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A Comparison Of Thermal Explosions In Pbx 9501 And Pbx N 9
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Book Synopsis A Comparison of Thermal Explosions in PBX 9501 and PBX N-9 by :
Download or read book A Comparison of Thermal Explosions in PBX 9501 and PBX N-9 written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have used a variety of observables to study the response of HMX based energetic materials formulations to thermal stimuli. In this paper, we compare the response of PBX 9501 and PBX N-9 to a temperature of 205 C. Both undergo thermal runaway at this boundary condition with similar preignition behavior. However, the post-ignition burn propagations of the two formulations are very different with the final reaction violence significantly lower for PBX N-9 than for PBX 9501.
Book Synopsis Thermal Expansion of PBX 9501 and PBX 9502 Plastic-bonded Explosives by :
Download or read book Thermal Expansion of PBX 9501 and PBX 9502 Plastic-bonded Explosives written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Two applications of thermal expansion measurements on plastic-bonded explosive (PBX) composites are described. In the first dilatometer application, thermal expansion properties of HMX-based PBX 9501 are measured over a broad thermal range that includes glass and domain-restructuring transitions in the polymeric binder. Results are consistent with other thermal measurements and analyses performed on the composite, as well as on the binder itself. The second application used the dilatometer to distinguish the reversible and irreversible components of thermal expansion in PBX 9502, a TATB-based explosive. Irreversible expansion of the composite is believed to derive from the highly-anisotropic coefficient of thermal expansion (CTE) values measured on single T A TB crystals, although the mechanism is not well understood. Effects of specimen density, thermal ramp rate, and thermal range variation (warm first or cold first) were explored, and the results are presented and discussed. Dilatometer measurements are ongoing towards gaining insight into the mechanism(s) responsible for PBX 9502 irreversible thermal expansion.
Download or read book Thermal Explosions written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Pressure Wave Measurements During Thermal Explosion of HMX-Based High Explosives by :
Download or read book Pressure Wave Measurements During Thermal Explosion of HMX-Based High Explosives written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Five different experiments on thermal heating of explosive materials have been performed. Three experiments thermally exploded PBX 9501 (HMX/Estane/BDNPA-F; 9512.512.5 wt %) donor charges while two others thermally exploded LX-04 (HMX/Viton A; 85/15 wt %). These donor charges were encased in 304 stainless steel. The transmitted two-dimensional pressure waves were measured by gauges in acceptor cylinders of Teflon, PBX 9501, or LX-04 that were in contact with the donors' steel case. A fifth experiment measured the pressure in an acceptor charge of PBX 9501 that had a 100 mm stand-off from the top of the steel case of the thermally cooked off PBX 9501 donor charge. Reactive flow hydrodynamic modeling using a rapid deflagration velocity of approximately 500 m/s was able to reproduce the pressure gauge records for both the in contact and stand off experiments that used PBX 9501 donors and acceptors.
Book Synopsis Thermal Expansion of Plastic Bonded Explosives PBX 9501 and 9502 by :
Download or read book Thermal Expansion of Plastic Bonded Explosives PBX 9501 and 9502 written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Propagation of Reactions in Thermally-damaged PBX-9501 by :
Download or read book Propagation of Reactions in Thermally-damaged PBX-9501 written by and published by . This book was released on 2010 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: A thermally-initiated explosion in PBX-9501 (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) is observed in situ by flash x-ray imaging, and modeled with the LLNL multi-physics arbitrary-Lagrangian-Eulerian code ALE3D. The containment vessel deformation provides a useful estimate of the reaction pressure at the time of the explosion, which we calculate to be in the range 0.8-1.4 GPa. Closely-coupled ALE3D simulations of these experiments, utilizing the multi-phase convective burn model, provide detailed predictions of the reacted mass fraction and deflagration front acceleration. During the preinitiation heating phase of these experiments, the solid HMX portion of the PBX-9501 undergoes a [beta]-phase to [delta]-phase transition which damages the explosive and induces porosity. The multi-phase convective burn model results demonstrate that damaged particle size and pressure are critical for predicting reaction speed and violence. In the model, energetic parameters are taken from LLNL's thermochemical-kinetics code Cheetah and burn rate parameters from Son et al. (2000). Model predictions of an accelerating deflagration front are in qualitative agreement with the experimental images assuming a mode particle diameter in the range 300-400 [mu]m. There is uncertainty in the initial porosity caused by thermal damage of PBX-9501 and, thus, the effective surface area for burning. To better understand these structures, we employ x-ray computed tomography (XRCT) to examine the microstructure of PBX-9501 before and after thermal damage. Although lack of contrast between grains and binder prevents the determination of full grain size distribution in this material, there are many domains visible in thermally damaged PBX-9501 with diameters in the 300-400 [mu]m range.
Download or read book Thermal Stability of PBX 9501 written by and published by . This book was released on 19?? with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Shock Compression of Condensed Matter 2009 by : Mark L. Elert
Download or read book Shock Compression of Condensed Matter 2009 written by Mark L. Elert and published by American Institute of Physics. This book was released on 2009-12-22 with total page 766 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume embodies the most recent research on shock compression of condensed matter, and includes 363 plenary, invited and contributed papers on topics including equation of state, phase transitions, chemical reactions, warm dense matter, fracture, geophysics and planetary science, energetic materials, optical studies, materials modeling, and recent experimental developments in the field of shock compression of condensed matter.
Book Synopsis Violent Reactions and DDT in Hot, Thermally Damaged HMX-Based PBXs by :
Download or read book Violent Reactions and DDT in Hot, Thermally Damaged HMX-Based PBXs written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Thermal Decomposition of New and Aged LX-04 and PBX 9501 by :
Download or read book Thermal Decomposition of New and Aged LX-04 and PBX 9501 written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: One-Dimensional-Time-To-Explosion (ODTX) experiments were conducted to study the thermal decomposition of aged LX-04, aged PBX 9501, HMX class 1 and class 2, Estane and Estane/BDNPA-F (PBX 950 1 plasticized-binder) materials. The tests involved heating 12.7 mm diameter spherical samples in pre-heated aluminum anvils until explosion. The times to explosion at different heating temperatures were compared to historical data on new LX-04 and PBX 9501 compounds to study any changes to their thermal stability. New and aged LX-04 showed comparable decomposition kinetics. The data for aged PBX 9501 showed slightly longer explosion times at equivalent temperatures. Analysis of the error in time measurement is limited and complicated by several experimental factors but the small time change appears to be experimentally significant. The thermal decomposition of these PBXs were modeled using a coupled thermal and heat transport code (chemical TOPAZ) using separate kinetics for HMX and binder decomposition. Separate decomposition models were developed for HMX and the reactive PBX 9501 binder component (1:1 Estane:BDNPA/F) based on the measured explosion times. Thermal aging models can describe longer explosion times by the loss of plasticizer-binder constituent which was more thermally reactive.
Book Synopsis Deflagration Behavior of PBX 9501 at Elevated Temperature and Pressure by :
Download or read book Deflagration Behavior of PBX 9501 at Elevated Temperature and Pressure written by and published by . This book was released on 2008 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report the deflagration behavior of PBX 9501 at pressures up to 300 MPa and temperatures of 150-180 C where the sample has been held at the test temperature for several hours before ignition. The purpose is to determine the effect on the deflagration behavior of material damage caused by prolonged exposure to high temperature. This conditioning is similar to that experienced by an explosive while it being heated to eventual explosion. The results are made more complicated by the presence of a significant thermal gradient along the sample during the temperature ramp and soak. Three major conclusions are: the presence of nitroplasticizer makes PBX 9501 more thermally sensitive than LX-04 with an inert Viton binder; the deflagration behavior of PBX 9501 is more extreme and more inconsistent than that of LX-04; and something in PBX 9501 causes thermal damage to 'heal' as the deflagration proceeds, resulting in a decelerating deflagration front as it travels along the sample.
Book Synopsis Measurement of Explosion Time as a Function of Impact Pressure for PBX 9501 Subject to Weak Planar Shocks by :
Download or read book Measurement of Explosion Time as a Function of Impact Pressure for PBX 9501 Subject to Weak Planar Shocks written by and published by . This book was released on 1997 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: At low pressures, the mechanical heating of the material is insufficient to generate ignition. At high pressures, prompt ignition is observed. At intermediate pressures, between (approximately) 0.75 to 2.0 GPa, mechanical heating is calculated to achieve sufficient heating to generate ignition after a variable induction time, equivalent to the induction time observed in purely thermal ignition experiments. These calculations depend on the calculation of at least two complex physical mechanisms in the material, mechanical heating and thermal decomposition. The authors present measurements of the surface temperature of confined PBX 9501 subject to weak planar shock with pressures spanning the range from moderate heating to prompt ignition.
Book Synopsis Shock Wave Science and Technology Reference Library, Vol. 5 by : Blaine Asay
Download or read book Shock Wave Science and Technology Reference Library, Vol. 5 written by Blaine Asay and published by Springer Science & Business Media. This book was released on 2009-12-16 with total page 630 pages. Available in PDF, EPUB and Kindle. Book excerpt: Los Alamos National Laboratory is an incredible place. It was conceived and born amidst the most desperate of circumstances. It attracted some of the most brilliant minds, the most innovative entrepreneurs, and the most c- ative tinkerers of that generation. Out of that milieu emerged physics and engineering that beforehand was either unimagined, or thought to be f- tasy. One of the ?elds essentially invented during those years was the science of precision high explosives. Before 1942, explosives were used in munitions and commercial pursuits that demanded proper chemistry and con?nement for the necessary e?ect, but little else. The needs and requirements of the Manhattan project were of a much more precise and speci?c nature. Spatial and temporal speci?cations were reduced from centimeters and milliseconds to micrometers and nanoseconds. New theory and computational tools were required along with a raft of new experimental techniques and novel ways of interpreting the results. Over the next 40 years, the emphasis was on higher energy in smaller packages, more precise initiation schemes, better and safer formulations, and greater accuracy in forecasting performance. Researchers from many institutions began working in the emerging and expanding ?eld. In the midst of all of the work and progress in precision initiation and scienti?c study, in the early 1960s, papers began to appear detailing the ?rst quantitative studies of the transition from de?agration to detonation (DDT), ?rst in cast, then in pressed explosives, and ?nally in propellants.
Book Synopsis ישום סמני טביעות אצבעות הדנ"א לצרכי השבחה וזיהוי של תפוחי אדמה by :
Download or read book ישום סמני טביעות אצבעות הדנ"א לצרכי השבחה וזיהוי של תפוחי אדמה written by and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1982 with total page 998 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Convective Burning in Gaps of PBX 9501 by :
Download or read book Convective Burning in Gaps of PBX 9501 written by and published by . This book was released on 2000 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Impact or thermal ignition of high explosives results in deformation that can lead to fracture. Fracture, combined with high pressure, dramatically increases the available surface area and potentially changes the mode of combustion. Recent impact and cook-off experiments on PBX 9501 (HMX, octahydro-1,3,5,7- tetranitro-1,3,5,7-tetrazocine, with a binder) have shown complex cracking patterns caused by impact or pressurization. Fast reactive waves have been observed to propagate through the cracks at about 500 m/s. We present experiments that investigate the propagation of fast reactive waves in cracks of PBX 9501, focusing on the reactive wave velocity and on the interplay of pressure and crack size. Experiments at initial pressures of 6.0 MPa reveal monotonic reactive wave propagation velocities of around 7 m/s for a 100 micrometer slot. We observe reactive wave velocities as high as 100 m/s in experiments at initial pressures of 17.2 MPa and various slot widths. Similar experiments at lower pressure exhibit oscillatory reactive wave propagation in the slot with periodic oscillations whose frequencies vary with combustion vessel pressure. This is the first reported observation of oscillatory combustion in cracks of an energetic material such as PBX 9501. Threshold pressure experiments for combustion propagation into closed-end slots of PBX 9501 find that combustion propagates into 2 mm, 1 mm, 100 micrometer, 50 micrometer, and 25 micrometer slots at approximately 0.1, 0.2, 0.9, 1.6, and 1.8 MPa, respectively.
Download or read book English Tests; Teacher Pack written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
