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Modeling The Thermal Deformation Of Tatb Based Explosives Part 1
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Book Synopsis Modeling the Thermal Deformation of TATB-based Explosives. Part 1 by :
Download or read book Modeling the Thermal Deformation of TATB-based Explosives. Part 1 written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We detail a modeling approach to simulate the anisotropic thermal expansion of polycrystalline (1,3,5-triamino-2,4,6-trinitrobenzene) TATB-based explosives that utilizes microstructural information including porosity, crystal aspect ratio, and processing-induced texture. This report, the first in a series, focuses on nonlinear thermal expansion of "neat-pressed" polycrystalline TATB specimens which do not contain any binder; additional complexities related to polymeric binder and irreversible ratcheting behavior are briefly discussed, however detailed investigation of these aspects are deferred to subsequent reports. In this work we have, for the first time, developed a mesoscale continuum model relating the thermal expansion of polycrystal TATB specimens to their microstructural characteristics. A self-consistent homogenization procedure is used to relate macroscopic thermoelastic response to the constitutive behavior of single-crystal TATB. The model includes a representation of grain aspect ratio, porosity, and crystallographic texture attributed to the consolidation process. A quantitative model is proposed to describe the evolution of preferred orientation of graphitic planes in TATB during consolidation and an algorithm constructed to develop a discrete representation of the associated orientation distribution function. Analytical and numerical solutions using this model are shown to produce textures consistent with previous measurements and characterization for isostatic and uniaxial "die-pressed" specimens. Predicted thermal strain versus temperature for textured specimens are shown to be in agreement with corresponding experimental measurements. Using the developed modeling approach, several simulations have been run to investigate the influence of microstructure on macroscopic thermal expansion behavior. Results from these simulations are used to identify qualitative trends. Implications of the identified trends are discussed in the context of thermal deformation of engineered components whose consolidation process is generally more complex than isostatic or die-pressed specimens. Finally, an envisioned application of the modeling approach to simulating thermal expansion of weapon systems and components is outlined along with necessary future work to introduce the effects of binder and ratcheting behavior. Key conclusions from this work include the following. Both porosity and grain aspect ratio have an influence on the thermal expansion of polycrystal TATB considering realistic material variability. Thepreferred orientation of the single crystal TATB [001] poles within a polycrystal gives rise to pronounced anisotropy of the macroscopic thermal expansion. The extent of this preferred orientation depends on the magnitude of deformation, and consequently, is expected to vary spatially throughout manufactured components much like porosity. The modeling approach presented here has utility toward bringing spatially variable microstructural features into macroscale system engineering modelsAbstract Not Provided.
Book Synopsis In-Situ Monitoring of the Microstructure of TATB-based Explosive Formulations During Temperature Cycling Using Ultra-small Angle X-ray Scattering by :
Download or read book In-Situ Monitoring of the Microstructure of TATB-based Explosive Formulations During Temperature Cycling Using Ultra-small Angle X-ray Scattering written by and published by . This book was released on 2008 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: TATB (1,3,5 triamino-2,4,6-trinitrobenzene), an extremely insensitive explosive, is used both in plastic-bonded explosives (PBXs) and as an ultra-fine pressed powder (UFTATB). With both PBXs and UFTATB, an irreversible expansion occurs with temperature cycling known as ratchet growth. In TATB-based explosives using Kel-F 800 as binder (LX-17 and PBX-9502), additional voids, sizes hundreds of nanometers to a few microns account for much of the volume expansion caused by temperature cycling. These voids are in the predicted size regime for hot-spot formation during ignition and detonation, and thus an experimental measure of these voids is important feedback for hot-spot theory and for determining the relationship between void size distributions and detonation properties. Also, understanding the mechanism of ratchet growth allows future choice of explosive/binder mixtures to minimize these types of changes to explosives, further extending PBX shelf life. This paper presents the void size distributions of LX-17, UFTATB, and PBXs using commercially available Cytop M, Cytop A, and Hyflon AD60 binders during temperature cycling between -55 C and 70 C. These void size distributions are derived from ultra-small angle x-ray scattering (USAXS), a technique sensitive to structures from about 10 nm to about 2 mm. Structures with these sizes do not appreciably change in UFTATB, indicating voids or cracks larger than a few microns appear in UFTATB during temperature cycling. Compared to Kel-F 800 binders, Cytop M and Cytop A show relatively small increases in void volume from 0.9% to 1.3% and 0.6% to 1.1%, respectively, while Hyflon fails to prevent irreversible volume expansion (1.2% to 4.6%). Computational mesoscale models of ratchet growth and binder wetting and adhesion properties point to mechanisms of ratchet growth, and are discussed in combination with the experimental results.
Author :National Academies of Sciences, Engineering, and Medicine Publisher :National Academies Press ISBN 13 :0309379350 Total Pages :133 pages Book Rating :4.3/5 (93 download)
Book Synopsis Applying Materials State Awareness to Condition-Based Maintenance and System Life Cycle Management by : National Academies of Sciences, Engineering, and Medicine
Download or read book Applying Materials State Awareness to Condition-Based Maintenance and System Life Cycle Management written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2016-04-25 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: In August 2014, the committee on Defense Materials Manufacturing and Infrastructure convened a workshop to discuss issues related to applying materials state awareness to condition-based maintenance and system life cycle management. The workshop was structured around three focal topics: (1) advances in metrology and experimental methods, (2) advances in physics-based models for assessment, and (3) advances in databases and diagnostic technologies. This report summarizes the discussions and presentations from this workshop.
Book Synopsis Numerical Modeling of Explosives and Propellants, Second Edition by : Charles L. Mader
Download or read book Numerical Modeling of Explosives and Propellants, Second Edition written by Charles L. Mader and published by CRC Press. This book was released on 1997-08-29 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Charles Mader, a leading scientist who conducted theoretical research at Los Alamos National Laboratory for more than 30 years, sets a new standard with this reference on numerical modeling of explosives and propellants. This book updates and expands the information presented in the author's landmark work, Numerical Modeling of Detonations, published in 1979 and still in use today. Numerical Modeling of Explosives and Propellants incorporates the considerable changes the personal computer has brought to numerical modeling since the first book was published, and includes new three-dimensional modeling techniques and new information on propellant performance and vulnerability. Both an introduction to the physics and chemistry of explosives and propellants and a guide to numerical modeling of detonation and reactive fluid dynamics, Numerical Modeling of Explosives and Propellants offers scientists and engineers a complete picture of the current state of explosive and propellant technology and numerical modeling. The book is richly illustrated with figures that support the concepts, and filled with tables for quick access to precise data. The accompanying CD-ROM contains computer codes that are the national standard by which modeling is evaluated. Dynamic material properties data files and animation files are also included. There is no other book available today that offers this vital information.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Theoretical Studies of Interactions Between TATB Molecules and the Origins of Anisotropic Thermal Expansion and Growth by :
Download or read book Theoretical Studies of Interactions Between TATB Molecules and the Origins of Anisotropic Thermal Expansion and Growth written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: TATB containing explosives tend to permanently expand as their temperatures are increased or thermally cycled, a phenomenon known as ''ratchet-growth.'' Several mechanisms as to the cause of the non-reversible growth have been proposed, and are taken up here using various different modeling techniques. High-level quantum chemistry calculations have been used in parameterization of a classical potential function suitable for atomistic simulations of TATB. The quantum-chemistry-based force field for TATB was validated by comparing condensed phase properties obtained from molecular dynamics simulations with available experimental data. No permanent growth was manifest at the molecular level. Dissipative particle dynamics simulations were carried out in order to study the geometric packing effects on the mesoscopic scale, similar to the scales representative of Ultrafine. No permanent growth was identified when only simple packing effects were considered in the TATB model. However, non-reversible growth was displayed when crystal fracture capabilities were incorporated in the model, suggesting that crystal fracture induced by the anisotropic volume expansion of TATB is the root cause for the permanent growth seen in TATB containing explosives.
Book Synopsis Chemical-decomposition Models for the Thermal Explosion of Confined HMX, TATB, RDX, and TNT Explosives by :
Download or read book Chemical-decomposition Models for the Thermal Explosion of Confined HMX, TATB, RDX, and TNT Explosives written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Chemistry Resolved Kinetic Flow Modeling of TATB Based Explosives by :
Download or read book Chemistry Resolved Kinetic Flow Modeling of TATB Based Explosives written by and published by . This book was released on 2011 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Detonation waves in insensitive, TATB based explosives are believed to have multi-time scale regimes. The initial burn rate of such explosives has a sub-microsecond time scale. However, significant late-time slow release in energy is believed to occur due to diffusion limited growth of carbon. In the intermediate time scale concentrations of product species likely change from being in equilibrium to being kinetic rate controlled. They use the thermo-chemical code CHEETAH linked to an ALE hydrodynamics code to model detonations. They term their model chemistry resolved kinetic flow as CHEETAH tracks the time dependent concentrations of individual species in the detonation wave and calculates EOS values based on the concentrations. A HE-validation suite of model simulations compared to experiments at ambient, hot, and cold temperatures has been developed. They present here a new rate model and comparison with experimental data.
Book Synopsis Temperature-dependent Shock Initiation of TATB-based High Explosives by :
Download or read book Temperature-dependent Shock Initiation of TATB-based High Explosives written by and published by . This book was released on 1993 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of temperature on the shock sensitivity of two TATB formulations PBX 9502 and LX-17 are studied over the temperature range -54°C to 252°C. The shock Hugoniot curves over this same temperature range are developed. Thermal expansion properties and porosities are used to help determine the mechanisms of thermal sensitization. Impact sensitivities over the range from ambient to 300°C are reported. Analyses of these results imply that thermal sensitization is the result of purely chemical kinetics enhancement and intracrystalline hot-spot growth. Additional results on the ambient shock sensitivity of PBX 9502 and LX-17 following thermal cycling to 252°C and back to ambient is presented.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1994 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings written by and published by . This book was released on 1989 with total page 830 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Literature Review of Shock Sensitivity Changes of TATB Due to Thermal Cycling by :
Download or read book A Literature Review of Shock Sensitivity Changes of TATB Due to Thermal Cycling written by and published by . This book was released on 2016 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: Insensitive high explosives (IHEs) based on 1,3,5-triamino 2,4,6-trinitro-benzene (TATB) are the IHEs of choice for use in nuclear warheads over conventional high explosives when safety is the only consideration, because they are very insensitive to thermal or mechanical initiation stimuli. It is this inherent insensitivity to high temperatures, shock, and impact, which provides detonation design challenges when designing TATB explosive systems while at the same time providing a significant level of protection against accidental initiation. Although classified as IHE, over the past few years the focus on explosive safety has demonstrated that the shock sensitivity of TATB is influenced with respect to temperature. A number of studies have been performed on TATB and TATB formulations, plastic bonded explosives (PBX) 9502, and LX-17-01 (LX-17), which demonstrates the increase in shock sensitivity of the explosive after it has been preheated or thermally cycled over various temperature ranges. Many studies suggest the change in sensitivity is partly due to the decomposition rates of the temperature elevated TATB. Others point to the coefficient of thermal expansion, the crystalline structures of TATB and/or the combination of all factors, which create voids which can become active hot spots. During thermal cycling, TATB is known to undergo an irreversible increase in specific volume called ratchet growth. This increase in specific volume correlates to a decrease in density. This decrease in density and increase in volume, demonstrate the creations of additional void spaces which could serve as potential new initiation hot spots thus, increasing the overall sensitivity of the HE. This literature review evaluates the published works to understand why the shock sensitivity of TATB-based plastic bonded explosives (PBXs) changes with temperature.
Book Synopsis Thermal Decomposition and Reaction of Confined Explosives. [TNT, TATB, LX-04, LX-10]. by :
Download or read book Thermal Decomposition and Reaction of Confined Explosives. [TNT, TATB, LX-04, LX-10]. written by and published by . This book was released on 1976 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Some new experiments designed to accurately determine the time interval required to produce a reactive event in confined explosives subjected to temperatures which will cause decomposition are described. Geometry and boundary conditions were both well defined so that these experiments on the rapid thermal decomposition of HE are amenable to predictive modelling. Experiments have been carried out on TNT, TATB and on two plastic-bonded HMX-based high explosives, LX-04 and LX-10. When the results of these experiments are plotted as the logarithm of the time to explosion versus 1/T K (Arrhenius plot), the curves produced are remarkably linear. This is in contradiction to the results obtained by an iterative solution of the Laplace equation for a system with a first order rate heat source. Such calculations produce plots which display considerable curvature. The experiments have also shown that the time to explosion is strongly influenced by the void volume in the containment vessel. Results of the experiments with calculations based on the heat flow equations coupled with first-order models of chemical decomposition are compared. The comparisons demonstrate the need for a more realistic reaction model.
Book Synopsis Comprehensive Characterization of Voids and Microstructure in TATB-based Explosives from 10 Nm to 1 Cm by :
Download or read book Comprehensive Characterization of Voids and Microstructure in TATB-based Explosives from 10 Nm to 1 Cm written by and published by . This book was released on 2010 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper outlines the characterization of voids and Microstructure in TATB-based Explosives over several orders of magnitude, from sizes on the order of 10 nm to about 1 cm. This is accomplished using ultra small angle x-ray scattering to investigate voids from a few nm to a few microns, ultra small angle neutron scattering for voids from 100 nm to 10 microns, and x-ray computed microtomography to investigate microstructure from a few microns to a few centimeters. The void distributions of LX-17 are outlined, and the microstructure of LX-17 is presented. Temperature cycling and compressive creep cause drastically different damage to the microstructure. Temperature cycling leads to a volume expansion (ratchet growth) in TATB-based explosives, and x-ray scattering techniques that are sensitive to sizes up to a few microns indicated changes to the void volume distribution that had previously accounted for most, but not all of the change in density. This paper presents the microstructural damage larger than a few microns caused by ratchet growth. Temperature cycling leads to void creation in the binder poor regions associated with the interior portion of formulated prills. Conversely, compressive creep causes characteristically different changes to microstructure; fissures form at binder-rich prill boundaries prior to mechanical failure.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1996 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Materials under Extreme Loadings by : Eric Buzaud
Download or read book Materials under Extreme Loadings written by Eric Buzaud and published by John Wiley & Sons. This book was released on 2013-03-04 with total page 405 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents recent and cutting edge advances in our understanding of key aspects of the response of materials under extreme loads that take place during high velocity impact and penetration. The focus of the content is on the numerous challenges associated with characterization and modeling of complex interactions that occur during these highly dynamic events. The following specific topics, among others, are addressed: characterization of material behavior under extreme loadings (estimate of damage, effects related to moisture contents, large pressures, large strain rates, etc.); measurement of microstructural changes associated with damage and mesoscopic scale modeling; macroscopic modeling, using the framework of the theory of viscoplasticity and damage; modeling and simulation of localization, cracking, and dynamic fragmentation of materials; application to penetration mechanics and trajectory instabilities. The book gathers together selected papers based on work presented as invited lectures at the 2nd US-France symposium held on 28-30 May 2008 in Rocamadour, France. The conference was organized by Eric Buzaud (DGA, Centre d'Études de Gramat) under the auspices of the International Center for Applied Computational Mechanics (ICACM).
Download or read book ERDA Research Abstracts written by and published by . This book was released on 1975 with total page 756 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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