Topic
Crack closure
About: Crack closure is a research topic. Over the lifetime, 28157 publications have been published within this topic receiving 588158 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this paper, Tungsten-carbide cobalt alloys in the range of technically relevant compositions were fractured under controlled conditions, and stable and unstable crack propagation were shown to be equivalent with respect to crack geometry and energy release rates.
Abstract: Tungsten-carbide cobalt alloys in the range of technically relevant compositions an microstructures were fractured under controlled conditions. Stable and unstable crack propagation are shown to be equivalent with respect to crack geometry and energy release rates. Based on microscopic observations and on measurements using SEM micrographs, the nature of the process zone, the maximum extension of plastic deformation, the types of crack paths, and the area fractions of these crack paths are determined. The results, which are in partial disagreement with earlier work, provide the basis for the qualitative understanding and the quantitative description of fracture processes in composites combining a ductile phase embedded in a brittle matrix.
209 citations
TL;DR: In this paper, the J-line integral was used to extract the magnitude of crack tip stress intensity factors from finite element solutions for thermal stress crack problems, and the properties of the J line integral in the presence of thermal stresses were determined.
Abstract: Methods of using the J-line integral to extract the magnitude of crack tip stress intensity factors from finite element solutions for thermal stress crack problems are presented. The properties of the J-line integral in the presence of thermal stresses are determined. From these properties a procedure for calculating crack tip stress intensity factors is developed. Also a superposition method involving crack surface tractions is presented for thermal stress crack problems. In this procedure the J-line integral path must include segments of the crack surface. All methods developed are illustrated by numerical examples.
209 citations
TL;DR: In this article, a molecular-dynamics model for crack propagation under steady-state conditions is developed to analyze intergranular fracture along a flat 99 [1 1 0] symmetric tilt grain boundary in aluminum.
Abstract: A traction-displacement relationship that may be embedded into a cohesive zone model for microscale problems of intergranular fracture is extracted from atomistic molecular-dynamics simulations. A molecular-dynamics model for crack propagation under steady-state conditions is developed to analyze intergranular fracture along a flat 99 [1 1 0] symmetric tilt grain boundary in aluminum. Under hydrostatic tensile load, the simulation reveals asymmetric crack propagation in the two opposite directions along the grain boundary. In one direction, the crack propagates in a brittle manner by cleavage with very little or no dislocation emission, and in the other direction, the propagation is ductile through the mechanism of deformation twinning. This behavior is consistent with the Rice criterion for cleavage vs. dislocation blunting transition at the crack tip. The preference for twinning to dislocation slip is in agreement with the predictions of the Tadmor and Hai criterion. A comparison with finite element calculations shows that while the stress field around the brittle crack tip follows the expected elastic solution for the given boundary conditions of the model, the stress field around the twinning crack tip has a strong plastic contribution. Through the definition of a Cohesive-Zone-Volume-Element an atomistic analog to a continuum cohesive zone model element - the results from the molecular-dynamics simulation are recast to obtain an average continuum traction-displacement relationship to represent cohesive zone interaction along a characteristic length of the grain boundary interface for the cases of ductile and brittle decohesion. Keywords: Crack-tip plasticity; Cohesive zone model; Grain boundary decohesion; Intergranular fracture; Molecular-dynamics simulation
209 citations
TL;DR: In this article, a new form of the maximum strain energy release rate (G-criterion) was proposed for predicting the mixed mode crack propagation, which can predict the shear failure but not the tensile failure, and the capacity of the F-Criterion in predicting both mode I and mode II propagation was demonstrated for two models subjected to uniaxial compression for a single crack and a set of two cracks.
209 citations
209 citations