1,720,967 research outputs found
Earing prediction in cup drawing based on non-associated flow rule
No full textAn anisotropic constitutive model based on Non-Associated Flow Rule (Non-AFR), which incorporates plane stress yield functions (Hill's quadratic function and Yld2000-2d by Barlat et al.), was implemented to finite element codes (ABAQUS, LS-DYNA 3D) by using User Material options. By using Non-AFR, Yld2000-2d is capable of predicting more than four ears which is possible only with Yld2004 by Barlat et al. when used with an Associated Flow Rule. A short review of the Non-Associated Flow Rule was provided. Simulation of the cup drawing process for a rigid container sheet alloy using mini-die geometry was performed to show the cup height profile (earing profile) obtained from Non-AFR. The simulation results were compared with experimental earing profile data and it was shown that the simulations using Yld2000-2d and the Non-AFR led to the excellent prediction of the earing profile
Convolute cut-edge design for an earless cup in cup drawing
No full textA convolute cut-edge design is performed using FEM (Finite Element Method) for a single step cup drawing operation in order to produce an earless cup profile. Mini-die drawing based on a circular blank shape is initially carried out in order to verify the earing prediction of the Yld2004 model for a body stock material. A realistic cup geometry is then employed to design a non-circular convolute edge shape. An iterative procedure based on finite element method is initially used to design a convolute shape for an earless target cup height. A constant strain method is suggested to obtain a new convolute prediction for the next iteration from the current solution. The Yld2004 model is also introduced to predict the anisotropy of the materials precisely
Convolute cut-edge design for a circular cup based on FEM and an analytical approach
No full textA convolute cut-edge design was developed for a single step cup drawing operation in order to produce an earless cup profile. An iterative procedure, based on the finite element method and a constant strain method using a new anisotropic yield function (Barlat et al., called Yld2004-18p), was used to design a convolute shape for an earless target cup height. A simplified analytical approach that relates the earing profile to r-value directionality was presented in this work. R-value directionality was included with the incompressible condition from the compressive mode at the rim. The result obtained from the iterative procedure was compared with the one from the analytical approach suggested. It is proven that both Yld2004 model and the simplified analytical method provide an accurate prediction of the convolute cut-edge shape. © 2007 American Institute of Physics
On the use of stress-based forming limit curve for forming and fracture
No full textThe forming limit curve (FLC) or diagram illustrates the major and minor strains expected on the surface of a deforming sheet material at the onset of local necking. Since determining forming limits experimentally is costly and time consuming, it is desirable to develop a theoretical model. In this work, the equal biaxial strain hardening behavior and the anisotropic yield function Yld2000-2d (Barlat et al. [4]) are used as input to the model that calculates forming limits according to the Marciniak-Kuczynski (M-K) imperfection theory for strain localization. The resultant strain-based forming limit curves are mapped to stress-based FLC in stress space. The mapping procedure from strain space to stress space was explained in detail for a general nonquadratic yield function. A solution to the challenge of assessing formability in stress space is proposed by using a single parameter which indicates the necking based on plastic state variables. The necking parameter was utilized for the simulation including the forming of an automotive part and the fracture in a beverage can end
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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