Models of Explosively Driven Metal

Dehn, James

doi:10.21236/ada151942

Cited by 7 publications

(2 citation statements)

References 10 publications

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“…This process is readily extendable to most simple geometries with as ingle degree of freedom and was generalized by Thomasa ss ummarized by Dehn [ 11,17].S tern subsequently extended the modelt oa symmetric systems where the presenceo ft wo unknown velocitiesr equires coupling of the momentum equation to the energye quation [17]. The most commono fsuch systemsi st he asymmetric sandwich, which also pertains to the experiment in the current study.T his geometry is depicted in Figure 1.…”

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confidence: 88%

Validation of the Gurney Model in Planar Geometry for a Conventional Explosive

Loiseau

Georges

Higgins

2016

Propellants Explo Pyrotec

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1IntroductionThe high-velocity projection of materials is one of the primary uses of condensed phase explosives. As such,t he efficacy with which ag iven high explosive accelerates material, and the velocity with which materiali st hrown for ag iven configuration, are essential considerations. Af ully rigorous modelling treatment of the acceleration of am etal flyer by ah igh explosive typically involves the use of ah ydrocode with detonation product equation of state data fitted to cylinder test experiments. However,a nalytical tools are often desirablei ne ngineering design, scaling studies, and as am etric for comparing the efficiency of explosives.The analyticalm odel developed by Gurney is the seminal method for estimating the terminal velocity of metals accelerated by high explosive [ 1].G urney'sm ethoda llows for an analytic estimation of terminal material velocity for alarge number of charge geometries using asingle,empirical parameter representingt he energetic yield of ap articular explosive. This parameter,t ermed the Gurney energy, can be extracted from aw ide variety of experiments. Because of the elegance, simplicity,a nd reasonable accuracy of the method, extensions to the Gurney modelh ave been widely used for seventy years.T he Gurney energy of an explosive remains an essentialm etric by which the propulsive capabilityo fa ne xplosive is judged and is ubiquitouslyr eferenced in most literature sources studying the explosive acceleration of metals, particularly in the context of cylinder test experiments [2][3][4].While ac omprehensive literature review is not possible in this paper,w ew ould point to some key references:K ennedy [5,6] and Jones [7] present re-derivationso ft he ex-Abstract:T he analytical modeld eveloped by Gurney is as eminal tool for analyzingt he acceleration of metal flyers driven by detonating high explosives.D espite the continued relevance of this model, relatively few experimental validations over aw ide range of flyer-to-chargem ass ratios exist in the openl iterature. The current study presents experimental results for planar aluminum flyers propelled by ac onventional explosive over ar angeo fm ass ratios varying from 4.65 to 0.03. Flyer velocityw as measured via Het-erodyne Laser Velocimetry (PDV),p ermitting ac ontinuous measurement of the acceleration process. Measured flyer velocities are compared to terminal velocity estimations from the Gurneym odel. Experimental terminal velocities are compared to theo pen face and asymmetric sandwich Gurney models. Excellent agreement is observedf or terminal velocity predictionsc onsideringt he gasdynamic simplificationsi nherent in the model formulation.

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confidence: 88%

Validation of the Gurney Model in Planar Geometry for a Conventional Explosive

Loiseau

Georges

Higgins

2016

Propellants Explo Pyrotec

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“…Dehn (2) has published equations based on Taylor's method that account for the acceleration of the expanding warhead case accompanying detonation as described in the lit-erat~re(~3'~). These are approximated by Eq.…”

Section: Velocity Of Expanding Donor Casementioning

confidence: 99%

A Simple Method for Calculating Sympathetic Detonation of cylindrical, cased explosive charges

Victor¹

1996

Propellants Explo Pyrotec

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Sympathetic detonation involves the propagation of detonation between individual explosive‐containing devices. When many such devices are stored together, the possibility of mass propagation exists. With mass propagation, the entire stored mass detonates nearly simultaneously. Such propagation is the most feared hazard of such explosive items in transportation and storage environments because of its potential for sudden extreme damage and loss of life. Safety requirements, including those for insensitive munitions, are best met if explosive devices can be designed to minimize the risk of sympathetic detonation. This paper presents a simple method for predicting the marginal conditions at which sympathetic detonation of cylindrical munitions just occurs (or just fails). The method can be easily and rapidly used in preliminary design studies to minimize subsequent hazard risks. It allows design and safety engineers to examine in minutes or hours what would take weeks or months of hydrocode calculations and months or years of field testing. The method involves algebraic solution of two‐dimensional shock propagation effects in an extension of Ferm and Ramsay's method for predicting shock initiation by spherical impactors(1). The donor case expansion velocity is calculated using the well‐known Gurney formula for cylinders as amplified by Dehn(2). The calculated initiation behavior of the acceptor charge(s) requires input data from wedge test results in the familiar Pop plot form, although a combination of card‐gap test data and failure diameter data can also be used (with reduced reliability) as a basis for estimating the Pop plot. The calculated results compare well with both hydrocode calculations and test data.

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