On the power-law pressure dependence of the plastic strain rate of crystals under intense shock wave loading

Malygin, G. A.; Ogarkov, S. L.; Andriyash, A. V.

doi:10.1134/s1063783413040197

Cited by 24 publications

(11 citation statements)

References 21 publications

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“…Malygin, Ogarkov, and Andriyash have recently given a dislocation model explanation of the fourth power law in which dislocation generation accounts for a large part of the pressure dependence but dislocation drag resistance to dislocation motion is also involved. [64] B.…”

Section: ½12mentioning

confidence: 98%

Dislocation Mechanics of High-Rate Deformations

Armstrong

2015

Metall Mater Trans A

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Four topics associated with constitutive equation descriptions of rate-dependent metal plastic deformation behavior are reviewed in honor of previous research accomplished on the same issues by Professor Marc Meyers along with colleagues and students, as follow: (1) increasing strength levels attributed to thermally activated dislocation migration at higher loading rates;(2) inhomogeneous adiabatic shear banding; (3) controlling mechanisms of deformation in shock as compared with shock-less isentropic compression experiments and (4) Hall-Petchbased grain size-dependent strain rate sensitivities exhibited by nanopolycrystalline materials. Experimental results are reviewed on the topics for a wide range of metals.

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Section: ½12mentioning

confidence: 98%

Dislocation Mechanics of High-Rate Deformations

Armstrong

2015

Metall Mater Trans A

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“…Malygin et al, 2013). In the absence of any thermal assistance homogeneous nucleation can occur only if the applied stress is at least as large as the theoretical shear strength of the crystal lattice (Tschopp and McDowell, 2008).…”

Section: Dynamic Discrete Dislocation Plasticity Simulations Of Sourcmentioning

confidence: 99%

The mechanisms governing the activation of dislocation sources in aluminum at different strain rates

Gurrutxaga-Lerma

Balint

Dini

et al. 2015

Journal of the Mechanics and Physics of Solids

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a b s t r a c tThis article examines the time to activate Frank-Read sources in response to macroscopic strain rates ranging from 10 1 s À 1 to 10 10 s À 1 in aluminium under athermal conditions. We develop analytical models of the bowing of a pinned dislocation segment as well as numerical simulations of three dimensional dislocation dynamics. We find that the strain rate has a direct influence on both the activation time and the source strength of FrankRead sources at strain rates up to 10 6 s À 1 , and the source strength increases in almost direct proportion to the strain rate. This contributes to the increase in the yield stress of materials at these strain rates. Above 10 6 s À 1 , the speed of the bowing segments reaches values that exceed the domain of validity of the linear viscous drag law, and the drag law is modified to account for inertial effects on the motion of the dislocation. As a result the activation times of Frank-Read sources reach a finite limit at strain rates greater than 10 8 s À 1 , suggesting that Frank-Read sources are unable to operate before homogeneous nucleation relaxes elastic stresses at the higher strain rates of shock loading. Elastodynamic calculations are carried out to compare the contributions of Frank-Read sources and homogeneous nucleation of dislocations to plastic relaxation. We find that at strain rates of 5 Â 10 7 s À 1 homogeneous nucleation becomes the dominant generation mechanism.

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“…7 True stress-true strain curves for large and small grain-size 2169 samples loaded via SHPB in compression Fig. 8 Flow stress at 10 % strain determined from this research and other austenitic stainless steels; 2169 from Follansbee et al [12,13], Nitronic 50 from Guo and Nemat-Nasser [30], 304L from Follansbee [13] and 316L from Follansbee [13], Sencer et al [25] and Gray et al [31] coefficient A. Malygin et al [36] related A to the inverse of the dislocation viscous drag coefficient however they were unable to match the theory to data within published limits on the values of the coefficient. Very little else has been discussed in the literature about the origins of A although it seems reasonable, as has been hypothesized by Millett et al [37], that A could also be considered to be related to deformation mechanisms at play in shocked materials, particularly a material's ability to accommodate plasticity via dislocation generation and motion.…”

Section: Discussionmentioning

confidence: 99%

“…discounting the points where the Bland number (a dimensionless number defined by Swegle and Grady [32] as the ratio of sample thickness to steady-wave propagation distance as defined by Bland [33]) is less than unity. Previous research has suggested that the fourth power relation is related to dissipative mechanisms at the shock front, including dislocation activity in crystalline materials [34] or more specifically the nucleation, density and velocity of dislocations [35] and the power law pressure dependence of the density of geometrically necessary dislocations generated at the shock wave front in combination with the rate of viscous motion of dislocations [36]. As the fourth power rule appears to be largely universal, particularly for metallic materials, the division of data from different materials appears via the Fig.…”

Section: Discussionmentioning

confidence: 99%

The Behaviour of 2169 Steel Under Uniaxial Stress and Uniaxial Strain Loading

Whiteman

Keightley

Millett

2016

J. dynamic behavior mater.

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A series of plate impact and uniaxial stress compression experiments have been undertaken on 2169 steel, a nitrogen strengthened austenitic stainless steel. The shock experiments ranged from impact stresses of 3.7-17.8 GPa, recording the wave profiles of the shock and spall behaviour observed at the rear target surfaces. Target and impactor configurations were varied to observe the effects of tensile strain-rates achieved at spall planes. Spall strength was observed to vary linearly with impact stress and tensile strain-rate although was less rate sensitive than 300 series steels suggestive of an influence of the shock induced microstructure on void nucleation. A fourth power relationship between strain-rate in the shock front and shock stress was observed similar to many other materials. The linear coefficient A relating the two is discussed in terms of dislocation mobility. Uniaxial stress compression experiments were undertaken on two grain sizes of the same material at a range of strain-rates from *10 -4 to 10 3 s -1 . The data is consistent with other published data on 2169 steel showing a clear grain-size dependence on flow stress and higher flow stresses than other common austenitic steels.

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On the power-law pressure dependence of the plastic strain rate of crystals under intense shock wave loading

Cited by 24 publications

References 21 publications

Dislocation Mechanics of High-Rate Deformations

Dislocation Mechanics of High-Rate Deformations

The mechanisms governing the activation of dislocation sources in aluminum at different strain rates

The Behaviour of 2169 Steel Under Uniaxial Stress and Uniaxial Strain Loading

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