1,721,031 research outputs found
Stress fields due to inclined notches and shoulder fillets in shafts under torsion
No full textClosed-form expressions of the stress fields in notched rounded bars subjected to torsion are obtained. The notch profile is mathematically described according to Neuber's conformal mapping z = (u + iv)(q), which gives parabolic and hyperbolic profiles depending on q. The notch axis is inclined with respect to the rounded bar axis. This condition results in two eigenvalue functions: the former is associated with the antisymmetric stress field and gives a stress distribution of asymptotic nature when the notch radius is equal to zero. Conversely, the latter is associated with the symmetric stress field and results in a non-singular stress distribution. This specific condition has been noted in the literature only rarely, where only the antisymmetric part of the stress field is discussed in detail. Theoretical results are compared with numerical data as determined from two models weakened by a parabolic notch and a hyperbolic notch, both notches having the local axis inclined to 45 degrees with respect to the bar longitudinal axis. The agreement is found to be satisfactory
A study of fatigue resistance in joints welded in steel and light alloy according to deformation energy at the weld toes and roots
No full textWELDIN
Fatigue properties of ductile cast iron containing chunky graphite
No full textThis work deals with experimental determination of high cycle fatigue properties of EN-GJS-400 ductile cast iron containing chunky graphite. Constant amplitude axial tests were performed at room temperature under a nominal load ratio R= 0. In order to evaluate the influence of chunky graphite morphology on fatigue life, fatigue tests were carried out also on a second set of specimens without this microstructural defect. All samples were taken from the core of a large casting component. Metallurgical analyses were performed on all the samples and some important microstructural parameters (nodule count and nodularity rating, among others) were measured and compared. It was found that a mean content of 40% of chunky graphite in the microstructure (with respect to total graphite content) does not influence significantly the fatigue strength properties of the analysed cast iron. Such result was attributed to the presence of microporosity detected on the surface fracture of the specimens by means of electron scanning microscope. © 2012 Elsevier B.V
On the intensity of linear elastic high order singularities ahead of cracks and re-entrant corners
No full textThe paper deals with high order elastic singular terms at cracks and re-entrant corners (sharp V-notches), which are commonly omitted in linear elastic analyses by the argument that the strain energy and displacements in the near-tip region should be bounded. The present analysis proves that these terms are fully included in the elastic part of complete elastic-plastic stress and strain solutions.
The intensities of high order singular terms are found to be linked to the linear elastic stress intensity factor and the extension of the plastic zone along the crack bisector line. The smaller the plastic radius, the smaller the intensities of high order singular terms are.
A physical justification of the existence of high order singular terms is provided on the basis of the strain energy density distribution detected along the crack bisector line. Finally, the influence of the V-notch opening angle is made explicit, discussing also the relationship between the singularity orders and the solution of a Williams' type sinusoidal eigen-equation
In-plane and out-of-plane stress field solutions for V-notches with end holes
No full textClosed form expressions of stress distributions for V-notches with end holes and varying opening angles are presented. The solution for the elastic plane problem is obtained by means of the Kolosov-Muskhelishvili approach by using a reduced number of complex terms. The exponents of the potential functions are simple combinations of Williams' eigenvalues for pointed V-notches in mode I and mode II. The degree of accuracy of the new solution, which is approximate, is found to be very satisfactory for engineering applications. When the V-notch opening angle is equal to zero, the solution matches the keyhole notch solutions already reported in the literature by Neuber (for mode I) and by Kullmer and Radaj (mode I and mode II) and based on the Airy stress function. In parallel, the out-of-plane problem is solved by means of an holomorphic function H(z) where the exponent is still linked to the leading order eigenvalue of the pointed V-notch in mode III. For this loading mode the solution is exact. When the notch opening angle is equal to zero and also the notch root radius tends to zero the solution matches Kullmer's keyhole notch solution
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
Fatigue tests on a compression fork-pin coupling of a front motorbike suspension under fully reversed bending load
No full textThe forecarriage of a motorbike allows the driver to turn the vehicle in the desired direction and control its behaviour during the motion. In particular the fork-pin compression coupling of the front suspension is very important for the reliability and the safety of the mean. A failure of this component is very dangerous because it would make the vehicle unmanageable and it could provoke severe injuries to the driver. Therefore it is a very critical component and the designer’s aim is to assure its reliability but at the same time keep the production costs low.
One of the most important cause of failure is due to fatigue under fully reversed bending load. In this work, fatigue behaviour of fork-pin couplings, produced by the Paioli Meccanica S.p.a. of Bologna, is analysed and the results of the tests, carried out on an ad-hoc testing system, are summarised
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