Void growth and failure in notched bars

Becker, Richard; Needleman, A.; Richmond, O.; Tvergaard, Viggo

doi:10.1016/0022-5096(88)90014-2

Cited by 199 publications

(85 citation statements)

References 31 publications

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“…There are numerous works analyzing the ductile rupture of notched bars by means of numerical solutions, for example, , (Becker et al, 1988) and (Besson et al, 2001). In particular, (Besson et al, 2001) and (Besson et al, 2003) utilize the localization bifurcation criterion as a localization indicator as we do.…”

Section: Ductile Fracture In Notched Barsmentioning

confidence: 99%

A finite thickness band method for ductile fracture analysis

Huespe

Needleman

Oliver

et al. 2009

International Journal of Plasticity

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We present a finite element method with a finite thickness embedded weak discontinuity to analyze ductile fracture problems. The formulation is restricted to small geometry changes. The material response is characterized by a constitutive relation for a progressively cavitating elastic-plastic solid. As voids nucleate, grow and coalesce, the stiffness of the material degrades. An embedded weak discontinuity is introduced when the condition for loss of ellipticity is met. The resulting localized deformation band is given a specified thickness which introduces a length scale thus providing a regularization of the post-localization response. Also since the constitutive relation for a progressively cavitation solid is used inside the band in the post-localization regime, the traction-opening relation across the band depends on the stress triaxiality. The methodology is illustrated through several example problems including mode I crack growth and localization and failure in notched bars. Various finite element meshes and values of the thickness of the localization band are used in the calculations to illustrate the convergence with mesh refinement and the dependence on the value chosen for the localization band thickness.

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Section: Ductile Fracture In Notched Barsmentioning

confidence: 99%

A finite thickness band method for ductile fracture analysis

Huespe

Needleman

Oliver

et al. 2009

International Journal of Plasticity

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“…Values of n on the order of 100 are frequently used for metals (see e.g., Ref. 10), so that the value of e at yield is within a few percent of y for the strain rates that are encountered in our analysis. The elastic part of the strain rate,…”

Section: Fig 1 Geometry Of the Analyzed Problemmentioning

confidence: 99%

Delamination of a strong film from a ductile substrate during indentation unloading

Abdul-Baqi

Giessen

2001

J. Mater. Res.

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In this work, a finite element method was performed to simulate the spherical indentation of a ductile substrate coated by a strong thin film. Our objective was to study indentation-induced delamination of the film from the substrate. The film was assumed to be linear elastic, the substrate was elastic–perfectly plastic, and the indenter was rigid. The interface was modeled by means of a cohesive surface. The constitutive law of the cohesive surface included a coupled description of normal and tagential failure. Cracking of the coating itself was not included. During loading, it was found that delamination occurs in a tangential mode rather than a normal one and was initiated at two to three times the contact radius. Normal delamination occurred during the unloading stage, where a circular part of the coating, directly under the contact area was lifted off from the substrate. Normal delamination was imprinted on the load versus displacement curve as a hump. There was critical value of the interfacial strength above which delamination was prevented for a given material system and a given indentation depth. The energy consumption by the delamination process was calculated and separated from the part dissipated by the substrate. The effect of residual stress in the film and waviness of the interface on delamination was discussed.

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“…Tvergaard (1981) and Needleman and Tvergaard (1984) tried to modify Gurson's model by adding more parameters so as to bring shear band bifurcation predictions of the Gurson constitutive relation into closer agreement with corresponding results of full numerical analysis and to take into account the eects of rapid void coalescence at failure. A sophisticated process was implemented to determine the parameters for making comparisons of the calculations between the modi®ed Gurson model and those of experimental results (Becker et al, 1988). As another approach, Li (1985b) proposed to use dilatational constitutive equations to account for the voiding damage.…”

Section: Introductionmentioning

confidence: 99%

On the mechanism of void growth and the effect of straining mode in ductile materials

Ling

Shen

2000

International Journal of Plasticity

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Finite element analysis is employed to investigate void growth embedded in elastic±plastic matrix material. Axisymmetric and plane stress conditions are considered. The simulation of void growth in a unit cell model is carried out over a wide range of triaxial tensile stressing or large plastic straining for various strain hardening materials to study the mechanism of void growth in ductile materials. Triaxial tension and large plastic strain encircling around the void are found to be of most importance for driving void growth. The straining mode of incremental loading which favors the necessary strain concentration around void for its growth can be characterized by the vanishing condition of a parameter called``the third invariant of generalized strain rate''. Under this condition, it accentuates the internal strain concentration and the strain energy stored/dissipated within the material layer surrounding the void. Experimental results are cited to justify the eect of this loading parameter. #

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Void growth and failure in notched bars

Cited by 199 publications

References 31 publications

A finite thickness band method for ductile fracture analysis

A finite thickness band method for ductile fracture analysis

Delamination of a strong film from a ductile substrate during indentation unloading

On the mechanism of void growth and the effect of straining mode in ductile materials

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