1,720,952 research outputs found
FLAx REinforced Aluminium (FLARE): A bio-based Fibre Metal Laminate alternative combining impact resistance and vibration damping
No full textFibre metal laminates (FML) were initially conceived as a hybrid material, aiming to create synergy between the impact resistance of metals and excellent fatigue resistance of fibre reinforced polymers. The purpose of this approach was to overcome the limitations of single-material structures. However, despite its considerable promise, the use of the FML concept has primarily been confined to aerospace applications and heavily relies on synthetic fibres that carry significant environmental implications. Hence, given the growing concerns about climate change and the challenges posed by recycling glass fibre composites, a new generation of FMLs with a reduced carbon footprint should be envisaged. Research on flax fibre composites reveals convincing mechanical properties and remarkable damping capacities. However, the broader adoption of these composites remains restricted primarily due to issues related to low impact resistance, moisture absorption and flammability concerns. The FML concept presents a viable solution to surmount these constraints, consequently facilitating the integration of these materials into primary structures. Hence, the research endeavour aimed to attain comprehensive insights into FLAx REinforced aluminium (FLARE), particularly focusing on its impact resistance and vibration damping capabilities, which are believed to be the principal benefits of this hybrid material. The research goal was divided into three distinct research tasks: conducting experimental analyses to characterise the damping behaviour of FLARE, evaluating the impact resistance through experimental means, and validating predictive tools to offer initial insights into the design principles governing such a FML. FLARE, along with flax fibre reinforced epoxy (FFRE) and GLARE specimens, were manufactured using wet layup combined with vacuum bagging techniques. First, tensile tests were conducted to validate the applicability of the metal volume fraction (MVF) approach in predicting the mechanical properties of FLARE. Intriguingly, the well-known non-linear behaviour exhibited by flax was not observed in the case of FLARE. The results revealed that while the MVF method provided a satisfactory approximation, it was the "inelastic" modulus of FFRE that predominantly contributed to the stiffness of FLARE.Dynamic mechanical analysis and vibration beam tests were carried out to assess the influence of incorporating metallic layers on the vibration damping characteristics of flax fibre composites. The investigation revealed that the metallic layer predominantly governs the damping behaviour of the FML. Notably, an inverse rule of mixture emerged as the most effective means of approximating its loss factor. Low-velocity impact tests were conducted to gain insights into the impact response of FLARE in comparison to conventional FMLs. The analysis indicated that the aluminium layers play a significant role in energy absorption, whereas the composite strength emerges as the critical factor influencing impact resistance. A quasi-static analytical model was also assessed, offering an initial estimation of the impact response, yet it warrants further refinement.In conclusion, the FML concept holds promise for FLARE, but its application requires a novel approach compared to previous methods, to render FLARE viable for practical real-world applications.Aerospace Engineerin
Flax fibre metal laminates (FLARE): A bio-based FML alternative combining impact resistance and vibration damping?
No full textFibre metal laminates (FML) were originally developed as a hybrid material, to create synergy between the impact resistance of metals and excellent fatigue and corrosion resistance of fibre reinforced polymers, and to overcome the shortcomings of monolithic materials. Yet, the scope of the FML concept is predominantly limited to GLAss REinforced laminates (GLARE) for aerospace structures [1]. However, with the rising concerns about climate change, and the issues of recycling glass fibre composites, a new generation of FMLs with a reduced carbon footprint should be envisaged. This can be achieved by using bio-based fibre reinforced composite layers, particularly flax fibre instead of glass fibre composite, rendering FMLs with lower embodied energy, in which aluminium layers can be easily recycled by incineration with energy recuperation of the flax composite. Flax fibres demonstrate promising specific mechanical properties compared to glass fibres, particularly regarding tensile stiffness and bending stiffness and strength. This means that flax fibres can outperform glass fibres in stiffness-based designs, and in applications in which the loading mode is predominantly in bending. This includes applications in the transportation and construction sectors as well as secondary structures for civil aircraft, such as automotive panels, flooring, and bridge decks. Additionally, flax fibre composites demonstrate high damping capabilities due to the unique hierarchical structure of these fibres. This makes them particularly suitable for applications where vibrational and acoustic damping is of interest which includes many of the above given examples. However, they also have disadvantages such as high moisture absorption that can restrict their use [2]. The FML concept would overcome these limitations and thus allow the introduction of these materials in primary structures. In this study, the combination of flax fibre reinforced epoxy with thin aluminium layers is realised as a partially biobased alternative to current FMLs, aiming to obtain primarily good vibration damping properties and improved impact resistance. The impact behaviour of the flax fibre reinforced aluminium (FLARE) will be evaluated by low velocity impact and quasi-static indentation tests to identify the role of each material constituent. The results will be compared with a predictive model based on the work of F. Morinière et al. [3]. For the damping properties, to cover a wide range of frequencies and to compare methods, the vibration absorption capacities will be measured by dynamic mechanical analysis and vibration beam tests. The results will be compared to the model predictions from the metal volume fraction method. Finally, this study will give a first overview of the properties of FLARE and will verify the validity of the predictive tools developed for conventional FMLs, which help in the design phase to optimise the structure according to specific requirementsStructural Integrity & CompositesBio-based Structures & Material
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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