1,720,977 research outputs found
Un metodo per la mitigazione delle vibrazioni indotte dal traffico ferroviario tramite barriere assorbenti – sperimentazione in sito
No full textEnergy release as a parameter for fatigue design of additive manufactured metals
Full text linkAdditive manufacturing (AM) is spreading in a wide range of industrial fields. The influence of the printing parameters on the mechanical performance is still an open issue among researchers, particularly when dealing with fatigue loads, which can lead to an unexpected failure. Classical fatigue tests require a large amount of time and materials to be consumed. Compared to the traditional fatigue assessment, the thermographic method (TM) is able to derive in a very rapid way the SN curve and fatigue limit of the material monitoring its energetic release during fatigue tests. In this work, for the first time, the energetic release during fatigue test has been evaluated in specimens made of AISI 316L, obtained by SLM technique. Compared to literature data, the specimens show premature failure, even at low stress levels, with brittle fracture surfaces. The internal microstructure seems to be strictly related to the energetic release of the material
Investigation of the tribological properties of different textured lead bronze coatings under severe load conditions
No full textThe purpose of this paper is to investigate the variation in the coefficient of friction (CoF) and also the wear in a lead bronze coating under different texture conditions. The tribological tests were performed using a tribometer with pin on disk configuration. Several kinds of textures, realised by a surface laser texturing, were tested by varying the diameter, depth, and density of the dimples under severe working conditions. The innovative aspect concerns the behaviour of the textured lead bronze coating and the lubrication conditions when the sample is subjected to extreme load conditions. Confocal microscopies and SEM (Scanning Electron Microscopy) / EDS (Energy Dispersive X‐Ray Spectroscopy) analyses were performed to evaluate the texture behaviour and also the surface deterioration of the coating. The results show that the application of texture processing leads to an improvement in the tribological properties of the coating. By analysing separately the variation of the different geometric parameters of the dimples, it has been shown that the best results are obtained with a diameter of 50 μm, a density of 5%, and a depth of 5 μm
Determination of fatigue limit by static thermographic method and classic thermographic method on notched specimens
Full text linkThe aim of the present work is to investigate the possibility to evaluate the fatigue limit of such a component through the so-called Static Thermographic Method (STM). This new approach has been proposed in 2013 by Risitano and Risitano to determinate the fatigue limit of metallic materials through static tensile tests. Investigating the trend of the surface temperature of the material during static tensile test, the method proposes to correlate the first deviation from linearity of the surface temperature to a damage limit that has been proven to have relation with the fatigue limit. Static tensile tests at different stress rate have been carried out on V-notched specimens. Stepwise fatigue tests have been carried out in order to apply the classic Thermographic Method that has been hugely validated to determinate the fatigue limit of metallic components. Static tests at different stress rate showed that the method is dependent on this parameter; anyway, this dependence does not affect the results achieved in terms of fatigue limit. The experimental results showed a good agreement with the energetic methods considered in the present work
Fatigue life evaluation of automotive mechanical components by using smart design algorithm
No full textThe aim of this work is to develop a so-called “smart design” in MATLABTM environment. The design process consists of an innovative and automatic algorithm aimed at rapidly evaluating the fatigue damage of automotive mechanical components, starting from the load cycle that the component is subjected. In this work, the target component is the front halfshaft of a sport utility vehicle. The algorithm works as follows. A driving cycle has been acquired through an experimental setup consisting of a control unit, a GPS and an OBD port. A mathematical model of the vehicle, based on longitudinal vehicle dynamics, has been developed in SimulinkTM environment to evaluate the traction torque at the wheel. A torsional fatigue tests campaign has been carried out on nine front halfshafts of the vehicle to evaluate the torque amplitude–number of cycles curve of the component. The output histories, computed with the rainflow method, have been referred to a load ratio R = −1, according to the experimental fatigue tests, by the application of three different mean stress fatigue criteria: Goodman, Gerber, and Morrow. At the end, cumulative fatigue damage on the component has been evaluated by the application of the Palmgren–Miner rules. The results show that the Goodman criteria, with a fatigue damage value of around 20%, represents the most precautionary criteria for the fatigue design of an automotive component
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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