the cracked brazilian disc (cbd) specimen is widely used in order to determine mode-i/ii and mixed-mode fracture toughness of a rock medium. in this study, the stress intensity factor (sif) on the crack-tip in this specimen is calculated for various geometrical crack conditions using the extended-finite element method (x-fem). this method is based upon the finite element method (fem). in this m...

AlGaN/GaN high electron mobility transistor (HEMT) hetero-structures were grown on the 2-in Si (1 1 1) substrate using metalorganic chemical vapor deposition (MOCVD). Low-temperature (LT) AlN layers were inserted to relieve the tension stress during the growth of GaN epilayers. The grown AlGaN/GaN HEMT samples exhibited a maximum crack-free area of 8mm 5mm, XRD GaN (0 0 0 2) full-width at half-...

The technique of metal magnetic memory (MMM) has great advantages in detecting early failures such as stress concentration and fatigue damage of ferromagnetic components, which has been widely applied due to its high efficiency, low requirements for surface preparation and ease of operation. However, research into the quantitative description of defect characteristics is still far from adequate...

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 pseudo strain-hardening behavior of fiber reinforced engineered cementitious composites (ECC) is a desirable characteristic for it to act as a substitute for concrete to suppress brittle failure. The use of ECC in the industry is, however, limited by its high cost. To achieve higher cost/performance ratio, ECC can be strategically applied in parts of a structure that is under relatively hig...

Fracture toughness is important for any material, but to date there have been few investigations of this mechanical property in soft mammalian tissues. This paper presents new data on porcine muscle tissue and a detailed analysis of all previous work. The conclusion is that, in most cases, fracture toughness has not in fact been measured for these tissues. Reanalysis of the previous work shows ...

The authors of this experimental research work have made an attempt to experimentally investigate the ultimate flexural load of ferrocement slabs of size 700mm. X 200mm. X 15mm. (thickness) reinforced with PVC coated steel weld mesh, and compare the results with slabs using GI-coated steel weld mesh, by varying the number of layers from 1-3. Ordinary Portland Cement, locally available river san...

in reinforced concrete design, there are situations where transfer of shear across a specific plane needs to be considered. examples of such situation include corbels, bearing shoes, ledger beam bearing, and a host of connection between precast concrete elements. in this study, the shear transfer behavior of reinforced concrete is investigated experimentally by conducting test on 6 precracked p...

plastic shrinkage is one of the most important parameter which must be considered in hot weather concreting. if plastic shrinkage is not prevented, cracking will be significant, especialy if silica fume is used in the mix. in this paper, the effect of silica fume in bleeding and evaporation was investigated in laboratory. the results showed that in restrained shrinkage, beside relative humidity...

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