UNLABELLED The diagnoses of cracked teeth and incomplete coronal fracture have historically been symptom based. The dental operating microscope at 16x magnification can fundamentally change a clinician's ability to diagnose such conditions. Clinicians have been observing cracks under extreme magnification for nearly a decade. Patterns have become clear that can lead to appropriate treatment pri...

This paper presents numerical analysis of stress intensity factors (SIFs) of inclined cracks due to mechanical mismatches. According to literature survey, tremendous amounts of SIFs can be found elsewhere. However, the SIFs for inclined cracks are difficult to obtain especially when mechanical mismatch at the crack interface are considered. ANSYS finite element program is used to model the crac...

This paper studies the initiation of cohesive cracks in the thermal shock problem through a variational analysis. A two-dimensional semi-infinite slab with an imposed temperature drop on its free surface is considered. Assuming that cracks are periodically distributed and orthogonal to the surface, at short times we show that the optimum is a distribution of infinitely close cohesive cracks. Th...

A new technique using contrast enhanced micro-computed tomography (micro-CT) was developed to improve the ability to detect dentinal cracks in teeth and assess associated risks to oral health. Extracted, whole human molars that exhibited visual evidence of external cracks following extraction and machined, partially fractured elephant dentin specimens were labeled by BaSO(4) precipitation and i...

The effect of preexisting subsurface cracks on the strength of lap splices was investigated. Ten full-scale beams with No. 11 (No. 36) bars and lap splice lengths of 33, 79, and 120 in. (838, 2007, and 3048 mm) were tested. The beams had mitigating features that prevented catastrophic failure upon propagation of the preexisting cracks, such as staggered splices and the presence of some reinforc...

Controlled vertical drying deposition method was used to make high-quality single crystal close-packed colloidal films formed of different radii polystyrene latex spheres on glass substrates coming from a low concentration water suspension (0.1% volume fraction). Regardless of the spheres radii the film thickness was about 6.3 microns. However, cracks destroyed the crystalline film structure du...

Consider a three-dimensional homogeneous isotropic elastic solid containing a flat pressurized crack, fi. The problem of finding the resulting stress distribution can be reduced to a hypersingular integral equation over Q for the crack-opening displacement. Here, this equation is transformed into a similar equation over a circular region D, using a conformal mapping between Q and D. This new eq...

The present article seek to investigate the function of elliptical steel damper function in steel frames seismic resisting. The elliptical damper is a kind of earthquake energy dissipater in structure which acts based on the steel yielding feature. Thus, this damper in frame lateral displacement mechanism is expected to have a satisfying hysteretic behavior in terms of energy absorption is on a...

In this study, enamel micro-cracks produced around composite restorations were observed on surfaces and vertical sections, using a stereomicroscope and a scanning electron microscope (SEM). The effects of various clinical factors, i.e. the curing system, the marginal form and the polishing period after filling, on the incidence of marginal enamel micro-cracks were examined. Enamel micro-cracks ...