A study of creep cavities near reheat cracking in AISI Type 316H austenitic stainless steel headers, removed from long-time high temperature operation in nuclear power plants, is reported. It is shown how application of scanning electron microscopy (SEM), cryogenic fractography and small angle neutron scattering (SANS) can be applied, in a complementary way, to observe and quantify creep cavita...

An integrated fatigue damage diagnosis and prognosis framework is proposed in this paper. The proposed methodology integrates a Lamb wave-based damage detection technique and a Bayesian updating method for remaining useful life (RUL) prediction. First, a piezoelectric sensor network is used to detect the fatigue crack size near the rivet holes in fuselage lap joints. Advanced signal processing ...

Fatigue crack propagation tests were conducted on the powder metallurgy nickel-base superalloy KM4 at room temperature. Two different heat treatments were investigated, one which produced a relatively coarse grain size around 55 μm, and another which produced a very fine grain size around 6 μm. Tests were conducted at 50 Hz and 1000 Hz in an advanced servohydraulic testing machine at R-ratios b...

Two parameters are identified for characterizing the deformation in the plastic zone near the tip of a crack when mixed mode conditions prevail. Details of the near-tip stress and strain distributions are presented f or hardening materials in which a diffus e plastic zone occurs under plane stress conditions. For small scale yielding the two near-tip parameters are related to the two elastic s ...

X-ray absorption microtomography, a high resolution variant of medical “CT”, quantifies threedimensional microstructures efficiently and noninvasively. With this imaging modality, determination of the three-dimensional spatial distribution of crack opening as a function of applied load has helped clarify important physical processes of roughness-induced fatigue crack closure. There is a real ne...

Managing pipe damaged by Stress Corrosion Cracking (SCC) has been a formidable challenge to the pipeline industry. The development of a practical solution for the measurement and evaluation of SCC has been marred by the complexity of crack shapes, their distribution within a crack colony, and the lack of non-destructive technology capable of reliably measuring the crack depths. Laser ultrasonic...

The ®nite element alternating method is extended further for analyzing multiple arbitrarily curved cracks in an isotropic plate under plane stress loading. The required analytical solution for an arbitrarily curved crack in an in®nite isotropic plate is obtained by solving the integral equations formulated by Cheung and Chen (1987a, b). With the proposed method several example problems are solv...

Perturbation of a steadily propagating crack with a straight edge is solved using the method of matched asymptotic expansions (MAE). This provides a simplified analysis in which the inner and outer solutions are governed by distinct mechanics. The inner solution contains the explicit perturbation and is governed by a quasi-static equation. The outer solution determines the radiation of energy a...

We review results from searches for mixing and CP violation in the D 0-D 0 system. No evidence for mixing or CP violation is found, and limits are set for the mixing parameters x, y, x ′ , y ′ , and several CP-violating parameters.

This paper presents data from a preliminary investigation on the neurophysiological changes that occur when a person attempts to crack a password. A password cracking scenario was provided to a small cohort of university students and while they were attempting to crack into the password, their EEG was recorded. The results indicate that the overall frontal lobe power (at electrode position F7) ...