Journal ArticleDOI
Void Nucleation Effects in Biaxially Stretched Sheets
C. C. Chu,Alan Needleman +1 more
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In this article, the effects of void nucleation occurring during the deformation history on forming limit curves are considered for both in-plane and punch stretching employing a constitutive model of a porous plastic solid.Abstract:
The effects of void nucleation occurring during the deformation history on forming limit curves are considered for both in-plane and punch stretching employing a constitutive model of a porous plastic solid. Both plastic strain controlled and stress controlled nucleation processes are simulated by a two parameter void nucleation criterion. For in-plane stretching, plastic strain controlled nucleation can have, in certain circumstances, a significantly destabilizing effect on the forming limit curve. However, within the framework of plane stress theory which neglects the enhance ment of the hydrostatic stress due to necking, a stress controlled nucleation process is not found to be significantly destabilizing. In punch stretching a ductile rupture criterion, which limits the maximum volume fraction of voids, as well as the ap pearance of a well defined thickness trough, is adopted as a localized necking criterion. Only plastic strain controlled void nucleation is considered here in out-ofplane stretching. The resulting forming limit curves have the same shape as those obtained previously with void nucleation neglected.read more
Citations
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Journal ArticleDOI
Analysis of the cup-cone fracture in a round tensile bar
Viggo Tvergaard,Alan Needleman +1 more
TL;DR: In this article, a set of elastic-plastic constitutive relations that account for the nucleation and growth of micro-voids is used to model the failure of a round tensile test specimen.
Journal ArticleDOI
On localization in ductile materials containing spherical voids
TL;DR: In this article, an axisymmetric numerical model and a set of approximate constitutive equations for a voided material suggested by Gurson were used to analyse bifurcation into a localized mode.
Book ChapterDOI
Material Failure by Void Growth to Coalescence
TL;DR: In this paper, a convected coordinate formulation of the field equations is used to describe the material failure by coalescence of microscopic voids, and a detailed micromechanical study of shear band bifurcation that accounts for the interaction between neighboring voids and the strongly nonhomogeneous stress distributions around each void has been carried out, and also elaborated in this chapter.
Journal ArticleDOI
Modification of the Gurson Model for shear failure
Ken Nahshon,John W. Hutchinson +1 more
TL;DR: In this paper, an extension of the Gurson model is proposed that incorporates damage growth under low triaxiality straining for shear-dominated states, which can be used to characterize important growth and coalescence features.
Journal ArticleDOI
An extended model for void growth and coalescence
TL;DR: In this article, a model for the axisymmetric growth and coalescence of small internal voids in elastoplastic solids is proposed and assessed using void cell computations.
References
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Journal ArticleDOI
Continuum Theory of Ductile Rupture by Void Nucleation and Growth: Part I—Yield Criteria and Flow Rules for Porous Ductile Media
Journal ArticleDOI
Limit strains in the processes of stretch-forming sheet metal
TL;DR: In this paper, a theoretical analysis of the process of the generation of the groove based on anisotropic plasticity theory is presented, and the system of equations derived was solved numerically with the aid of a computer, which enabled the limiting strain of the sheet metal to be determined as a function of the material.
Journal ArticleDOI
Cavity formation from inclusions in ductile fracture
A. S. Argon,Jay Im,R. Safoglu +2 more
TL;DR: In this article, the authors examined the conditions for cavity formation from equiaxed inclusions in ductile fracture and found that critical local elastic energy conditions are necessary but not sufficient for cavities formation.
Journal ArticleDOI
Ductile fracture in metals
TL;DR: In this article, Tipper et al. showed that the cup-and-cone fracture in single-phase ductile metals appears to originate at holes formed by drawing away of material from non-metallic inclusions, as suggested by Tipper.
Book ChapterDOI
Limits to ductility set by plastic flow localization
Alan Needleman,James R. Rice +1 more
TL;DR: The theory of strain localization is reviewed with reference both to local necking in sheet metal forming processes and to more general three dimensional shear band localizations that sometimes mark the onset of ductile rupture as mentioned in this paper.