Interference fit effect on holed single plates loaded with tension-tension stresses

This paper deals with the influence of interference fit coupling on the fatigue strength of holed plates. The effect was investigated both experimentally and numerically. Axial fatigue tests have been carried out on holed specimens made of high performance steel (1075MPa of Ultimate strength and 990MPa of Yield strength) with or without a pin, made of the same material, press fitted into their central hole. Three different conditions have been investigated: free hole specimens, specimens with 0.6% of nominal specific interference and specimens with 2% of nominal specific interference. The experimental stress-life (S–N) curves pointed out an increased fatigue life of the interference fit specimens compared with the free hole ones. The numericalinvestigation was performed in order to analyse the stress fields by applying an elastic plastic 2D simulation witha commercial Finite Element software. The stress history and distribution along the contact interference of the fitted samples indicates a significant reduction of the local stress range due to the externally applied loading (remote stress) since a residual and compressive stress field is generated by the pin insertion

Interference fit effect on holed single plates loaded with tension-tension stresses

This paper deals with the influence of interference fit coupling on the fatigue strength of holed plates. The effect was investigated both experimentally and numerically. Axial fatigue tests have been carried out on holed specimens made of high performance steel (1075MPa of Ultimate strength and 990MPa of Yield strength) with or without a pin, made of the same material, press fitted into their central hole. Three different conditions have been investigated: free hole specimens, specimens with 0.6% of nominal specific interference and specimens with 2% of nominal specific interference. The experimental stress-life (S–N) curves pointed out an increased fatigue life of the interference fit specimens compared with the free hole ones. The numerical investigation was performed in order to analyse the stress fields by applying an elastic plastic 2D simulation with a commercial Finite Element software. The stress history and distribution along the contact interference of the fitted samples indicates a significant reduction of the local stress range due to the externally applied loading (remote stress) since a residual and compressive stress field is generated by the pin insertion

Study of the performance of standard RPC chambers as a function of bakelite temperature

A systematic study of the performance of the Resistive Plate Chambers as a function of the bakelite temperature is presented. The current, the rate and the efficiency were measured in the temperature range 22-40degreesC. The values of the relative humidity during the data taking were in the range 40-60%. Measurements show a strong dependence of the efficiency on bakelite temperature. (C) 2003 Elsevier Science B.V. All rights reserved

Laboratory implementation of edge illumination X-ray phase-contrast imaging with energy-resolved detectors

Edge illumination (EI) X-ray phase-contrast imaging (XPCI) has potential for applications in different fields of research, including materials science, non-destructive industrial testing, small-animal imaging, and medical imaging. One of its main advantages is the compatibility with laboratory equipment, in particular with conventional non-microfocal sources, which makes its exploitation in normal research laboratories possible. In this work, we demonstrate that the signal in laboratory implementations of EI can be correctly described with the use of the simplified geometrical optics. Besides enabling the derivation of simple expressions for the sensitivity and spatial resolution of a given EI setup, this model also highlights the EI’s achromaticity. With the aim of improving image quality, as well as to take advantage of the fact that all energies in the spectrum contribute to the image contrast, we carried out EI acquisitions using a photon-counting energy-resolved detector. The obtained results demonstrate that this approach has great potential for future laboratory implementations of EI. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Effects of feeding raw or extruded linseed on the ruminal ecosystem of sheep

Polyunsaturated fatty acids affect bacterial and protozoal population, inducing important modifications in rumen metabolism. The aim of this study was to investigate the effect of linseed extrusion on in situ ruminal degradability and microbial number and distribution. Six ruminally fistulated sheep were divided in 3 groups and fed one of the following diets according to a replicated Latin square design: (a) control, based on mixed hay and maize grains; (b) as in (a) plus 130 g of grounded raw linseed; (c) as in (b) except that the linseed was extruded. Extrusion decreased linseed dry matter and fat degradabilities. There was a marked reduction of total protozoal population in sheep fed supplemented diets. No effects were observed between groups on bacterial concentration, hay dry matter and NDF in situ degradabilities

Interference fit effect on holed single plates loaded with tension-tension stresses

This paper deals with the influence of interference fit coupling on the fatigue strength of holed plates. The effect was investigated both experimentally and numerically. Axial fatigue tests have been carried out on holed specimens made of high performance steel (1075MPa of Ultimate strength and 990MPa of Yield strength) with or without a pin, made of the same material, press fitted into their central hole. Three different conditions have been investigated: free hole specimens, specimens with 0.6% of nominal specific interference and specimens with 2% of nominal specific interference. The experimental stress-life (S–N) curves pointed out an increased fatigue life of the interference fit specimens compared with the free hole ones. The numericalinvestigation was performed in order to analyse the stress fields by applying an elastic plastic 2D simulation witha commercial Finite Element software. The stress history and distribution along the contact interference of the fitted samples indicates a significant reduction of the local stress range due to the externally applied loading (remote stress) since a residual and compressive stress field is generated by the pin insertion

Design and Optimization of a Pneumatic Clamping System for Direct-Driven Rotary Tables

Modern direct-driven and high-speed rotary tables with torque motor are optimally suited for all handling and assembly applications that require the shortest indexing times and flexible positioning. The following paper is devoted to the study, the design, and the optimization of an innovative table clamping system (brake for accurate positioning) actuated by pneumatic energy, working at a maximum clamping pressure of 6 bar. The challenge for the aforementioned application is related to developing a solution able to provide a maximum tangential torque (with clamping actuated) in the range of thousands of Nm without leveraging the use of high-pressure hydraulic energy. The optimization of the proposed solution is based on the precise calculation of the stresses in order to perform a fatigue assessment and on the elastic deformation of the clamps in order to set the correct tolerances between the mating parts. Eventually, an experimental campaign is carried out in order to tune the numerical model, which is then used to validate the proposed design solution

Energy characterization of Pixirad-1 photon counting detector system

This work is focused on the characterization of the Pixirad-1 detector system from the spectroscopic point of view. An energy calibration has been carried out using different X-ray sources such as fluorescence lines, synchrotron radiation and radioactive elements. The energy resolution has been measured as function of the energy and the results have been compared with theoretical estimation. Last, the charge sharing fraction has been evaluated by exploiting the monochromatic energy of the Elettra synchrotron beam

A new measure of health motivation influencing food choices and its association with food intakes and nutritional biomarkers in European adolescents

Objective:To develop a scale to assess health motivation influencing food choices and to explore its performance in the associations with food intakes and nutritional biomarkers. Design:Psychometric study using cross-sectional self-report questionnaires and nutritional biomarkers. Setting:Multi-centre investigation conducted in ten European cities. Participants:2954 adolescents who were included in the HELENA study and completed the Food Choices and Preferences (FCP) questionnaire. Results:Nineteen out of 124 items of the FCP questionnaire were in the same dimension. Sixteen presented adequate parameters for the Scale of evaluatiOn of Food choIcEs (SOFIE). The scores were positively associated with the intakes of cereals, dairy products, meats and eggs, and fish, as well as with blood concentrations of vitamin C, ß-carotene, n-3 fatty acids, cobalamin, holo-transcobalamin and folate; scores were negatively associated with the intake of alcohol. Conclusions:SOFIE can improve the assessment of motivation influencing food choices based on items with the best performance and is proposed as a new measure to health-related studies