Mechanisms of deformation under shock loading

Mogilevsky, M. M.

doi:10.1016/0370-1573(83)90030-3

Cited by 27 publications

(3 citation statements)

References 58 publications

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“…Additionally, unless the flyer and target are made of the same material, there is inevitably a region at the impact surface that is not in uniaxial strain but has a shear component present simply due to the difference in Poisson's ratio at this site. Such a feature has been observed microstructurally in metals (Mogilevsky & Newman 1983). Thus the impact face is a site seeing the highest strain rates, having the largest flaws and experiencing additional loading modes relative to the bulk of the material.…”

Section: Discussionmentioning

confidence: 76%

The onset of damage in shocked alumina

Bourne

2001

Proc. R. Soc. Lond. A

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Shock wave profiles have been measured simultaneously using the velocity interferometry system for any reflector (VISAR) and embedded foil stress gauges. The gauge is backed using a transparent rear window made of polymethylmethacrylate, through which the laser beam entering the VISAR cavity is also shone. The technique is applied to grades of alumina of differing purity shocked just above the threshold normally taken to be the Hugoniot elastic limit (HEL). In the case of one of the aluminas, the result is analogous to metals with a small spall (dynamic tensile strength) signal recorded. In the case of the other materials, the signals show marked differences, indicating both the need for simultaneous measurement using a variety of sensors and the limitations of the present definitions for the mechanical thresholds in dynamic compression (HEL) and tension (spall strength).

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Section: Discussionmentioning

confidence: 76%

The onset of damage in shocked alumina

Bourne

2001

Proc. R. Soc. Lond. A

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“…Such a dependence of dislocations generation has been also previously studied in quasi-static relaxation simulation in uniaxially compressed fcc crystals. 11) …”

Section: Simulation Technique and Resultsmentioning

confidence: 97%

Orientation Dependence of Shock Structure with Melting in L-J Crystal from Molecular Dynamics

Жаховский

Zybin

Nishihara

et al. 2000

Prog. Theor. Phys. Suppl.

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We use molecular dynamics to study the structure of steady shock waves with melting transition traveling along the 100 , 110 , and 111 directions in the Lennard-Jones (L-J) perfect fcc crystal. Unlike shock waves in gases and fluids, solid shocks exhibit oscillatory behaviour of profiles within the front that persists even in the strong shocks with melting. Surprisingly, shock wave along the 100 direction compresses the L-J crystal to the final overheated solid state in contrast to 110 and 111 cases wherein the crystal melted at the same shock velocity us = 4.39 km/s. Moreover, the 110 and 111 melting shock waves differ widely in the front structure: the 111 profile without oscillations is closely similar to that of the fluid shocks, whereas the 110 shock exhibits a steady precursor of solitary wave train. The evolution of velocity and pair distribution functions across the shock layer are explored to study the shock-induced structure transformations and melting transition occuring within the region of length roughly (10 ÷ 30) σ, σ = 3.405Ȧ. §1. IntroductionThe purpose of this paper is to address one of the important questions in physics of shock waves in solids: that is, what are the properties of nonequilibrium layer where the material transforms in going from the initial state in front of the shock to the final high-pressure and high-temperature equilibrium state behind the shock ? Understanding the internal structure of a shock wave is crucial to the development of appropriate continuum constitutive models as well as theoretical treatments of shock-induced phenomena, such as detonation. 1) This problem calls for high resolution in time-and space-measurements, and it is particularly well approached by the molecular dynamics (MD) simulation method.Previous MD studies of shock waves in solids have been primarily devoted to the simulation of shocks traveling along the 100 direction in fcc Lennard-Jones perfect crystal 2), 3) and demonstrated that the microscopic mechanism of their propagation is inherently more complex because plastic flow is governed by creation and motion of defects, not by viscous dissipation as in fluids. Owing to specially developed techniques for MD simulation in the reference frame of the shock which greatly reduces the statistical noise, we have found an oscillatory behaviour of 100 profiles within the shock front (also reported in certain of early simulation works 2) although not observed in subsequent studies) and examined it in close details. 4) It is suggested * )

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“…These include spallation within the target (dynamic tensile failure) and non-onedimensional, late-time plastic deformation due to lateral release loading (Stevens & Tuler 1971;Gray et al 1989;Gray 1993Gray , 2000. Shock recovery techniques have been developed over the past years using varying means of trapping momentum and different devices to introduce the pulse (Smith 1958;Dieter 1961;Zukas 1966;Mahajan 1970;Murr 1981;Mogilevsky & Newman 1983;Murr & Meyers 1983;Mogilevskii 1985;Meyers 1994;Llorca et al 2002). These techniques include design-orientation simulation to optimize target geometry (DeCarli & Meyers 1981;Rabie et al 1984;Tanaka et al 1984;Norwood et al 1986;Clifton et al 1990;Nellis & Gratz 1993;Hagelberg et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Computational design of recovery experiments for ductile metals

Bourne

Gray

2005

Proc. R. Soc. A.

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Previous work on the shock loading of metals, has shown that one-dimensional strain histories may be only be approximated in a loaded sample if it is to be recovered at late times to examine microstructure. This proceeds through the use of a system of partial momentum traps and soft, shock-recovery techniques. However, limitations in the degree of uniaxial loading, and on the trapping of tensile pulses, have led to redesign of the target. In the current paper the technique is first assessed, and then modifications are explored to further refine it. Additionally it is illustrated how it may be applied to successfully recover targets of lower innate fracture toughness than has been previously documented. In the first part of the paper, the authors review work undergone to shock recover metals, and highlight associated constraints. In the latter part of the paper, a series of hydrocode simulations is presented to illustrate the design of an improved shock recovery technique that has now been adopted.

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Mechanisms of deformation under shock loading

Cited by 27 publications

References 58 publications

The onset of damage in shocked alumina

The onset of damage in shocked alumina

Orientation Dependence of Shock Structure with Melting in L-J Crystal from Molecular Dynamics

Computational design of recovery experiments for ductile metals

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