1,720,974 research outputs found
Modelling of riveted joints with a new rivet element
No full textRiveting is a well established technology in the manufacturing of aeronautical structures as well as in the automotive industries. Despite its simplicity, the rivet presents a local stiffness that is not easy to properly model within a large finite element analysis. However, precision in the local stiffness evaluation is essential to perform any structural analysis when several rivet are applied in a joint structure. The result is that any rivet requires a local mesh refinement or, and this is the most common case, a drastic simplification of its structural modelling characteristics. In the present paper the structural behavior of a riveted lap joint connection was investigated experimentally and numerically using a new rivet finite element. The Rivet Element, based on a closed-form solution of a theoretical model of the rivet joint, is able to precisely evaluate, in FE analysis, both local and overall stiffness of riveted joints with a very low contribution of dofs. A comparison with a joint model performed with very refined non-linear 3D model of rivet and with experimental data is performed and a good agreement is demonstrated
Modellazione di una giunzione rivettata soggetta a carichi ortogonali mediante un nuovo elemento rivetto
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Variazioni del degassamento negli ultimi 2000 anni nell’area dei Colli Albani, registrare dagli speleotemi presenti in una cava di tufo associata alla villa romana de I Centroni (Morena, Roma).
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Structural analysis of riveted structures using a new FE modelling technique
No full textA theoretical approach, in order to define the structural behaviour of riveted joints, is presented. The closed form solutions lead to the definition of a Rivet Element useful to FE models of multi-riveted structures. The objective is an accurate evaluation of the local stiffness of riveted joints in FE analysis, which is fundamental to perform a reliable simulation of multi-joint structures and, consequently, a good estimate of loads acting on connections; this makes it possible to introduce new general criteria allowing, for example, to predict fatigue behaviour. On the other hand, a low number of degrees of freedom is needed when several connections are present in a complex structure. The goal is to reach a reliable model of the rivet region which can be used as the basis to develop a Rivet Element in FE analysis. The proposed Rivet Element combines the precision in the simulation with a very limited number degrees of freedom in the finite element model of a complex structure having several rivets. In the present paper the structural behavior of two simple riveted specimens is investigated experimentally and numerically using a new Rivet Element. A comparison with a joint model performed with very refined non-linear 3D models of rivet and with experimental data is performed and a good agreement is shown.</jats:p
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
Experimental characterization and numerical simulation of riveted lap-shear joints using Rivet Element
No full textIn aeronautical and automotive industries the use of rivets for applications requiring several joining points is now very common. In spite of a very simple shape, a riveted junction has many contact surfaces and stress concentrations that make the local stiffness very difficult to be calculated. To overcome this difficulty, commonly finite element models with very dense meshes are performed for single joint analysis because the accuracy is crucial for a correct structural analysis. Anyhow, when several riveted joints are present, the simulation becomes computationally too heavy and usually significant restrictions to joint modelling are introduced, sacrificing the accuracy of local stiffness evaluation. In this paper, we tested the accuracy of a rivet finite element presented in previous works by the authors. The structural behaviour of a lap joint specimen with a rivet joining is simulated numerically and compared to experimental measurements. The Rivet Element, based on a closed-form solution of a reference theoretical model of the rivet joint, simulates local and overall stiffness of the junction combining high accuracy with low degrees of freedom contribution. In this paper the Rivet Element performances are compared to that of a FE non-linear model of the rivet, built with solid elements and dense mesh, and to experimental data. The promising results reported allow to consider the Rivet Element able to simulate, with a great accuracy, actual structures with several rivet connections
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