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, the brittle-ductile transition size effect of metal specimens is discussed using the strain energy density theory, assuming that the critical strain energy factor, S c r, is a material constant, predictions on the fracture behavior of metals can be made.
Abstract: Fracture toughness is an indication of the resistance of a material to physical separation by a process of unstable macrocrack propagation. Conceptually, it is an intrinsic material parameter that should not vary with changes in specimen size, speed of loading, temperature, etc. The brittle-ductile transition size effect of metal specimens is discussed using the strain energy density theory. By assuming that the critical strain energy factor, S c r , is a material constant, predictions on the fracture behavior of metals can be made. The following remarks are helpful toward defining a fracture toughness parameter associated with instability of the macrocrack: 1. The dominant or continuum crack travels in the elastic portion of the material always skirting around or bypassing the yield material and hence releases only elastic energy. 2. Stable macrocrack growth in metals is the result of necking or constraint from specimen boundary. 3. The last ligament of macrofracture will terminate in a plane inclined to the free surface or boundary of the specimen.
34 citations
TL;DR: In this paper, a noncontact method of strain measurement was applied in the case of semicrystalline polymers, where yielding occurs through inhomogeneous deformation (necking), and the true stress-strain curves at various crosshead speeds tested.
34 citations
TL;DR: In this article, microstructural changes that take place in the plastic zone ahead of the crack tip are found to be more important in fracture than the microscopic processes immediately at the tip itself.
34 citations
TL;DR: In this article, the global and local tensile properties of friction stir welded AA2024 joints were measured with the aid of digital image correlation (DIC) method and a novel model was proposed to describe the local constitutive behavior of the joints based on DIC data.
34 citations
01 Sep 2000
TL;DR: In this article, a theoretical model using the "many slices" approach is introduced to simulate the neck growth of metal sheets. And the effects of changing strain path and grain sizes on the limit strains are then investigated both theoretically and experimentally.
Abstract: Forming processes of metal sheets are generally limited by plastic instability phenomena and flow localization. The occurrence of these phenomena is dependent on the material properties such as strain-hardening exponent, strain rate sensitivity, anisotropy parameters and grain size and is also dependent on the strain path. The formability of the sheet metals can be assessed by the forming limit diagram (FLD). In this study, a theoretical model using the ‘many slices’ approach is introduced to simulate the neck growth. The effects of changing strain path and grain sizes on the limit strains are then investigated both theoretically and experimentally. The low carbon steel ST12 and austenitic stainless steel 321 are used in the experimental approach. The theoretical and experimental FLDs of these sheets are obtained for different grain sizes and after pre-straining in uniaxial and biaxial tension parallel to the prior rolling direction. It is shown that the limit strains are quite sensitive to the gr...
34 citations