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1
Dean, Rachel. "Forensic applications of fragmentation of materials by explosives." Thesis, Cranfield University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422190.
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2
Gupta, Sakshi. "Investigation on the enhancement of raman signal and fluorescent organic materials for explosives detection." Thesis, IIT Delhi, 2016. http://localhost:8080/iit/handle/2074/7022.
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Frota, Octávia. "Development of a low cost cook-off test for assessing the hazard of explosives." Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/9323.
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A low cost Cook-Off experimental facility has been established to provide a convenient method of ranking explosives in their response to Cook-Off by the time to event under two widely different heating rates and at two different scales. This thesis describes the literature review undertaken as preparation for the purposed study and all the experimental work developed comprising the design of the trials vehicles, the demonstration of their suitability for Fast and Slow Cook-Off trials with confined explosive systems, the preparation of the samples and test vehicles to be trialled as well as the set-up of adequate facilities to undertake the scheduled firing programme. Results are reported for Cook-Off tests on TNT, RDX, and their mixtures. The emphasis of the study is on time to event, and temperature at event, and in addition a qualitative assessment of the violence of the event was made by examination of the fragments of the vehicles, although it is accepted that the relatively light and low cost design of the vehicle may lead to variable confinement in the early stages of the explosive event, and hence to a wider spread of responses than would be obtained from a more heavily confined and more costly vehicle. The test vehicles give results, which differentiate between the various explosives and explosive mixtures trialled and between the scales. More experiments are required to establish the reproducibility of the measurements. The design of the equipment makes this a relatively inexpensive undertaking. The experiment was modelled using published kinetic data, but the calculated time to event differed from that observed to different extents at the two scales. It is hypothesised that the mechanism may change over the prolonged heat soaks and that quantitative scaling is not possible with the available information. Further work is also suggested using a different type of Cook-Off test vehicle, which will in our opinion reduce even further the cost of Cook-Off testing, due to reduction in man-hours of preparation involved and manufacture cost of the Cook-Off test vehicles, and consequently of ranking of explosives.
4
Reding, Derek James. "Shock induced chemical reactions in energetic structural materials." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28174.
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Thesis (M. S.)--Aerospace Engineering, Georgia Institute of Technology, 2009.Committee Chair: Hanagud, Sathya; Committee Member: Kardomateas, George; Committee Member: McDowell, David; Committee Member: Ruzzene, Massimo; Committee Member: Thadhani, Naresh.
5
Thomas, Samuel William III. "Molecules and materials for the optical detection of explosives and toxic chemicals." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36260.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2006.Vita.
Includes bibliographical references.
Optical chemosensing, especially using amplifying fluorescent polymers, can allow for the highly sensitive and selective vapor-phase detection of both explosives and highly toxic chemicals, including chemical warfare agents. There are varieties of analyte targets, however, that remain challenging for detection by these methods. Research towards improving this technology has obvious implications for homeland security and soldier survivability. This dissertation details the development of new molecules, materials, and transduction schemes aimed at improving both the versatility and sensitivity of optical chemical detection. Chapter One provides an introduction to the field of fluorescent polymer sensors, principally focusing on their utility in the detection of nitroaromatic explosives. Brief descriptions of other analytical methods used for explosives detection are also included. Chapter Two describes the synthesis and optical properties of a new class of conjugated polymers that contain alkyl-amino groups directly bound to the arene rings of poly(phenylene ethynylene)s and poly(fluorene)s. These materials displayed red-shifted absorption and emission spectra, large Stokes Shifts, as well as long excited state lifetimes.
(cont.) Also described is the use of films of these readily oxidized polymers in the vapor-phase detection of hydrazine down to a concentration of 100 parts-per-billion. This new scheme for the detection of hydrazine vapor relies on the analyte's reduction of oxidized traps ("unquenching") within the polymer film to give a fluorescence "turn-on" signal. Chapter Three begins with an introduction to the various classes of explosive molecules, as well as to the concept of "tagging" plastic explosives with higher vapor pressure dopants in order to make them easier to detect. This is followed by a description of how the taggant DMNB was successfully detected using high band-gap poly(fluorene)s. The higher energy conduction bands of these materials allowed for exergonic electron transfer to DMNB and fluorescence quenching in both the solution and solid states. Phosphorescence is the theme of Chapter Four, in which two research projects based on highly phosphorescent cyclometalated Pt(II) complexes are summarized. This includes the synthesis and optical characterization of a phosphorescent poly(fluorene), one of the repeat units of which is a Pt(ppy)(acac)-type complex. Comparisons of its intrinsic photophysical properties and oxygen-induced quenching behavior to model compounds are also summarized.
(cont.) Chapter Four also details investigations into using oxidative addition reactions of new bis-cyclometalated Pt(II) complexes for the dark-field turn-on chemical detection of cyanogen halides. Incorporating substituents on the ligands that force steric crowding in the square plane accelerated the addition of cyanogen bromide to these complexes, which also correlated with the room-temperature phosphorescence efficiency of these complexes. Exposure of polymer films doped with these complexes gave a dark-field turn on signal to the blue of the reactant that corresponded to the phosphorescence of the Pt(IV) oxidative addition product. Finally, Chapter Five focuses on iptycenes, a very useful structural moiety in the field of optical chemosensing. The development of an improved synthetic procedure for the preparation of the iptycene group is described. This procedure has been showed to be effective in the preparation of a series of new iptycene-containing molecules, including a poly(iptycene). To conclude, the unique counter-aspect ratio alignment behavior of a poly(iptycene) in a stretch-aligned polymer film is summarized. This is rationalized by a "threading" model, in which the chains of the poly(vinyl chloride) matrix occupy the internal-free-volume defined by the poly(iptycene).
by Samuel William Thomas, III.
Ph.D.
6
Collins, Adam Leigh. "Environmentally responsible energetic materials for use in training ammunition." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610529.
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Wang, Guangyu. "An MD-SPH Coupled Method for the Simulation of Reactive Energetic Materials." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491559185266293.
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8
Aronson, Joshua Boyer. "The Synthesis and Characterization of Energetic Materials From Sodium Azide." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/7597.
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A tetrazole is a 5-membered ring containing 4 nitrogens and 1 carbon. Due to its energetic potential and structural similarity to carboxylic acids, this ring system has a wide number of applications. In this thesis, a new and safe sustainable process to produce tetrazoles was designed that acheived high yields under mild conditions. Also, a technique was developed to form a trityl-protected tetrazole in situ. The rest of this work involved the exploitation of the energetic potential of tetrazoles. This moiety was successfully applied in polymers, ionic liquids, foams, and gels. The overall results from these experiments illustrate the fact that tetrazoles have the potential to serve as a stable alternative to the troublesome azido group common in many energetic materials. Due to these applications, the tetrazole moiety is a very important entity.
9
Salinas, Soler Yolanda. "Functional hybrid materials for the optical recognition of nitroaromatic explosives involving supramolecular interactions." Doctoral thesis, Editorial Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/31663.
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La presente tesis doctoral titulada ¿Materiales funcionales híbridos para el reconocimiento
óptico de explosivos nitroaromáticos mediante interacciones supramoleculares¿ se basa en la
combinación de principios de Química Supramolecular y de Ciencia de los Materiales para el
diseño y desarrollo de nuevos materiales híbridos orgánico-inorgánicos funcionales capaces de
detectar explosivos nitroaromáticos en disolución.
En primer lugar se realizó una búsqueda bibliográfica exhaustiva de todos los sensores
ópticos (cromogénicos y fluorogénicos) descritos en la bibliografía y que abarca el periodo
desde 1947 hasta 2011. Los resultados de la búsqueda están reflejados en el capítulo 2 de esta
tesis.
El primer material híbrido preparado está basado en la aplicación de la aproximación de los
canales iónicos y, para ello, emplea nanopartículas de sílice funcionalizadas con unidades
reactivas y unidades coordinantes (ver capítulo 3). Este soporte inorgánico se funcionaliza con
tioles (unidad reactiva) y una poliamina lineal (unidad coordinante) y se estudia el transporte
de una escuaridina (colorante) a la superficie de la nanopartícula en presencia de diferentes
explosivos. En ausencia de explosivos, la escuaridina (color azul y fluorescencia intensa) es
capaz de reaccionar con los tioles anclados en la superficie decolorando la disolución. En
presencia de explosivos nitroaromáticos se produce una inhibición de la reacción escuaridinatiol y la suspensión permanece azul. Esta inhibición es debida a la formación de complejos de
transferencia de carga entre las poliaminas y los explosivos nitroaromáticos.
En la segunda parte de esta tesis doctoral se han preparado materiales híbridos con
cavidades biomiméticas basados en el empleo de MCM-41 como soporte inorgánico
mesoporoso (ver capítulo 4). Para ello se ha procedido al anclaje de tres fluoróforos (pireno,
dansilo y fluoresceína) en el interior de los poros del soporte inorgánico y, posteriormente, se
ha hidrofobado el interior de material mediante la reacción de los silanoles superficiales con
1,1,1,3,3,3-hexametildisilazano. Mediante este procedimiento se consiguen cavidades
hidrófobas que tienen en su interior los fluoróforos. Estos materiales son fluorescentes cuando
se suspenden en acetonitrilo mientras que cuando se añaden explosivos nitroaromáticos a
estas suspensiones se observa una desactivación de la emisión muy marcada. Esta
desactivación de la emisión es debida a la inclusión de los explosivos nitroaromáticos en la
cavidad biomimética y a la interacción de estas moléculas (mediante interacciones de ¿-
stacking) con el fluoróforo. Una característica importante de estos materiales híbridos
sensores es que pueden ser reutilizados después de la extracción del explosivo de las
cavidades hidrofóbicas. En la última parte de esta tesis doctoral se han desarrollado materiales híbridos orgánicoinorgánicos funcionalizados con ¿puertas moleculares¿ que han sido empleados también para
detectar explosivos nitroaromáticos (ver capítulo 5). Para la preparación de estos materiales
también se ha empleado MCM-41 como soporte inorgánico. En primer lugar, los poros del
soporte inorgánico se cargan con un colorante/fluoróforo seleccionado. En una segunda etapa,
la superficie externa del material cargado se ha funcionalizado con ciertas moléculas con
carácter electrón dador (pireno y ciertos derivados del tetratiafulvaleno). Estas moléculas ricas
en electrones forman una monocapa muy densa (debida a las interacciones dipolo-dipolo
entre estas especies) alrededor de los poros que inhibe la liberación del colorante. En
presencia de explosivos nitroaromáticos se produce la ruptura de la monocapa, debido a
interacciones de ¿-stacking con las moléculas ricas en electrones, con la consecuencia de una
liberación del colorante atrapado en el interior de los poros observándose una respuesta
cromo-fluorogénicaSalinas Soler, Y. (2013). Functional hybrid materials for the optical recognition of nitroaromatic explosives involving supramolecular interactions [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/31663
Alfresco
Premiado
10
Conroy, Michael W. "Density Functional Theory Studies of Energetic Materials." Scholar Commons, 2009. http://scholarcommons.usf.edu/etd/3691.
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First-principles calculations employing density functional theory (DFT) were
performed on the energetic materials PETN, HMX, RDX, nitromethane, and a recently
discovered material, nitrate ester 1 (NEST-1). The aims of the study were to accurately
predict the isothermal equation of state for each material, improve the description of these
molecular crystals in DFT by introducing a correction for dispersion interactions, and
perform uniaxial compressions to investigate physical properties that might contribute to
anisotropic sensitivity.
For each system, hydrostatic-compression simulations were performed. Important
properties calculated from the simulations such as the equilibrium structure, isothermal
equation of state, and bulk moduli were compared with available experimental data to
assess the agreement of the calculation method. The largest contribution to the error was
believed to be caused by a poor description of van der Waals (vdW) interactions within
the DFT formalism.
An empirical van der Waals correction to DFT was added to VASP to increase
agreement with experiment. The average agreement of the calculated unit-cell volumes
for six energetic crystals improved from approximately 9% to 2%, and the isothermal
EOS showed improvement for PETN, HMX, RDX, and nitromethane. A comparison was
made between DFT results with and without the vdW correction to identify possible
advantages and limitations.
Uniaxial compressions perpendicular to seven low-index crystallographic planes
were performed on PETN, HMX, RDX, nitromethane, and NEST-1. The principal
stresses, shear stresses, and band gaps for each direction were compared with available
experimental information on shock-induced sensitivity to determine possible correlations
between physical properties and sensitivity. The results for PETN, the only system for
which the anisotropic sensitivity has been thoroughly investigated by experiment,
indicated a possible correlation between maximum shear stress and sensitivity. The
uniaxial compressions that corresponded to the greatest maximum shear stresses in HMX,
RDX, solid nitromethane, and NEST-1 were identified and predicted as directions with
possibly greater sensitivity. Experimental data is anticipated for comparison with the
predictions.
11
Landerville, Aaron Christopher. "First-principles studies of shock-induced phenomena in energetic materials." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0002902.
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12
Doblas, Jiménez David. "Exploration and detection of ultra-traces of explosives by chip calorimetry." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAE017/document.
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La détection de très faibles quantités de Matériaux Energétiques (ME) est un challenge important dans la lutte contre le terrorisme. En plus des méthodes de détection des ME par affinité chimique, il est aussi intéressant d'utiliser les variations enthalpiques dues à la décomposition des ME pour les détecter par analyse thermique. Cependant, la sensibilité des methodes classiques est insuffisante pour la détection des particules dont la masse se situe dans le domaine des nanogrammes. En revanche, la nanocalorimétrie est parfaitement adaptée pour la caractérisation de très faibles quantités d'échantillons et est de ce fait adaptée aux exigences de la détection. Afin d'explorer la possibilité de détecter et d'identifier des micro-particules solides de ME à l'aide de l'analyse thermique, nous avons élaboré des protocols optimisés pour la détection et l'identification de particules pures unitaires de quelques nanogrammes de ME ainsi que leurs mélanges. Les résultats montrent que la limite de détection se situe environ à quelques centaines de picrogrammes. Les expériences ont été complétées par de l'analyse structurale in-situ en utilisant sa combinaison avec de la DRX par faisceau nanofocus synchrotronBeing able to sense the minuscule amounts of energetic materials is crucial in the context of the fight against terrorism. Apart from the methods of detection of EM, which are specific to the chemical structure, one could use the enthalpy variations of the EM decomposition process for their detection by means of thermal analysis. However, the sensitivity of classical methods would be still insufficient to sense particles in the nanogram range. By contrast, the recently developed technique of chip calorimetry is perfectly suited for characterizing small amounts of samples and is therefore fully adequate for this task.In order to explore the possibilities of detection and identification of solid micro-particles of EM with thermal analysis, we discuss on the protocols optimized for the detection and identification of nanogram-size particles of EM and its mixtures with the chip calorimeter accessory. The results obtained on pure EM and its mixtures show that the detection threshold can be put at approximately several hundred picograms. The experiments were completed by the in-situ structural analysis using a combination with nanofocus synchrotron XRD
13
Aydelotte, Brady Barrus. "Fragmentation and reaction of structural energetic materials." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50253.
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Structural energetic materials (SEM) are a class of multicomponent materials which may react under various conditions to release energy. Fragmentation and impact induced reaction are not well characterized phenomena in SEMs. The structural energetic systems under consideration here combine aluminum with one or more of the following: nickel, tantalum, tungsten, and/or zirconium. These metal+Al systems were formulated with powders and consolidated using explosive compaction or the gas dynamic cold spray process.
Fragment size distributions of the indicated metal+Al systems were explored; mean fragment sizes were found to be smaller than those from homogeneous ductile metals at comparable strain rates, posing a reduced risk to innocent bystanders if used in munitions. Extensive interface failure was observed which suggested that the interface density of these systems was an important parameter in their fragmentation. Existing fragmentation models for ductile materials did not adequately capture the fragmentation behavior of the structural energetic materials in question. A correction was suggested to modify an existing fragmentation model to expand its applicability to structural energetic materials. Fragment data demonstrated that the structural energetic materials in question provided a significant mass of combustible fragments. The potential combustion enthalpy of these fragments was shown to be significant.
Impact experiments were utilized to study impact induced reaction in the indicated metal+Al SEM systems. Mesoscale parametric simulations of these experiments indicated that the topology of the microstructure constituents, particularly the stronger phase(s), played a significant role in regulating impact induced reactions. Materials in which the hard phase was topologically connected were more likely to react at a lower impact velocity due to plastic deformation induced temperature increases. When a compliant matrix surrounded stronger, simply connected particles, the compliant matrix accommodated nearly all of the deformation, which limited plastic deformation induced temperature increases in the stronger particles and reduced reactivity. Decreased difference between the strength of the constituents in the material also increased reactivity. The results presented here demonstrate that the fragmentation and reaction of metal+Al structural energetic materials are influenced by composition, microstructure topology, interface density, and constituent mechanical properties.
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Jiba, Zetu. "Coating processes towards selective laser sintering of energetic material composites." Diss., University of Pretoria, 2019. http://hdl.handle.net/2263/79246.
Full textAbstract:
This research aims to contribute to the safe methodology for additive manufacturing (AM) of
energetic materials. Coating formulation processes were investigated to find a suitable method
that may enable selective laser sintering (SLS) as the safe method for fabrication of high
explosive (HE) compositions. For safety and convenience reasons, the concept demonstration
was conducted using inert explosive simulants with properties quasi-similar to the real HE.
Coating processes for simulant RDX-based microparticles by means of PCL and 3,4,5-
trimethoxybenzaldehyde (as TNT simulant) are reported. These processes were evaluated for
uniformity of coating the HE inert simulant particles with binder materials to facilitate the SLS
as the adequate binding and fabrication method. The critical constraints being the coating
effectiveness required, spherical particle morphology, micron size range (>20 μm) and a good
powder deposition and flow, and performance under SLS to make the method applicable for
HEs.
Of the coating processes investigated, suspension system and single emulsion methods gave
required particle near spherical morphology, size and uniform coating. The suspension process
appears to be suitable for the SLS of HE mocks and potential formulation methods for active
HE composites. The density was estimated to be comparable with the current HE compositions
and plastic bonded explosives (PBXs) such as C4 and PE4, produced from traditional methods. The formulation method developed and the understanding of the science behind the processes
paves the way toward safe SLS of the active HE compositions and may open avenues for further
research and development of munitions of the future.Dissertation (MSc)--University of Pretoria, 2019.
Chemical Technology
MSc
Unrestricted
15
Palacios, Manuel A. "Materials and Strategies in Optical Chemical Sensing." Bowling Green State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1225902887.
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Ben, Jaber Sultan Saeed. "Development of nanostructures materials for detection of ultra-trace levels of explosives based on Surface-Enhanced Raman Spectroscopy (SERS)." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/10040377/.
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The detection of explosives and their derivatives is crucial for security, defence and safety. However, detection of low levels and vapour phase of explosives are a serious challenge for forensic practitioners. Scientists and researchers continue to improve sensitive detection methods with reasonable cost and portability. One of the promising techniques for such applications is Surface Enhanced Raman spectroscopy (SERS) due to its high sensitivity and ease of use. Several approaches were applied to improve the sensitivity of explosives detection based on the SERS technique. A wide range of materials were prepared, characterized and used as SERS substrates, including metals such as gold, silver, copper nanostructures, and semiconductors such as TiO2, ZnO. SERS activity of these materials was evaluated, and high quality detection of explosives was achieved at ultra-trace levels. Sensors with high selectivity, reproducibility, reusability and low limit of detection LOD were made. A new sensitive method for enhancement of Raman signals was demonstrated, whereby pre-irradiation (photo-excitation) of a semiconductor such as TiO2 coated with gold/silver nanoparticles, enables strong Raman enhancement at the nanoparticle sites, increasing sensitivity beyond the normal SERS effect. We call this effect photo-induced enhanced Raman spectroscopy— PIERS. In this system the molecules can be directly adsorbed onto the metallic particle, allowing controlled enhancement by both the electromagnetic and chemical enhancement factor. Various analytes were detected by PIERS including dyes, explosives and biomolecules with high sensitivity, reproducibility, and the substrate was reusable for self-cleaning by UV-irradiation. Further investigations were carried out for photo-induced enhancement including creation of oxygen vacancies on semiconductors surface by annealing in vacuum and etching, and a series of SERS measurements were performed of molecules on treated substrates. Silver nanocubes showed high SERS sensitivity of explosives with good specificity, and showed an important role for the preparation of SERS samples. The shape of AgNC contributed significantly to obtained high SERS enhancement. SERS measurements of vapour explosives were performed and showed to be an order of magnitude greater than reported enhancement, where the detection specificity was strongly improved. Free-metal ZnO nanostructures showed charge transfer enchantment, where ZnO nanocrystals exhibited better enhancement than ZnO thin films. The enhancement is further improved in the presence of copper species in the ZnO thin film structure.
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White, Bradley William. "Microstructure and strain rate effects on the mechanical behavior of particle reinforced epoxy-based reactive materials." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42801.
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The effects of reactive metal particles on the microstructure and mechanical properties of epoxy-based composites are investigated in this work. To examine these effects castings of epoxy reinforced with 20-40 vol.% Al and 0-10 vol.% Ni were prepared, while varying the aluminum particle size from 5 to 50 microns and holding the nickel particle size constant at 50 microns. In total eight composite materials were produced, possessing unique microstructures. The microstructure is quantitatively characterized and correlated with the composite constitutive response determined from quasi-static and dynamic compressive loading conditions at strain-rates from 1e-4 to 5e3 /s. Microstructures from each composite and at each strain rate were analyzed to determine the amount of particle strain as a function of bulk strain and strain rate. Using computational simulations of representative microstructures of select composites, the epoxy matrix-metallic particle and particle-particle interactions at the mesoscale under dynamic compressive loading conditions were further examined. From computational simulation data, the stress and strain localization effects were characterized at the mesoscale and the bulk mechanical behavior was decomposed into the individual contributions of the constituent phases. The particle strain and computational analysis provided a greater understanding of the mechanisms associated with particle deformation and stress transfer between phases, and their influence on the overall mechanical response of polymer matrix composites reinforced with metallic particles. The highly heterogeneous composite microstructure and the high contrasting properties of the individual constituents were found to drive localized deformations that are often more pronounced than those in the bulk material. The strain rate behavior of epoxy is shown to cause a strain rate dependent deformation response of reinforcement particle phases that are typically strain rate independent. Additionally, the epoxy matrix strength behavior was found to have a higher dependence on strain rate due to the presence of metal particle fillers. Discrepancies between experimental and simulation mechanical behavior results and these findings indicate a need for epoxy constitutive models to incorporate effects of particle reinforcement on the mechanical behavior.
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Narayanan, Vindhya. "Non-equilibrium Thermomechanics of Multifunctional Energetic Structural Materials." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7570.
Full textAbstract:
Shock waves create a unique environment of high pressure, high temperature and high strain-rates. It has been observed that chemical reactions that occur in this regime are exothermic and can lead to the synthesis of new materials that are not possible under other conditions. The exothermic reaction is used in the development of binary energetic materials. These materials are of significant interest to the energetic materials community because of its capability of releasing high heat content during a chemical reaction and the relative insensitivity of these types of energetic materials. Synthesis of these energetic materials, at nano grain sizes with structural reinforcements, provides an opportunity to develop a dual functional material with both strength and energetic characteristics.
Shock-induced chemical reactions pose challenges in experiment and instrumentation. This thesis is addressed to the theoretical development of constitutive models of shock-induced chemical reactions in energetic composites, formulated in the framework of non-equilibrium thermodynamics and mixture theories, in a continuum scale. Transition state-based chemical reaction models are introduced and incorporated with the conservation equations that can be used to calculate and simulate the shock-induced reaction process. The energy that should be supplied to reach the transition state has been theoretically modeled by considering both the pore collapse mechanism and the plastic flow with increasing yield stress behind the shock wave. A non-equilibrium thermodynamics framework and the associated evolution equations are introduced to account for time delays that are observed in the experiments of shock-induced or assisted chemical reactions. An appropriate representation of the particle size effects is introduced by modifying the initial energy state of the reactants. Numerical results are presented for shock-induced reactions of mixtures of Al, Fe2O3 and Ni, Al with epoxy as the binder.
The theoretical model, in the continuum scale, requires parameters that should be experimentally determined. The experimental characterization has many challenges in measurement and development of nano instrumentation. An alternate approach to determine these parameters is through ab-initio calculations. Thus, this thesis has initiated ab-initio molecular dynamics studies of shock-induced chemical reactions. Specifically, the case of thermal initiation of chemical reactions in aluminum and nickel is considered.
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Budzevich, Mikalai. "Atomistic Studies of Shock-Wave and Detonation Phenomena in Energetic Materials." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3717.
Full textAbstract:
The major goal of this PhD project is to investigate the fundamental properties of energetic materials, including their atomic and electronic structures, as well as mechanical properties, and relate these to the fundamental mechanisms of shock wave and detonation propagation using state-of-the-art simulation methods. The first part of this PhD project was aimed at the investigation of static properties of energetic materials (EMs) with specific focus on 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). The major goal was to calculate the isotropic and anisotropic equations of state for TATB within a range of compressions not accessible to experiment, and to make predictions of anisotropic sensitivity along various crystallographic directions. The second part of this PhD project was devoted to applications of a novel atomic-scale simulation method, referred to as the moving window molecular dynamics (MW-MD) technique, to study the fundamental mechanisms of condensed-phase detonation. Because shock wave is a leading part of the detonation wave, MW-MD was applied to demonstrate its effectiveness in resolving fast non-equilibrium processes taking place behind the shock-wave front during shock-induced solid-liquid phase transitions in crystalline aluminum. Next, MW-MD was used to investigate the fundamental mechanisms of detonation propagation in condensed energetic materials. Due to the chemical complexity of real EMs, a simplified AB model of a prototypical energetic material was used. The AB interatomic potential, which describes chemical bonds, as well as chemical reactions between atoms A and B in an AB solid, was modified to investigate the mechanism of the detonation wave propagation with different reactive activation barriers. The speed of the shock or detonation wave, which is an input parameter of MW-MD, was determined by locating the Chapman-Jouguet point along the reactive Hugoniot, which was simulated using the constant number of particles, volume, and temperature (NVT) ensemble in MD. Finally, the detonation wave structure was investigated as a function of activation barrier for the chemical reaction AB+B ⇒ A+BB. Different regimes of detonation propagation including 1-D laminar, 2-D cellular, and 3-D spinning and turbulent detonation regimes were identified.
20
Dursun, Hayrettin. "Determination Of The Postexplosion Residues Of Nitro Group Containing Explosives In Soil With Gc-ms And Gc-tea." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12609014/index.pdf.
Full textAbstract:
There is an increase in bombing assaults in recent years in our country. Determining the explosive material used in these cases by the quick and correct analysis of the evidence obtained after the explosions, is an important starting point for the investigations which are done to reach the perpetrators. The forensic chemistry investigations have to be correct, exact and rapid in order to reach the right criminal. In this study, the Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Thermal Energy Analyser (GC-TEA) methods which are being used for the determination of the explosive materials&rsquoresidues used in bombing attacks are optimized with the standard solutions of 2,4,6-Trinitrotoluene (TNT) and 1,3,5-trinitro-1,3,5-triazocyclohexane (RDX) and standard mixture solution. The two methods were compared by analysing the postexplosion soil samples. Also an efficient and applicable sample preparation procedure was developed. The results showed that both methods are efficient and sensitive for the postexplosion investigations. It is seen that GC-TEA has lower detection limit and simple chromatograms due to its selectivity against only nitro group containing explosives. However it is concluded that there is a need for a reliable and sensitive method like GC-MS which provides identification and library search, for the determination of the organic components which can not be identified with GC-TEA
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Walker, Jeremy D. "Exploring the Synthesis and Characterization of Nanoenergetic Materials from Sol-Gel Chemistry." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14573.
Full textAbstract:
Nanoenergetic composite materials have been synthesized by a sol-gel chemical process where the addition of a weak base molecule induces the gelation of a hydrated metal salt solution. A proposed proton scavenging mechanism, where a weak base molecule extracts a proton from the coordination sphere of the hydrated iron (III) complex in the gelation process to form iron (III) oxide/hydroxide, FeIIIxOyHz, has been confirmed for the weak base propylene oxide (PO), a 1,2 epoxide, as well as for the weak bases tetrahydrofuran (THF), a 1,4 epoxide, and pyridine, a heterocyclic nitrogen-containing compound. THF follows a similar mechanism as PO; the epoxide extracts a proton from the coordination sphere of the hydrated iron complex forming a protonated epoxide which then undergoes irreversible ring-opening after reaction with a nucleophile in solution. Pyridine also extracts a proton from the hydrated metal complex, however, the stable six-membered molecule has low associated ring strain and does not endure ring-opening.
Fe2O3/Al energetic systems were synthesized from the epoxides PO, trimethylene oxide (TMO) and 3,3 dimethyl oxetane (DMO). Surface area analysis of the synthesized matrices shows a direct correlation between the surface area of the iron (III) oxide matrix and the quantified exothermic heat of reaction of the nano-scaled aluminum-containing energetic material due to the magnitude of the interfacial surface area contact between the iron (III) oxide matrix and the aluminum particles. The Fe2O3(PO)/Al systems possess the highest heat of reaction values due to the oxide interfacial surface area available for contact with the aluminum particles. Also, reactions containing nano-scale aluminum react differently than those containing micron-scale aluminum.
RuO2/Al energetic systems behave differently dependent on the atmosphere the sample is heated. Heating the RuO2/Al samples in an inert atmosphere results in the complete reduction of the ruthenium oxide matrix to Ru(0) before reaction with the aluminum particles, resulting in the exothermic formation of RuxAly intermetallics, with the stoichiometry dependent on the initial Ru:Al concentration. However, heating the samples in an oxygen-rich atmosphere results in an exothermic reaction between RuO2 and Al.
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Lloyd, Hayleigh Jayne. "Co-crystallisation of energetic materials : a step-change in the control of properties and performance of munitions." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28860.
Full textAbstract:
The research described in this thesis seeks to explore a concept that has the potential to make a step-change for the control of the properties of energetic materials (sensitivity, long-term storage, processability, performance, etc.), resulting in safer munitions with enhanced performance. This concept is co-crystallisation and involves crystallisation of the energetic material with one or more molecular components in order to modify the properties of the composition. The concept has been demonstrated in the pharmaceutical sector as a successful means of altering the physical properties of active pharmaceutical ingredients, e.g. solubility, bioavailability, stability to humidity. This project therefore aims to exploit the concepts of crystal engineering and co-crystallisation as applied to selected energetic materials in order to achieve the following objectives: (i) develop an enhanced understanding of how structure influences key properties such as sensitivity, (ii) control the sensitivity of existing, approved energetic materials, and (iii) identify new energetic materials with enhanced properties, e.g. reduced sensitivity, higher performance, and increased thermal stability. The compound 3,5-nitrotriazolone (NTO) was crystallised with a selection of co-formers to produce salts and co-crystals. The structure properties of these materials were explored using single-crystal and powder X-ray diffraction, and structural features were correlated with properties such as crystal density, difference in pKa of co-formers, thermal properties, and sensitivity to impact. Detonation velocities of the co-crystals were calculated based on densities, chemical composition, and heats of formation. Co-former molecules included a series of substituted anilines, substituted pyridines (including 4,4’-bipyridine, 2-pyridone), and substituted triazoles. A co-crystal was formed between NTO and 4,4’-bipyridine on crystallisation from ethanol, whilst a salt was formed when crystallised from water. Upon heating the salt to 50ºC, the co-crystal was formed. Structural differences between the salts formed by NTO with 3,5-DAT and 3,4- DAT were correlated with structural features. 3,5-DAT.NTO is substantially less impact sensitive than 3,4-DAT.NTO, and this is attributed to the layered structure of 3,5-DAT.NTO. An investigation into triazole-based NTO salts under high pressure was conducted. A new polymorph of 3,5-DAT.NTO was discovered upon increasing the pressure to 2.89 GPa. The high-pressure phase appears to retain the layered structure and remains in this phase up to 5.33 GPa, although it was not recoverable upon decompression to atmospheric pressure. The compression behaviour of the unit cell volume for phase I of 3,5-DAT.NTO has been fitted to a 3rd-order Birch- Murnaghan equation of state (EoS) with V0 = 957.7 Å3, B0 = 8.2 GPa and B’0 = 14.7. The unit cell was found to be most compressible in the a and c directions. Under high pressure 3,4-DAT.NTO does not give any indication of a phase change occurring up to 6.08 GPa. The coefficients of the 3rd-order Birch-Murnaghan EoS have been determined to be V0 = 915.9 Å3, B0 = 12.6 GPa and B’0 = 6.5.
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Rieger, Max [Verfasser], Klaus [Gutachter] Müller-Buschbaum, and Robert [Gutachter] Luxenhofer. "Preconcentration with Metal-Organic Frameworks as adsorbents for airborne Explosives and Hazardous Materials - A study using inverse gas chromatography / Max Rieger ; Gutachter: Klaus Müller-Buschbaum, Robert Luxenhofer." Würzburg : Universität Würzburg, 2019. http://d-nb.info/1180286693/34.
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Tucker, Michael D. "Characterization of impact initiation of reactions in aluminum-based, intermetallic-forming reactive materials." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42754.
Full textAbstract:
The objective of this work is to evaluate the reaction initiation characteristics of quasi-statically compressed intermetallic-forming aluminum-based reactive materials upon impact initiation, consisting of equi-volumetric tantalum-aluminum, tungsten-aluminum, nickel-aluminum, and pure aluminum. A modified Taylor rod-on-anvil setup was employed to determine the reaction initiation threshold kinetic energy and actual energy for plastic deformation and subsequent reaction. Experimental sample remnants were recovered and examined through X-ray diffraction to determine reaction products.The overall results indicate that of the various intermetallic-forming systems investigated, Ta+Al was the most reactive and was the only system where any reaction products were retrieved. While all of the intermetallic systems reacted in air, only Ta+Al and W+Al reacted in vacuum environment suggesting differences in reaction mechanisms influencing the reactivity of intermetallic mixtures. Based on the threshold energy for onset of reaction it appears that the Ta-Al compacts show reaction conditions below those required for reaction of Al in air. This combined with the fact that Ta+Al compacts also react in vacuum implies that the Ta+Al undergoes anaerobic intermetallic reaction while the other systems react with the oxidation of Al. The effect of compact packing density on the kinetic energy threshold for reaction initiation were also evaluated. It was observed more densely packed Ta+Al and Ni+Al powder compacts react more easily than less densely packed samples. While the effect of packing density is not as obvious in the case of pure Al and W+Al powder compacts. Finally, a particle size effect is seen on Ni+Al on samples of < 92% density where coarser (+325 -200 mesh) equal-volumetric powder mixtures were observed to be more reactive than finer Ni+Al (-325 mesh).
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Kirchhof, Edemar. "Estimativa de vida útil de explosivo PBX (Plastc Bonded Explosive) no envelhecimento acelerado." Instituto Tecnológico de Aeronáutica, 2014. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=3135.
Full textAbstract:
Os materiais energéticos compósitos têm tempo de vida útil dependente de vários fatores que podem reduzir esta estimativa, tais como temperatura, umidade, e a proximidade de outros produtos químicos. Em função de estes materiais serem utilizados como principal matéria prima para a fabricação de propelentes e explosivos, há uma necessidade de conhecer os processos de decomposição destes explosivos e as principais causas que podem influenciar na segurança, no manuseio e na estocagem por longos períodos sem perder as propriedades, as quais foram desenvolvidas. Com o desenvolvimento e fabricação de explosivos e propelentes pela Divisão de Sistemas de Defesa - ASD torna-se evidente a utilização de metodologias que possam ser utilizadas para validar a vida útil destes artefatos bélicos para a segurança do pessoal e das instalações. Neste trabalho foram utilizadas análises térmicas de Calorimetria Exploratória Diferencial, Termogravimetria, análise de estabilidade química a vácuo, e testes de descarga eletrostática para verificar as condições do explosivo após a maceração e cura, comparando com os testes realizados após o envelhecimento acelerado, conforme os parâmetros cinéticos obtidos pela técnica de DSC e pelos métodos de Ozawa e método de Kissinger. A energia de ativação apresentou um valor aproximado de 200 KJmol-1, com desvio patrão de 1 % para ambos os lotes, após um período de 12 e 7 anos de envelhecimento natural a 25 C e mais 25 semanas de envelhecimento acelerado a 60 C.
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Taylor, M. J. "Plasma propellant interactions in an electrothermal-chemical gun." Thesis, Department of Environmental and Ordnance Systems, 2009. http://hdl.handle.net/1826/4010.
Full textAbstract:
This Thesis covers work conducted to understand the mechanisms
underpinning the operation of the electrothermal-chemical gun. The
initial formation of plasma from electrically exploding wires, through to
the development of plasma venting from the capillary and interacting
with a densely packed energetic propellant bed is included. The prime
purpose of the work has been the development and validation of
computer codes designed for the predictive modelling of the
elect rothe rmal-ch em ical (ETC) gun.
Two main discussions in this Thesis are:
a proposed electrically insulating vapour barrier located around
condensed exploding conductors and
the deposition of metallic vapour resulting in a high energy flux to
the surface of propellant, leading to propellant ignition.
The vapour barrier hypothesis is important in a number of fields where
the passage of current through condensed material or through plasma
is significant. The importance may arise from the need to disrupt the
fragments by applying strong magnetic fields (as in the disruption of
metallic shaped charge jets); in the requirement to generate a metallic
vapour efficiently from electrically exploding wires (as per ETC ignition systems); or in the necessity to re-use the condensed material after a
discharge (as with lightning divertor strips).
The ignition by metallic vapour deposition hypothesis relies on the
transfer of latent heat during condensation. It is important for the
efficient transfer of energy from an exploded wire (or other such
metallic vapour generating device) to the surface of energetic material.
This flux is obtained far more efficiently through condensation than
from radiative energy transfer, because the energy required to
evaporate copper is far less than that required to heat it to
temperatures at which significant radiative flux would be emitted
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Taylor, Michael J. "Plasma propellant interactions in an electrothermal-chemical gun." Thesis, Cranfield University, 2002. http://dspace.lib.cranfield.ac.uk/handle/1826/4010.
Full textAbstract:
This Thesis covers work conducted to understand the mechanisms underpinning the operation of the electrothermal-chemical gun. The initial formation of plasma from electrically exploding wires, through to the development of plasma venting from the capillary and interacting with a densely packed energetic propellant bed is included. The prime purpose of the work has been the development and validation of computer codes designed for the predictive modelling of the elect rothe rmal-ch em ical (ETC) gun. Two main discussions in this Thesis are: a proposed electrically insulating vapour barrier located around condensed exploding conductors and the deposition of metallic vapour resulting in a high energy flux to the surface of propellant, leading to propellant ignition. The vapour barrier hypothesis is important in a number of fields where the passage of current through condensed material or through plasma is significant. The importance may arise from the need to disrupt the fragments by applying strong magnetic fields (as in the disruption of metallic shaped charge jets); in the requirement to generate a metallic vapour efficiently from electrically exploding wires (as per ETC ignition systems); or in the necessity to re-use the condensed material after a discharge (as with lightning divertor strips). The ignition by metallic vapour deposition hypothesis relies on the transfer of latent heat during condensation. It is important for the efficient transfer of energy from an exploded wire (or other such metallic vapour generating device) to the surface of energetic material. This flux is obtained far more efficiently through condensation than from radiative energy transfer, because the energy required to evaporate copper is far less than that required to heat it to temperatures at which significant radiative flux would be emitted
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Tsang, Sideny C. N. "Processing and rheological studies of cellulosic materials." Thesis, Sheffield Hallam University, 1987. http://shura.shu.ac.uk/20456/.
Full textAbstract:
The present studies are concerned with the modelling of the manufacturing process of nitrocellulose-base propellant in which cellulose acetate is substituted as a model for the explosive nitrocellulose. An investigation of the inter-relationships between processing and rheological and morphological properties has been carried out on cellulose acetate doughs, using modified torque and capillary extrusion rheometers. Some of the doughs show a yield stress and behave as Herschel-Bulkley fluids. The yield stress is found to be smaller than that of nitrocellulose doughs, and there is some evidence of shear heating. Mixing time and mixing temperature showed no influence on the rheological parameters of the doughs. These results suggest that the change in rheological properties of propellant doughs is attributed to the change in crystallinity and fibrosity after processing. The rheological properties of doughs are greatly affected by extrusion temperature, solvent, plasticiser and filler content. The interaction between the solvents and plasticisers with cellulose acetate was explained by adopting a model consisting of a rigid backbone chain from which protruded flexible side groups. In good solvents these side groups extend causing interactions between molecules, giving rise to dough up and elasticity. In poor solvents, dough up becomes difficult and the elasticity is low because the flexible side groups retract towards the stiff backbone chain. The morphology of solvated doughs is examined using solution viscometry, infrared spectroscopy, scanning electron microscope, differential scanning calorimetry, x-ray diffraction and dynamic mechanical thermal analysis. All these techniques showed that the solvation process had no significant effect on the molecular architecture of the cellulose acetate, in which the original crystallinity of the material is low. From this it was concluded that changes in the rheological properties of nitrocellulose doughs as a function of the process variables was due to changes induced in the crystallites rather than in the amorphous regions.
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Celik, Bayar Caglar. "Theoretical Investigation Of Tautomeric Equilibria In Certain Explosive Materials." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615630/index.pdf.
Full textAbstract:
Explosive materials have always been attracting the attention of scientists. Various explosives either in pure bulk form or as admixtures are synthesized and investigated from different points of view. However, because of dangerous character of these materials, their syntheses and properties have to be forecasted by theoretical studies.
The new research trends of explosive materials generally include the designs of novel derivatives of well&ndashknown explosives to improve their detonation performances (heats of explosion, detonation velocities and detonation pressures) and thermal stabilities and decrease their sensitivities towards friction, electric spark, shock and impact either experimentally or theoretically. NTO (5&ndash
nitro&ndash
2,4&ndash
dihydro&ndash
3H&ndash
1,2,4&ndash
triazol&ndash
3&ndash
one) and PATO (3&ndash
picrylamino&ndash
1,2,4&ndash
triazole) are very important secondary explosives that take place in the literature for many years in terms of their explosive properties. In this thesis study, new species of these explosives have been designed to enhance their detonation performances (ballistic properties) and to lower their sensitivities and reactivities computationally. Additionally, aromatic nitration reactions and their mechanisms for unprotonated and protonated PATO species have been analyzed. The ab initio quantum chemistry methods, Hartree&ndash
Fock (HF) and Density Functional Theory (DFT), have been used in the calculations with Pople basis sets. Novel NTO and PATO tautomeric species have been designed and investigated to enlighten the effects of tautomerism on their quantum chemical properties and detonation performances in the gas phase. Various aromatic nitration mechanisms (carbon and nitrogen mono&ndash
nitration mechanisms) of unprotonated tautomeric PATO species as well as PATO have been designed in gas phase and the reaction states (pre&ndash
transition states, transition states, intermediates and nitration products) have been detected belonging to these mechanisms. Nitrations in solution phase have also been analyzed. The reaction states have been detected for carbon and nitrogen mono&ndash
nitrations of protonated PATO species in the gas phase. The detonation performances of unnitrated and nitrated PATO products have been presented.
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Liu, Yen-Shan. "Development of an advanced nanocalorimetry system for rapid material characterizations." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4834.
Full textAbstract:
The development of a versatile system capable of providing rapid, portable, and
inexpensive detection of explosives and energetic compounds is needed critically to offer
an enhanced level of protection against current and future threats to homeland security, as
well as to satisfy a wide range of applications in the fields of forensic analysis, emergency
response, and industrial hazards analysis. The hand-held nanocalorimeter will serve as a
first-of-its-kind screening tools for explosive and energetic compounds directly in the
settings where they are needed with high efficiency, reduced cost, and simplicity with ease
of use. Unlike current explosives detectors, this system is based on calorimetric
techniques that are inherently capable of providing direct measurements of energy release
potential and therefore do not depend on prior knowledge of familiar compounds.
The microfabricated calorimetry instrument consists of (i) a thermal control
module incorporating arrays of microfabricated heaters and temperature sensors, as well
as any necessary electronic interconnections, and (ii) a sample encapsulation module
incorporating etched enclosures designed to accommodate either solid or liquid samples. Initial work has led to successful fabrication of a chip capable of sampling nano-sized
solid or liquid compounds. Control algorithms incorporating the DSC principle have also
been written using LabVIEW. Device performance of the original and redesigned chips
were tested by studying the thermal transitions associated with the boiling points of
acetone and pentane. With the redesigned chip, the heat loss issue was reduced: the
measured input heat was reduced from 32 times of the required energy to 5 times of the
required energy. Future work will focus on modifying the chip design and control
algorithm to improve accuracy and sensitivity, developing a trace analysis software to link
it to a database of explosive information, and adapting different fabrication procedures for
high temperature operation and large scale production.
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Clevenger, Lawrence Alfred. "Controlled and explosive silicidation of metal/amorphous-silicon multilayer thin films." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14210.
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Quihuis, Nicholas R. "Stemming the Flow of Improvised Explosive Device Making Materials through Global Export Control Regimes." Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/17444.
Full textAbstract:
Approved for public release; distribution is unlimitedThe effects of Improvised Explosive Devices (IEDs) continue to be felt throughout the world, and especially in battlefields, such as Afghanistan. The United States currently leads the counter-IED effort through various demand side efforts, such as those led by JIEDDO and Project Global Shield. The purpose of this thesis was to determine the feasibility of a new supply-side effort to counter IEDs through global export control similar to the multilateral export control regimes of Weapons of Mass Destruction (WMD) and missile technologies. A comparative method was used that utilized the existing regime literature for success and effectiveness, and then measured those regimes against six variables that focused on technology, as well as the organizations, which provided the framework to determine the success and feasibility of a new regime that focuses on lower technology items. The results show that although IEDs continue to be a presence throughout the world, it lacks the grander threat similar to that of WMD technology to make a new regime successful. Further, the results show that IED technology and material are difficult to classify and track, which makes global export control efforts extremely difficult.
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Johansson, Susanna. "Mer än fyrverkeri : Att informera gymnasieungdomar om explosiva och energetiska material." Thesis, Mälardalen University, School of Innovation, Design and Engineering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-10078.
Full textAbstract:
Detta examensarbete utreder hur information kan anpassas textuellt och formges efter en specifik målgrupp. Informationen behandlar explosiva och energetiska material, var de används och av vilka, och hur hanteringen sker säkert. Arbetsprocessen har innefattat metoder för textanalys, fokusgrupp och jämställt språk och har lett fram till ett designförslag. De texter som har analyserats har dels varit tagna från examensarbetets samarbetspartner, KCEM, och dels tagna från andra branscher som genom målgruppsanpassat material informerar om sina möjligheter. En fokusgrupp sattes samman av ett representativt urval av målgruppen. Under ett strukturerat gruppmöte fick de kommentera informationsmaterial som riktar sig till dem som homogen grupp. Informationen har anpassats för hela målgruppen genom att tillämpa en metod för jämställt språk. De teorier som sedan använts för att anpassa slutprodukten textuellt och grafiskt är pragmatisk textlingvistik, metadiskurs och visuell metadiskurs. Den pragmatiska textlingvistiken har bidragit med en helhetssyn på språk som ett verktyg för att överföra intentioner och budskap. Metadiskurs och visuell metadiskurs har sedan tillämpats för att överföra teorin till praktiken.
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Hammond, Lloyd Charles 1961. "The structural response of submerged air-backed plates to underwater explosions." Monash University, Dept. of Civil Engineering, 2000. http://arrow.monash.edu.au/hdl/1959.1/9244.
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Vera, Lino Gary Álvaro. "Propuesta de reducción del inventario de lento movimiento en una empresa de explosivos." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2013. http://hdl.handle.net/10757/273491.
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Hildal, Kjetil. "Steam explosions during granulation of Si-rich alloys. : Effect of Al- and Ca-additions." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Natural Sciences and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-52.
Full textAbstract:
Steam explosions are possible during granulation of Si and FeSi75. These explosions are a great hazard, and must be avoided. Norwegian ferroalloy producers have initiated a research program to learn more about such violent melt-water interactions, in a joint effort with NTNU and SINTEF. The focus has primarily been on important parameters that can be controlled industrially, such as water temperature and metal composition. This thesis-work has focused on the effect of small additions of Al and Ca in Si-metal and FeSi75. However, within the same project, experiments on the effect of water temperature have also been carried out.
The work has primarily been of experimental character. Two experimental apparatuses have been used. The first apparatus allows us to rapidly melt a sample of metal in an inert atmosphere to a desired temperature, expose the surface of the melt to an oxidizing agent (i.e. water) and then rapidly cool the sample to room temperature. The oxide that forms at the surface is examined with a microprobe. Thus, information regarding the composition and substance of the oxide layer is available. The second apparatus is suitable for releasing single drops of melt into a water tank, where they can be triggered and explode. A variety of techniques have been used in order to monitor the experiment: regular video, high-speed film, high-speed video, open-shutter imaging and pressure transducer measurements.
Both Si and FeSi75 must be triggered in order to explode. Trigger pressures range from 0.3 MPa (FeSi75) to 2 MPa (Si-metal). We have established at which depths the molten drops can be triggered. Molten drops of FeSi75 can be triggered at depths twice of those of molten drops of Si. The latter can be triggered even if they are partially solidified.
The explosion itself is strong enough to trigger neighbor drops as far away as 400 mm. Thus, we cannot rule out the possibility of large-scale steam explosions during granulation of molten Si or FeSi75, which is in accordance with industrial practice.
By the use of high-speed imaging techniques and pressure measurements, we have been able to describe qualitatively what happens when a molten drop of Si/FeSi75 fragments rapidly in water. As the melt fragments, the rapid heat transfer generates vapor as bubbles, which expand and collapse in a cyclic manner. Large pressure pulses are generated upon collapse of the steam bubble, that is, when water jets impact in the center of the collapsing bubble.
The first step in the oxidation of liquid silicon is the formation of gaseous SiO. The fate of this gas now depends on the flow conditions at the surface of the melt. In the case of a molten drop descending in water, most of the gas is flushed away from the surface. Thus, there are only minor traces of oxygencontaining material (i.e. silica) at the surface of the solidified drop.
The addition of small amounts of Al and/or Ca dramatically changes the behavior of the molten drop. A strange effect is the two-fold increase in the fall velocity for molten drops of silicon. A similar effect was detected for molten drops of FeSi75. Alloying elements such as Al and Ca greatly reduce the risk for a steam explosion of molten Si. The significance of these elements is related to the oxidation reactions at the surface of the molten drop of metal. As silicon reacts with water vapor and oxidizes, hydrogen gas is formed. If Al and Ca are present in the melt, these elements will speed up the hydrogen generation considerably. This gas is strongly influencing on the probability for a steam explosion to occur. H2 stabilizes the vapor film around the drop, that is, much stronger trigger pressures are needed to collapse the film. Even if the trigger pressure is strong enough to collapse the vapor film, violent interactions are almost completely absent. A fragmentation of the melt is observed, but the heat transfer is apparently not rapid enough to generate steam bubbles, i.e. the generation of steam is below the critical limit.
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Flannigan, Matthew Brian. "Phytoremediation for the treatment of energetic material releases on testing and training ranges at Eglin Air Force Base." Thesis, University of Iowa, 2011. https://ir.uiowa.edu/etd/962.
Full textAbstract:
In order to protect natural resources and ecosystems at Eglin Air Force Base (EAFB), a strategy must be developed for the containment and/or treatment of explosive contaminants on testing and training ranges under continuous use. Phytoremediation is the direct use of living plants for in situ (in place) remediation of contaminated soil, sludges, sediments, and groundwater through contaminant removal, degradation, or containment. Due to its ability to continuously treat large areas at low cost with low impact to the site, phytoremediation was implemented through a field study at EAFB in order to increase range sustainability.
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Muñoz, Estrada Vianett Berenice. "Characterization of n-type Bi₂Te₂.₇Se₀.₃ and p-type Bi₀.₅Sb₁.₅Te₃ ternary like semiconductors fabricated by shock-waved (explosive) consolidation." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2007. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Breidenich, Jennifer L. "Impact-initiated combustion of aluminum." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54403.
Full textAbstract:
This work focuses on understanding the impact-initiated combustion of aluminum powder compacts. Aluminum is typically one of the components of intermetallic-forming structural energetic materials (SEMs), which have the desirable combination of rapid release of thermal energy and high yield strength.
Aluminum powders of various sizes and different levels of mechanical pre-activation are investigated to determine their reactivity under uniaxial stress rod-on-anvil impact conditions, using a 7.62 mm gas gun. The compacts reveal light emission due to combustion upon impact at velocities greater than 170 m/s. Particle size and mechanical pre-activation influence the initiation of aluminum combustion reaction through particle-level processes such as localized friction, strain, and heating, as well as continuum-scale effects controlling the amount of energy required for compaction and deformation of the powder compact during uniaxial stress loading. Compacts composed of larger diameter aluminum particles (~70µm) are more sensitive to impact initiated combustion than those composed of smaller diameter particles. Additionally, mechanical pre-activation by high energy ball milling (HEBM) increases the propensity for reaction initiation.
Direct imaging using high-speed framing and IR cameras reveals light emission and temperature rise during the compaction and deformation processes. Correlations of these images to meso-scale CTH simulations reveal that initiation of combustion reactions in aluminum powder compacts is closely tied to mesoscale processes, such as particle-particle interactions, pore collapse, and particle-level deformation. These particle level processes cannot be measured directly because traditional pressure and velocity sensors provide spatially averaged responses. In order to address this issue, quantum dots (QDs) are investigated as possible meso-scale pressure sensors for probing the shock response of heterogeneous materials directly. Impact experiments were conducted on a QD-polymer film using a laser driven flyer setup at the University of Illinois Urbana-Champaign (UIUC). Time-resolved spectroscopy was used to monitor the energy shift and intensity loss as a function of pressure over nanosecond time scales. Shock compression of a QD-PVA film results in an upward shift in energy (or a blueshift in the emission spectra) and a decrease in emission intensity. The magnitude of the shift in energy and the drop in intensity are a function of the shock pressure and can be used to track the particle scale differences in the shock pressure. The encouraging results illustrate the possible use of quantum dots as mesoscale diagnostics to probe the mechanisms involved in the impact initiation of combustion or intermetallic reactions.
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Farías, Cabrera Grace Liliam, and Vela Leonardo Francisco Chumbiauca. "Elaboración de un modelo estocástico para la atención de problemas en un Centro de atención de llamadas que brinda soporte a Tecnologías y Sistemas de Negocio." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas - UPC, 2013. http://hdl.handle.net/10757/273507.
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Rosencrantz, Stephen D. "Characterization and Modeling Methodology of Polytetrafluoroethylene Based Reactive Materials for the Development of Parametric Models." Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1193425334.
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Mazzeu, Maria Alice Carvalho. "Estudo da compatibilidade de RDX e HMX com polímeros e materiais inertes." Instituto Tecnológico de Aeronáutica, 2010. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=984.
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A compatibilidade química de explosivos é estudada para avaliar potenciais riscos quando os mesmos são colocados em contato com outros materiais durante a produção, armazenamento e manuseio. Esta compatibilidade pode ser estudada por vários métodos, tais como DSC (Calorimetria Exploratória Diferencial), TG (Termogravimetria), Estabilidade química a vácuo, microcalorimetria, calorimetria de fluxo de calor, etc. Os métodos de ensaios e a definição de critérios de avaliação são elementos importantes quando um estudo de compatibilidade está sendo realizado. Nesse trabalho, a compatibilidade química de dois importantes explosivos utilizados em armamentos, RDX (ciclotrimetilenotrinitroamina) e HMX (ciclotetrametilenotetranitroamina), foi estudada com polímero fluorado (Viton B) e alumínio em pó (Al 123), usando os métodos DSC, TG e Estabilidade química a vácuo. Os três métodos forneceram informações importantes sobre a compatibilidade química dos materiais, através dos parâmetros térmicos e volume de gás liberado. Observou-se que o HMX apresenta compatibilidade com Viton B e Al, da mesma forma que o RDX apresenta compatibilidade com Viton, porém no estudo de compatibilidade do RDX com Al, com os métodos DSC e TG, nota-se um pico adicional, após o pico de decomposição, o que é um indicativo de incompatibilidade. Os métodos foram comparados em relação aos fatores que podem influenciar o resultado, servindo de base para futuros estudos de compatibilidade química. A conclusão é que, quando se utilizam os métodos DSC e TG, os sistemas HMX - Al, HMX - Viton e RDX - Viton são compatíveis, porém o sistema RDX - Al apresenta um grau de incompatibilidade. Entretanto, todos são compatíveis quando se utiliza o método da estabilidade química a vácuo.
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Junior, Paulo Roberto Leite. "Projeto óptico de espoleta de proximidade a laser para bombas de fins gerais e altímetro laser de curto alcance." Instituto Tecnológico de Aeronáutica, 2006. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=272.
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Este trabalho tem por objetivo o estudo de sistemas a laser para aplicações em espoletas para bombas de fins gerais, em bombas de efeito de sopro e também a construção e integração de um protótipo de laboratório de um sistema a laser que possa operar como uma espoleta de proximidade. Dentro do escopo de pesquisa, serão apresentadas características de bombas de fins gerais e as vantagens na utilização de uma espoleta de proximidade a laser sobre os efeitos terminais desse tipo de bomba. Será também apresentada uma concepção de um modelo de engenharia para essa espoleta, visando sua aplicação em artefatos utilizados pela Força Aérea Brasileira, incluindo o projeto óptico de uma espoleta a diodo laser para bombas de fins gerais e outro para bombas de efeito de sopro, tratando em detalhes os métodos de formatação do feixe de luz produzido por lasers semicondutores. Serão apresentados os resultados de simulações do sistema de emissão utilizando programas específicos para simulações ópticas. Finalmente, será apresentado o projeto óptico real para validação dos resultados simulados e serão discutidos os aspectos de desempenho do sistema gerado.
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Hamad, Baran, and Markus Englund. "Improved Release Mechanisms for Aerospace Applications." Thesis, Uppsala universitet, Tillämpad mekanik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-448399.
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Hold down release mechanisms (HDRMs) are used for tightly attaching segments of bodies together when it is desired to release them rapidly at some point. When transporting sensitive payloads on launch vehicles, the challenge arises of releasing the fastened segments of the spacecraft without risking damage to the costly equipment. Non-explosive HDRMs are favourable from a safety perspective as there is a lower risk of producing potentially destructive shock-waves throughout the structure. One variant of a non-explosive HDRM uses a so called 'split spool initiator'. This initiator can only be used once in the actuator mechanism and to reuse the HDRM the initiator must be replaced. The purpose of this thesis is to design an improved split spool initiator which can be reusable while conserving the functionality aspects of the existing design. To achieve this, different ideas were considered and ultimately a solution using shape memory alloys (SMAs) was explored. A prototype was constructed to demonstrate the functionality of the design and simulations are done to determine the forces acting on different parts of the mechanism.Hold down release-mekanismer (HDRM) används för att säkert kunna fästa samman delar av strukturer för att sedan kunna lossa dessa vid rätt tillfälle. När det transporteras känslig last på exempelvis rymdfarkoster uppkommer utmaningen att göra så på ett sätt som inte riskerar att skada den ofta dyra utrustningen. Det finns en mängd olika HDRM, dessa kan delas upp i två typer som är icke explosiva release-mekanismer och pyrotekniska release-mekanismer. Icke explosiva release-mekanismer har en fördel över pyrotekniska som är att de inte producerar potentiellt destruktiva chock-vågor som sprids genom strukturen. En typ av icke-explosiva release-mekanismer är den så kallade split spool-initieraren. Denna kan endast användas en gång när fästelementet är aktiverat och för att kunna använda fästelementet igen måste hela initieraren bytas ut. Syftet med denna studie har varit att att designa en förbättrad split spool-initierare som är återanvändbar, medan funktionaliteten hos den ursprungliga designen är bevarad. För att åstadkomma detta övervägdes olika idéer och slutligen valdes en lösning som använder minnesmetaller eller Shape memory alloys på engelska (SMA). En prototyp konstruerades för att demonstrera funktionaliteten hos designen. Simuleringar gjordes även för att bestämma krafter som agerade på split spool-strukturen och för att få en överblick över spänningsfördelningen genom initieraren.
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Baker, Wade Andrew. "Development and Validation of a Finite Element Dummy Lower Limb Model for Under-body blast Applications." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/86657.
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An under-body blast (UBB) refers to the use of a roadside explosive device to target a vehicle and its occupants. During Operation Iraqi Freedom, improvised explosive devices (IEDs) accounted for an estimated 63% of US fatalities. Furthermore, advancements in protective equipment, combat triage, and treatment have caused an increase in IED casualties surviving with debilitating injuries. Military vehicles have been common targets of IED attacks because of the potential to inflict multiple casualties.
Anthropomorphic test devices (ATDs) are mechanical human surrogates designed to transfer loads and display kinematics similar to a human subject. ATDs have been used successfully by the automotive industry for decades to quantify human injury during an impact and assess safety measures. Currently the Hybrid III ATD is used in live-fire military vehicle assessments. However, the Hybrid III was designed for frontal impacts and demonstrated poor biofidelity in vertical loading experiments.
To assess military vehicle safety and make informed improvements to vehicle design, a novel Anthropomorphic Test Device (ATD) was developed and optimized for vertical loading. ATDs, commonly referred to as crash dummies, are designed to estimate the risk of injuries to a human during an impact. The main objective of this study was to develop and validate a Finite Element (FE) model of the ATD lower limb.Master of Science
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Kotyk, Maciej. "Analiza odporności na pękanie materiału warstwowego Al-Ti." Rozprawa doktorska, Uniwersytet Technologiczno-Przyrodniczy w Bydgoszczy, 2018. http://dlibra.utp.edu.pl/Content/1233.
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Zasadniczym celem pracy jest analiza wybranych właściwości mechanicznych nowego materiału warstwowego AA2519-AA1050-Ti6AI4V oraz jego materiałów bazowychThe reason for the work is determination and analysis of selected mechanical properties of the new layer material AA2519-AA1050-Ti6AI4V and its base materials
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Matthew, Christopher P. "Design studies for stand off bomb detection." Thesis, Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/3752.
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Cheng, Guanbing. "Contribution à l'étude de la Transition Déflagration Détonation (TDD) dans des Mélanges Gazeux Binaires H2/C3H8/Air." Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2012. http://tel.archives-ouvertes.fr/tel-00740126.
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Cette étude traite de la détonation et de la Transition Déflagration Détonation, TDD, en conduite dans les mélanges binaires H2/C3H8-Air. L'accent est mis sur les mécanismes d'accélération de flamme en présence d'obstacles. Les grandeurs caractéristiques de détonation autonome (célérité, pression et taille de cellule) et la distance de TDD ont été mesurées pour différentes richesses et proportions d'hydrogène dans le propane. En particulier, les effets de l'obstacle (longueur et nature) et du diamètre du tube sur la TDD ont été examinés. Les résultats montrent que les corrélations classiques Taille de cellule - Longueur d'induction chimique pour la détonation et Taille de cellule - Longueur de transition pour la TDD - bien établies pour les mélanges simples - restent valables pour ces mélanges binaires. L'addition du C3H8 à H2 diminue la détonabilité du combustible binaire. Des visualisations d'accélération de flamme par ombroscopie ont été réalisées à l'aide de caméras ultra-rapides dan le but d'identifier les mécanismes physiques contrôlant ce processus pour différentes configurations d'obstacles. Les enregistrements ont mis en évidence deux phases de propagation. Dans la première, les instabilités intrinsèques de la flamme, l'augmentation de sa surface ainsi que la combustion turbulente retardée - résultant de la zone de recirculation entre deux obstacles successifs - jouent un rôle prédominant. Dans la deuxième, l'accélération est contrôlée par l'interaction du front de flamme et des ondes de choc réfléchies sur les obstacles ou sur les parois du confinement. Il en résulte une forte accélération de la flamme avec établissement d'un régime de blocage thermique qui, dans certaines conditions, mène à l'apparition de la détonation.
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Avachat, Siddharth. "Experimental and numerical analyses of dynamic deformation and failure in marine structures subjected to underwater impulsive loads." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44904.
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The need to protect marine structures from the high-intensity impulsive loads created by underwater explosions has stimulated renewed interest in the mechanical response of sandwich structures. The objective of this combined numerical and experimental study is to analyze the dynamic response of composite sandwich structures and develop material-structure-property relations and design criteria for improving the blast-resistance of marine structures. Configurations analyzed include polymer foam core structures with planar geometries. A novel experimental facility to generate high-intensity underwater impulsive loads and carry out in-situ measurements of dynamic deformations in marine structures is developed. Experiments are supported by fully dynamic finite-element simulations which account for the effects of fluid-structure interaction, and the constitutive and damage response of E-glass/polyester composites and PVC foams.
Results indicate that the core-density has a significant influence on dynamic deformations and failure modes. Polymeric foams experience considerable rate-effects and exhibit extensive shear cracking and collapse under high-magnitude multi-axial underwater impulsive loads. In structures with identical masses, low-density foam cores consistently outperform high-density foam cores, undergoing lesser deflections and transmitting smaller impulses. Calculations reveal a significant difference between the response of air-backed and water-backed structures. Water-backed structures undergo much greater damage and consequently need to absorb a much larger amount of energy than air-backed structures. The impulses transmitted through water-backed structures have significant implications for structural design. The thickness of the facesheets is varied under the conditions of constant material properties and core dimensions. The results reveal an optimal thickness of the facesheets which maximizes energy absorption in the core and minimizes the overall deflection of the structure.
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Risse, Benedikt. "Continuous crystallization of ultra-fine energetic particles by the Flash-Evaporation Process." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0144/document.
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Sous l'effet d'une forte impulsion mécanique, d'une chaleur très forte ou d'une décharge électrostatique, un explosif comme le TNT ou le RDX peut accidentellement être initié. L'énergie apportée à l'explosif est convertie en chaleur, appelée point-chaud, dans des endroits spécifiques, contenant des impuretés, bulles de gaz, pores ouverts ou autres hétérogénéités. La taille d'un point-chaud de quelques micromètres peut être déjà suffisante pour initier une déflagration ou même une détonation. En réduisant la taille des particules de l'explosif, la formation des points-chauds est empêchée conduisant à un matériau moins sensible. Au sein de ce travail, un procédé continu est développé, fondé sur le principe de la cristallisation-flash, et permettant la préparation de particules énergétiques submicroniques en quantité de plusieurs grammes. Le procédé repose sur une opération de séchage par atomisation, au cours de laquelle une solution surchauffée est atomisée d'une manière continue. Afin de diminuer la taille moyenne des particules et d'obtenir une distribution de taille des particules très étroite, une étude paramétrique est réalisée. Au moyen de la cristallisation-flash, la préparation de composites énergétiques de haute qualité en grandes quantités est un succès. La qualité et quantité de ce composite énergétique sont uniques. Grâce au potentiel de ce procédé, la cristallisation-flash peut permettre la préparation de nombreuses substances et compositions énergétiques ou inertesHigh explosives, such as TNT or RDX, may be accidentally initiated under the influence of a strong mechanical impulse, great heat or an electrostatic discharge. Smallest impurities, open pores, entrapped gases or other inhomogeneities within the explosive matrix may convert the delivered energy into heat, causing the formation of a so called hot-spot. A hot-spot size of a few micrometers can already be sufficient to initiate a deflagration or even a detonation of the explosive. By decreasing the particle size of the explosive, the formation of hot-spots is inhibited, resulting in a less sensitive material. In this work, a continuous operating flash-crystallization process was developed, being able to produce energetic submicron particles in a multigram scale. The process bases on a spray drying process where superheated solutions are continuously atomized. A parametric study was performed on this process in order to decrease the particle size and obtaining a narrower particle size distribution. By means of this flash-crystallization process, highly homogeneous energetic composites were prepared in a large scale. The quality and amount of the energetic composite are unique. The versatility of the flash-crystallization process allows the preparation of a large number of energetic and inert substances and compositions