1,720,961 research outputs found
Hybrid metal extrusion and bonding
No full textIn this chapter, a new and novel solid-state joining method for metals and alloys is presented, where the best features of gas metal arc welding, friction stir welding and cold pressure welding are combined. The invention, which is known as the Hybrid Metal Extrusion & Bonding (HYB) process, utilizes continuous extrusion as a technique to squeeze the aluminium filler material into the groove between the two plates to be joined under high pressure to achieve metallic bonding. The PinPoint extruder is the core of the HYB technology. This is because the different tool parts constituting the extruder head are both interchangeable and replaceable so that their geometry can be tailor-made to handle a wide range of different applications, ranging from butt, lap, slot, fillet and multi-pass welding to plate surfacing and additive manufacturing. Originally, the idea was to use the HYB process only for welding of aluminium alloys. But over the years the method has evolved into a multi-material joining process capable of handling a wide range of base metal combinations (Al, Fe, Ti and Cu). At present, up to four different metals can be joined together in one pass using the HYB PinPoint extruder and AA6082 as filler wire. In the future the advantages of customising the filler wire composition for specific welding applications will be further explored
Mechanical Qualification of the Hybrid Metal Extrusion & Bonding (HYB) Process for Butt Welding of 4 mm Plates of AA6082-T6
Full text linkHybrid Metal Extrusion & Bonding (HYB) is a novel solid state joining technique mainly developed for aluminum alloys. By the use of filler material addition and plastic deformation sound joints can be produced at operational temperatures below 400°C. Here, we present the results from an exploratory investigation of the mechanical integrity of a 4 mm AA6082-T6 HYB joint, covering both hardness, tensile and Charpy V-notch testing of different weld zones. The joint is found to be free from defects like pores, internal cavities and kissing-bonds. Still, a soft heat affected zone (HAZ) is present. The joint yield strength is 54 % of the base material, while the corresponding joint efficiency is 66 %. Therefore, there is room for further optimization of the HYB process. This work is now in progress
On the fatigue properties of a third generation aluminium-steel butt weld made by Hybrid Metal Extrusion & Bonding (HYB)
No full textThe present investigation is concerned with the high-cycle axial fatigue behaviour of a third generation Al-steel butt weld made by Hybrid Metal Extrusion & Bonding (HYB). In this particular weld, metallurgical bonding is achieved by a combination of microscale mechanical interlocking and intermetallic compound (IMC) formation, where the IMC layer is in the sub-micrometre range (<1μm). During high-cycle axial fatigue testing this microstructure provides a high intrinsic resistance against interfacial cracking. In the as-welded condition, fatigue fracture typically initiates at the weld toe on the aluminium side of the joint due to the unfavourable effect of having a geometrical stress riser localised inside the soft heat-affected zone. Since the interfacial bond strength is not a limiting factor, the fatigue properties of the Al-steel HYB butt weld are seen to fully match those of corresponding Al-Al weldments produced by gas metal arc welding, laser beam welding and friction stir welding. © 2021 Elsevier Lt
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
Evaluation and Origin of Residual Stress in Hybrid Metal and Extrusion Bonding and Comparison with Friction Stir Welding
No full textHybrid metal and extrusion bonding (HYB) is an emerging solid-state welding technique that was developed about ten years ago. HYB exploits the fundamental idea of the well-established friction stir welding (FSW) technology, but a filler material is employed to enhance control of the microstructure and the mechanical properties of the joint. HYB and FSW allow joining to be performed at lower temperatures than classical fusion welding methods. Still, thermal gradient effects seem impossible to be entirely avoided, thus leading to residual stress within the weld region and neighbouring material. Although the FSW-induced residual stress evaluation has been extensively studied and understood, the evaluation and interpretation of HYB-induced residual stress have not been tackled so far. In the present paper, a quantitative investigation on residual stress and its origin in HYB was carried out for the first time. Specifically, a 4 mm thick AA6082-T6 HYB and a 4 mm thick AA6082-T6 FSW butt welds were considered. For the particular case of HYB, an AA6082-T4 was used as the filler material. In both cases, the full-field longitudinal residual stress was experimentally assessed using the Contour Method. The results showed that the HYB joint yields a higher magnitude of tensile residual stress compared to that of the FSW counterpart. A physical explanation for this difference in magnitude was attributed to the lower yield stress point exhibited by the filler material. Furthermore, the analysis revealed peak values of residual stress as high as 205±25 MPa and 165±15 MPa, for the HYB and FSW joint, respectively. Despite this, a similar distribution of residual stress across the weld was observed in both cases. An additional qualitative analysis on the transverse distortion of the welds outlined a pronounced undesired “V-like” deformation of the HYB joint of approximately 1.4°. By contrast, the FSW joint seemed not to show any perceptible bend
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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