1,720,970 research outputs found
Composite materials for wind energy applications
Get PDFWeight and strength of materials are important in design for wind energy and aerospace industries. It is a major advance to design new materials for these kinds of applications to achieve high efficiency reducing weight. Sandwich composites and Fibre Metal Laminates (FMLs) are outstanding materials owing to superior mechanical properties. However, they need to be evaluated under static and dynamic loading to which these kinds of applications are subjected.
The purpose of the thesis is the investigation of sandwich composite and FMLs for wind turbine blade and aerospace structure evaluating Digital Image Correlation (DIC) and modelling of sandwich composites and FMLs to provide an insight into the failure processes in these materials.
In this thesis, sandwich composites with four different core materials and five different surface finishing options were studied. There are advantages in having a softer core near the outer surface to improve impact and mechanical performance and grooves in the core are used to improve resin infusion and draping for curved structures. For the sandwich composites investigated, PVC and PET foam cored sandwich composites can be a substitute foam core material especially for wind turbine blades instead of using balsa cored sandwich composite. In addition, saw-cut (foam is partially cut) and flexi-cut (with grooves on both sides) are surface finishing options often employed to improve the energy absorption and increase the flexural behaviour in a beneficial way. The behaviour of curved sandwich composites was also assessed.
In addition, FMLs with three different metal and three different design configurations have been evaluated. The most important parameter for the FMLs are the thickness when considering flexural and impact response of the FMLs.
Both of these studies can be guidelines for designing materials for wind turbine blade and aerospace applications to decrease structure weight and increase the mechanical strength of the structure.Open Acces
Impact Performance Improvement of Multiscale Hybrid Fiber Reinforced Polymer Composites with CNT
No full textImproving the interface properties of carbon nanotubes increases the mechanical performance of fiber-reinforced polymer matrix composites. Studies on different fiber types and different polymer matrix materials present promising results in literature. The effect of carbon nanotube (CNT) additives on impact performance of fiber reinforced polymer matrix composites produced by vacuum infusion method and drop weight impact test applied. Glass and carbon 1 m2 fiber fabrics were divided into 9 equal square pieces and placed on top of each other to make them multi-layered structure. Fiber reinforcements were produced using vacuum infusion method with epoxy resin. 0.5% of the total composite weight was added to CNT with same production parameters and intraply hybrid composite containing glass, carbon and aramid fibers was also produced. Samples were produced from the composite plates and the drop weight impact test was performed with 50 J impact energy in accordance with ASTM D7136 standard. While this increase could be observed in glass fiber and carbon fiber reinforced composites, the impact energy absorption performance in carbon fiber reinforced composite increased more than 100%. CNT increased the impact performance of multi-layer fiber reinforced polymer matrix composites
Impact Performance Improvement of Multiscale Hybrid Fiber Reinforced Polymer Composites with CNT
No full textImproving the interface properties of carbon nanotubes increases the mechanical performance of fiber-reinforced polymer matrix composites. Studies on different fiber types and different polymer matrix materials present promising results in literature. The effect of carbon nanotube (CNT) additives on impact performance of fiber reinforced polymer matrix composites produced by vacuum infusion method and drop weight impact test applied. Glass and carbon 1 m2 fiber fabrics were divided into 9 equal square pieces and placed on top of each other to make them multi-layered structure. Fiber reinforcements were produced using vacuum infusion method with epoxy resin. 0.5% of the total composite weight was added to CNT with same production parameters and intraply hybrid composite containing glass, carbon and aramid fibers was also produced. Samples were produced from the composite plates and the drop weight impact test was performed with 50 J impact energy in accordance with ASTM D7136 standard. While this increase could be observed in glass fiber and carbon fiber reinforced composites, the impact energy absorption performance in carbon fiber reinforced composite increased more than 100%. CNT increased the impact performance of multi-layer fiber reinforced polymer matrix composites
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
Impact Performance Improvement of Multiscale Hybrid Fiber Reinforced Polymer Composites with CNT
Get PDFImproving the interface properties of carbon nanotubes increases the mechanical performance of fiber-reinforced polymer matrix composites. Studies on different fiber types and different polymer matrix materials present promising results in literature. The effect of carbon nanotube (CNT) additives on impact performance of fiber reinforced polymer matrix composites produced by vacuum infusion method and drop weight impact test applied. Glass and carbon 1 m2 fiber fabrics were divided into 9 equal square pieces and placed on top of each other to make them multi-layered structure. Fiber reinforcements were produced using vacuum infusion method with epoxy resin. 0.5% of the total composite weight was added to CNT with same production parameters and intraply hybrid composite containing glass, carbon and aramid fibers was also produced. Samples were produced from the composite plates and the drop weight impact test was performed with 50 J impact energy in accordance with ASTM D7136 standard. While this increase could be observed in glass fiber and carbon fiber reinforced composites, the impact energy absorption performance in carbon fiber reinforced composite increased more than 100%. CNT increased the impact performance of multi-layer fiber reinforced polymer matrix composites
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
The effect carbon nanotube on three-point bending behavior of fiber reinforced composite
Get PDF71-79The aim of this research article has been to show the effect of Carbon Nanotube (CNT) additive on the performance of
composite plate materials with fiber reinforced polymer matrix produced by vacuum infusion method under bending test. In
this study, multiple layered composite plates have produced by glass, carbon, and aramid fiber reinforcements with 0.5%
CNT addition by mass. In addition, a hybrid composite plate containing glass, carbon and aramid (Kevlar) fiber has
produced with CNT addition by using the same production parameters. Three point bending test has performed on the
composite plates under 1 mm/min bending with ASTM D7264 standard. As a result, CNT addition has increased the flexural
performance but has decreased the elongation of glass and carbon fiber reinforced systems. In aramid reinforced system,
both flexural strength and elongation has increased. However, in the hybrid fiber reinforced system, different fiber types
have damaged at different elongation distances within the structure under different loads, and gradually more than one
failure have observed. When the CNT has added to the hybrid system, the elongation increased but the flexural strength has
decreased
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
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