Power law and exponential ejecta size distributions from the dynamic fragmentation of shock-loaded Cu and Sn metals under melt conditions

Durand, Olivier; Soulard, Laurent

doi:10.1063/1.4832758

Cited by 72 publications

(38 citation statements)

References 70 publications

(111 reference statements)

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“…This peak corresponds to a local concentration of matter caused by the effects of surface tension which minimize the energy of the jet at its tip, as already mentioned in Ref. [26]. Note that the bulk density ~ 6500 mg/cm 3 is slightly below the nominal density of Sn because the metal releases and its temperature is high.…”

Section: The Continuum Point Of Viewmentioning

confidence: 88%

“…In particular the classical hydrodynamics approaches suffer a lack of modeling and characterization of the rheological behavior of metals after shock loading; and data on surface tension and viscosity are needed. To our knowledge, only recent MD simulations performed on atomistic systems allowed to provide directly from computations ejecta size distributions [25][26][27]. Particulate…”

Section: Introductionmentioning

confidence: 99%

“…The analysis tools implemented for the characterization of the particles/aggregates/ejecta (these terms refer to the same thing) in size, velocity, position and mass are also described in Ref. [25][26]. In particular, the system is divided in voxels and the Hoshen-Kopelman algorithm [33] is used to label the atoms that belong to the same aggregate.…”

Section: Introductionmentioning

confidence: 99%

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Mass-velocity and size-velocity distributions of ejecta cloud from shock-loaded tin surface using atomistic simulations

Durand

Soulard

2015

Journal of Applied Physics

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Abstract:The mass (volume and areal densities) versus velocity as well as the size versus velocity distributions of a shock-induced cloud of particles are investigated using large scale molecular dynamics (MD) simulations. A generic three-dimensional tin crystal with a sinusoidal free surface roughness (single wavelength) is set in contact with vacuum and shock-loaded so that it melts directly on shock. At the reflection of the shock wave onto the perturbations of the free surface, two-dimensional sheets/jets of liquid metal are ejected. The simulations show that the distributions may be described by an analytical model based on the propagation of a fragmentation zone, from the tip of the sheets to the free surface, within which the kinetic energy of the atoms decreases as this zone comes closer to the free surface on late times. As this kinetic energy drives (i) the (self-similar) expansion of the zone once it has broken away from the sheet and (ii) the average size of the particles which result from fragmentation in the zone, the ejected mass and the average size of the particles progressively increase in the cloud as fragmentation occurs closer to the free surface.Though relative to nanometric scales, our model may help in the analysis of experimental profiles.2

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Section: The Continuum Point Of Viewmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mass-velocity and size-velocity distributions of ejecta cloud from shock-loaded tin surface using atomistic simulations

Durand

Soulard

2015

Journal of Applied Physics

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“…As an example, in case where the defects are parallel grooves, Durand et al have recently used Molecular Dynamic (MD) simulations of large systems to show that the ejection process is as follows: (i) the ejected material forms sheets of liquid metal which go thinner and thinner; (ii) when sheets are sufficiently thin, holes appear and sheets break to form filaments; and (iii) those filaments stretch and finally break also to form spherical clusters. 1,4 It appears that the breaking of the sheets starts when the thickness is about several nanometers. So, to study the last parts of this phenomenon, microscopic simulations seem to be the good tool, and those MD simulations made possible to get the entire size distribution of the final spherical aggregates.…”

Section: Introductionmentioning

confidence: 99%

Communication: Slab thickness dependence of the surface tension: Toward a criterion of liquid sheets stability

Filippini

Bourasseau

Ghoufi

et al. 2014

The Journal of Chemical Physics

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Microscopic Monte Carlo simulations of liquid sheets of copper and tin have been performed in order to study the dependence of the surface tension on the thickness of the sheet. It results that the surface tension is constant with the thickness as long as the sheet remains in one piece. When the sheet is getting thinner, holes start to appear, and the calculated surface tension rapidly decreases with thickness until the sheet becomes totally unstable and forms a cylinder. We assume here that this decrease is not due to a confinement effect as proposed by Werth et al. [Physica A 392, 2359[Physica A 392, (2013] on Lennard-Jones systems, but to the appearance of holes that reduces the energy cost of the surface modification. We also show in this work that a link can be established between the stability of the sheet and the local fluctuations of the surface position, which directly depends on the value of the surface tension. Finally, we complete this study by investigating systems interacting through different forms of Lennard-Jones potentials to check if similar conclusions can be drawn.

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“…The ejecta source and RM sheet breakup has also been studied extensively with MD simulations [55][56][57][58][59][60], and more research on dynamic particle sizing diagnostics is reported, works that includes holography and Mie scattering [61,62].…”

Section: Smentioning

confidence: 99%

Foreword to the Special Issue on Ejecta

Buttler

Williams

Najjar

2017

J. dynamic behavior mater.

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A Brief History of Ejecta Physics 1950s and 1960sThere exists anecdotal evidence that ejecta research began in the 1950s, but little of this early research was documented publicly. In Russia, the ejecta phenomenon was first observed in plate impact experiments, and shown to be dependent on the initial surface roughness [1]. The Los Alamos PHERMEX radiographic facility was used to study the production and interaction of jets from shocked surfaces, starting from its very first shot in 1963 [2]. By 1969, Bristow and Hyde [3] describe the results of a mature program in the UK using photographic imaging of ejecta processes to infer whether melt had occurred at the surface of shocked materials. They showed that drive nonuniformity and subsurface fragmentation (spall/scabbing) were also contributory factors in determining the nature of ejecta produced. 1970sThe earliest published ejecta research was done by James Asay [4]. Asay went on to develop a non-radiographic ejecta diagnostic, the eponymous Asay foil [5]. Later, he developed a prescriptive model of ejecta, where he associated the amount of mass ejected from a shocked surface to the volume of surface defects, the rise time of the shock impulse, the yield strength of the material, and the phase of the material on release, i.e., liquid or solid [6]; interestingly he also observed that ejecta production was independent over broad ranges to the peak loading stress P S . Los Alamos National Laboratory (LANL) also became active in the development of ejecta diagnostics, as released by Hopson and Olinger [7].Ejecta physics is a young field, having developed over the last 60 years or so. Essentially, ejecta forms as a spray of dense particles generated from the free surface of metals subjected to strong shocks, but the detailed mechanisms controlling the properties of this particulate ejecta are only now being fully elucidated. The field is dynamic and rapidly growing, with military and industrial applications, and applications to areas such as fusion research.This Special Issue on Ejecta reports the current state of the art in ejecta physics, describing experimental, theoretical and computational work by research groups around the world. While much remains to be done, the dramatic recent progress in the field, some of it first reported here, means that this volume provides a particularly timely review.In this foreword, we provide a brief historical overview of the development of ejecta physics, to define the context for the work in the rest of this Special Issue.

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Power law and exponential ejecta size distributions from the dynamic fragmentation of shock-loaded Cu and Sn metals under melt conditions

Abstract: Large scale molecular dynamics (MD) simulations are performed to study and to model the ejecta production from the dynamic fragmentation of shock-loaded metals under melt conditions. A generic 3D crystal in contact with vacuum containing about 10 8 atoms and

Cited by 72 publications

References 70 publications

Mass-velocity and size-velocity distributions of ejecta cloud from shock-loaded tin surface using atomistic simulations

Mass-velocity and size-velocity distributions of ejecta cloud from shock-loaded tin surface using atomistic simulations

Communication: Slab thickness dependence of the surface tension: Toward a criterion of liquid sheets stability

Foreword to the Special Issue on Ejecta

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