We report here atomic force microscopy experiments designed to uncover the nature of failure mechanisms occuring within the process zone at the tip of a crack propagating into a silica glass specimen under stress corrosion. The crack propagates through the growth and coalescence of nanoscale damage spots. This cavitation process is shown to be the key mechanism responsible for damage spreading ...

The crack stability condition in rate sensitive brittle materials is analysed. The analysis shows that a crack begins to extend before a maximum load ( P , , ) appears in fracture toughness (XI) tests and the extension depends on the n-value in the relation. This suggests that the evaluation of a true KI;value is quite difficult. An analytical method for using the KT. -value (the lnltlal stress...

1. Abstract This paper concerns with the identification of multiple cracks in a beam by measurements of the damage-induced variations in the static deflection of the beam under a prescribed load condition. Each crack is simulated by an equivalent linear elastic rotational spring connecting the two adjacent segments of the beam. Sufficient conditions on the static measurements which allow for th...

The tearing and healing of a one-dimensional crack in a solid, in the presence of external tectonic forces, pre-stress, static friction, cohesion and dynamic friction is investigated. It is found that cohesive forces have a strong influence on the velocity of rupture; the velocity of rupture is always less than or equal to the velocity of sound. The extension of the crack ceases either when the...

Few studies have focused on a description of the fracture toughness properties of dentin in terms of resistance-curve (R-curve) behavior, i.e., fracture resistance increasing with crack extension, particularly in light of the relevant toughening mechanisms involved. Accordingly, in the present study, fracture mechanics based experiments were conducted on elephant dentin in order to determine su...

In this paper, we present a novel finite element model to simulate alkali-silica reaction in realistic concrete meso-structure. Application of the internal ASR loading leads evolution multiple deviated cracks and corresponding macroscopic expansion. A particular crack-extension algorithm solution scheme provide numerical stability allow complicated crack patterns while preserving physics. The p...

A new cohesive zone model is developed in order to study the mechanisms of adhesive and cohesive failures of soft rubbery materials. The fracture energy is estimated here using a strategy similar to that of Lake and Thomas (LT) by considering the dissipation of stored elastic energy followed by the extension and relaxation of polymer chains. The current model, however, departs from that of LT i...

Neutron diffraction measurements have been performed to determine the full residual stress tensor along the expected crack path in an austenitic stainless steel (Esshete 1250) compact tension weld specimen. A destructive slitting method was then implemented on the same specimen to measure the stress intensity factor profile associated with the residual stress field as a function of crack length...

The well-known J integral of elastic fracture mechanics has been related to potential energy-release rate associated with crack extension and has proved to be of great value in fracture testing. In particular, the pathindependence of the J integral has been used to an advantage in performing acoustoelastic measurements along a closed contour surrounding a crack tip. In Mode I (opening mode) for...