1,721,263 research outputs found
Is 2D numerical modelling of welding process able to capture the residual notch stress intensity factor values?
No full textBecause of its local nature, the influence of residual stresses on fatigue life of welded joints in the high cycle regime can be quantified by the residual notch stress intensity factor (R-NSIF). The standard methodology used for its assessment requires a very fine mesh and this is the reason why 2D numerical models were used first in literature. The calculation of R-NSIF values via 3D models is very recent. It was found possible thanks to rapid numerical techiques such as the peak stress method. This approach was proven to work well but R-NSIF values coming from 3D models were not consistent with those obtained through 2D models. This work is aimed at solving that apparent discrepancy. 2D and 3D welding process numerical simulations applied to a carbon steel were carried out taking into account effects of metallurgical transformations and by varying the main geometrical parameters of the plates. It was found that 2D models are able to capture the R-NSIF value that is observed in the stationary residual stress distribution of the corresponding 3D models
Casting and Solidification Processing
Full text linkCasting is one of the most important shaping processes, largely used and consolidated throughout the world to produce near-net-shaping parts [...
Lightweight design versus raw materials criticalities
Full text linkThe 4th list of Critical Raw Materials has been published by the European Commission at the beginning of September 2020. A trend of increased criticality is observed for all raw materials in 2020 compared to 2017 and four new critical raw materials appeared (bauxite, titanium, lithium, and strontium) that pose new restrictions in lightweight design of metallic components. Based on a materials selection methodology developed in literature to face such emerging issues, the criticality assessment of light alloys is evaluated and rationally considered in lightweight design by using a trade-off material selection strategy. A simplified case-study is proposed as an example
Materials selection in a critical raw materials perspective
Full text linkCritical Raw Materials (CRMs) are those raw materials that are economically and strategically important for the European economy but have a high-risk associated with their supply. Used in environmental technologies, consumer electronics, health, steel-making, defence, space exploration, and aviation, these materials are not only ‘critical’ for key industry sectors and future applications, but also for the sustainable functioning of the European economy. In this scenario, ‘mitigating actions’ need to be developed to reduce criticalities linked to the use of those raw materials. Recycling and substitution, when possible, are strategic solutions but a more efficient use of such CRMs in design, obtained by a correct alloy selection, is become nowadays mandatory. A method for metallic alloys selection in a CRMs perspective, based on the definition of the alloy critical index, is described. The proposed method allows selecting the alloy for the current application that minimizes its criticality associated to CRMs. The method is illustrated with example
Welding metallurgy of stainless steels
No full textStainless steels (SS) are irreplaceable materials in many industrial applications due to their excellent combination of mechanical and chemical properties. Oil & Gas extraction, petrochemical and urea industry, kitchen utensils, cutlery, surgical instruments and implants, bridges, aircraft, rail cars, monuments and sculptures are only some examples where SS are used. But it is also true that the success of stainless steels is due to the development and study of joining techniques such as fusion welding and solid-state welding. Stainless steels are characterized by good weldability provided that proper recommendations are followed. Secondary phases may precipitate with detrimental effects on corrosion resistance and mechanical properties. For a fixed geometry, a sound SS welded joint is thus the result of an optimization of process parameters that may differ for each welding method, e.g., arc-welding, high power density welding or friction stir welding. This chapter is aimed at describing the fundamentals of welding metallurgy with reference to the main families of stainless steels such as austenitic, ferritic, martensitic and duplex steels. Welded joints of dissimilar materials will also be briefly treated. Finally, modelling of the evolution of secondary phases under isothermal and non-isothermal conditions will be described in detail
Assessment of Metallurgical and Mechanical Properties of Welded Joints via Numerical Simulation and Experiments
Full text linkWelding has been the most important joining technique applied to metallic materials since the early twentieth century when arc welding was introduced [...
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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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