The Experts below are selected from a list of 96 Experts worldwide ranked by ideXlab platform
Ulf Bjorkman - One of the best experts on this subject based on the ideXlab platform.
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Fibre Flow Research History: Part II. Continuation
2020Co-Authors: Ulf BjorkmanAbstract:The history of Fibre flow research is continued. Own experiences are related to principal questions about theory formation for Technical Fibre flow systems. Suggestions for future modelling are presented.
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A Band Rheometer for Fibre Flow Studies
2020Co-Authors: Ulf BjorkmanAbstract:The design of a shear flow instrument for Fibre flow studies is described. The main goal was to create an as simple and homogeneous shear flow field as possible, in combination with the possibility of making observation in different directions. A Fibre flow example will be discussed and, shortly, the general flow mechanisms in Technical Fibre suspensions. Properly scaled and modified, this design may possibly also be useful for studying flow mechanisms in other types of structural fluids.
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irreversibility and dissipation afterthoughts to Technical Fibre flow
2010Co-Authors: Ulf BjorkmanAbstract:Irreversibility and dissipation are closely related. The flow of Technical Fibre suspensions with Fibres enough large to be observed by eye is well suited to investigate the mechanisms behind the irreversibility. In the first part of this work such mechanisms in a compressive flows of a Technical wood Fibre suspensions are discussed. In the second part the results are generalised to more general non-fibrous flow systems. The work ends with some more philosophical reflections regarding the relation between irreversibility and dissipation.
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the non newtonian fluid mechanics of Technical Fibre suspensions compressive flows
Applied Rheology, 2009Co-Authors: Ulf BjorkmanAbstract:The flow of non-Newtonian Technical Fibre suspensions (paper pulps) through a number of contractions is analysed and compared. Traditionally Technical Fibre flows are modelled as flow of Fibres in ...
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The nonlinear history of Fibre flow research. Part 2 : Continuation, reflections and suggestions
Applied Rheology, 2008Co-Authors: Ulf BjorkmanAbstract:Technical Fibre flows are normally flocky but have theoretically mainly been treated as individual Fibre flows. The reason for this can only be understood through the subject's historic development. In Part 1 of this investigation the origin of Fibre flow research was traced to the beginning of the 19th century, and was followed through its formative years at the first half of the 20th century up to about WWII. This second and final part takes us up to about the 1960s when the present main theoretical research tradition had been firmly established. An example of an alternative approach is given. Finally, some suggestions for future work are advanced. In Appendix methods of characterising the inner geometry of Technical Fibre suspensions are discussed.
A.w. Van Vuure - One of the best experts on this subject based on the ideXlab platform.
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Mechanical behaviour of hemp Fibre composites in relation to their microstructure by micro strain mapping, computed tomography, and biochemical analysis
2020Co-Authors: C.a. Fuentes, P. Willekens, Jordi Petit, Jörg Müssig, Luisa M. Trindade, J. Witters, Y. Ruan, A.w. Van VuureAbstract:This manuscript describes the effects of alterations in biochemical composition on structural morphology and the mechanical behaviour of elementary and Technical Fibres of hemp used for composite applications. First, the strength and apparent Young's modulus distribution of Technical Fibres of hemp of 96 hemp samples, corresponding to 32 different hemp accessions cultivated in 3 locations, were analysed using Weibull distribution. From these, 2 samples (one with high and one with low Fibre strength) were selected for further analysis. Next, full-field strain measurement at the micro-scale during tensile loading was used for evaluating both, the stress-strain behaviour at a global scale and the local mechanical behaviour heterogeneity at a micro-scale, along elementary and Technical Fibres of hemp. At the composite level, the local behaviour of each phase of the composite (Fibre and matrix) and of the Fibre/matrix interphase during a transversal 3 point bending test were characterized. Results show that the strength of Technical Fibres of hemp is highly dependent on the shear strength between elementary Fibres, which itself is related to the biochemical composition of the middle lamellae. A correlation between the strength of a Technical Fibre and their elementary Fibres was also observed. At the composite level, the relation of the composite mechanical behaviour (Young's modulus and strength) with the Technical or elementary Fibre mechanical behaviour is complex and might depend on the combination of multiple factors such as the matrix (thermoset or thermoplastic), or the Technical Fibre sample employed (weak or strong) and the level of Fibre-matrix wetting (impregnation) and adhesion.
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In-depth study of the microstructure of bamboo Fibres and their relation to the mechanical properties
Journal of Reinforced Plastics and Composites, 2018Co-Authors: Lina Osorio, E. Trujillo, Frederic Lens, Jan Ivens, Ignaas Verpoest, A.w. Van VuureAbstract:The mechanical properties of bamboo Technical Fibre, from the species Guadua angustifolia, have been studied showing values of strength up to 800 MPa and E-modulus up to 43 GPa, proving their adequ...
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Effect of chemical treatments on the mechanical properties of Technical flax Fibres with emphasis on stiffness improvement
Composites Science and Technology, 2018Co-Authors: Dieter Perremans, Ignaas Verpoest, Kevin Hendrickx, A.w. Van VuureAbstract:Abstract The weak visco-elastic interphase between elementary fibers in a reinforcing Technical flax fiber is presumed to play a crucial role in the stiffness reduction during loading. To avoid this stiffness reduction, ethanedial (glyoxal), 3-aminopropyltriethoxysilane (APS) and dimethyloldihydroxyethylene urea (DMDHEU) were investigated as potential fiber treatments in this paper. Tensile tests on single Technical fibers show that treating the fibers in an aqueous 3 wt% glyoxal solution was sufficient to increase the Technical fiber modulus from 41.6 ± 2.3 GPa to 57.3 ± 2.9 GPa. Further, spectroscopic techniques (FTIR, NMR and XPS) detected increased amounts of acetal and ester bonds after glyoxal treatment. This suggests that cross-linking has taken place between pectin and hemicellulose molecules in the amorphous interphase between elementary Fibres. APS and DMDHEU treatments were less successful in improving the Technical Fibre stiffness due to their lower reactivity towards hydroxyl functionalities compared to glyoxal.
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Effect of the middle lamella biochemical composition on the non-linear behaviour of Technical Fibres of hemp under tensile loading using strain mapping
Composites Part A-applied Science and Manufacturing, 2017Co-Authors: C.a. Fuentes, P. Willekens, Jordi Petit, C. Thouminot, Jörg Müssig, Luisa M. Trindade, A.w. Van VuureAbstract:Abstract This manuscript describes the effects of alterations in biochemical composition on structural morphology and the mechanical behaviour of Technical Fibres of hemp used for composite applications. First, the strength and apparent Young’s modulus distribution of Technical Fibres of hemp of 96 hemp samples, corresponding to 32 different hemp accessions cultivated in 3 locations, were analysed using Weibull distribution. From these, 2 samples (one with high and one with low Fibre strength) were selected for further analysis. Next, full-field strain measurement at the micro-scale during tensile loading via digital image correlation analysis was used for evaluating both, the stress-strain behaviour at a global scale and the local mechanical behaviour heterogeneity at a micro-scale, along a Technical Fibre of hemp. The analysis reveals 2 typical types of tensile stress-strain curves, and a complex and very irregular pattern of strain concentrations, which are associated to the Technical Fibre strength. The non-linear behaviour of the stress-strain curve is explained by the development of shear strain at the elementary Fibre (botanically defined as the individual cell) interphases. Micro tomography and biochemical analysis of the Technical Fibre microstructure showed that alterations in cell wall composition, in particular substitution of pectin, leads to changes in the non-linear behaviour of Technical Fibres of hemp under tensile loading.
A Norton - One of the best experts on this subject based on the ideXlab platform.
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structural biocomposites from flax part i effect of bio Technical Fibre modification on composite properties
Composites Part A-applied Science and Manufacturing, 2006Co-Authors: T Stuart, Mark Hughes, R D Mccall, H S S Sharma, A NortonAbstract:Abstract The use of enzymes, chelators and enzyme/chelator systems was explored as an environmentally friendly means of improving the quality of flax Fibre for composite applications. A commercial pectinolytic enzyme preparation and Ethylene Diamine Tetraacetic Acid (EDTA) were used separately and in combination on a commercial flax Fibre. An improvement in Fibre cleanliness and separation of the Fibre bundles into ultimates was observed. When this Fibre was, subsequently, used as reinforcement in an epoxy matrix, improved composite properties were obtained. With the EDTA modified Fibre reinforced composites, tensile strength improvements in excess of 50% were recorded.
T Stuart - One of the best experts on this subject based on the ideXlab platform.
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structural biocomposites from flax part i effect of bio Technical Fibre modification on composite properties
Composites Part A-applied Science and Manufacturing, 2006Co-Authors: T Stuart, Mark Hughes, R D Mccall, H S S Sharma, A NortonAbstract:Abstract The use of enzymes, chelators and enzyme/chelator systems was explored as an environmentally friendly means of improving the quality of flax Fibre for composite applications. A commercial pectinolytic enzyme preparation and Ethylene Diamine Tetraacetic Acid (EDTA) were used separately and in combination on a commercial flax Fibre. An improvement in Fibre cleanliness and separation of the Fibre bundles into ultimates was observed. When this Fibre was, subsequently, used as reinforcement in an epoxy matrix, improved composite properties were obtained. With the EDTA modified Fibre reinforced composites, tensile strength improvements in excess of 50% were recorded.
Nele De Belie - One of the best experts on this subject based on the ideXlab platform.
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Assessment of the performance of cottonised flax in natural Fibre reinforced cementitious composites
2020Co-Authors: Nele De Belie, Didier Snoeck, Pieter DejongheAbstract:Cottonisation of flax not only makes flax usable for producing textiles, it also further divides the Technical Fibre into (bundles of) elementary Fibres and removes partly the alkali-sensitive pectin and hemicellulose. An experimental investigation was performed to assess the characteristics of cottonised flax in Fibre reinforced cementitious composites. The Fibre and composite properties are compared with Technical flax and PVA Fibres. Strength/strain curves of the Fibres and composites are compared to evaluate the mechanical performance. Not only tensile strength and stiffness but also first crack strength and peak stress, work of fracture as a measure for multiple cracking and the visual closure of individual cracks by self healing are analysed. Cottonisation of flax enhances modulus of elasticity, peak stress and strength at first crack of concrete, in comparison to Technical flax Fibres.
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Mechanical and self-healing properties of cementitious composites reinforced with flax and cottonised flax, and compared with polyvinyl alcohol Fibres
Biosystems Engineering, 2012Co-Authors: Didier Snoeck, Nele De BelieAbstract:Flax stems are often considered waste material. However, since flax Fibre has superior mechanical properties amongst natural Fibres, it can be used as reinforcement in cementitious composites. Durability of flax, however, is endangered in alkaline environments by the deterioration of alkali-sensitive pectin and hemicellulose. Cottonisation of flax not only makes flax suitable for producing textiles; it divides the Technical Fibre into bundles of elementary Fibres and partially removes the alkali-sensitive pectin and hemicellulose. Therefore, the characteristics of cottonised flax (CF) in Fibre reinforced cementitious composites were assessed. The Fibre and composite properties were compared with Technical flax (TF) Fibres and synthetic polyvinyl alcohol Fibres. Strength/strain curves of the natural Fibre reinforced cementitious materials were analysed to evaluate the mechanical performance. Not only were tensile strength and stiffness evaluated, but also first crack strength, peak stress, work of fracture as a measure for multiple cracking (MC), and the visual closure of individual cracks by self-healing. Cottonisation of flax enhanced the modulus of elasticity, the peak stress and the strength at first crack formation of cementitious materials, in comparison to TF Fibres. The self-healing of cracks was independent of the Fibre type. Cracks narrower than 30 μm healed completely and crack widths between 30 μm and 150 μm only partly healed.
