1,720,982 research outputs found
Properties and applications of additively manufactured metallic cellular materials: a review
Get PDFAdditive manufacturing (AM) refers to a collection of manufacturing methods involving the incremental addition of material to build a part directly in its final or near-final geometry, usually in a layer-by-layer process. Metal AM in particular has seen great industrial adoption and maturation. This technology enables increased freedom of design in engineered materials with complex geometries, of which architected cellular or lattice structures are particularly promising in a wide range of applications. These materials are similar to stochastic foams which have found many industrial applications over the last few decades, but regular cellular structures possess a higher degree of control over the manufactured architectures made possible by additive manufacturing. These architected porous materials have properties that can be fine-tuned for a particular application (for mechanical performance, permeability, thermal properties, etc.). The control over the design and manufacturing of such architected structures in comparison to stochastic structures opens new application possibilities and enables a range of new products and features. This potential is only starting to be realized as metal AM techniques are maturing and are increasingly being adopted in various industries, and as design-for-AM capabilities improve. This review paper summarizes the unique properties of AM lattice structures and how these have been successfully employed for specific applications so far, and highlights various application areas of potential interest for the near future. The focus in this review paper is therefore on unique achievable properties and the associated applications for metal additively manufactured lattice structures. © 2021 The Author(s
Additively manufactured Ti–6Al–4V thin struts via laser powder bed fusion: Effect of building orientation on geometrical accuracy and mechanical properties
No full textPorous metal lattice structures have a very high potential in biomedical applications, setting as innovative new generation prosthetic devices. Laser powder bed fusion (L-PBF) is one of the most widely used additive manufacturing (AM) techniques involved in the production of Ti6Al4V lattice structures. The mechanical and failure behavior of lattice structures is strongly affected by geometrical imperfections and defects occurring during L-PBF process. Due to the influence of multiple process parameters and to their combined effect, the mechanical properties of these structures are not yet properly understood. Despite the major commitment to characterize and better comprehend lattice structures, little attention has been paid to the impact that single struts have on the overall lattice properties. In this work, the authors have investigated the tensile strength and fatigue behavior of thin L-PBF Ti6Al4V lattice struts at different building orientations (0°, 15°, 45°, and 90°). This investigation has been focused on the effect that microstructural defects (particularly porosity) and actual surface geometry (including surface texture and geometrical errors such as varying cross-section shape and size) have on the mechanical performances of the struts in relation to their building direction. The results have shown that there is a tendency, particularly for low printing angles, of fatigue life to decrease with decreasing of the building angle. This is mainly due to the surge in surface texture and loss in cross-sectional regularity. On the other hand, the monotonic tensile test results have shown a low sensitivity to these factors. The strut failure behavior has been examined employing dynamic digital image correlation (DIC) of tensile tests and scanning electron imaging (SEM) of the fracture surfaces
Efficient optimization framework for L-PBF fatigue enhanced Ti6Al4V lattice component
Get PDFIndustries today face challenges in incorporating metallic additively manufactured lattice structures in critical components subjected to fatigue loading. This work explores the relationship between fatigue properties and the printing orientation of Laser-Powered Bed Fusion (LPBF) lattice structures. This relation is at the base of a cost-effective and time-efficient optimization workflow able to determine the optimal lattice printing orientation for improved fatigue life. Fatigue resistance is tested under uniaxial conditions on miniaturized specimens that mimic the lattice sub-unit elements: struts and nodes. The collected data is used as input for the optimization algorithm to determine the specimen orientation that maximizes fatigue life. The optimized specimens are manufactured, tested under three-point-bending conditions, and analysed using metrological x-ray computed tomography to verify the improvement. The proposed workflow is able to produce a 24 % increase in specimen fatigue life by simply adjusting the orientation on the printing plane
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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