1,720,957 research outputs found
Study on structural integrity of welded components using the LMM
Get PDFIndustries, which have structures, subjected to high temperatures, such as the nuclear power plant industry, give paramount importance to structural integrity assessments due to the obvious catastrophic effect an unfortunate failure might cause. The presence of welds increases the susceptibility of premature failure within the structures. Hence identifying the structural response of welded components under cyclic loading conditions and developing methods to predict their safe life is of significant importance. The work within this thesis focuses on the investigation of cyclic plasticity and creep-cyclic plasticity interaction of welded components, and the consequential damage assessment using the Linear Matching Method (LMM). Firstly, a numerical investigation and parametric study on the cyclic plasticity behaviour of a butt-welded pipe under cyclic thermal and constant pressure load is undertaken. The most critical results are used to create limit load envelopes that may be used to design welded pipes within the specified range.;Secondly, through a series of case studies, the effect of various complex loading conditions on the evolution and progress of fatigue damage, creep damage and creep-fatigue interaction of welded connectors, commonly found in power plants, are identified and discussed comprehensively using the Direct Steady Cycle Analysis (DSCA) and the extended Direct Steady Cycle Analysis(eDSCA) method within the Linear Matching Method Framework (LMMF). Finally, the subroutine is enhanced to account for any previous residual stress such as the welding residual stress (WRS) on the shakedown-ratchet limit interaction curves and the creep-fatigue endurance. With a welded flange case study, the effect of WRS on mean strain during the transient cycles and the fatigue damage at steady state is demonstrated.Industries, which have structures, subjected to high temperatures, such as the nuclear power plant industry, give paramount importance to structural integrity assessments due to the obvious catastrophic effect an unfortunate failure might cause. The presence of welds increases the susceptibility of premature failure within the structures. Hence identifying the structural response of welded components under cyclic loading conditions and developing methods to predict their safe life is of significant importance. The work within this thesis focuses on the investigation of cyclic plasticity and creep-cyclic plasticity interaction of welded components, and the consequential damage assessment using the Linear Matching Method (LMM). Firstly, a numerical investigation and parametric study on the cyclic plasticity behaviour of a butt-welded pipe under cyclic thermal and constant pressure load is undertaken. The most critical results are used to create limit load envelopes that may be used to design welded pipes within the specified range.;Secondly, through a series of case studies, the effect of various complex loading conditions on the evolution and progress of fatigue damage, creep damage and creep-fatigue interaction of welded connectors, commonly found in power plants, are identified and discussed comprehensively using the Direct Steady Cycle Analysis (DSCA) and the extended Direct Steady Cycle Analysis(eDSCA) method within the Linear Matching Method Framework (LMMF). Finally, the subroutine is enhanced to account for any previous residual stress such as the welding residual stress (WRS) on the shakedown-ratchet limit interaction curves and the creep-fatigue endurance. With a welded flange case study, the effect of WRS on mean strain during the transient cycles and the fatigue damage at steady state is demonstrated
Study on the effect of welding residual stress on creep-cyclic plasticity behaviour
Get PDFCreep-cyclic plasticity and creep-fatigue damage interaction of a welded flange are studied considering both the thermo-mechanical load and the welding residual stress (WRS). The presence of WRS was found to have a minimal effect on the shakedown and ratcheting interaction curve, though the stress distribution changes considerably in the presence of WRS. The effect of WRS is predominant for the initial cycles after which it relaxes so that at steady state the creep-cyclic plasticity response is similar with and without WRS. Depending on the magnitude and sign of the WRS at different locations in the weldment, it has both detrimental and beneficial effect on the creep-fatigue life. Investigations are carried out using the Linear Matching Method (LMM), which is further modified to assess the creep- fatigue damage considering both transient cycles and the WRS. Results show that the presence of weldment induces tensile and compressive stress/strain at the vicinity of the weldment, which substantially influences the creep and fatigue damage. The presence of WRS further complicates this. For all the combinations of damage calculations undertaken, with and without the consideration of WRS or mean strain, the order of elements with maximum damage differed
Creep-cyclic plasticity and damage assessment of an SS304 weldolet
Get PDFCreep-fatigue and creep-ratcheting life assessment of an SS304 weldolet considering full creep-cyclic plasticity interaction is investigated using the extended direct steady cycle analysis within the linear matching method framework. The creep behavior is modeled using the Norton relationship, which is modified by the Arrhenius rule to account for the temperature variation within the weldolet. The introduction of a creep dwell increases the reverse plasticity resulting from the creep relaxation. This leads to both creep-fatigue and creep-ratcheting damage mechanisms at different regions within the weldment. For thermal load dominated loading combinations, creep ratcheting due to both cyclically enhanced creep and creep enhanced plasticity are observed based on the dwell period. The effect of dwell period, load and temperature on the creep-fatigue and creep-ratcheting interaction of a weldolet are presented. The simultaneous presence of various damage mechanisms at different locations within the weldment highlights the importance and requirement of the proposed creep-cyclic plasticity investigations at weld locations
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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