1,720,959 research outputs found
INVESTIGATION OF FRACTURE MECHANISMS OF BAMBOO CULM BY EXPERIMENTAL AND FINITE ELEMENT METHODS FOR IMPROVED DURABILITY PERFORMANCE IN CONSTRUCTION
No full textIn first part of this study, the aim was to investigate the effect of material composition and geometrical attributes on the fracture mechanisms of bamboo in various modes of loading by finite element method (FEM). In second part of this study, the failure modes in bamboo bolt connection was investigated in uniaxial tension by considering fiber direction in FEM in order to address the lack of information and test standards about the use and evaluation of full-culm connection. Thirdly, to further elucidate the influence of treatment modification on bamboo mechanical behaviour, the incidental effects of smoke treatment on the mechanical properties of Madake bamboo's (Phyllostachys bambusoides) hierarchical structure was investigated. In fourth part of this study, the underlying effect of thermal modification on shrinkage behaviour of bamboo culm was investigated by numerical simulation. Finally, the fundamental mechanisms governing the transverse fracture initiation stage and propagation in bamboo with respect to its structural arrangement was investigated by experimental and finite element methods
INVESTIGATION OF FRACTURE MECHANISMS OF BAMBOO CULM BY EXPERIMENTAL AND FINITE ELEMENT METHODS FOR IMPROVED DURABILITY PERFORMANCE IN CONSTRUCTION
Get PDF京都工芸繊維大学博士（工学）In first part of this study, the aim was to investigate the effect of material composition and geometrical attributes on the fracture mechanisms of bamboo in various modes of loading by finite element method (FEM). In second part of this study, the failure modes in bamboo bolt connection was investigated in uniaxial tension by considering fiber direction in FEM in order to address the lack of information and test standards about the use and evaluation of full-culm connection. Thirdly, to further elucidate the influence of treatment modification on bamboo mechanical behaviour, the incidental effects of smoke treatment on the mechanical properties of Madake bamboo's (Phyllostachys bambusoides) hierarchical structure was investigated. In fourth part of this study, the underlying effect of thermal modification on shrinkage behaviour of bamboo culm was investigated by numerical simulation. Finally, the fundamental mechanisms governing the transverse fracture initiation stage and propagation in bamboo with respect to its structural arrangement was investigated by experimental and finite element methods
Numerical modelling of the warping behaviour at the first layer-build plate interface in 3D-printed models produced via the fused deposition modelling process
Get PDFThe material structure of 3D-models printed via the fused deposition modelling (FDM) technique is mainly affected in the z-direction of the 3D-print as a result of the layer-by-layer approach which tend to exhibit a deformation behavior corresponding to a type of transversely orthotropic material. Moreover, uncontrolled parameters such as printing temperature and printing speed have been reported to adversely affect 3D-print quality leading to undesired effects such as distortion and warpage. The additive manufacturing process is a relatively new field in advanced manufacturing where further research and innovation are required to overcome the limited strength and structural performance observed in presently 3D-printed components. In line with the above, this study proposes the numerical investigation of the warping behavior in PLA (Polylactic acid) - based 3D printed models by considering the finite element method (FEM) software of LS-DYNA. The warping investigation was specifically centered on the cooling cycle prevailing between the layer-by-layer structures. The findings of this study showed that warpage would most likely occur in the thermal process model corresponding to abrupt change in temperature due to a buildup of strain between the bottom most layers of the 3D model and the build plate. The findings of this study, which shed light on the warping behaviour in 3D-models, has direct implications on the final quality of 3D-printed components
Antibacterial and Antifungal Properties of Composite Polyethylene Materials Reinforced with Neem and Turmeric
No full textWith the increased scientific interest in green technologies, many researches have been focused on the production of polymeric composites containing naturally occurring reinforcing particles. Apart from increasing mechanical properties, these additions can have a wide range of interesting effects, such as increasing the resistance to bacterial and fungal colonization. In this work, different amounts of two different natural products, namely neem and turmeric, were added to polyethylene to act as a natural antibacterial and antifungal product for food packaging applications. Microscopic and spectroscopic characterization showed that fractions of up to 5% of these products could be dispersed into low-molecular weight polyethylene, while higher amounts could not be properly dispersed and resulted in an inhomogeneous, fragile composite. In vitro testing conducted with Escherichia coli, Staphylococcus aureus, and Candida albicans showed a reduced proliferation of pathogens when compared to the polyethylene references. In particular, turmeric resulted in being more effective against E. coli when compared to neem, while they had similar performances against S. aureus. Against C. albicans, only neem was able to show a good antifungal behavior, at high concentrations. Tensile testing showed that the addition of reinforcing particles reduced the mechanical properties of polyethylene, and in the case of turmeric, it was further reduced by UV irradiation
Durability evaluation of madake bamboo by FE analysis of fracture with consideration of fibre direction
Get PDFThe flexural stiffness of bamboo is inherently influenced by heterogeneous material characteristic owing to its unique hierarchical structure. In addition, low interfacial strength and unequal distribution of fibres lead to a complex fracture behavior in the material. This research study aims to probe into the limited durability of MADAKE bamboo (Phyllostachys bambusoides) by investigating its fracture mechanism through numerical simulation. The influence of functionally graded material (FGM) on the fracture behavior of bamboo culm was evaluated. A half-solid cylindrical model consisting of a rigid section and a 4-layered wall section was simulated in pure bending mode on LS-DYNA. The effects of material homogeneity and inhomogeneity were replicated by inputting elastic and orthotropic-elastic material data comprising of longitudinal to flexural stiffness ratio. These ratios were derived from experimental results of three-point flexural test. Analysis of results, based on maximum principal strain, showed that the homogeneous model displayed fracture characteristics similar to conventional elastic material. In contrast, the inhomogeneous model displayed maximum principal strain on the lateral surface corresponding to fracture mode of bamboo culms observed in nature. Numerical study of material heterogeneity is a step further in understanding the fracture mechanics of functionally graded materials
Durability evaluation of madake bamboo by FE analysis of fracture with consideration of fibre direction
Get PDFThe flexural stiffness of bamboo is inherently influenced by heterogeneous material characteristic owing to its unique hierarchical structure. In addition, low interfacial strength and unequal distribution of fibres lead to a complex fracture behavior in the material. This research study aims to probe into the limited durability of MADAKE bamboo (Phyllostachys bambusoides) by investigating its fracture mechanism through numerical simulation. The influence of functionally graded material (FGM) on the fracture behavior of bamboo culm was evaluated. A half-solid cylindrical model consisting of a rigid section and a 4-layered wall section was simulated in pure bending mode on LS-DYNA. The effects of material homogeneity and inhomogeneity were replicated by inputting elastic and orthotropic-elastic material data comprising of longitudinal to flexural stiffness ratio. These ratios were derived from experimental results of three-point flexural test. Analysis of results, based on maximum principal strain, showed that the homogeneous model displayed fracture characteristics similar to conventional elastic material. In contrast, the inhomogeneous model displayed maximum principal strain on the lateral surface corresponding to fracture mode of bamboo culms observed in nature. Numerical study of material heterogeneity is a step further in understanding the fracture mechanics of functionally graded materials
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
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