lens with transmissivity of 86.3%, and a VLM with beam deflection angle of 6.09° and transmissivity as high as 91.4%. The proposed all-dielectric metasurfaces are promising for GaN-based visible light-emitting diodes (LEDs), which would be robust and versatile for controlling the output light propagation and polarization, as well as enhancing the extraction efficiency of the LEDs.

  4. Abstracting event-based control models for high autonomy systems

    NASA Technical Reports Server (NTRS)

    Luh, Cheng-Jye; Zeigler, Bernard P.

    1993-01-01

    A high autonomy system needs many models on which to base control, management, design, and other interventions. These models differ in level of abstraction and in formalism. Concepts and tools are needed to organize the models into a coherent whole. The paper deals with the abstraction processes for systematic derivation of related models for use in event-based control. The multifaceted modeling methodology is briefly reviewed. The morphism concepts needed for application to model abstraction are described. A theory for supporting the construction of DEVS models needed for event-based control is then presented. An implemented morphism on the basis of this theory is also described.

  5. Integrated Ring Oscillators based on high-performance Graphene Inverters

    PubMed Central

    Schall, Daniel; Otto, Martin; Neumaier, Daniel; Kurz, Heinrich

    2013-01-01

    The road to the realization of complex integrated circuits based on graphene remains an open issue so far. Current graphene based integrated circuits are limited by low integration depth and significant doping variations, representing major road blocks for the success of graphene in future electronic devices. Here we report on the realization of graphene based integrated inverters and ring oscillators. By using an optimized process technology for high-performance graphene transistors with local back-gate electrodes we demonstrate that complex graphene based integrated circuits can be manufactured reproducibly, circumventing problems associated with doping variations. The fabrication process developed here is scalable and fully compatible with conventional silicon technology. Therefore, our results pave the way towards applications based on graphene transistors in future electronic devices. PMID:24005257

  6. High efficiency tantalum-based ceramic composite structures

    NASA Technical Reports Server (NTRS)

    Stewart, David A. (Inventor); Leiser, Daniel B. (Inventor); DiFiore, Robert R. (Inventor); Katvala, Victor W. (Inventor)

    2010-01-01

    Tantalum-based ceramics are suitable for use in thermal protection systems. These composite structures have high efficiency surfaces (low catalytic efficiency and high emittance), thereby reducing heat flux to a spacecraft during planetary re-entry. These ceramics contain tantalum disilicide, molybdenum disilicide and borosilicate glass. The components are milled, along with a processing aid, then applied to a surface of a porous substrate, such as a fibrous silica or carbon substrate. Following application, the coating is then sintered on the substrate. The composite structure is substantially impervious to hot gas penetration and capable of surviving high heat fluxes at temperatures approaching 3000.degree. F. and above.

  7. High Fidelity of Base Paring by 2-Selenothymidine in DNA

    SciTech Connect

    Hassan, A.; Sheng, J; Zhang, W; Huang, Z

    2010-01-01

    The base pairs are the contributors to the sequence-dependent recognition of nucleic acids, genetic information storage, and high fidelity of DNA polymerase replication. However, the wobble base pairing, where T pairs with G instead of A, reduces specific base-pairing recognition and compromises the high fidelity of the enzymatic polymerization. Via the selenium atomic probing at the 2-position of thymidine, we have investigated the wobble discrimination by manipulating the steric and electronic effects at the 2-exo position, providing a unique chemical strategy to enhance the base pair specificity. We report here the first synthesis of the novel 2-Se-thymidine ({sup Se}T) derivative, its phosphoramidite, and the Se-DNAs. Our biophysical and structural studies of the 2-Se-T DNAs reveal that the bulky 2-Se atom with a weak hydrogen-bonding ability can largely increase mismatch discriminations (including T/G wobble and T/C mismatched base pairs) while maintaining the {sup Se}T/A virtually identical to the native T/A base pair. The 2-Se atom bulkiness and the electronic effect are probably the main factors responsible for the discrimination against the formation of the wobble {sup Se}T/G base pair. Our investigations provide a potential novel tool to investigate the specific recognition of base pairs, which is the basis of high fidelity during replication, transcription, and translation. Furthermore, this Se-atom-specific substitution and probing are useful for X-ray crystal structure and function studies of nucleic acids.

  8. High speed electric motors based on high performance novel soft magnets

    NASA Astrophysics Data System (ADS)

    Silveyra, J. M.; Leary, A. M.; DeGeorge, V.; Simizu, S.; McHenry, M. E.

    2014-05-01

    Novel Co-based soft magnetic materials are presented as a potential substitute for electrical steels in high speed motors for current industry applications. The low losses, high permeabilities, and good mechanical strength of these materials enable application in high rotational speed induction machines. Here, we present a finite element analysis of Parallel Path Magnetic Technology rotating motors constructed with both silicon steel and Co-based nanocomposite. The later achieved a 70% size reduction and an 83% reduction on NdFeB magnet volume with respect to a similar Si-steel design.

  9. Parallel Microcracks-based Ultrasensitive and Highly Stretchable Strain Sensors.

    PubMed

    Amjadi, Morteza; Turan, Mehmet; Clementson, Cameron P; Sitti, Metin

    2016-03-01

    There is an increasing demand for flexible, skin-attachable, and wearable strain sensors due to their various potential applications. However, achieving strain sensors with both high sensitivity and high stretchability is still a grand challenge. Here, we propose highly sensitive and stretchable strain sensors based on the reversible microcrack formation in composite thin films. Controllable parallel microcracks are generated in graphite thin films coated on elastomer films. Sensors made of graphite thin films with short microcracks possess high gauge factors (maximum value of 522.6) and stretchability (ε ≥ 50%), whereas sensors with long microcracks show ultrahigh sensitivity (maximum value of 11,344) with limited stretchability (ε ≤ 50%). We demonstrate the high performance strain sensing of our sensors in both small and large strain sensing applications such as human physiological activity recognition, human body large motion capturing, vibration detection, pressure sensing, and soft robotics. PMID:26842553

  10. Citizenship. Nevada Competency-Based Adult High School Diploma Project.

    ERIC Educational Resources Information Center

    Nevada Univ., Las Vegas. Coll. of Education.

    This document is one of ten curriculum guides developed by the Nevada Competency-Based Adult High School Diploma (CBAHSD) Project. This curriculum guide on citizenship is divided into twelve topics. The topics included are How to Become a Citizen, Voter Registration, Political Parties, Nominations, Elections, Evaluating Issues, Public Opinion,…

  11. Mathematics. Nevada Competency-Based Adult High School Diploma Project.

    ERIC Educational Resources Information Center

    Nevada Univ., Las Vegas. Coll. of Education.

    This document is one of ten curriculum guides developed by the Nevada Competency-Based Adult High School Diploma (CBAHSD) Project. This curriculum guide on mathematics is divided into three topics. The topics included are Problem Solving, Computation, and Geometry and Measurement. Competency statements and performance indicators are provided for…

  12. High School Art Education Guide. Competency-Based Education.

    ERIC Educational Resources Information Center

    Frederick County Public Schools, MD.

    Arranged into 26 sections, this curriculum guide provides high school teachers with a competency based approach to teaching art education. Following a statement of appreciation, the philosophy and goals for art education in Maryland are presented. An excerpt from Edmund Feldman's "Varieties of Visual Experience" discusses aesthetic expression.…

  13. High Density Polymer-Based Integrated Electgrode Array

    DOEpatents

    Maghribi, Mariam N.; Krulevitch, Peter A.; Davidson, James Courtney; Hamilton, Julie K.

    2006-04-25

    A high density polymer-based integrated electrode apparatus that comprises a central electrode body and a multiplicity of arms extending from the electrode body. The central electrode body and the multiplicity of arms are comprised of a silicone material with metal features in said silicone material that comprise electronic circuits.

  14. Content-Based Curriculum for High-Ability Learners.

    ERIC Educational Resources Information Center

    VanTassel-Baska, Joyce, Ed.; Little, Catherine A., Ed.

    The 14 chapters in this volume are intended to facilitate differentiated curriculum development for gifted students that is substantive, rigorous, and in keeping with disciplinary structures. The chapters are: (1) "Content-Based Curriculum for High Ability Learners: An Introduction" (Joyce VanTassel-Baska); (2) "Accelerating Learning Experiences…

  15. A high energy output nanogenerator based on reduced graphene oxide

    NASA Astrophysics Data System (ADS)

    Li, Weiping; Zhang, Yupeng; Liu, Liangliang; Li, Delong; Liao, Lei; Pan, Chunxu

    2015-10-01

    In this paper, we report a novel graphene-based nanogenerator for high energy harvesting. Experimental and theoretical results revealed that the energy output mechanism is the joint action of the strain effect (band engineering) and the triboelectric effect of reduced graphene oxide. It was found that the current could be adjusted by experimental parameters, such as the electrolyte concentration and rotation rate. Furthermore, the voltage output could be amplified by series connection of the system. Compared with other nanogenerators, the present graphene-based nanogenerator provides advantages, such as simple assembly, flexibility and high structural stability. It is expected that this nanogenerator will be of potential application in active sensors and sustainable power sources.In this paper, we report a novel graphene-based nanogenerator for high energy harvesting. Experimental and theoretical results revealed that the energy output mechanism is the joint action of the strain effect (band engineering) and the triboelectric effect of reduced graphene oxide. It was found that the current could be adjusted by experimental parameters, such as the electrolyte concentration and rotation rate. Furthermore, the voltage output could be amplified by series connection of the system. Compared with other nanogenerators, the present graphene-based nanogenerator provides advantages, such as simple assembly, flexibility and high structural stability. It is expected that this nanogenerator will be of potential application in active sensors and sustainable power sources. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04971g

  16. High resolution data base for use with MAP

    SciTech Connect

    Tapley, W.C.; Harris, D.B.

    1987-05-05

    A high resolution cartographic data base of thw World is available from the CIA. We obtained this data, extracted portions of the data, and produced cartographic files of varying resolutions. The resulting data files are of the proper format for use with MAP (2), our in-house cartographic plotting program.

  17. Klystron based high power rf system for proton accelerator

    SciTech Connect

    Pande, Manjiri; Shrotriya, Sandip; Sharma, Sonal; Patel, Niranjan; Handu, Verander E-mail: manjiri08@gmail.com

    2011-07-01

    As a part of ADS program a proton accelerator (20 MeV, 30 mA) and its high power RF systems (HPRF) are being developed in BARC. This paper explains design details of this klystron based HPRF system. (author)

  18. Planning and Implementing a High Performance Knowledge Base.

    ERIC Educational Resources Information Center

    Cortez, Edwin M.

    1999-01-01

    Discusses the conceptual framework for developing a rapid-prototype high-performance knowledge base for the four mission agencies of the United States Department of Agriculture and their university partners. Describes the background of the project and methods used for establishing the requirements; examines issues and problems surrounding semantic…

  19. A highly reliable RAID system based on GPUs.

    SciTech Connect

    Curry, Matthew L.

    2010-06-01

    While RAID is the prevailing method of creating reliable secondary storage infrastructure, many users desire more flexibility than offered by current implementations. To attain needed performance, customers have often sought after hardware-based RAID solutions. This talk describes a RAID system that offloads erasure correction coding calculations to GPUs, allowing increased reliability by supporting new RAID levels while maintaining high performance.

  20. Mental Health Care in a High School Based Health Service.

    ERIC Educational Resources Information Center

    Jepson, Lisa; Juszczak, Linda; Fisher, Martin

    1998-01-01

    Describes the mental-health and medical services provided at a high-school-based service center. Five years after the center's inception mental health visits had quadrupled. One third of students utilizing the center reported substance abuse within their family. Other reasons for center use included pregnancy, suicidal ideation, obesity,…

  1. Health. Nevada Competency-Based Adult High School Diploma Project.

    ERIC Educational Resources Information Center

    Nevada Univ., Las Vegas. Coll. of Education.

    This document is one of ten curriculum guides developed by the Nevada Competency-Based Adult High School Diploma (CBAHSD) Project. This curriculum guide on health is divided into ten topics. The topics included are Nutrition, Reproduction, Menstruation, Contraception, Alcohol Abuse, Tobacco, Immunization, Disease, Accident Prevention, and…

  2. Curriculum-Based Measures of Writing for High School Students

    ERIC Educational Resources Information Center

    Diercks-Gransee, Barbara; Weissenburger, Jacalyn Wright; Johnson, Cindy L.; Christensen, Paul

    2009-01-01

    The purpose of this study was to determine whether technically adequate curriculum-based measures of writing could be identified for use with high school students. The participants included 10th-grade general and special education students from two public school districts in Wisconsin. Students (n = 82) completed two narrative writing samples in…

  3. College-Based High Schools Fill Growing Need

    ERIC Educational Resources Information Center

    Manzo, Kathleen Kennedy

    2005-01-01

    College-based programs that motivate underachieving teenagers to graduate and pursue further education is part of a menu of initiatives Guilford County, North Carolina, has introduced to meet the academic, social, and emotional needs of students in its middle and high schools, where racial and ethnic diversity and poverty have been on the rise. As…

  4. High resolution, MRI-based, segmented, computerized head phantom

    SciTech Connect

    Zubal, I.G.; Harrell, C.R.; Smith, E.O.; Smith, A.L.; Krischlunas, P.

    1999-01-01

    The authors have created a high-resolution software phantom of the human brain which is applicable to voxel-based radiation transport calculations yielding nuclear medicine simulated images and/or internal dose estimates. A software head phantom was created from 124 transverse MRI images of a healthy normal individual. The transverse T2 slices, recorded in a 256x256 matrix from a GE Signa 2 scanner, have isotropic voxel dimensions of 1.5 mm and were manually segmented by the clinical staff. Each voxel of the phantom contains one of 62 index numbers designating anatomical, neurological, and taxonomical structures. The result is stored as a 256x256x128 byte array. Internal volumes compare favorably to those described in the ICRP Reference Man. The computerized array represents a high resolution model of a typical human brain and serves as a voxel-based anthropomorphic head phantom suitable for computer-based modeling and simulation calculations. It offers an improved realism over previous mathematically described software brain phantoms, and creates a reference standard for comparing results of newly emerging voxel-based computations. Such voxel-based computations lead the way to developing diagnostic and dosimetry calculations which can utilize patient-specific diagnostic images. However, such individualized approaches lack fast, automatic segmentation schemes for routine use; therefore, the high resolution, typical head geometry gives the most realistic patient model currently available.

  5. Carbon nanotube transistor based high-frequency electronics

    NASA Astrophysics Data System (ADS)

    Schroter, Michael

    At the nanoscale carbon nanotubes (CNTs) have higher carrier mobility and carrier velocity than most incumbent semiconductors. Thus CNT based field-effect transistors (FETs) are being considered as strong candidates for replacing existing MOSFETs in digital applications. In addition, the predicted high intrinsic transit frequency and the more recent finding of ways to achieve highly linear transfer characteristics have inspired investigations on analog high-frequency (HF) applications. High linearity is extremely valuable for an energy efficient usage of the frequency spectrum, particularly in mobile communications. Compared to digital applications, the much more relaxed constraints for CNT placement and lithography combined with already achieved operating frequencies of at least 10 GHz for fabricated devices make an early entry in the low GHz HF market more feasible than in large-scale digital circuits. Such a market entry would be extremely beneficial for funding the development of production CNTFET based process technology. This talk will provide an overview on the present status and feasibility of HF CNTFET technology will be given from an engineering point of view, including device modeling, experimental results, and existing roadblocks. Carbon nanotube transistor based high-frequency electronics.

  6. Alternative Processing of High Temperature Hafnium and Zirconium Based Materials

    NASA Technical Reports Server (NTRS)

    Gasch, Matthew; Gusman, Michael; Ellerby, Don; Irby, Edward; Johnson, Sylvia M.

    2003-01-01

    The behavior of refractory hafnium and zirconium based materials are being investigated at NASA Ames as part of ongoing research aimed at developing superior heat resistant materials for aerospace applications. Hafnium and zirconium diboride based materials have shown high temperature capabilities in simulated reentry environments indicating that these materials may successfully operate as reusable oxidation resistant components for leading edge applications. Due to the refractory nature of these materials, processing of fine-grained uniform microstructures poses a number of challenges. To better understand the process-property-microstructure relationship, processing of these materials has been carried out with conventional hot pressing in addition to the novel approach of Spark Plasma Sintering (SPS). The two processing methods are compared and contrasted in an evaluation of the sintering behavior of high temperature diboride based materials and preliminary physical and mechanical properties are presented.

  7. High performance network and channel-based storage

    NASA Technical Reports Server (NTRS)

    Katz, Randy H.

    1991-01-01

    In the traditional mainframe-centered view of a computer system, storage devices are coupled to the system through complex hardware subsystems called input/output (I/O) channels. With the dramatic shift towards workstation-based computing, and its associated client/server model of computation, storage facilities are now found attached to file servers and distributed throughout the network. We discuss the underlying technology trends that are leading to high performance network-based storage, namely advances in networks, storage devices, and I/O controller and server architectures. We review several commercial systems and research prototypes that are leading to a new approach to high performance computing based on network-attached storage.

  8. Neural network based feed-forward high density associative memory

    NASA Technical Reports Server (NTRS)

    Daud, T.; Moopenn, A.; Lamb, J. L.; Ramesham, R.; Thakoor, A. P.

    1987-01-01

    A novel thin film approach to neural-network-based high-density associative memory is described. The information is stored locally in a memory matrix of passive, nonvolatile, binary connection elements with a potential to achieve a storage density of 10 to the 9th bits/sq cm. Microswitches based on memory switching in thin film hydrogenated amorphous silicon, and alternatively in manganese oxide, have been used as programmable read-only memory elements. Low-energy switching has been ascertained in both these materials. Fabrication and testing of memory matrix is described. High-speed associative recall approaching 10 to the 7th bits/sec and high storage capacity in such a connection matrix memory system is also described.

  9. Low Noise, High Detectivity Photodetectors based on Organic Materials

    NASA Astrophysics Data System (ADS)

    Guo, Fawen

    Organic photodetectors (OPDs) are potentially useful in many applications because of their light weight, flexibility and good form factors. Despite the high detectivities that have been frequently reported for OPDs recently, the application of these OPDs for weak light detection has been rarely demonstrated. In this thesis, low noise, high gain photodetectors based on organic and ZnO nanoparticles were proposed and demonstrated for highly sensitive UV light detection. The nanocomposite photodetector works in a hybrid mode of photodiode and photoconductor with the transition controlled by the UV light illumination. The nanocomposite detector shows two orders of magnitude higher sensitivity than silicon detectors in the UV range, which is the first time an organic, solution-processed detector has been shown to significantly outperform the inorganic photonic devices. In the fullerene-based photodetector, the dark-current has been successfully reduced by a cross-linked TPD (C-TPD) buffer layer. The high detectivity of 3.6 x 1011 cm Hz½ W-1 (Jones) at 370 nm and the wide Linear dynamic range (LDR) of 90 dB, along with a response speed faster than 20 kHz, suggests that the fullerene-based organic photodetectors proposed here can open the way for many potential applications. The ZnO nanoparticles have been introduced into the C-TPD buffer layer of the fullerene-based photodetector to increase the photoconductive gain and reduce the noise current. The peak external quantum efficiency (EQE) value of approximately 400% and the peak specific detectivity of 6.5 x 10 12 Jones at the wavelength of 390 nm, along with the record high LDR of 120 dB, enable the photodetector to be used in wide range of applications such as imaging, communication, and defense. The extremely high sensitivity of the photodetector also makes it particularly attractive for very weak light detection.

  10. Highly crystalline MOF-based materials grown on electrospun nanofibers

    NASA Astrophysics Data System (ADS)

    Bechelany, M.; Drobek, M.; Vallicari, C.; Abou Chaaya, A.; Julbe, A.; Miele, P.

    2015-03-01

    Supported Metal Organic Frameworks (MOFs) with a high specific surface area are of great interest for applications in gas storage, separation, sensing, and catalysis. In the present work we report the synthesis of a novel composite architecture of MOF materials supported on a flexible mat of electrospun nanofibers. The system, based on three-dimensional interwoven nanofibers, was designed by using a low-cost and scalable multistep synthesis protocol involving a combination of electrospinning and low-temperature atomic layer deposition of oxide materials, and their subsequent solvothermal conversion under either conventional or microwave-assisted heating. This highly versatile approach allows the production of different types of supported MOF crystals with controlled sizes, morphology, orientation and high accessibility.Supported Metal Organic Frameworks (MOFs) with a high specific surface area are of great interest for applications in gas storage, separation, sensing, and catalysis. In the present work we report the synthesis of a novel composite architecture of MOF materials supported on a flexible mat of electrospun nanofibers. The system, based on three-dimensional interwoven nanofibers, was designed by using a low-cost and scalable multistep synthesis protocol involving a combination of electrospinning and low-temperature atomic layer deposition of oxide materials, and their subsequent solvothermal conversion under either conventional or microwave-assisted heating. This highly versatile approach allows the production of different types of supported MOF crystals with controlled sizes, morphology, orientation and high accessibility. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06640e