A.N. Norris and J.D. Achenbach The Technological Institute Northwestern University Evanston, IL 60201 Crack diffraction in a transversely isotropic material is analyzed. The solution is given for the diffracted field generated by incidence of a plane time-harmonic wave on a semiinfinite crack located in a plane normal to the axis of symmetry of the material. The exact solution is obtained by Fo...

Cracks creation in solids can be accompanied by electromagnetic emission (EME). On the faces of new created crack electric charges constitute electric dipole system and due to crack walls vibration an EME signal is detected with frequency from 1 to 10 MHz corresponding to crack length 0.1 to 1 mm. The second source of EME signal is later activated due to whole sample mechanical vibrations with ...

The mesoscopic concept is applied to the description of microcracked brittle materials. The mesoscopic equations are solved in a special case when the microcracks are developing according to the Rice-Griffith evolution law. The evolution of the crack distribution function is investigated in case of simple loading conditions and for two different initial crack distribution functions. The time de...

We recently developed a method to measure cortical bone fracture initiation toughness using a double-notched beam in four-point bending. This method was used to test the hypothesis that mineralization around the two notch roots is correlated with fracture toughness and crack extension (physical damage). Total energy absorbed to failure negatively correlated with average mineralization of the be...

Scratch-induced cracking is a serious problem for the use of glass products. At the scratch process, both median (vertical to the glass surface) and lateral (horizontal to the glass surface) cracks are formed. In this study, morphology of the scratch-induced cracks in a commercial soda-lime-silica glass was investigated by the scanning electron microscopy for the specimen broken across the scra...

Perturbation of a steadily propagating crack with a straight edge is solved using the method of matched asymptotic expansions (MAE). This provides a simplified analysis in which the inner and outer solutions are governed by distinct mechanics. The inner solution contains the explicit perturbation and is governed by a quasi-static equation. The outer solution determines the radiation of energy a...

According to the Gri th criterion, a crack propagation occurs provided that the derivative of the energy functional with respect to the crack length reaches some critical value. We consider a generalization of this criterion to the case of nonlinear cracks satisfying a non-penetration condition and investigate the dependence of the shape derivative of the energy functional on the crack shape. I...

Infra-red video sequences were taken of directly bonded silicon wafer pairs undergoing the razor blade crack length test for bond strength in a specially designed jig. A series of tests were carried out under controlled atmospheres of nitrogen at various relative humidities. Analysis of the video images showed that the crack continues to propagate rapidly for several minutes after the blade has...

A B S T R A C T Using a model of a single layered foundation to describe a highway or an airfield pavement and an integral formulation, the problem of a pavement containing on-the-top layer a crack of finite length 2c is solved for the stress distribution around the crack tip. The analysis shows that the stresses possess the usual 1/e 1⁄2 singular behavior which is characteristic of crack probl...