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Crack closure
About: Crack closure is a research topic. Over the lifetime, 28157 publications have been published within this topic receiving 588158 citations.
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TL;DR: In this article, the deformation field consistent with a Prandtl stress distribution travelling with an advancing plane-strain crack is analyzed and the functional form of the near tip crack profile in an elastic-plastic solid.
Abstract: Analysis of the deformation field consistent with a Prandtl stress distribution travelling with an advancing plane-strain crack reveals the functional form of the near tip crack profile in an elastic-plastic solid. The crack opening δ is shown to have the form δ ∼ r In (const./r) at a distance r from the tip. This observation coupled with data generated from finite element investigations of growing cracks in small-scale yielding permits the construction of a relation characterizing the deformation at an extending crack tip. A ductile crack-growth criterion consisting of the attainment of a critical opening at a small characteristic material distance from the tip is adopted. Predictions of the stability of a growing crack for both small-scale yielding specimens and those subject to general yielding are discussed.
284 citations
TL;DR: In this article, the authors consider fracture swarm formation in sedimentary rock and identify three regimes of fracture spacing according to the magnitude of the subcritical index of the fracturing material, and use a subcritical crack-propagation rule, where propagation velocity during stable growth scales with the cracktip stress intensity factor.
Abstract: Abstract Swarms or clusters represent an exception to the widely accepted idea that fracture spacing in sedimentary rock should be proportional to mechanical layer thickness. Experimental studies and static stress analysis do not provide adequate explanation for fracture swarm occurrence. The problem is re-examined numerically, accounting for the dynamics of pattern development for large populations of layer-confined fractures. Two crucial aspects of this model are: (1) the inclusion of three-dimensional effects in calculating mechanical interaction between simultaneously propagting fractures; and (2) the use of a subcritical crack-propagation rule, where propagation velocity during stable growth scales with the crack-tip stress intensity factor. Three regimes of fracture spacing are identified according to the magnitude of the subcritical index of the fracturing material. For low subcritical index material (n = 5) numerous fractures propagate simultaneously throughout a body resulting in irregular spacing that is, on average, much less than layer thickness. For intermediate subcritical index (n = 20) one fracture propagates at a time, fully developing its stress shadow and resulting in a pattern with regular spacing proportional to layer thickness. For high subcritical index cases (n = 80) fractures propagate in a fashion analogous to a process zone, leaving a fracture pattern consisting of widely spaced fracture clusters.
282 citations
TL;DR: In this article, an interdisciplinary view of metal fatigue in polycrystalline metals is presented, where fatigue resistance is defined in terms of the difficulty of crack growth in one of two possible directions, the first being related to the texture of a material, and the second to the orientation of the applied loading system.
Abstract: An interdisciplinary view of metal fatigue in polycrystalline metals is presented. Fatigue resistance is defined in terms of the difficulty of crack growth in one of two possible directions, the first being related to the texture of a material, and the second to the orientation of the applied loading system. The fatigue initiation phase is considered to be negligible for polycrystalline metals, and fatigue limits are equated to one of two threshold conditions, one quantified in terms of microstructural fracture mechanics, and the other determined by continuum mechanics. The importance of the intensity and distribution of microstructural barriers to fatigue crack growth is underlined, especially in relation to mechanical conditions such as stress–strain state and to material conditions such as grain size and the shape and orientation of inclusions and their size relative to microstructural barriers.MST/1883
278 citations
TL;DR: In this article, the asymptotic stress and deformation fields for a crack tip embedded in a power-law elastic-plastic material are developed for a plane problems, and the most singular term in the series solution is the HRR solution, after Hutchinson and Rice and Rosengren.
277 citations
TL;DR: In this paper, a general model for normal/shear cracking in quasi-brittle materials is presented, which is defined in terms of the normal and shear stresses on the average plane of the crack and the corresponding relative displacements, and implemented in two ways: directly as the constitutive law of an interface element in the context of discrete crack analysis, or as the law of a generic cracking plane in a multicrack formulation.
Abstract: A simple but general model for normal/shear cracking in quasi-brittle materials is presented. It is defined in terms of the normal and shear stresses on the average plane of the crack and the corresponding normal and shear relative displacements. A crack surface in stress space determines crack initiation under pure tension, shear-tension, or shear-compression loading. Two independent fracture energy parameters are used: the classical Mode I fracture energy GfI, and the asymptotic Mode II fracture energy GfIIa under very high shear-compression and no dilatancy. The cracking model proposed can be implemented in two ways: directly as the constitutive law of an interface element in the context of discrete crack analysis, or as the law of a generic cracking plane in a multicrack formulation in the context of smeared crack analysis. In this paper, the first approach is presented and examples are given of numerical constitutive testing and verification with experimental data.
275 citations