Fretting fatigue in dovetail blade roots: Experiment and analysis

A biaxial fatigue experiment is described which is capable of simulating the loading experienced by a dovetail blade root in an aircraft gas turbine. A comprehensive stress analysis of the experimental configuration has been undertaken and a semi-analytical approach has been developed to provide accurate estimates of surface tractions and subsurface stress fields. The forces (normal and shear) and moment for the semi-analytical model are calculated from the global finite element analysis of the dovetail in which coarse elements were used. The bulk stress and the bending stress in the disk and blade were evaluated by calculating the membrane and bending stresses across the thickness of the disk and blade. Short crack arrest methods have been applied to the results of the stress analysis to predict the fatigue performance of the blade specimens. The results show a good agreement with the experimental observations.     

What is the source of the Fullerton-Cattell "principle"?

Points out that there is no basis for the common tendency of writers on psychophysics to attribute the statement "Equally often noticed differences are equal unless always or never noticed" to G. S. Fullerton and J. M. Cattell (1892). No such statement appears in their monograph and its spirit seems contrary to their work's goals. The 1st attribution of the statement to Fullerton and Cattell appears to have been made by L. L. Thurstone (1932). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tractive rolling of tyred cylinders

The case of contact between two rigid cylinders, one of which carries an elastic tyre, is analysed using a piece-wise linear method. Several configurations are treated—frictionless contact, sliding, free rolling without slip and tractive rolling. The last case is of particular interest in many process industries. The effects of tyre thickness, Poisson's ratio, tractive force and coefficient of friction on the traction distribution and creep ratio are each considered.     

Quantifying the recrystallization texture of tantalum

The utilization of crystallographic texture is gaining acceptance as a commercially viable tool for characterizing the attributes and confirming the quality of engineering materials. Traditionally, x-ray diffraction (XRD) involving the measurement and subsequent analysis of normal-orientation pole figures is used to determine the preferred orientation in sheet metals. Unfortunately, most XRD techniques are incapable of providing quantifying texture information of wrought tantalum. This is because integrative texture measurement methods cannot detect the presence of texture gradients and bands known to be detrimental to the performance of tantalum for select applications. Instead, discrete orientation measurement techniques such as electron backscatter diffraction are required to resolve the microtexture of tantalum. Inverse pole figure maps generated using orientation imaging microscopy have been used to gain qualitative insight into the texture character of wrought tantalum. Recently, a numerical means for quantifying the texture uniformity of tantalum (as well as other materials) from discrete orientation data has been devised and demonstrated.     

Partial slip problem for two semi-infinite strips in contact

Two semi-infinite strips brought into frictional contact, end-to-end, by a normal pressure are then subjected to a monotonically increasing or oscillating tangential force remote from the interface. The full stress tensor for the partial slip regime is found.     

Mechanics of fretting fatigue tests

A popular fretting fatigue test, in which oscillating tension is applied in phase with the fretting force, is analysed. The configuration is a generalization of the well-known Mindlin contact problem, and it is shown that the addition of bulk tension has a substantial effect on the stick-slip geometry and the shear traction at the interface. The largest tension induced, which is thought to be responsible for the initiation of fatigue cracks, is also slightly increased.     

Calorie restriction, stress and the ubiquitin-dependent pathway in mouse livers

Calorie restriction (R), the only known method to delay the aging process and extend mean and maximal lifespan, has been shown to delay the age-related decline in protein degradation. There are several proteolytic pathways. The ubiquitin- and ATP-dependent proteolytic pathway (UPP) is frequently associated with degradation of damaged abnormal and/or regulatory proteins. We examined the effect of aging and R on supernatants of livers taken from young (4.5 months) and old (23 months) Emory mice. Aging was associated with increased levels of endogenous ubiquitin conjugates, enhanced ability to form high molecular weight conjugates and ubiquitin activating (E1) and ubiquitin conjugating (E2) activity in the control (C) liver supernatants. The age-related increase in levels of endogenous ubiquitin conjugates in liver appears to be primarily due to increased E1 and E2 activities. R prevented the age-related increase in E1 and E2 activity, and thus prevented the age-related increase in levels of ubiquitin conjugates. In spite of the age-related increase in ubiquitin conjugates, no age-related changes in ubiquitin-dependent proteolytic pathway were observed in the C animals. R was associated with an enhanced ability (130%) to degrade beta-lactoglobulin by the ubiquitin-dependent proteolytic pathway in livers from 4.5-month-old animals relative to age-matched C livers. However, rates of the ubiquitin-dependent degradation of beta-lactoglobulin in the 23-month-old C and R animals were indistinguishable. There were no age- or diet-related differences in the ability to degrade another substrate, oxidized ribonuclease (RNase).     

Paternal stimulation during infancy: Effects upon aggression and open-field performance of mice.

Studied aggression in random-bred albino Tuck TT strain male mice from 1st matings, reared by both parents (n = 13) and from 2nd matings, reared only by the mother (n = 15). Prolonged isolation from weaning induced more aggression in Ss from 1st matings than in Ss from a 2nd mating. In a 2nd experiment, fathers of 40 Ss were removed (a) shortly after mating, (b) at the litters' birth, or (c) at weaning. In offspring isolated from weaning, Ss in condition c were significantly more aggressive than those in a, while those in b showed an intermediate response. These differences did not occur when the period of isolation was broken by 50 days of communal housing before aggression testing, although Ss in c defecated more in the open field. It is suggested that young mice "imprint" toward the same odors of adult males which in later life elicit intermale aggression. (24 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An experimental and theoretical study of the offset launchtechnique for the enhancement of the bandwidth of multimode fiber links

This paper reports an experimental and theoretical study of bandwidth enhancement in multimode fiber links achieved by using offset launch techniques. It is found, both from theory and experiment, that an up to four-fold bandwidth enhancement can be obtained compared to standard overfilled launch techniques despite exciting over 50% of the fiber modes, thus allowing good stability. The enhancement technique is found to be achieved for a range of fibers with different core diameters and core refractive index profiles. The level of bandwidth enhancement depends upon the inherent bandwidth of the fiber, being particularly effective in improving the performance of low bandwidth “worst case” fibers. The launch is found to be stable with respect to environmental variations, showing bandwidth enhancement for injection positions or connector offsets of up to 5 μm from optimum. In addition, unlike many restricted launch techniques, it is found to be tolerant to angular fiber misalignment for angles up to 6° from normal