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Necking
About: Necking is a research topic. Over the lifetime, 5280 publications have been published within this topic receiving 113945 citations.
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TL;DR: The modes of strain localization in the tensile testing of a sheet sample are diffuse necking, localized necking and localization in an unstable shear band as mentioned in this paper, and it is shown that the materials have similarH vs strain curves in the range of uniform tensile straining, but the curves diverge widely at higher strains whereH falls below 1.
Abstract: The modes of strain localization in the tensile testing of a sheet sample are diffuse necking, localized necking and, in some materials, localization in an unstable shear band. In a tensile test of a rate insensitive material, the normalized strain hardening parameter,H = (1/σ)(dσ/de) has the values ofH = 1 for diffuse necking andH = 0.5 for localized necking. Curves ofH vs strain were obtained up to large values of plastic strain using the hydraulic bulge test. The materials selected were commercially important sheet alloys in the condition normally used for forming. It is shown that the materials have similarH vs strain curves in the range of uniform tensile straining, but the curves diverge widely at higher strains whereH falls below 1. This has important consequences on strain localization behavior. The limit strains of the alloys in simple tension and punch stretching show reasonable correlation with their values ofH and those alloys which are susceptible to catastrophic shear failure have low values ofH at high strains. Strain rate sensitivity adds to or subtracts from theH values obtained in this study and has an additional influence on strain localization.
37 citations
TL;DR: In this article, the Johnson-Cook constitutive model was modified to consider the effects of both strain and strain rates on the strain hardening coefficient, and the results obtained from the improved Johnson-cook model are in remarkable accordance with those obtained from experimental work.
37 citations
TL;DR: In this article, the authors show that both the estimated value of the effective elastic thickness and the derived b-profile are dependent on the assumption of the depth of necking, which leads to an underestimation of the lithospheric strength and an overestimation of thinning factors.
37 citations
TL;DR: In this paper, the Hall-Petch and dislocation strengthening mechanisms were the key models of strengthening based on the calculations and microstructure characterizations since by increasing the TiB2 particles, significant grain refinement and dislocal density were shown.
37 citations
TL;DR: In this paper, a rate dependent Taylor type crystal plasticity formulation is employed to study the effects of post-necking hardening behavior on the M-K based forming limit diagram predictions.
37 citations