The fracture toughness and strength of ceramics can be improved with respect to monolithic ceramics by developing graded materials as laminates composed of periodic alternating layers of one material separated by layers of a second material. The second layer must contain residual compressive stresses which are induced during densification because of differential thermal contraction of the layer...

An important task in mixed-mode fracture analysis and prediction is the simulation of crack growth under mixed-mode conditions. To complete such a task, one must have (a) a computer code capable of handling the kinematics of general crack growth and determining the stress and deformation states during crack growth, and (b) a fracture criterion that can properly predict the instant and direction...

Although concrete is one of the most widely used construction materials, it is characterized by substantially low tensile strength in comparison to its compression strength, and the occurrence of cracks is unavoidable. In addition, cracks progress due to environmental conditions including damage by freezing, neutralization, and salt, etc. Moreover, detrimental damage can occur in concrete struc...

A mechanically retentive structure and meticulous surface cleanliness are critical factors in providing fracture resistance and clinical success of metal ceramic restorations. This investigation compared the porcelain/metal interfaces of deliberate compressive fractures of ceramic crowns between conventional preparation and application of the Radio Frequency Glow Discharge Treatment (RFGDT) bef...

Introduction: There are several electromagnetic techniques that can be used for detecting surface-breaking cracks in metals, including potential drop, AC field measurement and eddy current methods. Each method possesses its own advantages and limitations in a specific application. In recent years, the use of microwaves has shown an increasing potential and success as a new technique for non-des...

In this study, we investigated a method for the non-destructive detection of cracks based on an ultrasonic transit timing method. This method is considered to be an effective means for crack monitoring over an extensive coverage area. Aluminum specimens were prepared with a range of crack sizes and subjected to a tone burst wave to investigate the relationship between crack depth and the transi...

Abstract. Experiments were performed to observe the fracture behavior of thinwall and initially-flawed aluminum tubes to internal gaseous detonation loading. The load can be characterized as a propagating pressure jump with speed of 2.4 km/s and magnitude ranging from 2 to 6 MPa, followed by an expansion wave. Flaws were machined as external axial surface notches. Cracks ran both in the upstrea...

This paper describes a new technique for fabrication of nondestructive inspection (NDI) standards with real cracks. This includes cracks in holes, on curved surfaces, on shot peened surfaces, in and under coatings and at buried surfaces. The method uses permanently mounted MWM-Array eddy current sensors to detect crack initiation and monitor crack growth. These sensors have been used in fatigue...

Sand-®lled cracks from the Lower Fine-grained Quartzite of Dalradian (late Proterozoic) age on the Island of Islay, western Scotland, may be divided into two main types, both of which form orthogonal and non-orthogonal closed patterns on bedding surfaces. Type 1 cracks are short and lenticular in cross-section, contain sand which had been injected downwards, and are found on the bottoms of cros...

DETECTING DEFECTS IN CHERRIES USING MACHINE VISION By Patchrawat Uthaisombut This thesis describes machine vision procedures which are able to classify defective cherries from non-defective cherries. Defects can be divided into bruises, dry cracks, and wet cracks. Bandpass lters that enhance the intensity contrast between bruised and unbruised cherries are determined. An optimum combination of ...