共查询到20条相似文献,搜索用时 31 毫秒
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Craig M. Tarver Paul A. Urtiew Steven K. Chidester Leroy G. Green 《Propellants, Explosives, Pyrotechnics》1993,18(3):117-127
LX-10 is a high energy density solid explosive consisting of 94.5% octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and 5.5% Viton A Binder pressed to 1.865 g/cm3 (98.4% of theoretical maximum density). In this paper the shock compression and initiation of chemical reaction in LX-10 by sustained shock pressures of 0.4 to 3 GPa are studied experimentally using embedded pressure and particle velocity gauges. The resulting pressure and particle velocity histories are evaluated theoretically using the ignition and growth reactive flow computer model of shock initiation and detonation. Manganin resistance and polyvinylidene fluoride (PVF2) ferroelectric pressure gauges are both employed in the low pressure (0.4 – 0.7 GPa) shock compression experiments. Multiple manganin pressure and multiple electromagnetic foil particle velocity gauges measure the growth of reaction at various positions in LX-10 shocked to 1 – 3 GPa. The reactive flow modeling results imply that less than one percent of the LX-10 shocked to 0.4 – 0.7 GPa reacts in fifteen microseconds. For the higher pressure experiments, the ignition and growth model accurately calculates the pressure and/or particle velocity buildup in LX-10 as the reaction grows toward detonation. The LX-10 calculations are compared to those for the well-calibrated explosive PBX-9404, which contains 94% HMX and a reactive binder. Since it has the inert binder Viton A and better mechanical properties than PBX-9404, LX-10 is demonstrated to be significantly less reactive than PBX-9404 at these shock pressures. Therefore LX-10 is safer than PBX-9404 in many hazard and vulnerability scenarios to which solid explosives may be subjected. 相似文献
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Planewave transit times were measured in three explosives: PBX-9404, pressed TNT, and PBX-9502. Four nominally identical disks were used on each shot to measure the reproducibility of the transit time. Standard deviations in transit times were 1%–2% if most of the wave trajectory was in the initiation phase. The standard deviation in transit times is larger than the measurement precision; this indicates a distribution in the response to the input pressure wave. Comparison was made to results of previous wedge initiation experiments. We conclude that most of the scatter in run distances to detonation found in wedge experiments is not inherent in the initiation process or the explosive quality. The scatter may be due to the imprecision of the free-surface velocity measurement coupled with the power-law character of the relation between run distance to detonation and input pressure. 相似文献
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将浇注型PBX-1药柱以150、240m/s速度撞击靶板,用扫描电子显微镜(SEM)技术和差示扫描量热仪(DSC)技术对撞击加载后的样品进行了分析,研究了浇注PBX炸药药柱的动态撞击性能。结果表明,在150、240m/s撞击加载条件下,PBX-1炸药不发生反应或点火;浇注炸药药柱的损伤主要表现为炸药颗粒破碎和颗粒与黏结剂的脱离。随着撞击加载速度的增大,PBX-1炸药颗粒破碎程度增大,炸药颗粒与高分子基体发生脱离现象越严重;PBX-1炸药撞击前后,热分解性能没有发生本质性的变化。 相似文献
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R. C. Weingart R. K. Jackson C. A. Honodel R. S. Lee 《Propellants, Explosives, Pyrotechnics》1980,5(6):158-162
The shock initiation threshold of PBX-9404 has been studied over the pressure range 3.1 GPa-28 GPa with pulse lengths ranging from 0.007 μs-0.63 μs. The short-duration, high pressure pulses were produced by the impact of thin plastic flyer plates accelerated by electrically exploded metal foils. We performed the experiments on explosive pellets 25.4 mm in diameter with thicknesses of 6.0 mm, 10.1 mm and 19.1 mm. No dependence of the initiation threshold on pellet thickness was observed. The data are represented reasonably well by either the critical initiation energy or by the constant P2τ initiation criteria. 相似文献
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A threshold particle velocity criteria derived by E.R. Fitzgerald for the beginning of crystal lattice breakup and disintegration has been applied to shocked explosives and an inert material. In shocked explosives, reactions leading to detonation occur above a certain “threshold” magnitude. The computed crystal lattice breakup shock pressures compare rather well with observed experimental “threshold” shock pressures for six high explosives. The six explosives are: Comp-B3, Comp-B, TNT, PBX-9404, Tetryl, and H-6. In addition, the crystal lattice breakup criteria provides an explanation for the observed lowering of the detonation “threshold” shock pressure as the explosives are made more porous or less dense. Finally, the shock pressures, at which output from thermocouples embedded in shocked materials (PBX-9404 and Plexiglass) increases dramatically, compare favorably with predictions based on crystal lattice disintegration criteria. Consequently, it is tentatively concluded that crystal lattice breakup, or self-sustained phonon fission as Fitzgerald calls it, is responsible for the initiation of detonation in shocked explosives and enhanced thermocouple output in shocked materials. It is also postulated that the lattice breakup phenomena is also responsible for phase changes, increased chemical reactivity, and anomalous electrical activity which are observed in certain inert materials under relatively low level shock loading. 相似文献
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《Ceramics International》2022,48(1):463-471
The high reliability and extended life of seawater hydraulic components is dependent on the tribological properties of key friction pairs, more and more attention has been given to the performance degradation and lifetime of the friction pairs. In this paper, the wear process of Tungsten carbide (WC) with 6%wt of Ni (WC–6Ni)/SiC friction pair is studied through the tribological test under seawater lubrication. Considering the random effects and the complex wear mechanism of WC-6Ni/SiC, an efficient Inverse Gaussian (IG) process supported lifetime prediction model is established by coupling the multiple stresses under seawater lubrication, and the parameters in the proposed IG process model are derived. Two actual cases are used to validate the proposed method. The prediction model and experimental results show the high accuracy in time-varying lifetime prediction of WC-6Ni/SiC, which is of great significance to the evaluation of friction pair and the maintenance for seawater hydraulic components. 相似文献
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Theodore S. Sumrall 《Propellants, Explosives, Pyrotechnics》1998,23(2):68-72
The eutectic explosive TE-E7007 was developed as a General Purpose(GP) Insensitive High Explosive(IHE) candidate due to a number of factors including: low raw material cost; theoretical high performance and; potential endothermic characteristics during cook-off(1). This paper will report on large scale performance test results(fragment velocity and air blast overpressure) for this composition. Air blast impulse, peak overpressure and fragment velocity results are compared to H-6, PBX-109, and a number of other IHE candidates which were manufactured in government and industry laboratories(2). The overall performance for TE-E7007 was comparable to PBX-109 and was superior or equivalent to all other IHE candidates. For more detailed information on the explosive formulation for TE-E7007, the reader is referred to a paper on this subject previously published in this journal, Ref. 1 and a U.S. Patent(3). 相似文献
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《Propellants, Explosives, Pyrotechnics》2017,42(12):1431-1438
Transportation, handling, vibrations can lead to dynamic loadings requiring the characterization of the safety of plastic‐bonded explosives (PBX). One of the addressed situations is the fall of explosive on a surface. Knowing that initiation can occur at a lower height during a vertical fall of a projectile on an inclined target than on a horizontal one, devices were developed to determine the critical thresholds. In this paper, data obtained on four HMX and/or TATB‐based PBXs using pendulum drop configurations are detailed. Two analytical models are compared to estimate the heat released by friction at the interface. The model proposed in this paper yields the better agreement with data, and with finite element numerical simulations of the oblique impact on a given PBX. Lastly, the mechanical dissipation at the interface is estimated using this model and the simulations. This paper confirms that PBX/target friction cannot be the heating mechanism leading to initiation during oblique impacts. 相似文献
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《Polymer Composites》2017,38(11):2536-2543
The effects of fiber hybridization on damage behavior of hybrid glass/carbon composites under high‐velocity impact were investigated. The Hashin damage model is adopted to model the damage initiation of composites, and the bilinear form of damage evolution law based on the effective displacement is employed. The numerical results show a reasonable agreement with the experimental data. The residual velocity of impact projectile is approximately shown a linearly decreasing trend with the increasing of the thickness of glass fabric ply. As the proportion of glass fabric ply in the hybrid laminates increases, the impact resistance of laminates increased gradually. POLYM. COMPOS., 38:2536–2543, 2017. © 2015 Society of Plastics Engineers 相似文献
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María L. Lagan Emilio Berkenwald Pablo Acua Javier Enríquez Medrano Graciela Morales Diana Estenoz 《Polymer Engineering and Science》2019,59(Z2):E231-E246
New advances in the mathematical modeling of the bulk continuous high‐impact polystyrene (HIPS) process are presented. The model consists of three modules that allow the simulation of: (1) a polymerization reactor train, (2) a devolatilization (DV) stage, and (3) structure–properties relationships. The model is based on a kinetic mechanism that includes thermal initiation, chemical initiation by sequential decomposition of a multifunctional initiator, propagation, transfer to monomer, transfer to rubber, termination by combination and re‐initiation, as well as high temperature crosslinking and oligomer generation reactions. The present model is comprehensive from a kinetic perspective, since it can be used to simulate a HIPS process using initiators of any functionality and structure. The model is adjusted and validated using previously unpublished experimental data for bulk continuous HIPS polymerization in a pilot‐scale plant. The experimental work includes a series of polymerizations using three different multifunctional initiators: (1) luperox‐331 M80 (L331), (2) pinacolone diperoxide, and (3) diethyl ketone triperoxide. The pilot plant comprised the main stages of an industrial HIPS process: prepolymerization, finishing and DV. Theoretical results show a good agreement with the experimental measurements. POLYM. ENG. SCI., 59:E231–E246, 2019. © 2018 Society of Plastics Engineers 相似文献
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A. V. Dubovik 《Combustion, Explosion, and Shock Waves》2002,38(6):714-722
A model of mechanical initiation of solid explosives, applicable for analysis of sensitivity of individual substances and composite explosives, is developed. The model includes a system of equations of work softening of a high explosive charge under an impact, resulting dissipative heating, and heat release due to chemical reactions between the components of the explosive mixture. The critical parameters and reaction kinetics were numerically calculated for initiation of charges consisting of a mixture of ammonium perchlorate and polymethylmethacrylate. The results are compared to experimental data on sensitivity of this mixture to the impact. Key words: high explosive, impact, explosion, impact sensitivity. 相似文献
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Jie Li Ruth Misener Christodoulos A. Floudas 《American Institute of Chemical Engineers》2012,58(1):205-226
Scheduling of crude oil operations is a critical and complicated component of overall refinery operations, because crude oil costs account for about 80% of the refinery turnover. Moreover, blending with less expensive crudes can significantly increase profit margins. The mathematical modeling of blending different crudes in storage tanks results in many bilinear terms, which transforms the problem into a challenging, nonconvex, and mixed‐integer nonlinear programming (MINLP) optimization model. Two primary contributions have been made. First, the authors developed a novel unit‐specific event‐based continuous‐time MINLP formulation for this problem. Then they incorporated realistic operational features such as single buoy mooring (SBM), multiple jetties, multiparcel vessels, single‐parcel vessels, crude blending, brine settling, crude segregation, and multiple tanks feeding one crude distillation unit at one time and vice versa. In addition, 15 important volume‐based or weight‐based crude property indices are also considered. Second, they exploited recent advances in piecewise‐linear underestimation of bilinear terms within a branch‐and‐bound algorithm to globally optimize the MINLP problem. It is shown that the continuous‐time model results in substantially fewer bilinear terms. Several examples taken from the work of Li et al. are used to illustrate that (1) better solutions are obtained and (2) ε‐global optimality can be attained using the proposed branch‐and‐bound global optimization algorithm with piecewise‐linear underestimations of the bilinear terms. © 2011 American Institute of Chemical Engineers AIChE J, 2012 相似文献
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A multiple response extension is proposed for the univariate calibration problem and a sequential solution is developed. The sequential sampling procedure is a generalization of existing univariate results of Perng and Tong (1974) and is based on the theory developed by Chow and Robbins (1965). It is shown that the proposed multiple response procedure is at least as good as and in many instances better than the univariate method 相似文献
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A. Mubashar 《The Journal of Adhesion》2017,93(6):444-460
This research investigates the use of a meshless smoothed particle hydrodynamics (SPH) method for the prediction of failure in an adhesively bonded single lap joint. A number of issues concerning the SPH based finite element modelling of single lap joints are discussed. The predicted stresses of the SPH finite element model are compared with the results of a cohesive zone based finite element model. Crack initiation and crack propagation in the adhesive layer are also studied. The results show that the peel stresses predicted by the SPH finite element model are higher and the shear stresses are lower than those predicted by the cohesive zone finite element model. The crack initiation and propagation response of the two models is similar, however, the SPH finite element model predicted a lower failure load than the cohesive zone finite element model. It is concluded that the current implementation of SPH method is a promising method for modelling cohesive failure in bonded joins but requires further development to allow for interfacial crack growth and better stress prediction under tensile loading to compete with existing methods. 相似文献
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A. V. Dubovik 《Combustion, Explosion, and Shock Waves》2001,37(1):99-105
An approximate method is proposed to calculate the impact sensitivity indices (critical initiation pressure and critical charge thickness) for solid explosive mixtures (explosive compositions and mixtures of an oxidizer with a fuel). The calculation is based on some model concepts of the physicochemical and explosive properties of reactive mixtures. Test calculations of the sensitivity indices were performed for mixtures of HMX and TNT and mixtures of ammonium perchlorate with polymethylmethacrylate (PMMA) and TNT, and the results are compared with data of laboratory experiments on an impactor. 相似文献