The dilemma of diagnosing and possibly treating dentinal cracks continues to present a challenge in endodontics. The purpose of this in vitro study was to compare the effectiveness of transillumination and dyes in identifying root-end dentinal cracks. Fifty maxillary central incisors were decoronated, and the canals were instrumented to an ISO size 50 at the working length. The apical 3 mm of t...

Abstract-Continuing a recent investigation of interface cracks, attention is paid to the exterior crack. Two elastic solids bonded over a finite segment of their boundary and capable of transmitting shear and tensile tractions are considered. It is found that one of the edge cracks remains completely closed under shear alone, and opens gradually as the level of tension is increased. Both crack ...

Last month, sea-ice cover in the Arctic extended to just 5.95 million square kilometres — 1.68 million square kilometres less than the average between 1979 and 2000. While native fauna such as polar bears are threatened by dwindling summer sea ice, commercial opportunities are opening up in this newly accessible summer sea and are being pursued apace. The first commercial supertanker succeeded ...

In this paper we apply the method developed by Rice [1], of solving for the elastic field of a crack with a front perturbed from some reference shape, to solve the elasticity problems of somewhat circular planar tensile cracks under arbitrary load distributions. The method is based on a known solution for the stress intensity factor along a circular crack due to a pair of wedge-opening point fo...

– The problem of finding what direction cracks should move is not completely solved. A commonly accepted way to predict crack directions is by computing the density of elastic potential energy stored well away from the crack tip, and finding a direction of crack motion to maximize the consumption of this energy. I provide in this letter a specific case where this rule fails. The example is of a...

Beyond the limelight of teaching hospitals, the psychiatric profession is in a state of near-collapse. A lack of resources and man-power is resulting in an incomplete service which is unfair to patients and demoralising for doctors-the situation needs salvaging, and soon.

We have conducted experiments and numerical simulations to investigate supersonic cracks. The experiments are performed at 85 ◦C to suppress strain-induced crystallites that complicate experiments at lower temperature. Calibration experiments were performed to obtain the parameters needed to compare with a theory including viscous dissipation. We find that both experiments and numerical simulat...

Stress corrosion cracks (SCC) in low-pressure steam turbine discs are serious hidden dangers to production safety in the power plants, and knowing the orientation and depth of the initial cracks is essential for the evaluation of the crack growth rate, propagation direction and working life of the turbine disc. In this paper, a method based on phased array ultrasonic transducer and artificial n...

Abstract-An alternating method, in conjunction with the finite element method and a solution for multiple coplanar elliptical cracks in an intinite solid, is used to determine stress intensity factors for semi-elliptical surface flaws in cylindrical pressure vessels. The solution technique for multiple cracks in an infinite body has recently been developed by the prese.nt authors which implemen...