Dynamic yield behavior of shock-loaded iron from 76 to 573°k

Rohde, R. W.

doi:10.1016/0001-6160(69)90075-3

Cited by 69 publications

(16 citation statements)

References 22 publications

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“…The elastic precursor decay is obtained by subtracting the corresponding curve shown in fig.2 from a reference hyper-elastic state. Fig.2 is consistent with experimental observation that the rate of decay increases with the strain rate [39]. Here the strain rate's effect is not entirely comparable to experiment, as in the latter the magnitude of the shock itself would vary too [40].…”

supporting

confidence: 84%

Attenuation of the Dynamic Yield Point of Shocked Aluminum Using Elastodynamic Simulations of Dislocation Dynamics

et al. 2015

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When a metal is subjected to extremely rapid compression, a shock wave is launched that generates dislocations as it propagates. The shock wave evolves into a characteristic two-wave structure, with an elastic wave preceding a plastic front. It has been known for more than six decades that the amplitude of the elastic wave decays the further it travels into the metal: this is known as "the decay of the elastic precursor". The amplitude of the elastic precursor is a dynamic yield point because it marks the transition from elastic to plastic behaviour. In this letter we provide a full explanation of this attenuation using the first method of dislocation dynamics to treat the time dependence of the elastic fields of dislocations explicitly. We show that the decay of the elastic precursor is a result of the interference of the elastic shock wave with elastic waves emanating from dislocations nucleated in the shock front. Our simulations reproduce quantitatively recent experiments on the decay of the elastic precursor in aluminum, and its dependence on strain rate.The dynamic behaviour of crystalline solids subjected to shock compression plays a central role in diverse applications, including bird strikes in aerospace [1], crashworthiness in the automobile industry [2], and manufacturing processes such as laser shock peening [3], amongst many others. Upon being shocked within a range of strain rates and pressures of typically 10 6 − 10 10 s −1 and 5 − 50GPa [1], the shock front in crystalline materials often displays a characteristic two-wave structure near the loading surface: the plastic wave front leading to the Hugoniot shocked state is preceded by an elastic precursor wave [1]. The amplitude of the elastic precursor wave decays as the wave front advances[1, 4]-a phenomenon known as the 'decay of the elastic precursor'. The amplitude of the elastic wave marks the onset of plasticity, i.e. it is the dynamic yield point. The subsequent plastic wave is commonly ascribed to the generation and motion of dislocations, the agents of plasticity in crystalline solids [9].The cause of its attenuation remains unclear after six decades [4][5][6][7][8]. Clifton and Markenscoff [4] calculated analytically the amplitude attenuation of a planar elastic shock wave caused by the destructive interference of elastic wavelets emanating from pre-existing dislocations set into motion by the passage of a shock wave of infinite strain rate; dislocation generation by the shock was neglected. Consequently, the elastic precursor decay was attributed to the density and initial velocity of pre-existing dislocations. Armstrong et al.[10] studied the dislocation relaxation mechanisms during high strain rate shock loading, concluding that dislocation generation dominates plastic relaxation under shock loading. This is because the number of pre-existing dislocations is about two to three orders of magnitude less than that generated during the shock [1,4,7].In this letter we show that we can account for the experimentally observed residual disloca...

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confidence: 84%

Attenuation of the Dynamic Yield Point of Shocked Aluminum Using Elastodynamic Simulations of Dislocation Dynamics

et al. 2015

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“…(56) found,systematica11y, an increase in twin density as the pulse duration was increased from 0.5 to 1.0 ~s, in both the A1S1 1008 steel and Armco magnetic ingot iron. The twins generated by the shock pulse should not be confused with the ones formed by the elastic precursor wave, in iron; the latter ones were investigated by Rohde and coworkers (57,58). Although twins are generated by the elastic precursor waves, the volume percent of twins generated by the shock wave is an order of magnitude higher.…”

Section: Deformation Twinning a Effect Of Materials And Shock-wavementioning

confidence: 99%

Defect Generation in Shock-Wave Deformation

Meyers

Murr

1981

Shock Waves and High-Strain-Rate Phenomena in Metals

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“…s is the static flow stress and is regarded as the average between the yield stress and ultimate tensile stress for the purposes of this paper, and F~2 psi sec. Comparisons with recent measurements [13][14][15][16][17][18][19] show that Equation (12) description of actual test data. The interpretation is complicated by twinning, which is not very prevalent in fine-grained pipe steels but may have reduced the strength levels observed by Rhode [19] and by Oxley and Stevenson [17] at the highest strain rates.…”

Section: Plastic Deformationmentioning

confidence: 82%

“…This means that ~ 1.2 x 104-1.5 x 105 sec-1 for a crack propagating at 500 fps. The flow stress, t?, of steel under these conditions is likely to be 2 x to 3 x the value measured in an ordinary tensile test [13][14][15][16][17][18][19][20], and this will influence the magnitude of the COD, as described in the next section. Following the procedure in Reference 21, the rate dependence is approximated by a simple linear relation :…”

Section: Plastic Deformationmentioning

confidence: 99%

A model for unstable shear crack propagation in pipes containing gas pressure

et al. 1973

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A B S T R A C T A tentative analysis of an unstable shear crack propagating axially in the wall of a long pipe under gas pressure is developed. Six processes known to be associated with crack propagation are treated numerically: (1) axial decompression of the gas, (2) bulging of the pipe wall, (3) radial decompression of the gas, (4) local stress and strain intensification at the crack tip, (5) plastic deformation, and (6) ductile cracking. The treatment is quasi-static; dynamic effects in the pipe wall are ignored. Because the numerical descriptions included in the model are approximate and incomplete, several variants of the basic model are examined. The response of the model is evaluated for different line pressures, geometries, and material properties and compared with full-scale test data for 100% shear cracks. A wide range of speeds can be calculated for the limits within which the system parameters are specified including the speeds observed in practice. The bulging and decompression characteristics of the model cause the crack speed to be relatively insensitive to line pressure. Yet the calculated crack speeds are influenced by yield strength and toughness of the material. The model does not provide for nonaxial crack paths, nor does it adequately describe crack-arrest possibilities. The paper represents the first step in the analysis of a complex problem.

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Dynamic yield behavior of shock-loaded iron from 76 to 573°k

Cited by 69 publications

References 22 publications

Attenuation of the Dynamic Yield Point of Shocked Aluminum Using Elastodynamic Simulations of Dislocation Dynamics

Attenuation of the Dynamic Yield Point of Shocked Aluminum Using Elastodynamic Simulations of Dislocation Dynamics

Defect Generation in Shock-Wave Deformation

A model for unstable shear crack propagation in pipes containing gas pressure

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