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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01 Jan 1985
TL;DR: In this paper, the process zone at the crack tip of a concrete-like material can be simulated in two different alternative ways: (a) with a damage zone in front of the stress-free crack tip, or (b) with cohesive force distribution behind a fictitious crack tip.
Abstract: The process zone at the crack tip of a concrete-like material can be simulated in two different alternative ways: (a) with a damage zone in front of the stress-free crack tip, or (b) with a cohesive force distribution behind a fictitious crack tip. Both these numerical models are able to simulate the slow crack growth and to reproduce the scale effects of fracture toughness testing. With large structural sizes the softening structural behaviour disappears and the global ductility drastically decreases. In the damage model, this is due to the priority of the crack instability over the traditional structural instability. On the other hand, in the cohesive model, this is revealed by a bifurcation of the global equilibrium, the stress-singularity being not included in such a model.
128 citations
TL;DR: In this article, a series of Vickers indentation and counting of cracks around the indentation was used to measure the crack initiation in various commercial glass compositions, and the authors found that the crack resistance of glass does not have clear relationship with hardness, fracture toughness, nor "brittleness" which is a ratio of the hardness to the fracture toughness.
Abstract: Crack initiation in various commercial glass compositions was investigated by measuring “crack resistance”, which is determined by a series of Vickers indentation and counting of cracks around the indentation. The crack resistance of glass does not have clear relationship with hardness, fracture toughness, nor “brittleness” which is a ratio of the hardness to the fracture toughness. However, the crack resistance has a strong relationship with densification. Glass experiencing larger densification around the indentation shows higher crack resistance. Densification is assumed to reduce residual stress around the indentation, resulting in an increase in the crack resistance.
128 citations
TL;DR: In this paper, the authors developed a Stroh-type formalism for antiplane deformation and then investigated the fracture mechanics for an elliptical cavity in a magnetoelectroelastic solid under remotely uniform in-plane electromagnetic and/or anti-plane mechanical loading, which allowed them to take the electromagnetic field inside the cavity into account.
128 citations
TL;DR: In this paper, the effects of residual stresses arising from thermal expansion mismatch are taken into account, and a series of very useful inter-relationships between thermo-elastic constants for damaged and corresponding undamaged laminates are derived.
127 citations
01 Jan 1972
TL;DR: In this article, the concept of linear-elastic fracture mechanics is introduced and their application to the interpretation of fracture behavior of composite materials is illustrated, based on a description of the linear elastic stress field around the tip of a crack.
Abstract: The concepts of linear-elastic fracture mechanics are introduced and their application to the interpretation of fracture behavior of composite materials is illustrated. Linear-elastic fracture mechanics is based on a description of the linear-elastic stress field around the tip of a crack. The equations for stresses close to a crack tip in a homogeneous, isotropic plane plate are developed. These equations lead directly to the definition of the stress-intensity factor K, a single-parameter characterization of the crack-tip stress field. The level of K corresponding to crack extension and fracture is a measure of the fracture toughness of a material. For fibrous composites, crack-tip stress field equations and the stress-intensity factors for a linear-elastic special orthotropic homogeneous material are introduced. Small-scale plastic behavior at the crack tip and its influence on the crack-tip stress field and stress-intensity factor K are discussed. Crack extension force Ĝ is defined and related to the stress-intensity factor K. Crack-tip stress fields for two-material members with cracks at and near the interface are presented. Fracture analysis for two particulate composite systems, a WC-reinforced cobalt alloy and a W-particle reinforced glass composite are reviewed. A parallel filament glass-epoxy composite is traced through a failure analysis, as well as experiments designed to investigate the applicability of fracture mechanics, using a special orthotropic homogeneous material model, to describe the observed crack extension behavior. The general features of crack extension behavior, specifically the observed relation between Ĝ and crack speed a are discussed and illustrated for epoxy-aluminum adhesive joints. The influence of moisture and sustained loads on the crack extension behavior of epoxy adhesive joints are reported. This article concludes with a discussion of the areas of fracture mechanics, both analytical and experimental, that require attention to develop improved composite materials and structural systems.
127 citations