1,721,030 research outputs found
Prediction of ductile failure in materials for onshore and offshore pipeline applications
No full textThis paper shows the procedures needed to calibrate a numerical model intended for ductile damage estimation of bulk materials. For this purpose, an extensive experimental campaign has been carried out on three steels used for offshore/onshore pipe applications. Tests have been performed providing very different stress states: tensile and compressive uniaxial tests, multiaxial tensile tests on round notched bars, 3-point bend tests, again on notched geometries, and plane strain tensile tests on large grooved specimens. Based on the gathered results, a standard plasticity model has been tuned and then the damage model parameters have been identified for each investigated material. The chosen theoretical formulation can take into account all of the experimental evidence: hence, the numerical model represents a useful tool for finite element simulation of engineering problems where information concerning the materials ultimate resistance capability is needed. Moreover, the proposed calibration technique has general validity and can be used to tune other similar damage models. © 2013 The Author(s)
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
Caratterizzazione sperimentale del legame elasto-plastico ad elevete deformazioni mediante la prova di torsione .
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The effect of stress invariants on ductile fracture limit in steels
No full textIt is widely accepted that damage due to plastic deformation and ductile fracture in metals greatly depends on the triaxiality level (T) of the stress tensor, but according to recent developments described in the literature, it has been observed that the fracture limit epsilon(f) may depend also on the deviatoric parameter (X) of the stress state. In the present paper, several special fracture tests comprising tensile, torsion, flattening and bending have been devised for the specific purpose of investigating as much wide as possible region of the T, X domain. In addition, numerical simulations of each test have been set up to provide additional information whenever direct measures could not be feasible. Three steel grades for cold working applications, each characterized by two different heat treatments have been investigated in the experimental campaign. The results state that fracture limits in the epsilon(f) - T plane can be confined between two boundary curves. characterized by the values X = 0 and X = 1. The paper proposes that this evidence is a consequence of the application of Tresca criterion for shear failure. It is furthermore theoretically derived and experimentally verified that the two limits are linked together through the material hardening behaviour. Finally, it is discussed that an asymmetry between tension and compression states could exist as a consequence of the proposed approach. (C) 2009 Elsevier Ltd. All rights reserved
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
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