Topic
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 paper, the authors examined the corrosion fatigue of the aluminium-zinc-magnesium alloy 7017-T651 in seawater at frequencies from 0.1 to 70 Hz and found that the changes in fracture mode observed at certain critical crack velocities, and their dependence upon the square root of the reciprocal of the frequency of loading, are consistent with an environment-enhanced crack growth rate involving diffusion of hydrogen ahead of the crack tip during each fatigue cycle.
103 citations
TL;DR: In this paper, a model of the fatigue behavior of 3D semi-elliptical shallow-angle rolling contact fatigue (RCF) cracks was developed by combining numerically obtained (3D FEM) linear elastic fracture mechanics (LEFM) crack front loading histories with mixed-mode fatigue crack growth rate data.
103 citations
TL;DR: The cyclic stress-strain behavior of a wide variety of rigid polymers has been studied as mentioned in this paper, and three classes of fatigue response can be defined, each class displaying a characteristic evolutionary pattern in the stressstrain relation as deformation proceeds from the initial fatigue cycle to fatigue-crack propagation.
Abstract: The cyclic stress-strain behaviour of a wide variety of rigid polymers has been studied Three classes of fatigue response can be defined, each class displaying a characteristic evolutionary pattern in the stress-strain relation as deformation proceeds from the initial fatigue cycle to fatigue-crack propagation Ductile polymers undergo a marked decrease in deformation resistance prior to crack formation; the detailed mechanism by which this “softening” develops can be related to the material microstructure and thermomechanical history Amorphous polymers with a moderate degree of ductility soften slightly; in these materials crazing plays a dominant role in both the cyclic stress-strain response and the structural fatigue resistance Brittle and nearly-brittle polymers are essentially stable in cyclic deformation; the fatigue resistance of these materials is very sensitive to strain amplitude in cyclic deformation
103 citations
TL;DR: In this paper, a two-dimensional elastic phase field model was proposed to capture the effect of external stress on the tetragonal-to-monoclinic (T→M) phase transformation in zirconia.
103 citations
TL;DR: In this paper, the effects of the environment and material variables on the crack growth process in alloy 718 are reviewed and analyzed on the basis of deformation characteristics in the crack tip region.
Abstract: Observations concerning the effects of the environment and material variables on the crack growth process in alloy 718 are reviewed and analyzed on the basis of deformation characteristics in the crack tip region. The review of the role of material variables has focused on the effects of chemical composition and microstructure parameters including precipitate size and morphology as well as grain size and morphology. These analyses have suggested that the governing mechanism at the crack tip is the degree of homogeneity of plastic deformation and associated slip density. For conditions promoting homogeneous plastic deformation, with a high degree of slip density, the environmental damage contribution is shown to be limited, thus permitting the dominance of cyclic damage effects which are characterized by a transgranular crack growth mode and a lower crack growth rate. Under conditions leading to inhomogeneous plastic deformation and lower slip density the crack tip damage is described in terms of grain boundary oxidation and related intergranular fracture mode. Considering that the crack growth damage mechanism in alloy 718 ranges from fully cycle dependent to fully environment dependent, conflicting experimental observations under different operating conditions are examined and a sensitizing approach is suggested to increase the alloy resistance to environmental effects.
103 citations