Topic
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: In this article, an important and novel mechanism for ductile failure of the lithosphere is identified, which is intrinsic to the thermal-mechanical feedback in a temperature dependent plastic body with coupled elastic fields.
Abstract: An important and novel mechanism for ductile failure of the lithosphere is identified here, which is intrinsic to the thermal-mechanical feedback in a temperature dependent plastic body with coupled elastic fields. Both a temperature-dependent power-law visco-elasto-plastic rheology and a temperature-dependent elasto-plastic rheology are employed to study in a self-consistent fashion the deformation of the lithosphere subject to extension by means of a two-dimensional, finite-element code. A structural perturbation initially localizes elasto-plastic deformation only in its immediate vicinity. However, after 800,000 years have elapsed the localized zone of deformation takes off in a ‘crack-like’ fashion and travels to the bottom of the lithosphere in about 50,000 years time. When the plate is severed, thermal runaway is caused by mechanical heating triggered by the rapid energy transfer of the globally stored elastic energy into localized plastic dissipation in the ductile fault.
82 citations
TL;DR: In this article, the authors analyzed the effect of rejuvenation of deformation in previously stabilized sections while tunnel excavation is progressing and found that, occasionally, large deformation from specific ‘source’ sections is transferred along the tunnel axis to neighboring sections, causing additional time-delayed deformation and necking of the tunnel.
81 citations
TL;DR: The tensile deformation behavior of poly(1-butene) and two of its ethylene copoloymers was studied at room temperature by investigating true stress−strain curves at constant strain rates, elastic recovery properties, and in-situ WAXS patterns during the deformation process as mentioned in this paper.
Abstract: The tensile deformation behavior of poly(1-butene) and two of its ethylene copoloymers was studied at room temperature. This was done by investigating true stress−strain curves at constant strain rates, elastic recovery properties, and in-situ WAXS patterns during the deformation process. All samples showed a common rubberlike deformation behavior without necking down. The differential compliance, the recovery properties, and the evolution of the crystallite texture changed simultaneously at well-defined points. The strains at which these points occurred along the true stress−strain remained constants for the different samples despite their different percentage crystallinities. The same strain-controlled deformation behavior was also shown by a series of semicrystalline polymers in previous studies that carried out in our group. The well-defined way that the different samples respond to external stresses complies with our views of a granular substructure of the crystalline lamellae in a semicrystalline po...
81 citations
TL;DR: In this article, a critical level of necking that reconciles local isostasy with the finite strength of the lithosphere is discussed, which requires a flexural response, and the authors conclude that, while kinematic models are very successful in accounting for the observed characteristics of sedimentary basins, dynamic models are necessary to gain insight into the physical processes underlying basin formation and evolution.
81 citations
TL;DR: In this paper, the authors propose the concept of a forming window in strain space that identifies the strains that can be developed safely in a sheet element, bounded by failure limits corresponding to localized necking, shear fracture, and wrinkling.
Abstract: Developments in the numerical modeling of stamping processes and experimental measurements now make it possible to design stamping processes using sound engineering principles. This article shows how experimental and theoretical contributions have led to the concept of a forming window in strain space that identifies the strains that can be developed safely in a sheet element. It is bounded by failure limits corresponding to localized necking, shear fracture, and wrinkling. A robust stamping process is one in which the strains in the part lie well within the forming window. The nature of the window and the influence of material behavior on its shape can be predicted.
81 citations