Download or read book Testing and Modeling of PBX 9591 Shock Initiation written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes an ongoing effort to develop a detonation sensitivity test for PBX-9501 that is suitable for studying pristine and damaged HE. The approach involves testing and comparing the sensitivities of HE pressed to various densities and those of pre-damaged samples with similar porosities. The ultimate objectives are to understand the response of pre-damaged HE to shock impacts and to develop practical computational models for use in system analysis codes for HE safety studies. Computer simulation with the CTH shock physics code is used to aid the experimental design and analyze the test results. In the calculations, initiation and growth or failure of detonation are modeled with the empirical HVRB model. The historical LANL SSGT and LSGT were reviewed and it was determined that a new, modified gap test be developed to satisfy the current requirements. In the new test, the donor/spacer/acceptor assembly is placed in a holder that is designed to work with fixtures for pre-damaging the acceptor sample. CTH simulations were made of the gap test with PBX-9501 samples pressed to three different densities. The calculated sensitivities were validated by test observations. The agreement between the computed and experimental critical gap thicknesses, ranging from 9 to 21 mm under various test conditions, is well within 1 mm. These results show that the numerical modeling is a valuable complement to the experimental efforts in studying and understanding shock initiation of PBX-9501.
Download or read book Modeling The Shock Initiation of PBX 9501 in ALE3D written by and published by . This book was released on 2008 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The SMIS (Specific Munitions Impact Scenario) experimental series performed at Los Alamos National Laboratory has determined the 3-dimensional shock initiation behavior of the HMX-based heterogeneous high explosive, PBX 9501. A series of finite element impact calculations have been performed in the ALE3D [1] hydrodynamic code and compared to the SMIS results to validate the code predictions. The SMIS tests use a powder gun to shoot scaled NATO standard fragments at a cylinder of PBX 9501, which has a PMMA case and a steel impact cover. The SMIS real-world shot scenario creates a unique test-bed because many of the fragments arrive at the impact plate off-center and at an angle of impact. The goal of this model validation experiments is to demonstrate the predictive capability of the Tarver-Lee Ignition and Growth (I & G) reactive flow model [2] in this fully 3-dimensional regime of Shock to Detonation Transition (SDT). The 3-dimensional Arbitrary Lagrange Eulerian hydrodynamic model in ALE3D applies the Ignition and Growth (I & G) reactive flow model with PBX 9501 parameters derived from historical 1-dimensional experimental data. The model includes the off-center and angle of impact variations seen in the experiments. Qualitatively, the ALE3D I & G calculations accurately reproduce the 'Go/No-Go' threshold of the Shock to Detonation Transition (SDT) reaction in the explosive, as well as the case expansion recorded by a high-speed optical camera. Quantitatively, the calculations show good agreement with the shock time of arrival at internal and external diagnostic pins. This exercise demonstrates the utility of the Ignition and Growth model applied in a predictive fashion for the response of heterogeneous high explosives in the SDT regime.
Download or read book Modeling Three Dimensional Shock Initiation of PBX 9501 in ALE3D written by and published by . This book was released on 2008 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: A recent SMIS (Specific Munitions Impact Scenario) experimental series performed at Los Alamos National Laboratory has provided 3-dimensional shock initiation behavior of the HMX-based heterogeneous high explosive, PBX 9501. A series of finite element impact calculations have been performed in the ALE3D [1] hydrodynamic code and compared to the SMIS results to validate and study code predictions. These SMIS tests used a powder gun to shoot scaled NATO standard fragments into a cylinder of PBX 9501, which has a PMMA case and a steel impact cover. This SMIS real-world shot scenario creates a unique test-bed because (1) SMIS tests facilitate the investigation of 3D Shock to Detonation Transition (SDT) within the context of a considerable suite of diagnostics, and (2) many of the fragments arrive at the impact plate off-center and at an angle of impact. A particular goal of these model validation experiments is to demonstrate the predictive capability of the ALE3D implementation of the Tarver-Lee Ignition and Growth reactive flow model [2] within a fully 3-dimensional regime of SDT. The 3-dimensional Arbitrary Lagrange Eulerian (ALE) hydrodynamic model in ALE3D applies the Ignition and Growth (I & G) reactive flow model with PBX 9501 parameters derived from historical 1-dimensional experimental data. The model includes the off-center and angle of impact variations seen in the experiments. Qualitatively, the ALE3D I & G calculations reproduce observed 'Go/No-Go' 3D Shock to Detonation Transition (SDT) reaction in the explosive, as well as the case expansion recorded by a high-speed optical camera. Quantitatively, the calculations show good agreement with the shock time of arrival at internal and external diagnostic pins. This exercise demonstrates the utility of the Ignition and Growth model applied for the response of heterogeneous high explosives in the SDT regime.
Download or read book Ignition and Growth Modeling of the Shock Initiation of PBX 9502 at 55C and 196C written by and published by . This book was released on 2015 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book SHOCK INITIATION EXPERIMENTS ON PBX 9501 EXPLOSIVE AT PRESSURES BELOW 3 GPa WITH ASSOCIATED IGNITION AND GROWTH MODELING written by and published by . This book was released on 2007 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shock initiation experiments on the explosive PBX 9501 (95% HMX, 2.5% estane, and 2.5% nitroplasticizer by weight) were performed at pressures below 3 GPa to obtain in-situ pressure gauge data, run-distance-to-detonation thresholds, and Ignition and Growth modeling parameters. Propellant driven gas guns (101 mm and 155 mm) were utilized to initiate the PBX 9501 explosive with manganin piezoresistive pressure gauge packages placed between sample slices. The run-distance-to-detonation points on the Pop-plot for these experiments showed agreement with previously published data and Ignition and Growth modeling parameters were obtained with a good fit to the experimental data. This parameter set will allow accurate code predictions to be calculated for safety scenarios in the low-pressure regime (below 3 GPa) involving PBX 9501 explosive.
Download or read book LOW AMPLITUDE SINGLE AND MULTIPLE SHOCK INITIATION EXPERIMENTS AND MODELING OF LX 04 written by F. Garcia and published by . This book was released on 2006 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shock initiation experiments were performed on the plastic bonded explosive (PBX) LX-04 (85% HMX, 15% Viton binder) using single and multiple low amplitude shocks to obtain pressure history data for use in Ignition and Growth reactive flow modeling parameterization. A 100 mm diameter propellant driven gas gun was utilized to initiate the LX-04 explosive charges containing manganin piezoresistive pressure gauge packages placed between explosive discs. In the single shock experiments, the run distances to detonation at three shock pressures showed agreement with previously published data above 3 GPa. Even longer run distances to detonation were measured using 80 mm long by 145 mm diameter LX-04 charges impacted by low velocity projectiles from a 155 mm diameter gun. The minimum shock pressure required to cause low levels of exothermic reaction were determined for these large LX-04 charge dimensions. Multiple shocks were generated as double shocks by using a flyer plate with two materials and as reflected shocks by placing a high impedance material at the rear of the explosive charge. In both cases, the first shock pressure was not high enough to cause detonation of LX-04, and the second shock pressure, which would have been sufficient to cause detonation if generated by a single shock, failed to cause detonation. Thus LX-04 exhibited shock desensitization over a range of 0.6 to 1.4 GPa. The higher shock pressure LX-04 model was extended to accurately simulate these lower pressure and multiple shock gauge records. The shock desensitization effects observed with multiple shock compressions were partially accounted for in the model by using a critical compression corresponding to a shock pressure of 1.2 GPa. This shock desensitization effect occurs at higher pressures than those of other HMX-based PBX's containing higher HMX percentages.
Download or read book A Reactive Burn Model for Shock Initiation in a PBX written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the formulation of a reactive burn model for shock initiation, we endeavor to incorporate a number of effects based on the underlying physical concept of hot spot ignition followed by the growth of reaction due to diverging deflagration fronts. The passage of a shock front sets the initial condition for reaction, leading to a fraction of the hot spots that completely burn while others will quench. The form of the rate model is chosen to incorporate approximations based on the physical picture. In particular, the approximations imply scaling relations that are then used to mathematically separate various contributions. That is, the model is modular and refinements can be applied separately without changing the other contributions. For example, the effect of initial temperature, porosity, etc. predominantly enter the characterization of the non-quenching hot spot distribution. A large collection of velocity gauge data is shown to be well represented by the model with a very small number of parameters.
Download or read book Shock Initiation of PBX 9502 EDC 35 and LX 17 written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Shock Initiation Experiments on Ratchet Grown PBX 9502 written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study compares the shock initiation behavior of PBX 9502 pressed to less than nominal density (nominal density is 1.890 ± 0.005 g/cm3) with PBX 9502 pressed to nominal density and then ''ratchet grown'' to low density. PBX 9502 is an insensitive plastic bonded explosive consisting of 95 weight % dry-aminated tri-amino-tri-nitro-benzene (TATB) and 5 weight % Kel-F 800 plastic binder. ''Ratchet growth'' - an irreversible increase in specific volume - occurs when an explosive based on TATB is temperature cycled. The design of our study is as follows: PBX 9502, all from the same lot, received the following four treatments. Samples in the first group were pressed to less than nominal density. These were not ratchet grown and used as a baseline. Samples in the second group were pressed to nominal density and then ratchet grown by temperature cycling 30 times between -54 C and +80 C. Samples in the final group were pressed to nominal density and cut into 100 mm by 25.4 mm diameter cylinders. During thermal cycling the cylinders were axially constrained by a 100 psi load. Samples for shock initiation experiments were cut perpendicular (disks) and parallel (slabs) to the axial load. The four sample groups can be summarized with the terms pressed low, ratchet grown/no load, axial load/disks, and axial load/slabs. All samples were shock initiated with nearly identical inputs in plate impact experiments carried out on a gas gun. Wave profiles were measured after propagation through 3, 4, 5, and 6 mm of explosive. Side by side comparison of wave profiles from different samples is used as a measure of relative sensitivity. All reduced density samples were more shock sensitive than nominal density PBX 9502. Differences in shock sensitivity between ratchet grown and pressed to low density PBX 9502 were small, but the low density pressings are slightly more sensitive than the ratchet grown samples.
Download or read book Shock Initiation of PBX 9502 at Elevated Temperatures written by and published by . This book was released on 1995 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The shock sensitivity of PBX-9502 is known to change with temperature. Both volume expansion and increased internal energy may contribute to theis phenomenon. PBX-9502 was heated and its initiation and detonation behavior was examined, using MI and shock tracker gauging on a light gas gun. Sensitivity and reactive wave profiles were measured. Complementary experiments were done on PBX-9502 made to undergo ``ratchet growth``, or non-reversible anisotropic thermal expansion, under carefully controlled thermal cycling. This process causes noticeable size changes and significant changes in sensitivity. Sensitivity and reactive wave profiles are discussed in terms of density and microscopic material morphology.
Download or read book Modeling Shock Initiation in Composition B written by and published by . This book was released on 1993 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: A hydrodynamic modeling study of the shock initiation behavior of Composition B explosive was performed using the {open_quotes}Ignition and Growth of Reaction in High Explosive{close_quotes} model developed at the Lawrence Livermore National Laboratory. The HE (heterogeneous explosives) responses were computed using the CALE and DYNA2D hydrocodes and then compared to experimental results. The data from several standard shock initiation and HE performance experiments was used to determine the parameters required for the model. Simulations of the wedge tests (pop plots) and failure diameter tests were found to be sufficient for defining the ignition and growth parameters used in the two term version of the computational model. These coefficients were then applied in the response analysis of several Composition B impact initiation experiments. A description of the methodology used to determine the coefficients and the resulting range of useful application of the ignition and growth of reaction model is described.
Download or read book Short pulse Shock Initiation of Granular Explosives PBX 9404 written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation has examined how different rates of unloading affect the release of chemical energy in a granular explosive experiencing transient shock compression. A compressed-gas gun was used to generate two types of short-pulse shocks in the explosive PBX-9404. A shock pressure of 3.2 GPa sustained for 0.37 .mu.s was produced in both cases, but differences in flyer-plate properties resulted in different unloading histories. In one case the impact interface was rapidly unloaded by the initial release wave, while in the second case the unloading required multiple release waves over several microseconds. A VISAR system was used to observe the evolution of these two waves for distances up to 10 mm. The recorded waveforms showed that the unloading rates had a dominant effect on chemical energy release and growth towards detonation. This effect is important for considerations of critical impact criteria, and should provide a strong test for predictive shock-initiation models.
Download or read book Failure of Materials in Mechanical Design written by Jack A. Collins and published by John Wiley & Sons. This book was released on 1993-10-06 with total page 690 pages. Available in PDF, EPUB and Kindle. Book excerpt: Failure of Materials in Mechanical Design: Analysis, Prediction, Prevention, 2nd Edition, covers the basic principles of failure of metallic and non-metallic materials in mechanical design applications. Updated to include new developments on fracture mechanics, including both linear-elastic and elastic-plastic mechanics. Contains new material on strain and crack development and behavior. Emphasizes the potential for mechanical failure brought about by the stresses, strains and energy transfers in machine parts that result from the forces, deflections and energy inputs applied.
Download or read book Advanced Energetic Materials written by National Research Council and published by National Academies Press. This book was released on 2004-01-30 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced energetic materialsâ€"explosive fill and propellantsâ€"are a critical technology for national security. While several new promising concepts and formulations have emerged in recent years, the Department of Defense is concerned about the nation's ability to maintain and improve the knowledge base in this area. To assist in addressing these concerns, two offices within DOD asked the NRC to investigate and assess the scope and health of the U.S. R&D efforts in energetic materials. This report provides that assessment. It presents several findings about the current R&D effort and recommendations aimed at improving U.S. capabilities in developing new energetic materials technology. This study reviewed U.S. research and development in advanced energetics being conducted by DoD, the DoE national laboratories, industries, and academia, from a list provided by the sponsors. It also: (a) reviewed papers and technology assessments of non-U.S. work in advanced energetics, assessed important parameters, such as validity, viability, and the likelihood that each of these materials can be produced in quantity; (b) identified barriers to scale-up and production, and suggested technical approaches for addressing potential problems; and (c) suggested specific opportunities, strategies, and priorities for government sponsorship of technologies and manufacturing process development.
Download or read book Chemistry of Energetic Materials written by George A. Olah and published by Academic Press. This book was released on 2012-12-02 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of energetic materials is emerging from one primarily directed toward practical interests to an advanced area of fundamental research, where state-of-the-art methods and theory are used side by side with modern synthetic methods. This timely book integrates the recent experimental, synthetic, and theoretical research of energetic materials. Editors George Olah and David Squire emphasize the importance of structure and mechanism in determining properties and performances. They also explore new spectrometric methods and synthetic approaches in this useful reference. Discusses structural analysis by x-ray crystallography Explains chemical dynamics by photofragmentation translational spectroscopy Covers kinetic analysis by ultrafast absorption and emission spectroscopy Details syntheses of polycyclic caged amines, fuel additives, and polynitro compounds Examines computer-aided design of monopropellants Includes contributions by two Nobel laureates and five members of the National Academy of Sciences
Download or read book Budding Hopes written by Vivien Dean and published by JMS Books LLC. This book was released on 2022-02-12 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt: For eight months, Dr. Mark Vance has been visiting Sheehan’s Nursery to buy flowers for his mother’s grave, and every week, Hal Sheehan slips an extra lily into the bunch. Mark would love nothing more than to get to know the gentle giant better, but in 1950s Baltimore, a man just doesn’t ask another man out. His fears are compounded when a visit the day before Valentine’s casts doubts on Hal’s intentions. Maybe he really was meant to live a life of secrets. Or maybe he just needs the holiday to discover the best secret of them all.
Download or read book An Introduction to Text to Speech Synthesis written by Thierry Dutoit and published by Springer Science & Business Media. This book was released on 2013-12-01 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first book to treat two areas of speech synthesis: natural language processing and the inherent problems it presents for speech synthesis; and digital signal processing, with an emphasis on the concatenative approach. The text guides the reader through the material in a step-by-step easy-to-follow way. The book will be of interest to researchers and students in phonetics and speech communication, in both academia and industry.
