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...

In a hydrocarbon well, cement fills the annular gap between two steel casings or between a steel casing and rock formation, forming a sheath that isolates fluids in different zones of the well. For a well as long as several kilometers, the cement sheath covers a large area and inevitably contains small cracks. The cement sheath fails when a small crack grows and tunnels through the length of th...

The objective of the present paper was to show the various macro-lmicrostructural appearances of the ODs materials MA 956 and PM 2000 at the surface and in the bulk after exposure to high temperatures in combustion chambers (gaseous environment). At the surface a chromium oxide layer forms above the alumina layer originally formed after preoxidation. At locations where the surface has been melt...

Rolling friction has been explained in terms of crack propagation through an adhesive joint. The contact between a smooth cylinder and flat has been regarded as an adhesive junction bounded by two cracks moving in the same direction at the same speed, one crack continually opening and one closing. Propagation of these cracks requires a force which is calculated from crack theory and shown to be...

The paper presents the analysis of thermo-mechanical fatigue cracking of die casting die during industrial use. An innovative, production friendly approach to monitor the surface crack dimensions was introduced, which is based on measuring defect-fi n on the casting part. A new four moulds die casting die was monitored 40 000 cycles in order to complete the production series. The production was...

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...

Tidal cracks are linear features that appear parallel to coastlines in fast ice regions due to the actions of periodic and non-periodic sea level oscillations. They can influence energy and heat exchange between the ocean, ice, and atmosphere, as well as human activities. In this paper, the LINE module of Geomatics 2015 software was used to automatically extract tidal cracks in fast ice regions...

Loading conditions and complex geometry have led the cylinder heads to become the most challenging parts of diesel engines. One of the most important durability problems in diesel engines is due to the cracks valves bridge area. The purpose of this study is a thermo-mechanical analysis of cylinder heads of diesel engines using a two-layer viscoelasticity model. The results of the thermo-mechani...