A three-dimensional numerical study of mode I crack tip fields in pressure sensitive plastic solids

Subramanya, HY; Viswanath, S; Narasimhan, R.

doi:10.1016/j.ijsolstr.2006.08.003

Cited by 25 publications

(19 citation statements)

References 35 publications

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“…This figure confirms that stress levels drop appreciably as free surface of the specimen is approached. The above behavior is similar to that reported for isotropic plastic solids where high hydrostatic stress levels are found to prevail close to the crack tip at the mid-plane and reduce as the free surface is approached (Narasimhan and Rosakis 1990;Subramanya et al 2007). …”

Section: Contours Of Normal and Hydrostatic Stresssupporting

confidence: 87%

“…The layers of nodes are located at X 3 / h = 0.0, 0.038, 0.084, 0.14, 0.20, 0.28, 0.38, 0.5. Thus, the layers become gradually thinner as the free surface (X 3 = 0) is approached in order to capture the strong through-thickness variation of the field quantities close to the notch root (Narasimhan and Rosakis 1990;Subramanya et al 2007). …”

Section: Modeling Aspectsmentioning

confidence: 99%

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Finite element simulations of notch tip fields in magnesium single crystals

2014

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Recent experiments using three point bend specimens of Mg single crystals have revealed that tensile twins of {1012}-type form profusely near a notch tip and enhance the fracture toughness through large plastic dissipation. In this work, 3D finite element simulations of these experiments are carried out using a crystal plasticity framework which includes slip and twinning to gain insights on the mechanics of fracture. The predicted load-displacement curves, slip and tensile twinning activities from finite element analysis corroborate well with the experimental observations. The numerical results are used to explore the 3D nature of the crack tip stress, plastic slip and twin volume fraction distributions near the notch root. The occurrence of tensile twinning is rationalized from the variation of normal stress ahead of the notch tip. Further, deflection of the crack path at twin-twin intersections observed in the experiments is examined from an energy standpoint by modeling discrete twins close to the notch root.

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Section: Contours Of Normal and Hydrostatic Stresssupporting

confidence: 87%

Section: Modeling Aspectsmentioning

confidence: 99%

Finite element simulations of notch tip fields in magnesium single crystals

2014

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“…5, is because the crack front is driven by the hydrostatic stress gradient in the FMI mechanism [37]. Further, studies on 3-D crack tip fields in elastic-plastic solids show that the hydrostatic stress distribution along the thickness direction is uniform for the predominant portion of the specimen thickness [40,41]. Argon and Salama [37] analyzed the condition for breakdown of a blunted crack front perturbed along the thickness direction into fingers owing to the positive suction gradient ahead of it.…”

Section: Fracture Mechanismmentioning

confidence: 99%

On the mechanism and the length scales involved in the ductile fracture of a bulk metallic glass

2013

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“…Basu and Van der Giessen (2002) conducted a finite deformation analysis of crack tip fields in glassy polymers using a viscoplastic constitutive model that incorporated softening as well as orientation hardening. For pressure sensitive plastic solids, Subramanya et al (2007) performed a 3D finite element analysis of mode I crack tip fields under small-scale yielding (SSY) conditions. The crack tip for MGs was studied by Tandaiya et al(2007Tandaiya et al( , 2008, by using a continuum elastic-viscoplastic constitutive theory developed by Anand and Su (2005), and it was found that these features of plastic field, in turn, are influenced by the mechanical characteristics of MGs like Poisson's ratio and pressure sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Nature of crack-tip plastic zone in metallic glasses

Chen

Dai

2016

International Journal of Plasticity

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a b s t r a c tThe fracture of metallic glasses(MGs) can be induced by shear banding in a ductile mode or by cavitation in a brittle way. Plastic zone in front of a crack tip, which is greatly involved with localized shear band, cavitation and the resultant fracture morphology, is a key clue to unveil the secrets of the intrinsic ductility and fracture. However, the characteristics of plastic zone, i.e., stress and strain distributions, size and shape, have not been clearly unraveled for MGs so far. In this paper, an analytical solution of the plastic zone for mode I crack under plane strain condition is derived through J-integral based on a slip line field analysis and shape approximation, by taking pressure-sensitivity, dilatancy, and structural evolution into account. Two length scales of the plastic zone, i.e. the maximum radius R max and the radius along the crack line direction R x , are revealed to control shear flow instability and cavitation, and therefore failure modes. According to shear transformation zone (STZ) based free volume evolution dynamics, the critical values of the mode I stress intensity factor and the plastic zone size at crack initiation are obtained. The effects of Poisson's ratio, pressure sensitivity, and dilatancy on the stress/strain distributions, and the size of plastic zone are elucidated. It is found that larger Poisson's ratio and smaller dilatancy lead to higher fracture toughness and 'slender' critical plastic zone, facilitating a good ductility. The internal correlations of the fracture pattern (i.e. dimple structure) with the plastic zone are established, where the size of the fracture pattern is quantitatively characterized by the critical length of plastic zone. To be further, a shape change of the critical plastic zone from 'slender' (apt to shear plastic flow) to 'chubby' (inclined to cavitation) is revealed with increasing dilatancy or decreasing Poisson's ratio, which might shed light on the underlying mechanism of ductile-to-brittle transition in MGs.

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A three-dimensional numerical study of mode I crack tip fields in pressure sensitive plastic solids

Cited by 25 publications

References 35 publications

Finite element simulations of notch tip fields in magnesium single crystals

Finite element simulations of notch tip fields in magnesium single crystals

On the mechanism and the length scales involved in the ductile fracture of a bulk metallic glass

Nature of crack-tip plastic zone in metallic glasses

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