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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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Journal ArticleDOI
TL;DR: In this paper, an extension of the classical linear stability analysis applied to the dynamic extension of a round bar case has been developed to take into account the contribution of all perturbation modes on the preliminary evolution of pre-necks.

31 citations

Journal ArticleDOI
TL;DR: In this article, a main-chain liquid crystalline elastomer (LCE) undergoes the familiar polydomain−monodomain (P−M) transition, which is attributed to a change in the conformation of the elastic polymer backbones from hairpinned coils to extended chains.
Abstract: The mechanical response and the evolution of director orientation are characterized in a smectic, main-chain liquid crystalline elastomer (LCE) as it undergoes the familiar polydomain−monodomain (P−M) transition. Under uniaxial tension, the LCE behaves like an ordinary rubber-like network at low strains, and local director rotations are shown to slightly favor the perpendicular (“anomalous”) orientation of chain axes with respect to the draw direction. As strain increases, a well-defined yield stress is observed due to the onset of a necking instability. Macroscopic elongation proceeds by growth of the necked monodomain region, which appears to consume the non-necked polydomain region(s) at its boundaries. Within the necked region, the parallel (“normal”) orientation of chain axes with respect to the draw direction is strongly favored. The P−M transition is attributed to a change in the conformation of the elastic polymer backbones from hairpinned coils to extended chains. Under the conditions of temperat...

31 citations

Journal ArticleDOI
TL;DR: In this paper, the mechanical behavior in cross biaxial tension was investigated for two metallic sheets, an aluminium alloy and a dual phase steel, by digital image correlation, where minor and major strains were output along several paths, for a given load level just before necking, showing a wide range of strain states.
Abstract: The mechanical behavior in cross biaxial tension was investigated for two metallic sheets, an aluminium alloy and a dual phase steel. The heterogeneous strain field in the central gauge area of a cruciform specimen was analyzed by digital image correlation. Minor and major strains were output along several paths, for a given load level just before necking, showing a wide range of strain states, from uniaxial tension to biaxial state. The applied loads along the two loading directions were also recorded, the gap between the two signals being all the most important that the material anisotropy was significant. Moreover, the strain path ratio, defined as the ratio of the minor strain over the major strain, exhibited a sensible non-monotonic evolution along the transverse direction, compared to the rolling direction. Finally, a material parameter identification process with only biaxial tensile test for Bron and Besson anisotropic yield model was proposed, based on the minimization of experimental and numerical principal strains along a specified path in the gauge area of the cruciform specimen.

31 citations

Journal ArticleDOI
TL;DR: In this article, the micro-mechanisms of void coalescence at different stress triaxiality levels were investigated employing axisymmetrical smooth and notched tension specimens of spheroidized 37Mn5 steel.

31 citations

Journal ArticleDOI
TL;DR: In this article, the superplastic properties of a high specific strength steel (HSSS) with dual-phase microstructure and ultrafine grains were investigated under a temperature range of 873-973 K and at a wide strain rate range of 10 −4 −10 −1 /s.
Abstract: The superplastic behaviors of a high specific strength steel (HSSS) with dual-phase microstructure and ultrafine grains have been investigated under a temperature range of 873–973 K and at a wide strain rate range of 10 −4 –10 −1 /s. The ultrafine grained HSSS exhibits excellent superplastic properties. The microstructure observations at interrupted strains for tests under temperature of 973 K and at strain rate of 10 −3 /s have provided evidences of different mechanisms for two stages. At the first stage (strain range from 0% to 400%), the superplastic flow is attributed to the diffusional transformation from fcc austenite phase to intermetallic compound B2 phase coupled with grain boundary sliding. While intragranular dislocation activities should be the dominant mechanism for the second stage (strain range from 400% to 629%) due to the increased realistic strain rate by diffusive necking. The grain sizes of both phases are observed to be relatively stable and remain always sub-micron level during the high temperature tensile deformation, facilitating the superplastic flow.

31 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023174
2022351
2021241
2020249
2019213
2018238