bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Model for the Collapse of Explosively Driven Liners in spinning warheads
Authors: Carleone Joseph , Stefan Ryan 
Published: May 2005

AbstractAn analytical model has been developed for the rapid collapse of explosively driven metal shells that includes the effects of material strength and shell spin. The model can be used to approximate the collapse process of shaped charges and EFPs. A closed form solution for shell velocity as a function of shell position is developed and compared to several two‐dimensional and three‐dimensional continuum mechanic numerical simulations. Comparisons with the simulations include a parametric evaluation of shell geometry, initial conditions, and material strengths.The analytical model compares well with the numerical simulations for very thin shells. It shows that spin can significantly affect the final collapse velocity, and may even result in hollow penetrators. The model also shows that strength has a similar effect, and can greatly reduce the final collapse velocity.
Analytical and Numerical Study of the Shock Pressures in the Gap Test
Authors: Sanchidrián José A. 
Published: May 2005

AbstractThis paper analyzes the functional relationship of pressure induced in the gap versus distance travelled. P = k e−ax. An analytical shock matching calculation is described to evaluate the constant k as a function of the density and the velocity of detonation of the donor explosive. TDL code is used to check the values of the constants for several donor explosives, and to compute the decay constant a. Functions for pentolite are compared with experimental data from bibliography. The method can be used to predict equivalent gap test thicknesses for donor explosives different from the commonly used pentolite.
Combustion Behavior of Fluorocarbon/Boron/AP Propellant at high pressure
Authors: Oyumi Yoshio , Nagayama Kiyokazu 
Published: May 2005

AbstractThermal decomposition and the burning properties of fluorocarbon/boron/AP propellant granule have been investigated. The fluoro‐carbon binder (FBDR) was oxidized by the decomposition products of admixed ammonium perchlorate (AP) and its decomposition region was 150°C lowered in the slow thermolysis. The boron particles, however reacted with neither FBDR nor AP at 550°C. In the micro‐motor tests, the boron particles completely burnt at a pressure range of from 30 MPa to 80 MPa in a short period of time (one millisecond) even at a low characteristic exhaust velocity. Minimum free volume, however, was needed to complete the combustion reaction in the chamber case. The characteristic exhaust velocity significantly decreased at below the characteristic chamber length of 11 cm. The boronized propellant showed low temperature sensitivity between −30°C and 60°C.
Effect of milling on the burning rates of red lead‐ferrosilicon‐antimony(III) sulfide delay compositions
Authors: Nakamura Hidetsugu , Taniguchi Hiroyuki , Hara Yasutake 
Published: May 2005

AbstractIn order to clarify the effect of surface properties on the burning characteristics of a delay powder, the burning rates of the red lead‐ferrosilicon‐antimony(III) sulfide delay compositions have been measured when the ingredient was pulverized using a vibro‐mill. It was found that the burning rates increased with the mixing time when the ferrosilicon ingredient alone was pulverized before preparation of the delay powder. On the other hand, the burning rate decreased if the red lead or the antimony(III) sulfide were pulverized. The reason for this is ascribed to the chemical reaction in the combustion wave.
Studies on Thermal Decomposition Kinetics of Polyvinyl Nitrate
Authors: Mishra S. C. , Pant Jyotsna , Pant G. C. , Dutta P. K. , Durgapal U. C. 
Published: May 2005

AbstractNon‐isothermal TG curves for four samples of polyvinyl nitrate (PVN), having 15.71%, 14.95%, 13.34% and 11.76% nitrogen contents, were obtained at 5°C/min heating rate. The weight loss of PVN samples depends directly on their % N and occurs in three or more temperature zones. For PVN with 15.71% N (max 15.73% N in theory), the main decomposition step results in more rapid and complete weight loss than for PVN with lower % N, probably due to higher oxygen balance of the former. The TG data were subjected to kinetic analysis using a computer programme. For each decomposition step, the kinetic parameters (E and A) and the regression coefficient (r) were calculated on the basis of several kinetic models and equations consistent with the Arrhenius relationship. It was concluded that the thermal decomposition kinetics of all four PVN sample are best expressed by the Random nucleation model (Mampel unimolecular law) first‐order reaction. For the initial and slowest decomposition step, E ranged between 188 kJ/mol − 217 kJ/mol and In A between 46.88 s−1 ‐ 60.13 s−1. The In A versus E plots for all PVN samples exhibited a linear relationship, probably due to the kinetic compensation effect.
Pressure Oscillations in Regenerative Liquid Propellant Guns
Authors: Wren G. P. , Coffee T. P. , DeSpirito J. , Knapton J. D. , Klingenberg G. 
Published: May 2005

AbstractThe present paper deals with pressure oscillations in regenerative liquid propellant guns (RLPG) presenting the state‐of‐the‐art research into sources and control of these combustion instabilities. Pressure oscillations with amplitudes up to 50 % of mean pressure and frequencies up to 60 kHz or more are present in experimental data of RLPGs, especially at medium and large calibers. Amplitudes increase with the volumetric energy density of the liquid propellant and the mass flow rate during injection. Frequency analyses reveal that both acoustic modes and combustion noise are components of the recorded oscillations. Acoustic modes, in particular, have the potential to couple to resonant modes in near‐field mechanical structures. A multi‐phase, multi‐dimensional model investigation at ARL indicates that pressure waves reflected from internal boundaries are amplified as they pass the combustion zone of the highly pressure‐sensitive liquid propellant in a localized region near the injector. Experimental data lead to a similar understanding of the amplification of pressure oscillations in RLPGs. Experiments in the United States and in Germany confirm that the pressure oscillations can be mitigated by altering the combustion characteristics of the liquid propellant. Also, techniques that more effectively disperse the liquid propellant jet and thereby decrease the local accumulation of liquid propellant, may reduce pressure oscillations as shown in 30‐mm RLPG experiments. Further, energy‐absorb‐ing chamber walls or liners can serve as broad‐band filters and have been shown experimentally to be effective in reducing the amplitude of all frequencies. In addition, physical methods such as cavities and baffles reduce significantly specific acoustic frequencies of the oscillations.
X‐ray diffraction spectroscopic and thermal studies on 1,3,5‐trinitro‐hexahydropyrimidine (TNP)
Authors: Prabhakaran K. V. , Naidu S. R. , Kurian E. M. 
Published: May 2005

AbstractTNP, a heterocyclic nitramine containing a CNO2 functionality, has been studied as regards the kinetics and mechanism of thermal decomposition, morphology and the gaseous products evolved therof, using thermogravimetry (TG), differential thermal analysis (DTA), infrared spectroscopy (IR), differential scanning calorimetry (DSC), X‐ray diffraction (XRD) and hot stage microscopy. The elementary cell parameters obtained form the XRD pattern are: a = 18.818 ± 0.005 Å, b = 18.818 ± 0.005 Å and c = 4.867 ± 0.005 Å. The crystal belongs to the hexagonal system with c/a ratio = 0.259. IR spectra of TNP have also been recorded and the bands assigned. Kinetics of thermolysis has been followed both by isothermal TG and IR. The best linearity with a correlation coefficient of 0.986 was obtained for the three‐dimensional diffusion controlled Jander‐equation. Kinetic parameters were evaluated from the induction period as well as from isothermal TG. Activation energy was found to be 202.05 kJ/mol and log A(in s‐1) 22.78 from TG and 181.133 kJ/mol and log A (in s1) 20.97 from IR, respectively. The corresponding values were 171.17 kJ/mol and log A (in s‐1) 21.20 from the induction period data. The effect of a series of additives incorporated to the extent of 5 %, on the initial thermolysis of TNP, has also been studied. Evolved gas analysis by IR showed that CO2, NO2, NO and N2O are produced in larger amounts than CO and HCN. The cleavage of the NN bond appears to be the primary step in the thermolysis of TNP.
The Simplified Model for Predicting Shaped Charge Jet Parameters
Authors: Gui‐Xi Liu 
Published: May 2005

AbstractThe model is based on the more recent work of Hirsch and the original analytical work of Pugh, Eichelberger and Rostoker. Namely, the simplified Gurney formula for imploding cylinders derived by Hirsch is combined with the PER theory forming one‐dimensional computer code, and then it is used for predicting the 80‐mm diameter shaped charge jet parameters. Good agreement has been found with the experimental results.
Improving the Safety of a Pyrotechnic Igniter through a controlled experiment
Authors: Milman Benjamin , Sirota Issachar , Steinberg David M. 
Published: May 2005

AbstractOne of the important goals of quality management in today's competitive marketplace is to build quality into products and processes at the development stage. The use of statistically controlled experiments, in which several parameters are studied simultaneously, can help accomplish this goal efficiently. This paper describes a case study that illustrates the utility of controlled experiments in product development. The customer required improvements in the safety of a pyrotechnic igniter used in one of the products they purchased. The safety improvements could be met by replacing the “match‐head” initiator by a type IA/IW no fire initiator. However, there was concern that changing the initiator might degrade other important product performance characteristics. A controlled experiment was designed to compare three different initiators, the booster charge and the main charge. The experiment quickly and efficiently pointed to a superior initiator and the optimal charges to maintain high performance with enhanced product safety.
Surfactant coatings for the stabilization of barium peroxide and lead dioxide in pyrotechnic compositions
Authors: Brent G. F. , Harding M. D. 
Published: May 2005

AbstractBaO2 and PbO2 are widely used oxidizers which have been observed to suffer degradation after storage in unsealed systems. It is evident that reaction occurs with atmospheric water and carbon dioxide forming carbonates. The inhibition of these reactions by the application of protective coatings is considered, Such techniques appear to be gaining importance in pyrotechnic applications, and criteria for suitable coatants are discussed. Various surfactants were applied to BaO2 and evaluated in an accelerated aging test. Selected anionic and non‐ionic surfactants conferred improved aging resistance, with stearic acid giving the greatest advantage. A very high degree of protection was also afforded to PbO2. Low energy fuses based on a BaO2/Si composition were evaluated and a high resistance to aging was realized using the coated BaO2. There were no adverse effects on other properties, thus satisfying the criteria established for coatants.
Combustion of Ti and Zr Particles with KNO3
Authors: Miyata Kohsei , Kubota Naminosuke 
Published: May 2005

AbstractThis paper describes the thermochemical properties and combustion characteristics of pyrolants consisting of Ti/KNO3 and Zr/KNO3 mixtures. Differential thermal analysis (DTA) and thermogravimetry (TG) were conducted in order to elucidate the reaction processes of these pyrolants. The results of the experiments suggest that Ti particles react exothermically at 970 K with the decomposed gases of KNO3, and Zr particles react also exothermically at 700 K with liquified product of KNO3. Burning rates of the pyrolants were measured with a chimney type strand burner which was pressurized with argon gas. The burning rate of Ti/KNO3 is more sensitive to pressure than that of Zr/KNO3. The results indicate that a major exothermic reaction on the combustion wave of Zr/KNO3 pyrolants is in the condensed phase. The burning rates of both pyrolants are dependent on the oxidizer/fuel ratio and initial temperature of the pyrolants.
A Study of Some Charge‐Transfer Complexes of 2‐methyl‐1,3,6,8‐tetranitronaphthalene
Authors: Cuming S. , Wells C. H. J. 
Published: May 2005

AbstractCharge‐transfer complexes have been prepared with 2‐methyl‐1,3,6,8‐tetranitronaphthalene (I) as electron acceptor and various 9‐substituted anthracenes as electron donor. The electron affinity of (I) has been determined as 1.12 ± 0.07 eV, and the energy of activation for conduction in the complexes studied lie in the range 0.27 eV–0.74 eV.
Strain Rate Insensitivity of Damage‐Induced Surface Area in M30 and JA2 gun propellants
Authors: Gazonas George A. , Juhasz Arpad A. , Ford James C. 
Published: May 2005

AbstractUniaxial compression tests are conducted on single‐grain seven‐perforated specimens of M30 and JA2 gun propellant using the U.S. Army's high rate servohydraulic test apparatus in order to investigate the effects of strain rate, temperature, and percent axial strain on the combustion characteristics (apparent burn rate and pressurization rate) of the propellants. At room temperature M30 primarily deforms by macroscopic fracture and JA2 deforms by macroscopic flow. The total number of tests (sixteen) is minimized by designing the experimental program according to a 24 statistical design strategy. The single grains of deformed propellant are then burned in a newly designed 7.8‐cm3 mini closed‐bomb and plots of pressure, pressurization rate and surface area ratio versus time, and apparent burning rate versus pressure are compared with baseline results for the undeformed propellant specimens. The apparent burn rates of damaged M30 propellant vary considerably and the degree of damage induced surface area approaches six times that of the undeformed baseline M30 specimens. The apparent burn rates of JA2 are relatively unaffected by the induced deformation. Results indicate that the apparent burn rate of JA2 at 20 MPa is primarily dependent on the deformation temperature, yet the apparent burn rate of M30 at 20 MPa is dependent primarily on percent axial specimen strain. The apparent burn rates for these propellants are relatively insensitive to the deformation strain rate over the range 10−2 to 100 sec−1.
Synthesis of Trinitrophenyl C60 Derivative
Authors: Wang Naixing , Li Jisheng , Ji Gaijiao 
Published: May 2005

AbstractTrinitrophenyl C60 derivative was synthesized by allowing C60 to react with trinitrochlorobenzene and sodium azide. This fullerene derivative would first provide a brillant prospect in the energetic materials. The product structure was identified by FD‐MS, UV‐VIS, IR and 13C‐NMR.
Agglomeration of magnesium particles in magnesium‐sodium nitrate combustion
Authors: Bhaskara Rao R. , Srinivasa Rao P. , Singh Harihar 
Published: May 2005

AbstractAgglomeration phenomenon of magnesium particles during combustion of MgNaNO3 propellant has been studied. High speed photographs of combustion zones and the burning surface temperature data indicate that the metal particles form agglomerates on the burning surface in varying degree depending on the mass fraction of NaNO3. It is found that the increase of oxidizer content increases the metal agglomeration and the agglomerate size depends on the initial particle size of the ingredients.An attempt has been made to predict the size of the agglomerates based on the consideration that the agglomerate size depends on the thickness of the molten oxidizer layer enveloping the metal particles in the condensed phase and surface heat flux providing local temperature environment to agglomerate the metal particles and to eject from the burning surface for the vapour phase combustion. The results were compared with the experimental data. The prediction describes fairly well the observed effects of the concentration and particle size.
LOVA Propellant Aging: Effect of Residual Solvent
Authors: Pesce‐Rodriguez Rose A. , Fifer Robert A. 
Published: May 2005

AbstractAn investigation of LOVA propellant aging was performed to identify the cause of stabilization periods in certain propellant lots. Two important observations were made: (1) the level of residual solvent in propellant grains slowly decrease while in storage, and (2) during the drying process and while the grains are in storage, plasticizer “co‐migrates” with solvent, resulting in plasticizer accumulation at grain surfaces. It was also observed that while in storage, residual solvent may be oxidized to generate organic acids. Based on these results, it is proposed that stabilization periods result from processes related to migration, evaporation, and oxidation of residual solvent.
Thermal decomposition mechanisms of bis(2‐fluoro‐2,2‐dinitroethyl) formal (FEFO) and bis(2‐fluoro‐2,2‐dinitroethyl) difluoroformal (DFF) from simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) measurements
Authors: Minier Leanna M. G. , Behrens Richard 
Published: May 2005

AbstractThe simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) technique has been applied to measure the vapor pressures and evaluate the thermal decomposition chemistry of two energetic liquids, bis(2‐fluoro‐2,2‐dinitroethyl)formal (FEFO) and bis(2‐fluoro‐2,2‐dinitroethyl)difluoroformal (DFF). The resulting heat of vaporization (ΔHvap) and vapor pressure at 25°C are 20.3 ± 0.2 kcal/mol and 0.4 ± 0.1 millitorr for FEFO, and 17.3 ± 0.2 kcal/mol and 5.1 ± 1.1 millitorr for DFF. The thermal decomposition of FEFO indicates there are six major pyrolysis pathways. The results suggest that FEFO initially decomposes at 150°C by rearrangement of the nitro group (NO2) to the nitrite group (ONO), followed by loss of NO. Some NO2 is also formed at 170°C. Between 200°C–300°C, further pyrolysis occurs. In one pathway, the FEFO backbone remains intact and a high molecular‐weight product is formed. The other three pathways involve scission of the FEFO backbone; one yielding CO2 (possibly N2O), one yielding CH2O and CO, and one yielding C3H2NOF. Differences in the thermal decomposition behaviors in the liquid and gas phases are observed. In the thermal decomposition of DFF, the formal fluorine atoms stabilize the backbone structure. Numerous minor thermal decomposition products are also reported.
Cast PBX B2238 for Small‐Calibre High Performance Insensitive Munitions
Authors: Kent Ralph 
Published: May 2005

AbstractGenerally speaking, today's small‐calibre munitions, filled with conventional melt‐cast or pressed high explosives, are classified in the 1.1 or 1.2 Hazard Divisions because they explode when exposed to various threats, such as fuel fire and sympathetic detonation. The RDX‐based B2238 composition is a low‐cost and less sensitive cast PBX originally developed by SNPE for the initiation of cast PBX main charges. While it is easily initiated with conventional detonators, B2238 offers the same degree of insensitivity as other cast PBXs used for main charges (HEXABU 88A or OCTORANE 86B for example) and does not explode when exposed to fire and/or bullet impact. Feasibility tests carried out on several types of small‐calibre munitions have shown B2238 explosive filling to be an excellent solution in the design of small calibre insensitive munitions with a high performance (in terms of fragments and shaped charge jet) comparable to that of the most energetic conventional high explosives such as 98RDX/2wax. As a result, the new IM standards, currently being defined, should allow in the future to reclassify the small‐calibre munitions filled with B2238 in Hazard Divisions other than 1.1 and 1.2.
Study on the Nitrolysis of Hexamethylenetetramine by NMR spectrometry II. Some new evidences of the intermediate of HOCH2NHNO2 as a possible precursor to RDX
Authors: Fang Zhijie , Chen Li , Wang Shaofang , Chen Ju , Li Fuping 
Published: May 2005

AbstractIn this research, the RDX yield from nitrolysing hexamethylenetetramine (hexamine, HA) together with methylenedinitramine (MDNA) in 90% nitric acid was more than 100%. It was found that MDNA decomposed completely in 90% nitric acid, forming O(CH2ONO2)2, while in HNO3NH4NO3 system the decomposed fragments of MDNA condensed into RDX. On the basis of the comparison of the experimental results to the 1H‐NMR spectra obtained by following the decomposition reaction of MDNA with nitric acid, the intermediate, HOCH2NHNO2, was postulated as one of the possible precursors to RDX both in Hale and in K process.
BAMO/NMMO Copolymer with Polyester Initiation
Authors: Kawasaki Hidetoshi , Anan Toshiyuki , Kimura Eishu , Oyumi Yoshio 
Published: May 2005

AbstractIn order to improve of mechanical properties at low temperature region, 3,3‐bis(azidomethyl)oxetan (BAMO), 3‐nitratomethyl‐3‐methyloxetane (NMMO) and polyester (PE) copolymer were synthesized by using polyester initiator with boron trifluoride etherate. The molar ratio of each units in the BAMO/NMMO/PE copolymer was 7.4/2.6/0.39 according to the 1H‐NMR spectrum analysis and was almost exactly the same composition as the monomer fed (7/3/0.33). The relative composition of triad microstructures was same as theoretical value and they were randomly arranged. The PE, which was a replacement of 1,4‐butanediol, acted as an excellent soft segment in the copolymer, and the glass transition point of the elastomer was 4.8 degrees lowered by the replacement. This effect was also verified in the mechanical properties of the composite propellant and the tensile elongation was increased from 15% to 40%percnt; at −40 °C.
Burning Behaviour of Nitramine Model Formulations
Authors: Eckl Wilhelm , Weiser Volker , Langer Gesa , Eisenreich Norbert 
Published: May 2005

AbstractModel formulations of RDX and a hydrocarbon binder were studied by various methods to investigate the effect of additional fuel on the burning mechanism. The fuel reduces the burning rate at higher pressures and the pressure exponent. Extinguished burning surfaces show that the RDX is depleted at the surface. Emission spectra in the UV/VIS are dominated by the OH, NH and CN similar to the case of pure RDX. However, the OH decreases at higher distances from the surface obviously consumed by decomposition products of the fuel. At high pressures (> 2 MPa) soot emits strong continuous radiation. The temperatures obtained from the OH bands at 306 nm range from 2800 K to 3000 K which is close to the adiabatic flame temperature. The temperatures evaluated from the continuous radiation are considerably lower indicating radiation cooling.
Suitability of Modified Supercritical Carbon Dioxide as Solvent for polar substances
Authors: Niehaus Michael , Teipel Ulrich , Bunte Gudrun , Krause Horst H. 
Published: May 2005

AbstractAs solvent supercritical carbon dioxide offers unique possibilities, like non‐toxicity and therefore reduction of environmental pollution or access of low‐temperature processing resulting in additional process safety. Therefore, knowledge to the influence of modifiers due to better solubility of polar substances is important for evaluating novel manufacturing techniques like the RESS‐ or GAS‐process. Dynamic supercritical fluid extraction of PETN, nitroguanidine (NIGU) and RDX, respectively, with pure as well as with modified carbon dioxide indicated that all explosives except nitroguanidine were extracted though for RDX and 3‐nitro‐1,2,4‐triazole the use of modifiers proved to be necessary. The results show the high capacity of modified supercritical carbon dioxide as a solvent in RESS‐ and GAS‐processes.