摘要:

AbstractFor many years, carbon resistors have formed the basis for measurement of shock and detonation pressures associated with condensed explosives. The gauge is fabricated by heat‐sealing the resistor into a plastic material such as polystyrene. When subjected to a strong shock wave, the resistance decreases, and the resulting increase in conductance is a function of the magnitude of the pressure. The present investigation was concerned with the experimental derivation of revised calibration equations, which was necessitated by the need to incorporate a terminating resistor into the gauge circuitry. The use of this resistor decreased the effect of standing waves and eliminated oscillatory ringing in the recorded signal. Typical records over a wide range of pressures are presented. An error analysis of the recorded data showed that the uncertainty in the measured pressure was of the same order of magnitude as the uncertainty in the interpretation of the recorded voltage from which the conductance was computed. An extensive discussion of the relevancy of the experimental data is presented, and the need for additional calibration experiments is stresse

ISSN:0721-3115    

DOI:10.1002/prep.19950200402

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractPrecursor air shocks with velocities that are 50 % higher than the velocity of detonation occur not only in cylindrical holes, but also in flat slits. By attaching to the test charge a sufficiently long plexiglass body with the same hole or slit profiles it is possible to observe the end face of the test charge and, thus, to record the changes in the detonation profile caused by slits, in particular by such that are oblique to the direction of detonation. One result is, that there is no through‐detonation across thin slits that are at a flat angle to the detonation wav

ISSN:0721-3115    

DOI:10.1002/prep.19950200403

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe asymmetric sandwich Gurney formula is used extensively worldwide during explosive reactive armor and shaped‐charge war‐head design, in either its original form(1,2)or its extended form used to model implosion configurations(3–5). It is therefore very important to realize that calculations may contradict physical observations when the formula is used to calculate the velocity of thin plates having mass which is smaller than half the explosive mass per unit area. This inconsistency between calculation and experimental results is explained as resulting from the failure of the assumption made in deriving all the Gurney formulas that the velocity distribution of the explosive products is a linear function of the expansion coord

ISSN:0721-3115    

DOI:10.1002/prep.19950200404

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractA further development of the procedure based on pyrolysis gas chromatography (Py‐GC) for the characterization of plastic‐bonded explosives (PBX's) is described. After grinding, the PBX samples were pressed on a pyrolysis wire followed by Py‐GC analysis. The peak areas obtained were normalized and subsequently submitted to multivariate data analysis. The use of principal component analysis (PCA) was tested on five samples which differed slightly in composition and age. The results were promising and showed that PCA is a powerful tool for the differentiation between PBX samples. The pyrolysis conditions were examined and optimized. A dependency was found between the sample loading (mass) and the position of the samples in a PCA score plot and indicates that control of the sample loading is important in obtaining reproducible results. For PBX samples an optimum pyrolysis temperature was determined around 540°C, close to the previous selected pyrolysis temperature of 610°C. In examining the pyrolysis at lower temperatures it was found that RDX or HMX is pyrolyzed independently from the binder. It appeared that PBX samples were inhomogeneous despite a thorough mixing of the constituents during prep

ISSN:0721-3115    

DOI:10.1002/prep.19950200405

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractTo find an effective laser source to ignite energetic materials, the absorption spectra of some energetic materials are obtained by means of a photoacoustic spectroscopy (PAS). In this experiment, PAS covers the wavelength region of 400 nm‐1600 nm in which no other conventional method can take absorption spectra for powdered energetic materials. Photoacoustic spectra of 18 energetic materials are reported. In general, energetic materials tested showed peaks in 600 nm–800 nm and 1400 nm–1600 nm ranges. It is found that the energy required to initiate explosives in the case of ruby laser initiation were correlated with their photoacoustic signal intens

ISSN:0721-3115    

DOI:10.1002/prep.19950200406

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe effect of mass, diameter and type of detonator on parameters of shock waves generated in plexiglas block is examined by experimental and theoretical means. The quantities connected with the shock wave, such as, the mean velocity of the shock wave front, the profile of mass velocity behind this front, and the mean velocity of free surface of the loaded block are measured.To perform an numerical analysis of the shock wave parameters mentioned above on type and size of detonator the problem is considered of acting of detonation products of an explosive charge on a block of inert material. In this goal, the active mass of charge is determined and, next, the model assumptions and mathematical formulation of the problem of penetration of pressure pulse into inert medium are presented. The results of computer simulation and experimental data are compared.

ISSN:0721-3115    

DOI:10.1002/prep.19950200407

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractWe have investigated the concentration of the nitromethyl aci‐anion in nitromethane and nitromethane‐diethylenetriamine mixtures. Ultra‐violet absorption spectroscopy and electrical conductivity measurements have given direct experimental evidence that the aci‐anion concentration is increased as compared to that in pure nitromethane. The increase is consistent with a shift in the acid‐base equilibrium. In any one mixture that is in contact with air, we have also observed a subsequent decrease in the aci‐anion concentration as a function of time. A newly observed band in the vibrational spectrum of nitromethane has been assigned to the aci‐anion and was used to confirm the decrease in its concentration with time. We discuss the previously suggested link between the aci‐anion and the sensitivity of nitromethane and conclude that it is unlikely that there exists

ISSN:0721-3115    

DOI:10.1002/prep.19950200408

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe cookoff behaviour of several plasticized HTPB/AP and HTPB/RDX propellants has been evaluated using the standard Small‐Scale Cookoff Bomb (based on the NWC design) and a modified version of the standard equipment (whereby the reaction violence can be measured quantitatively) to investigate the effects of (1) plasticizer level on the thermomechanical properties and its role in moderating the cookoff response, and (2) heating rate. A change from slow to fast cookoff behaviour was observed for the plasticized HTPB/RDX propellants; the measured pressures/energy output at the slow heating rate were much lower than those at the fast heating rate for the same propellants. The thermal distribution/gradient at various positions and depths in the cylindrical propellant specimen, during fast and slow cookoff, were measured in order to understand the reversal in the severity of the response shown by the plasticized RDX propellants when the heating rate was changed. Thermomechanical properties of the propellants were measured and correlated with cookoff behaviour, to provide further insight into the cookoff mechanism

ISSN:0721-3115    

DOI:10.1002/prep.19950200409

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThree different copolymerization ratios of BAMO/NMMO copolymers were studied for the requirement of not only a high specific impulse but also an insensitive munition characteristics for HMX composite propellant. These molar ratios of BAMO/NMMO were 8/2, 7/3, 6/4. Although the heat of DSC measured was relatively largest in B/N(7/3) propellant, there was no difference in the thermal decomposition characteristics. The exothermic reactions of azide binder and of HMX occurred in the same temperature region. The faster burning rate was obtained by the more BAMO ratio in the binder. The shock sensitivity was the lowest in B/N(7/3) HMX composite propellant. This unexpected stability might be caused by the physical effect of the molecular structure of B/N(7/3) which might contribute to the sudden dumping of the impact shock. Although the detonation velocity, because faster as BAMO ratio, increased like as the burning rate, the detonation pressure was the lowest in B/N(7/3) propellant. The mixture of catocene and copper chromite augmented the burning rate 1.6 times with decreasing temperature sensitivity.

ISSN:0721-3115    

DOI:10.1002/prep.19950200410

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

ISSN:0721-3115    

DOI:10.1002/prep.19950200411

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY