o bjectives: the objective of this study was to assess the effect of new bonding techniques on enamel surface. materials and methods: sixty upper central incisors were randomly divided into two equal groups. in the first group, metal brackets were bonded using trans- bondxt and, in the second group, the same brackets were bonded with maxcemelite. the shear bond strength (sbs) of both agents to ...

Microcrystalline silicon (mc-Si:H) cells can reach efficiencies up to typically 10% and are usually incorporated in tandem micromorph devices. When cells are grown on rough substrates, ‘‘cracks’’ can appear in the mc-Si:H layers. Previous works have demonstrated that these cracks have mainly detrimental effects on the fill factor and open-circuit voltage, and act as bad diodes with a high rever...

A newly developed computational approach is proposed in the paper for the analysis of multiple crack problems based on the eigen crack opening displacement (COD) boundary integral equations. The eigen COD particularly refers to a crack in an infinite domain under fictitious traction acting on the crack surface. With the concept of eigen COD, the multiple cracks in great number can be solved by ...

In this section, we want to model a surface with flaws. We model it as a line from which N parallel cracks progress into the 2D material (see Fig. 2). The ensemble of cracks is submitted to a remote mode I loading p∞ as sketched in Fig. 2, but, because of the interactions between the cracks, each crack i (i = 1, ...N) is submitted locally to both a normal traction pi(x) and a shear traction ti(x).

The inspection of various structures often detects a fatigue cracks developed during long service life. These fatigue cracks significantly reduce remaining fatigue life and fatigue strength. Influence of the initial fatigue cracks size in non-load-carrying fillet-welded one-sided transverse attachment joints on the remaining fatigue life and fatigue strength is considered in this paper. A compu...

To model elastic wave scattering from fatigue cracks in metals, studies were conducted of wave scattering from artificial cracks using ultrasonic spectroscopy. The cracks are of two dimensional planar strips oriented at various angles and embedded in diffusion bonded titanium alloy. The crack is assumed to behave as a Griffith crack and expressions (derived by Achenbach1) to describe diffracted...

This study presents a new procedure based on Artificial Neural Network (ANN) for identification of double cracks in Functionally Graded Beams (FGBs). A cantilever beam is modeled using Finite Element Method (FEM) for analyzing a double-cracked FGB and evaluation of its first four natural frequencies for different cracks depths and locations. The obtained FEM results are verified against availab...

Abstract The rock mechanical behavior and damage characteristic is of great importance for in situ stress evaluation, wellbore stability analysis hydraulic fracturing design. velocities elastic waves are usually reduced the presence damage, it may be used determining progressive rock. Therefore, this paper aims to investigate characteristics transversely isotropic tight sand formation, paramete...