Spontaneous and forced shear localization in high-strain-rate deformation of tantalum

Chen, Y.-J; Meyers, Marc A.; Nesterenko, V. F.

doi:10.1016/s0921-5093(99)00110-0

Cited by 57 publications

(28 citation statements)

References 27 publications

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“…Thus, as is clearly stated in [8], the shear failure in these specimens is not caused by material propensity to this mode of failure but because of the geometrical details of the specimens. In fact, specimens of any material are bound to fail by shearing due to stress concentrations at these specimens, as was pointed out in [9]. This point may be a trivial one but we find it important as some researchers assign these geometrical instabilities to material properties which, as we just pointed out, is incorrect.…”

Section: Methodsmentioning

confidence: 70%

“…These constraints were termed by CHEN et al [9] as forced localization and they are present in many real situations such as in terminal ballistics of blunt projectiles penetrating hard targets. MOLINARI and CLIFTON [14] analyze the different softening mechanisms which can operate under shear loading, either static or dynamic.…”

Section: Discussionmentioning

confidence: 99%

“…Such are the geometries of the hat-shaped specimen (see TENG et al [8] and CHEN et al [9], for example), the notched specimens (see RITTEL et al [10]), and the truncated cone which was used by LI et al [11]. All of these special geometries introduce localized instabilities through stress concentrations which enhance the shear failure of these specimens.…”

Section: Methodsmentioning

confidence: 99%

“…Thus, compression experiments with the Kolsky bar should be done on straight cylinders which experience a uniform strain throughout their volume. The work of CHEN et al [9] demonstrates this issue very effectively since they tested two shapes of tantalum specimens in their Kolsky bar. The straight cylinders did not fail even under high loading rates and large strains, while the hat-shaped cylinders failed easily by shearing along the planes where the stresses were concentrated by the geometry.…”

Section: Methodsmentioning

confidence: 99%

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The effect of specimen dimensions on the propensity to adiabatic shear failure in Kolsky bar experiments

Rosenberg

Ashuach

Kreif³

2010

Matéria (Rio J.)

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The issue of adiabatic shearing is discussed in this work and a new interpretation is given to some failure phenomena which are usually termed as adiabatic shears. We propose that only a few materials undergo a truly inherent failure which is due to thermal softening at the shearing zone and that the interplay between microvoids, cracks and narrow shear bands should be taken into account through the temperature rise at the front of advancing cracks. Also, the size of the plastic zone ahead of a crack plays an important role in determining the brittleness of a given specimen and should be taken into account when specimens of different sizes are tested. Experimental results for several alloys in the Kolsky bar system support our approach.Keywords: Kolsky bar, SHPB, adiabatic shear banding. INTRODUCTIONAdiabatic shear banding is one of the major failure mechanisms of solids subjected to high rate loading. Extensive research on this subject has been conducted over the past 50 years, both experimentally and theoretically, much of which is summarized in BAI and DODD [1]. The most common explanation of this dynamic instability is based on the competing tendencies of the solid to strengthen at high strains (and strain rates) and, on the other hand, to soften with the temperature increase under adiabatic loading conditions. Although many materials seem to behave accordingly, the basic mechanism which causes this softening is still unresolved. Recent work on the subject is focused on the basic physics behind this process, as can be found in [2-5], for example. These works emphasize the link between adiabatic shearing and ductile fracture by the coalescence of microvoids, since the shear zones act as precursor sites for eventual failure by cracks (see [2]). GIOVANOLA [3,4] conducted a careful experimental study on 4340 steel specimens, in order to follow the evolution of strain localization and failure which he finds to proceed in two stages. He found that the first stage of localization (deformed bands) results in the formation of local perturbations for the strain field, such as machining marks. These perturbations grow as a result of the imbalance between strain hardening and thermal softening. In the second stage, softening is due to the nucleation and growth of microvoids, leading to the shear fracture within the band. GIOVANOLA [3,4] suggested that this process can take place under other conditions, including quasi-static loading. He also emphasized the role of the compressive stress which acts on the shear plane to reduce the microvoid nucleation process.FLOCKHART et al.[5] used numerical simulations to follow the shear band in dynamically compressed specimen, by analyzing the loci of velocity discontinuities within the specimen. They also claim that "the distinction between shear fracture and adiabatic shear failure is not clear", and that "material susceptibility to adiabatic shear alone does not guarantee that failure occurs by this mechanism, as shear fracture may intervene". This interplay between shear...

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Section: Methodsmentioning

confidence: 70%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

The effect of specimen dimensions on the propensity to adiabatic shear failure in Kolsky bar experiments

Rosenberg

Ashuach

Kreif³

2010

Matéria (Rio J.)

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“…A largura da banda de cisalhamento não deve ser considerada constante em toda a sua extensão, conforme mostra, em detalhes, a Figura 2. Assim sendo, este método de determinação da largura não pode ser considerado muito rigoroso, em razão de existir uma alta deformação localizada, tanto na parte superior, quanto inferior da amostra (Chen, 1999). No entanto, a razão entre o deslocamento (δ) e a largura da banda (ξ) descreve bem o estado de tensões de cisalhamento puro na região cisalhada (Andrade, 1994).…”

Section: Resultsunclassified

Aspectos microestruturais da falha de um aço IF deformado via compressão dinâmica a -196ºC

Lins¹,

Sandim

Vecchio³

2009

Rem: Rev. Esc. Minas

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Mesomechanics of Porous Materials Under Intense Dynamic Loading

Nesterenko

2001

Dynamics of Heterogeneous Materials

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Spontaneous and forced shear localization in high-strain-rate deformation of tantalum

Cited by 57 publications

References 27 publications

The effect of specimen dimensions on the propensity to adiabatic shear failure in Kolsky bar experiments

The effect of specimen dimensions on the propensity to adiabatic shear failure in Kolsky bar experiments

Aspectos microestruturais da falha de um aço IF deformado via compressão dinâmica a -196ºC

Mesomechanics of Porous Materials Under Intense Dynamic Loading

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