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Modeling Initiation in Exploding Bridgewire Detonators

Description: One- and two-dimensional models of initiation in detonators are being developed for the purpose of evaluating the performance of aged and modified detonator designs. The models focus on accurate description of the initiator, whether it be an EBW (exploding bridgewire) that directly initiates a high explosive powder or an EBF (exploding bridgefoil) that sends an inert flyer into a dense HE pellet. The explosion of the initiator is simulated using detailed MHD equations of state as opposed to specific action-based phenomenological descriptions. The HE is modeled using the best available JWL equations of state. Results to date have been promising, however, work is still in progress.
Date: May 18, 2005
Creator: Hrousis, C A
Partner: UNT Libraries Government Documents Department

A logic model for cook-off phenomenology in high explosives

Description: Logic models are valuable tools in the development of predictive models for complex physical processes. The use of deductive logic in the form of a possibility tree makes it straightforward to develop a comprehensive set of unique, alternative paths that describe the system. We demonstrate the power of this approach for the complex process of cook-off of high explosives (HE). The possibility tree describes the causal paths from heating HE to the alternative end states. One of these end states is a violent reaction. Conversion of the tree to the equivalent digraph yields a valuable visualization tool for examining the relationships between sub-processes and provides a sound framework for the development of analytical models.
Date: January 1, 2003
Creator: Eisenhawer, S. W. (Stephen W.); Bott, T. F. (Terrence F.); Luck, L. B.; Kingson, J. & Key, B. P. (Brian P.)
Partner: UNT Libraries Government Documents Department

ASME code ductile failure criteria for impulsively loaded pressure vessels

Description: Ductile failure criteria suitable for application to impulsively loaded high pressure vessels that are designed to the rules of the ASME Code Section VI11 Division 3 are described and justified. The criteria are based upon prevention of load instability and the associated global failure mechanisms, and on protection against progressive distortion for multiple-use vessels. The criteria are demonstrated by the design and analysis of vessels that contain high explosive charges.
Date: January 1, 2003
Creator: Nickell, Robert E.; Duffey, T. A. (Thomas A.) & Rodriguez, E. A. (Edward A.)
Partner: UNT Libraries Government Documents Department

Bio-Treatment of Energetic Materials Using White-Rot Fungus

Description: The nitramine explosive, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), is used by militaries around the world in high yield munitions and often in combination with hexahydro- 1,3,5-trirdtro- 1,3,5- triazine (RDX). Improper handling and disposal of manufacturing wastewater may lead to environmental contamination. In the past wastewater was collected in disposal lagoons where it evaporated, and deposited large amounts of explosives on the lagoon floor. Although lagoon disposal is no longer practiced, thousands of acres have been already contaminated. RDX and, to a lesser extent, HMX have leached through the soil subsurface and contaminated groundwater ( 1,2). Likewjse, burning of substandard material or demilitarization of out-of-date muriitions has also led to environmental contamination. The current stockpile of energetic materials at DOE sites requires resource recovery or disposition (RRD). A related challenge exists in the clean-up of the DOE sites where soil and ground water are contaminated with explosives. Current technologies such as incineration, molten salt process, supercritical water oxidation are expensive and have technical hurdles. Open burning and open detonation(OB/OD) is not encouraged by regulatory agencies for disposal of explosives. Hence, there is need for a safe . technology to degrade these contaminants. The fi.mgal process does not employ open burning or open detonation to destroy energetic materials. The fimgal process can be used by itself, or it can augment or support other technologies for the treatment of energetic materials. The proposed enzyme technology will not release any air pollutants and will meet the regulations of Clean Air Act amendments, the Resource Conservation and Recovery Act, and the Federal. Facilities Compliance Act. The goal for this project was to test the ability of white-rot fungus to degrade HMX. In our study, we investigated the biodegradation of HMX using white-rot fungus in liquid and solid cultures. The degradation of HMX was studied at 1, 10, 100 ...
Date: November 12, 1998
Creator: Shah, MM
Partner: UNT Libraries Government Documents Department

CRT compatibility evaluation of LX-16 and Halthane 73-18

Description: A preliminary compatibility study was carried out between the plastic-bonded PETN-based high explosive LX-16 and the adhesive Halthane 73-18. The work, based on the Chemical Reactivity Test (CRT), used non-standard times and temperatures to find conditions corresponding to accelerated decomposition. This study is a prequel to a more comprehensive isothermal and thermal cycling study that will include both material evaluation and test fire.
Date: August 24, 1999
Creator: Foltz, M F; Reyes, P & Foster, P A
Partner: UNT Libraries Government Documents Department

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

Description: 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.
Date: December 1, 1995
Creator: Behrens, R. & Bulusu, S.
Partner: UNT Libraries Government Documents Department

CRT compatibility evaluation of LX-16 and Halthane 73-18

Description: A preliminary compatibility study was carried out between the plastic-bonded PETN- based high explosive LX-16 and the adhesive Halthane 73-l 8. The work, based on the Chemical Reactivity Test (CRT), used non-standard times and temperatures to find conditions corresponding to accelerated decomposition. This study is a prequel to a more comprehensive isothermal and thermal cycling study that will include both material evaluation and test tire.
Date: March 26, 1999
Creator: Foltz, M F & Foster, P A
Partner: UNT Libraries Government Documents Department

On improving the penetration of commercial shaped charge perforators

Description: Computational analysis demonstrated that the penetration of a shaped charge jet could be substantially enhanced by imploding the liner in a high pressure light gas atmosphere. The gas pressure helps confine the jet on the axis of penetration in the latter stages of formation. A light gas, such as helium or hydrogen, is required in order to keep the gas density low enough so as not to inhibit liner collapse. The computational analysis has now been experimentally confirmed.
Date: April 1, 1999
Creator: Glenn, L A
Partner: UNT Libraries Government Documents Department

Compacting Plastic-Bonded Explosive Molding Powders to Dense Solids

Description: Dense solid high explosives are made by compacting plastic-bonded explosive molding powders with high pressures and temperatures for extended periods of time. The density is influenced by manufacturing processes of the powders, compaction temperature, the magnitude of compaction pressure, pressure duration, and number of repeated applications of pressure. The internal density variation of compacted explosives depends on method of compaction and the material being compacted.
Date: April 15, 2005
Creator: Olinger, B.
Partner: UNT Libraries Government Documents Department

Fragmentation in Biaxial Tension

Description: We have carried out an experiment that places a ductile stainless steel in a state of biaxial tension at a high rate of strain. The loading of the ductile metal spherical cap is performed by the detonation of a high explosive layer with a conforming geometry to expand the metal radially outwards. Simulations of the loading and expansion of the metal predict strain rates that compare well with experimental observations. A high percentage of the HE loaded material was recovered through a soft capture process and characterization of the recovered fragments provided high quality data, including uniform strain prior to failure and fragment size. These data were used with a modified fragmentation model to determine a fragmentation energy.
Date: June 13, 2006
Creator: Campbell, G H; Archbold, G C; Hurricane, O A & Miller, P L
Partner: UNT Libraries Government Documents Department

Expendable Precision Laser Aimer for Shaped Charges

Description: Certain shaped-charge cutting operations require a precision aiming system that is operationally convenient, robust, and constructed to allow the aiming system to be left in place for last-minute alignment verification until it is expended when the charge is fired. This report describes an aiming system made from low cost doubled-Nd:YAG 532 nm laser modules of the type used in green laser pointers. Drawings and detailed procedures for constructing the aiming system are provided, as are the results of some minimal tests performed on a prototype device.
Date: October 25, 2007
Creator: Ault, S & Kuklo, R
Partner: UNT Libraries Government Documents Department

Blast mitigation capabilities of aqueous foam.

Description: A series of tests involving detonation of high explosive blanketed by aqueous foam (conducted from 1982 to 1984) are described in primarily terms of recorded peak pressure, positive phase specific impulse, and time of arrival. The investigation showed that optimal blast mitigation occurs for foams with an expansion ratio of about 60:1. Simple analyses representing the foam as a shocked single phase mixture are presented and shown inadequate. The experimental data demonstrate that foam slows down and broadens the propagated pressure disturbance relative to a shock in air. Shaped charges and flyer plates were evaluated for operation in foam and appreciable degradation was observed for the flyer plates due to drag created by the foam.
Date: February 1, 2006
Creator: Hartman, William Franklin; Larsen, Marvin Elwood & Boughton, Bruce A.
Partner: UNT Libraries Government Documents Department

An Improved Reaction Rate Equation for Simulating the Ignition and Growth of Reaction in High Explosives

Description: We describe an improved reaction rate equation for simulating ignition and growth of reaction in high explosives. It has been implemented into CALE and ALE3D as an alternate to the baseline the Lee-Tarver reactive flow model. The reactive flow model treats the explosive in two phases (unreacted/reactants and reacted/products) with a reaction rate equation to determine the fraction reacted, F. The improved rate equation has fewer parameters, is continuous with continuous derivative, results in a unique set of reaction rate parameters for each explosive while providing the same functionality as the baseline rate equation. The improved rate equation uses a cosine function in the ignition term and a sine function in the growth and completion terms. The improved rate equation is simpler with fewer parameters.
Date: March 8, 2010
Creator: Murphy, M J
Partner: UNT Libraries Government Documents Department

Equation of state for high explosives detonation products with explicit polar and ionic species

Description: We introduce a new thermodynamic theory for detonation products that includes polar and ionic species. The new formalism extends the domain of validity of the previously developed EXP6 equation of state library and opens the possibility of new applications. We illustrate the scope of the new approach on PETN detonation properties and water ionization models.
Date: June 28, 2006
Creator: Bastea, S; Glaesemann, K R & Fried, L E
Partner: UNT Libraries Government Documents Department

Science and Technology Review March 2006

Description: This month's issue has the following articles: (1) Without Fanfare, Technicians Safely Keep the Laboratory Humming--Commentary by Bruce T. Goodwin; (2) These People Make Things Happen--Technicians at Lawrence Livermore, comprising more than 20 percent of the workforce, are essential to research efforts. March 2006; (3) The Shocking Truth about Detonations and Metals--The multichannel x-ray system Hydra records the changes in metals undergoing a high-explosives shock, revealing phenomena not predicted by material models; (4) Floating into Thin Air--High-flying balloon gathers images from x-ray sources that are out of this world; and (5) Carbon Goes Full Cycle in the Amazon--Recent measurements indicate that the Amazon River basin returns carbon to the atmosphere in only 5 years.
Date: January 18, 2006
Creator: Aufderheide, M B
Partner: UNT Libraries Government Documents Department

Reduction of Allowed Inventory When Chemicals are Located in Close Proximity with Explosives

Description: The objective of this report is to determine the allowed inventory of chemicals stored in the same bay, building or magazine, i.e., in close proximity, with high explosives (HE) that would, in the event of an accident, result in acceptable risks to colocated workers and the public.
Date: September 27, 2006
Creator: Chong, Y P & Nguyen, S N
Partner: UNT Libraries Government Documents Department

Compaction wave profiles in granular HMX

Description: Meso-scale simulations of a compaction wave in a granular bed of HMX have been performed. The grains are fully resolved in order that the change in porosity across the wave front is determined by the elastic-plastic response of the grains rather than an empirical law for the porosity as a function of pressure. Numerical wave profiles of the pressure and velocity are compared with data from a gas gun experiment. The experiment used an initial porosity of 36%, and the wave had a pressure comparable to the yield strength of the grains. The profiles are measured at the front and back of the granular bed. The transit time for the wave to travel between the gauges together with the Hugoniot jump conditions determines the porosity behind the wave front. In the simulations the porosity is determined by the yield strength and stress concentrations at the contact between grains. The value of the yield strength needed to match the experiment is discussed. Analysis of the impedance match of the wave at the back gauge indicates that the compaction wave triggers a small amount of burn, less than 1% mass fraction, on the micro-second time scale of the experiment.
Date: January 1, 2001
Creator: Menikoff, Ralph
Partner: UNT Libraries Government Documents Department

Experimental investigation of the representative volume element size.

Description: In this investigation, the minimum size of the representative volume element (RVE) of a heterogeneous material is determined experimentally using the digital image correlation (DIC) technique. The uniaxial compression experiment was conducted on the PBS 9501, a high explosive simulant material. The minimum size of the representative volume element (RVE) of the PBS 9501 heterogeneous material, where the average crystal diameter of the material is around 100{micro}m, was determined experimentally to be 1.5mm. This result is consistent with those numerical calculations on polycrystalline materials and some other composites.
Date: January 1, 2002
Creator: Liu, C. (Cheng); Stout, M. G. (Michael G.) & Asay, B. W. (Blaine W.)
Partner: UNT Libraries Government Documents Department

Insights into the shock initiation/detonation of homogeneous and heterogeneous HE

Description: It has long been known that there are fundamental differences between homogeneous and heterogeneous high explosives. The shock initiation behavior of these materials was first described in the literature by Campbell et al, in 1961. Chaiken was also involved in describing this process for liquid nitromethane. Since then, there have been a number of studies which have added considerable incite into the shock initiation/detonation behavior of these materials. We only give a few references here (Refs. 4 - 11) and these should be considered representative; e.g. they do not represent an exhaustive list of references available. Many of these studies were done on homogeneous explosives, most often nitromethane (NM) and include particle velocity gauge measurements, optical temperature measurements, VISAR measurements, as well as streak camera measurements of interfaces. In some cases NM was heterogenized by gelling and adding silica particles. Homogeneous materials are typically liquids or single crystals in which there are a minimal number of physical imperfections (e.g. bubbles or voids) that can cause perturbations in the input shock and the flow behind it. Homogeneous materials viewed with macroscopic probes characteristic of detonation physics experiments appear uniform. Heterogeneous explosives are generally all other types; these are usually pressed, cast, machined, or extruded into the shapes or parts desired. These materials contain imperfections of a variety of types that cause fluid-mechanical irregularities (called hot spots) when a shock or detonation wave passes over them. Such hot spots cause associated space/time fluctuations in the thermodynamic fields (e.g., the pressure or temperature fields) in the material. These thermodynamic variations affect the local chemical-heat-release rate - they produce an average heat-release rate that is a combination of chemistry and mechanics. Hot spots could be the result of voids, shock interactions, jetting, shock impedance mismatches, etc. Shock initiation of homogeneous explosives is due to ...
Date: January 1, 2001
Creator: Gustavsen, R. L. (Richard L.); Hill, L. G. (Larry G.); Engelke, R. P. (Raymond P.); Alcon, R. R. (Robert R.); Davis, L. L. (Lloyd L.) & Sheffield, S. A. (Stephen A.)
Partner: UNT Libraries Government Documents Department

Temperature measurements of partially-melted tin as a function of shock pressure

Description: Equilibrium equation of state theory predicts that the free surface release temperature of shock loaded tin will show a plateau of 505 K in the pressure range from 19.5 to 33.0 GPa, corresponding to the solid-liquid mixed-phase region. In this paper we report free surface temperature measurements on shock-loaded tin from 15 to 31 GPa using multi-wavelength optical pyrometry. The shock waves were generated by direct contact of detonating high explosive with the sample. The pressure in the sample was determined by free surface velocity measurements using Photon Doppler Velocimetry. The emitted thermal radiance was measured at four wavelength bands in the near IR region from 1.5 to 5.0 {micro}m. The samples in most of the experiments had diamond-turned surface finishes, with a few samples being polished or ball rolled. At pressures higher than 25 GPa the measured free surface temperatures were higher than the predicted 505 K and increased with increasing pressure. This deviation could be explained by hot spots and/or variations in surface emissivity and requires a further investigation.
Date: January 1, 2009
Creator: Seifter, Achim; Furlanetto, Michael R; Holtkamp, David B; Obst, Andrew W; Payton, J R; Stone, J B et al.
Partner: UNT Libraries Government Documents Department