Initiation of Detonation by the Interaction of Shocks with Density Discontinuities

Mader, Charles L.

doi:10.1063/1.1761113

Cited by 97 publications

(52 citation statements)

References 8 publications

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“…There exist a multitude of reasons why modeling and experiments cannot decouple the physical mechanisms which may lead to hot spot formation: adiabatic compression of trapped gases 15 , viscoplastic heating 16 , hydrodynamic jet impingement 17 , localized shear banding 18 , and many others 9 all play a role. A well-calibrated material model and equation of state might possibly capture all of the different mechanisms; unfortunately, such models are limited by the available thermophysical property data relevant to the high rates of deformation (> 10 4 s −1 ) and high pressures (> 1 GPa) associated with pore collapse.…”

Section: Introductionmentioning

confidence: 99%

Multiscale modeling of shock wave localization in porous energetic material

et al. 2018

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Shock wave interactions with defects, such as pores, are known to play a key role in the chemical initiation of energetic materials. The shock response of hexanitrostilbene is studied through a combination of large scale reactive molecular dynamics and mesoscale hydrodynamic simulations. In order to extend our simulation capability at the mesoscale to include weak shock conditions (< 6 GPa), atomistic simulations of pore collapse are used to define a strain rate dependent strength model. Comparing these simulation methods allows us to impose physically-reasonable constraints on the mesoscale model parameters. In doing so, we have been able to study shock waves interacting with pores as a function of this viscoplastic material response. We find that the pore collapse behavior of weak shocks is characteristically different to that of strong shocks.

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Section: Introductionmentioning

confidence: 99%

Multiscale modeling of shock wave localization in porous energetic material

et al. 2018

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“…Mader 1965;Carroll & Holt 1972;Khasainov et al 1981;Maiden & Nutt 1986;Kang, Butler & Baer 1992;Bourne & Field 1999;Menikoff 2003b;Tran & Udaykumar 2006) have examined energy localization mechanisms during the collapse of a single void, identifying several relevant mechanisms: shock focusing, adiabatic gas compression, jetting, hydrodynamic and viscoplastic work. A Reynolds number Re based on the void size can be defined as…”

Section: Introductionmentioning

confidence: 99%

Collapse of void arrays under stress wave loading

Swantek

Austin

2010

J. Fluid Mech.

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The interaction of an array of voids collapsing after passage of a stress wave is studied as a model problem relevant to porous materials, for example, to energy localization leading to hotspot formation in energetic materials. Dynamic experiments are designed to illuminate the hydrodynamic processes of collapsing void interactions for eventual input into device-scale initiation models. We examine a stress wave loading representative of accidental mechanical insult, for which the wave passage length scale is comparable with the void and inter-void length scales. A single void, two-void linear array, and a four-void staggered array are studied. Diagnostic techniques include high-speed imaging of cylindrical void collapse and the first particle image velocimetry measurements in the surrounding material. Voids exhibit an asymmetrical collapse process, with the formation of a high-speed internal jet. Volume and diameter versus time data for single void collapse under stress wave loading are compared with literature results for single voids under shock-wave loading. The internal volume history does not fall on a straight line and is in agreement with simulations, but in contrast to existing linear experimental data fits. The velocity field induced in the surrounding material is measured to quantify a region of influence at selected stages of single void collapse. In the case of multiple voids, the stress wave diffracts in response to the presence of the upstream void, affecting the loading condition on the downstream voids. Both collapse-inhibiting (shielding) and collapsetriggering effects are observed.

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“…Furthermore other hot spots are created in the explosive on its front surface by the hot plasma flowing in the interstices of the granular reactant. If the first two effects are those usually encountered in shock initiated explosives (Mader 1963, 1965, Ch6ret 1988, the third effect, characteristic of the laser ignition, results in a decrease of the duration of initiation and thus of the deflagration to detonation transition time. Therein lies the interest of the optical detonator, as compared to the electric gun; also the possibility of simultaneous ignitions at different points (Yang 1974) is rendered possible by this technique.…”

Section: Physical Problemsmentioning

confidence: 98%

“…At the same time, other authors focused their attention on fundamental and modelling studies, in view of a better understanding of various phenomena subsequent to DDT, and to reduce the number of experimental tests (Hsish et al 1989;Hoffman et al 1981;Beckstead et al 1977;Mader 1963Mader , 1965Mader , 1967Mader , 1978Baer andNunziato 1986, 1989). Recent papers in this field (Baer and Nunziato 1986) give comparisons between experimental and theoretical results for granular explosives and point out a good agreement.…”

Section: Introductionmentioning

confidence: 98%

Ignition and growth of a detonation by a high energy plasma

1992

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Abstract. Many experimental and numerical studies have been achieved to describe the transition process of deflagration to detonation when a projectile impacts an explosive. Also a large work has been done for the determination of various parameters -such as the impact pressure, the efficiency factors, etc. of the laser -material interaction. When a laser beam impacts an explosive, the p2~. criterion, characteristic of shock initiated detonations, is no longer valid due to the generated hot plasma whose effect is to decrease the DDT (Deflagration to Detonation Transition) duration. The present paper deals with a modelling of the plasmaexplosive medium allowing the determination of distances and times of the DDT process. The two phase modelling of the granular explosive takes into account the creation of hot spots. The pressure of the plasma is computed using a semi empirical model, while the temperature is obtained from Maxwell Boltzmann statistics. The authors focused their attention on the equation of state for the detonation products and the numerical process.

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Initiation of Detonation by the Interaction of Shocks with Density Discontinuities

Cited by 97 publications

References 8 publications

Multiscale modeling of shock wave localization in porous energetic material

Multiscale modeling of shock wave localization in porous energetic material

Collapse of void arrays under stress wave loading

Ignition and growth of a detonation by a high energy plasma

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