摘要:

AbstractTransient combustion processes inside a solid‐propellant crack cavity have been formulated and solved numerically, with emphasis placed on the coupling between combustion dynamics and propellant grain deformation and fracture. Sample calculations were performed for a center‐perforated propellant grain with an existing crack. Parametric study investigating the effect of several physical properties on the initiation of fracture was also carried out. Numerical results indicated that the existence of cracks in a propellant grain may impose a safety issue for a rocket motor due to the creation of large free volume and extra burning surface area. Comparison of calculated results of this analysis and those which do not consider propellant deformation and fracture revealed that the coupling between combustion and structural analyses is mandatory for accurate simulation of crack combustion event. It was also found that, from the parametric study, fracture initiation is very sensitive to the magnitude of pressure exponent of the propellant burning r

ISSN:0721-3115    

DOI:10.1002/prep.19940190502

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractAn on‐line system to measure hoop‐strain of strain evaluation cylinders (SECs) has been developed. The experimental results compared with the data measured by intermicrometer are acceptable. A modified mathematical equation to calculate thermal expansion coefficient of propellant is proposed and gives excellent agreement in comparing with the data measured by thermomechanical analysis (T

ISSN:0721-3115    

DOI:10.1002/prep.19940190503

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe synthesis and characterization of 2‐oxo‐1,3,5‐trinitro‐1,3,5‐triazacyclohexane (K‐6), a cyclic dinitrourea, is described. The laboratory synthesis was scaled‐up to provide 1.6 kilograms of crystalline K‐6 which was used for performance testing. K‐6 was formulated with 5% Viton A and pressed to 96.5% theoretical maximum density (TMD). Performance measurements in the form of front surface velocity measurements (tantalum plate push) and 1‐inch cylinder expansion experiments indicate K‐6 will out‐perform HMX by 4% at early volume expansions. Thermal response and shock sensitivity experiments on

ISSN:0721-3115    

DOI:10.1002/prep.19940190504

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractSolid propellant rocket technology makes use of polyurethane propellant system based on hydroxy terminated polybutadiene as binder. Processability of the propellant is determined by viscosity build‐up after unloading from the mixer, which in turn depends on rate of curing reaction between alcohols and isocyanate. For a typical binder system consisting of alcohols and isocyanate as in propellant composition, rate of curing has been studied using IR spectroscopy are carried out in solution phase. In this study, unaltered binder system was studied as such for the progress of the reaction as a function of time. Concurrently, viscosity studies were also carried out to study the rate of viscosity build‐up with time as reaction proceeds. With these studies two distinct phases have been brought out for the cure reaction of binder, first phase involving a linear reduction in concentration of the isocyanate groups followed by the second phase tending to equilibr

ISSN:0721-3115    

DOI:10.1002/prep.19940190505

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe rheology of a slurry of 1,3,5‐triamino‐2,4,6‐trinitrobenzene(TATB) in molten 2,4,6‐trinitrotoluene (TNT) suspension has been investigated. It was found that at high concentrations these suspensions are thixotropic. It has also been shown that these suspensions possess a shear‐dependent maximum packing fraction. This fact is relevant to the processing of these suspensions. A thixotropic model has been developed that successfully predicts flow curves for a chosen high concentration s

ISSN:0721-3115    

DOI:10.1002/prep.19940190506

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe preparation and properties of high‐melting aromatic nitrate esters are described. An objective of the study is to provide nitrate esters that exhibit good short‐term stability at temperatures of 150°C and a

ISSN:0721-3115    

DOI:10.1002/prep.19940190507

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractN,N′‐Bis(2‐nitro‐benzodifuroxanyl)‐1,3,5‐trinitro‐2,6‐diaminobenzene has been synthesized from 1,3‐diaminobenzene and trinitrotrichlorobenzene. The molecular structure of this compound has been determined by elemental analysis, IR,1HNMR, and

ISSN:0721-3115    

DOI:10.1002/prep.19940190508

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractTime dependent resistance measurements were performed on fast, high current electrical switches proposed for use in slapper detonators. The switches, consisting of a copper‐polymer‐copper laminate, are designed to conduct electrically after being impacted by an explosive‐driven copper flyer plate. The polymer film used in our experiments was Kapton (polypyromellitimide) and was expected to exhibit shock induced conduction at pressures of 9 GPa and above. While it is believed that shock pressures in the vicinity of 9 GPa were achieved in the switches, no significant shock conduction effect was observed. This was corroborated by observing identical electrical behaviour for switches based on Teflon (polytetrafluoroethylene) film, which is known to possess good insulating properties even under strong shocks. However, in spite of the lack of evidence of significant shock induced conduction in the Kapton based switch, its operation is satisfactory. The average switch closure resistance at practical voltage and current levels was found to be of the order of 0.15Ω, attained within a closure time of 10 ns to 20 ns. Also, the electrical characteristic of the switch performance was largely independent of the supply voltage, when a low impedance voltage source was used, though the closure resistance values displayed a large scatter with standard deviation of the order o

ISSN:0721-3115    

DOI:10.1002/prep.19940190509

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractAn equation for the decrease of stabilizer content in propellants is given, which describes the measured consumption of stabilizers such as diphenylamine, 2‐nitrodiphenylamine, acardite II and ethylcentralite very well. The equation was obtained with a kinetic formulation for the stabilizer depletion, which combines the reactions of first and zero order. According to this model, the times up to a complete consumption of the stabilizer are finite(they are infinite if the decrease is purely exponential), and can be calculated with the reaction rate constants of the model. The prediction of the life times is considerably improved. This new equation allows a normalized representation of the stabilizer decrease, which can reveal mechanistic changes in the course of the reactio

ISSN:0721-3115    

DOI:10.1002/prep.19940190510

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractThe compositions and microstructures, thermolyses, and sensitivities of 3,3‐bis(azidomethyl)oxetane (BAMO) copolymers with 3‐nitratomethyl‐3‐methyloxetane (NMMO) were characterized. The molar ratios of monomers fed in the copolymerizations were: BAMO/NMMO = 8/2, 7/3, and 6/4. The observed compositions were 81/19, 68/32, and 60/40, respectively. The relative compositions of trade microstructures were also exactly the same as theoretical values. The copolymerization of BAMO with NMMO behaved like an ideal system in the sense that the copolymer has approximately the same composition as the monomer fed. The microstructures of copolymers were also randomly arranged. Poly BAMO showed side chain decomposition in the initial stage of the thermolysis, on the other hand, backbone decomposition controlled the thermolysis of poly NMMO. The BAMO units and the NMMO units appeared to decompose more or less independently of one another and retained their individual decomposition characteristics despite being copolymerized. However, the heat generated by the NMMO decomposition, which occurred at 40°C lower than that of BAMO. activated the reaction of BAMO. Poly B/N(7/3) showed very interesting characteristics in sensitivities, mechanical properties, and the heat of decom

ISSN:0721-3115    

DOI:10.1002/prep.19940190511

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY