1,720,970 research outputs found
Mode II interlaminar fracture behavior of carbon bead-filled epoxy/glass fiber hybrid composite
No full textTo investigate the effect of including carbon beads on the mechanical properties of epoxy resin, the fracture toughness of carbon bead-filled epoxy was earlier evaluated using a CT (compact tension) specimens and Mode I fracture toughness was observed. Based on those results, in this study, the Mode Il interlaminar fracture toughness of carbon bead filled epoxy/glass fiber hybrid composites was evaluated using end notch flexure (ENF) specimens. The hybrid composites showed increased Mode II interlaminar fracture toughness. The optimal bead volume fraction was around 15%
Modelling of crystal growth process in heat exchanger method
No full textTransient two-dimensional model of bismuth germanium oxide (EGO) crystal growth by the heat exchanger method has been developed. The moving boundary problems for the melt/solid interface location, the temperature field in the whole calculation domain and the flow held in the melt were solved by the two mapping rule method, which enabled the simulation of the melt/solid interface, changing from hemispherical to planar shape. The maximum deflection of the interface was observed when the melt/solid interface is at the corner of crucible. The effects of the various growth parameters were studied on the interface shape, the temperature profile and the stream function using this model. As the excess heating temperature was increased, the maximum deflection of the interface decreased. The heal exchanger temperature hardly affects the maximum deflection of the melt/solid interface. The maximum deflection of the melt/solid interface is not very sensitive to the value of the thermal conductivity of the melt of EGO
The mechanical behavior of optical fiber sensor embedded within the composite laminate
No full textMechanical behavior, such as tensile and fatigue strength, of the optical fiber sensor embedded within the composite laminate was investigated. Tensile and fatigue tests were performed to evaluate the static and fatigue characteristics of optical fibers embedded within three types of laminated composite specimens, [0(6)/OF/0(6)](T), [0(2)/90(4)/OF/90(4)/0(2)](T) and [0(3)/90(3)/OF/90(3)/0(3)](T). The initiation of damage and fracture of the optical fiber were detected by observation of the intensity drop-off of laser signal transmitted through the optical fiber during test. Experimental results showed that the fatigue strength of optical fiber embedded within the cross-ply laminate is much lower than the fatigue strength of optical fiber within the unidirectional ply laminate. It was also found that the optical fiber embedded within unidirectional ply laminate fractured due to the fatigue damage accumulation of internal defects of optical fiber itself. However the optical fiber embedded within the cross-ply laminate fractured due to the growth of transverse matrix crack of host composite laminate. (C) 1999 Kluwer Academic Publishers
Low velocity impact and delamination buckling behavior of composite laminates with embedded optical fibers
No full textA drop-weight impact test and delamination buckling test were performed to investigate the development of impact damage and post-impact compression behavior of cross-ply composite laminates with optical fibers embedded in the interface of two different angle plies. It was found that the presence of optical fibers had little or marginal effect on the shape and size of damage area of the laminate when the optical fibers were embedded parallel to the host reinforcing fibers. Non-parallel optical fibers promoted unstable crack growth through the formation of resin rich regions, which in turn increased slightly the impact damage area. It was also shown that a large number of parallel optical fibers may have an ameliorating effect on delamination buckling strength as they promote the waviness of the delamination fracture surface
Axial crush and bending collapse of a aluminum/GFRP hybrid square tube and its energy absorption capability
No full textPerformance evaluation of precision nanopositioning devices caused by uncertainties due to tolerances using function approximation moment method
Full text linkPrecision nanopositioning is an important technology in industry and requires tight design specifications. Tolerances, although very small, are allocated in all dimensions of structures at devices and are understood as sources of performance variations. In this research, we aim to study detail influence of tolerances on various system response functions of a precision stage, especially parasitic motion and resonant frequencies. A function approximation moment method (FAMM) is developed and applied to study it. The variations are mathematically expressed as their statistical moments and the probabilities of satisfaction are obtained as a result of the FAMM. A finite element model of the target stage, which is nonmonolithic, is generated and verified with basic measurements. The possible initial deformation after assembly is found by the formulation of minimizing strain energy. With this model, the FAMM is used to estimate the statistical moments and probability density functions of the performance functions. The calculated results facilitate understanding of the characteristics of the stage in terms of probability. The inevitable mismatch, even under a small tolerance, is found to cause a large parasitic motion and should be considered in the design and manufacturing process. (c) 2006 American Institute of Physics
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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