1,721,456 research outputs found
A reduced Yld2004 function for modeling of anisotropic plastic deformation of metals under triaxial loading
No full textSolid elements are increasingly utilized in finite element analysis of sheet metal stamping processes with the rising application of advanced high strength steels (AHSSs) and aluminum alloys in auto industries as these advanced materials fail in a form of rupture with negligible necking during sheet metal stamping. However, there are rare orthotropic yield functions for the description of directional dependence of plastic deformation of body-centered cubic (BCC) materials and face-centered cubic (FCC) metals under spatial loading, especially for metals with moderate anisotropy. For this purpose, the Yld2004-18p function is revisited and modified to provide satisfactory predictability of orthotropic behavior of BCC and FCC materials under spatial loading with reduced experimental costs for the calibration of orthotropic coefficients. The reduced Yld2004 equation is utilized to characterize the directional dependence of plastic behavior of AHSSs and aluminum alloys to verify its promising accuracy and cost efficiency. The reduced Yld2004 function is also implemented into finite element analysis to assess its accuracy and computation efficiency compared with the Hill48, Yld2004-18p and the anisotropic Drucker equations. The application in both analytical prediction and numerical analysis proves that the reduced Yld2004 function provides competitive predictability of anisotropic plastic deformation for BCC and FCC metals with moderate directionality under triaxial stress states, but the cost for the parameter calibration is cut down by about half compared to the Yld2004-18p function. Considering the satisfactory accuracy, reduced cost for the parameter calibration as well as the fact that most metals are of gentle dependence on loading direction, the reduced Yld2004 function is expected to reliably reproduce actual stamping processes of the majority of AHSSs and aluminum alloys with virtual models thereby improving the credibility of both numerical design of tools and process optimization.
Strength modeling of sheet metals from shear to plane strain tension
No full textThis paper proposes a yield function to model sheet metal strength between shear and plane strain tension. The function is expressed as an equation of the three stress invariants to take into account the pressure sensitivity, the Lode dependence and the strength-differential effect on material strength. To validate the accuracy of the formulated yield function, experiments are conducted with the designed specimens to characterize the mechanical behavior of AA7075 and QP980 sheet between shear and plane strain tension. The yield function and the combined Swift-Voce hardening law are iteratively calibrated by using an inverse experimental-numerical scheme. The calibrated constitutive equations are utilized to numerically predict the load-stroke responses of different tests. The numerical prediction demonstrates that the proposed yield function calibrated by the inverse engineering approach can accurately describe the material strength in various loading conditions from the onset of yielding to ultimate rupture. Accordingly, the proposed yield function is recommended to model material strength under various loading conditions, and the inverse engineering approach is suggested for the calibration of its parameters.
Earing prediction of AA 2008-T4 with anisotropic Drucker yield function based on the second and third stress invariants
No full textThis paper applies anisotropic Drucker yield function [14] (Lou and Yoon, 2018, Int. J. Plasticity 101, 125-55) to predict earing profile after cup deep drawing of AA 2008-T4. The new yield function is implemented into ABAQUS/Explicit using semi-implicit integration algorithm to calculate the increment of plastic strain. Both associated and non-associated flow rules are incorporated in this study. The predicted anisotropy and cup height profile are compared with the experimental results and those predicted from the Hill48, Yld91 and Yld2004-18p yield functions. It is observed that the earing profile predicted from the new yield function shows high accuracy. The computation time is also compared to investigate the computation cost of different yield functions. The comparison reveals that it takes the shortest time for the Hill48 function, the anisotropic Drucker yield function reduces 30%∼40% of computation cost compared with the Yld91 and Yld2004-18p functions. It is concluded from the simulation of cup deep drawing that the new yield function can provide high accurate numerical analysis of plastic deformation for anisotropic metals with competitive computation cost
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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