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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, the formation of multiple necks and cracks around perforations in ductile materials is investigated, and expressions for the number of plane-strain radial necks formed by conical penetrators (with or without starter holes in the flat target), and also by round-ended projectiles into flat targets having starter holes or, in plain targets with no starter holes, after fracture of the initial circumferential neck has detached a circular cap of material (discing).

55 citations

Journal ArticleDOI
TL;DR: In this article, a quasi-one-dimensional model is used to describe the self-thinning process of carbon nanotubes in uniaxial elongation and simple shear.
Abstract: Rheological behavior of concentrated suspensions of chemical vapor deposition carbon nanotubes in uniaxial elongation and simple shear is studied experimentally and theoretically. Nanotubes are suspended in viscous host liquids—castor oil or its blends with n-decane. The elongational measurements are performed by analyzing self-thinning (due to surface tension effect) liquid threads of nanotube suspensions. A quasi-one-dimensional model is used to describe the self-thinning process, whereas corrections accounting for thread nonuniformity and necking are introduced a posteriori. The effects of nanotube concentration and aspect ratio, viscosity of the suspending liquid, and initial diameter of the self-thinning thread in uniaxial elongation are elucidated. The results for uniaxial elongation are compared with those for simple shear. The correspondence in the results of the shear and elongational measurements is addressed and interpreted. The results conform to the Herschel–Bulkley rheological constitutive equation (i.e., power law fluids with yield stress). However, the yield stress in elongation is about 40% higher than in simple shear flow, which suggests that the original Herschel–Bulkley model need modification with the yield stress being a function of the second invariant of the deviatoric stress tensor. The present effort is the first to study capillary self-thinning of Herschel–Bulkley liquids, which are exemplified here by suspensions of carbon nanotubes.

55 citations

Journal ArticleDOI
TL;DR: In this article, the prediction of forming limits computed from an initial defect approach combined with a rate-independent polycrystalline plasticity model is presented, and results are compared with the forming limit curves at necking and at failure for 6116-T4 aluminium.

55 citations

Journal ArticleDOI
TL;DR: In this paper, an experimental program was designed to probe the path-dependence of the fracture locus in ductile materials, where the material and loading conditions were chosen so that cavitation-induced failure is the basic damage mechanism.

55 citations

Journal ArticleDOI
TL;DR: A theoretical study of the stability of extending liquid filaments has been carried out in this article, where the interaction of surface tension and different fluid rheological properties is investigated, and it is also hypothesized that cohesive failure or fracture will occur if a critical stress level is reached.
Abstract: A theoretical study of the stability of extending liquid filaments has been carried out. The interaction of surface tension and different fluid rheological properties is investigated. It is also hypothesized that cohesive failure or fracture will occur if a critical stress level is reached. It is predicted that viscosity and viscoelasticity tend to stabilize the filaments. However, even extremely high viscosity filaments will neck and exhibit ductile failure. In highly viscoelastic fluids, defects tend to heal during stretch. Highly viscoelastic fluid filaments fail by fracture. The theory is used to predict the failure of molten polymer filaments as a function of molecular weight. The extensibility or spinnability of filaments is predicted to exhibit a maximum at intermediate molecular weights with capillarity-ductile failure occurring at low molecular weights and cohesive fracture, at high molecular weights. The results are compared to experiments on polyethylenes. There is general qualitative agreement especially with the behavior of low and high molecular weights where capillarity and fracture occur. The tendency to necking and ductile failure differs considerably among melts and is more pronounced in high-density than in low-density polyethylenes. The application to continuous spinline behavior is discussed, and draw resonance is suggested to be the continuous process analogue of ductile failure.

55 citations


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