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1
Grinholtz, D., M. Haddad, M. Talso, E. Émiliani, S. Doizi e O. Traxer. "Étude des contraintes induites par les fibres laser dans les urétéroscopes flexibles". Progrès en Urologie 26, n. 13 (novembre 2016): 699. http://dx.doi.org/10.1016/j.purol.2016.07.062.
Testo completo
2
Parasakthibala, Ms G., e Mrs A. S. Monisha. "A Review on Natural Fibers; Its Properties and Application Over Synthetic Fibers". International Journal for Research in Applied Science and Engineering Technology 10, n. 8 (31 agosto 2022): 1894–97. http://dx.doi.org/10.22214/ijraset.2022.46530.
Testo completoAbstract (sommario):
Abstract: Fibre is a long, thin strand or thread of material made by weaving or knitting threads together. Fibre is a hair like strand of material. A fibre is the smallest visible unit of any textile product. Fibres are flexible and may be spun into yarn and made into fabric. Natural fibres are taken from animals, vegetables or mineral sources. A few examples of widely used natural fibres include animal fibre such as wool and silk vegetables fibres, especially cotton and flax and asbestos, a mineral. Natural fibers are more important part in our human environment. Natural fibers are ecofriendly and inexpensive which are readily available in nature. In this chapter we discuss about the overview of natural fiber and their characteristic. this paper also deals with the impact of natural fibers over the synthetic fibers and also the application of natural fiber in various fields.
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Guo, Y., C. Wassgren, B. Hancock, W. Ketterhagen e J. Curtis. "Computational study of granular shear flows of dry flexible fibres using the discrete element method". Journal of Fluid Mechanics 775 (16 giugno 2015): 24–52. http://dx.doi.org/10.1017/jfm.2015.289.
Testo completoAbstract (sommario):
In this study, shear flows of dry flexible fibres are numerically modelled using the discrete element method (DEM), and the effects of fibre properties on the flow behaviour and solid-phase stresses are explored. In the DEM simulations, a fibre is formed by connecting a number of spheres in a straight line using deformable and elastic bonds. The forces and moments induced by the bond deformation resist the relative normal, tangential, bending and torsional movements between two bonded spheres. The bond or deforming stiffness determines the flexibility of the fibres and the bond damping accounts for the energy dissipation in the fibre vibration. The simulation results show that elastically bonded fibres have smaller effective coefficients of restitution than rigidly connected fibres. Thus, smaller solid-phase stresses are obtained for flexible fibres, particularly with bond damping, compared with rigid fibres. Frictionless fibres tend to align with a small angle from the flow direction as the solid volume fraction increases, and fibre deformation is minimized due to the alignment. However, jamming, with a corresponding sharp stress increase, large fibre deformation and dense contact force network, occurs for fibres with friction at high solid volume fractions. It is also found that jamming is more prevalent in dense flows with larger fibre friction coefficient, rougher surface, larger stiffness and larger aspect ratio.
4
Ullrich, Julia, Martin Eisenreich, Yvonne Zimmermann, Dominik Mayer, Nina Koehne, Jacqueline F. Tschannett, Amalid Mahmud-Ali e Thomas Bechtold. "Piezo-Sensitive Fabrics from Carbon Black Containing Conductive Cellulose Fibres for Flexible Pressure Sensors". Materials 13, n. 22 (16 novembre 2020): 5150. http://dx.doi.org/10.3390/ma13225150.
Testo completoAbstract (sommario):
The design of flexible sensors which can be incorporated in textile structures is of decisive importance for the future development of wearables. In addition to their technical functionality, the materials chosen to construct the sensor should be nontoxic, affordable, and compatible with future recycling. Conductive fibres were produced by incorporation of carbon black into regenerated cellulose fibres. By incorporation of 23 wt.% and 27 wt.% carbon black, the surface resistance of the fibres reduced from 1.3 × 1010 Ω·cm for standard viscose fibres to 2.7 × 103 and 475 Ω·cm, respectively. Fibre tenacity reduced to 30–50% of a standard viscose; however, it was sufficient to allow processing of the material in standard textile operations. A fibre blend of the conductive viscose fibres with polyester fibres was used to produce a needle-punched nonwoven material with piezo-electric properties, which was used as a pressure sensor in the very low pressure range of 400–1000 Pa. The durability of the sensor was demonstrated in repetitive load/relaxation cycles. As a regenerated cellulose fibre, the carbon-black-incorporated cellulose fibre is compatible with standard textile processing operations and, thus, will be of high interest as a functional element in future wearables.
5
Wang, Zhixun, Zhe Wang, Dong Li, Chunlei Yang, Qichong Zhang, Ming Chen, Huajian Gao e Lei Wei. "High-quality semiconductor fibres via mechanical design". Nature 626, n. 7997 (31 gennaio 2024): 72–78. http://dx.doi.org/10.1038/s41586-023-06946-0.
Testo completoAbstract (sommario):
AbstractRecent breakthroughs in fibre technology have enabled the assembly of functional materials with intimate interfaces into a single fibre with specific geometries1–11, delivering diverse functionalities over a large area, for example, serving as sensors, actuators, energy harvesting and storage, display, and healthcare apparatus12–17. As semiconductors are the critical component that governs device performance, the selection, control and engineering of semiconductors inside fibres are the key pathways to enabling high-performance functional fibres. However, owing to stress development and capillary instability in the high-yield fibre thermal drawing, both cracks and deformations in the semiconductor cores considerably affect the performance of these fibres. Here we report a mechanical design to achieve ultralong, fracture-free and perturbation-free semiconductor fibres, guided by a study on stress development and capillary instability at three stages of the fibre formation: the viscous flow, the core crystallization and the subsequent cooling stage. Then, the exposed semiconductor wires can be integrated into a single flexible fibre with well-defined interfaces with metal electrodes, thereby achieving optoelectronic fibres and large-scale optoelectronic fabrics. This work provides fundamental insights into extreme mechanics and fluid dynamics with geometries that are inaccessible in traditional platforms, essentially addressing the increasing demand for flexible and wearable optoelectronics.
6
Manikantan, Harishankar, Lei Li, Saverio E. Spagnolie e David Saintillan. "The instability of a sedimenting suspension of weakly flexible fibres". Journal of Fluid Mechanics 756 (9 settembre 2014): 935–64. http://dx.doi.org/10.1017/jfm.2014.482.
Testo completoAbstract (sommario):
AbstractSuspensions of sedimenting slender fibres in a viscous fluid are known to be unstable to fluctuations of concentration. In this paper we develop a theory for the role of fibre flexibility in sedimenting suspensions in the asymptotic regime of weakly flexible bodies (large elasto-gravitation number). Unlike the behaviour of straight fibres, individual flexible filaments rotate as they sediment, leading to an anisotropic base state of fibre orientations in an otherwise homogeneous suspension. A mean-field theory is derived to describe the evolution of fibre concentration and orientation fields, and we explore the stability of the base state to perturbations of fibre concentration. We show that fibre flexibility affects suspension stability in two distinct and competing ways: the anisotropy of the base state renders the suspension more unstable to perturbations, while individual particle self-rotation acts to prevent clustering and stabilizes the suspension. In the presence of thermal noise, the dominant effect depends critically upon the relative scales of flexible fibre self-rotation compared to rotational Brownian motion.
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LUSIS, Vitalijs, Andrejs KRASNIKOVS, Olga KONONOVA, Videvuds-Arijs LAPSA, Rimvydas STONYS, Arturs MACANOVSKIS e Arturs LUKASENOKS. "EFFECT OF SHORT FIBERS ORIENTATION ON MECHANICAL PROPERTIES OF COMPOSITE MATERIAL – FIBER REINFORCED CONCRETE". Journal of Civil Engineering and Management 23, n. 8 (20 novembre 2017): 1091–99. http://dx.doi.org/10.3846/13923730.2017.1381643.
Testo completoAbstract (sommario):
Traditional fiberconcrete structures have fibres in the mix oriented in all spatial directions, distributed in the structural element volume homogenously, what not easy to obtain in practice. In many situations, structurally more effective is the insertion of fibres into the concrete structural element body by forming layers, with a predetermined fibre concentration and orientation in every layer. In the present investigation, layered fibre concrete is under investigation. Short steel fibres were attached to flexible warps with the necessary fibres concentration and orientation. Warps were placed into the prismatic mould separating them by concrete layers without fibres. Prisms were matured and tested under four-point bending. The bending-affected mechanical behaviour of cracked fibre concrete was simulated numerically by using a developed structural model. Comparing the simulation results with experimental data, material micromechanical fracture mechanisms were analysed and evaluated.
8
Prabu, Krishnaa, J. Srinivasan e C. Prakash. "Ceramic and Glass Fibre Reinforced Flexible Composites for Particulate Filter Walls – A Novel Approach". Fibres and Textiles in Eastern Europe 27, n. 3(135) (30 giugno 2019): 91–97. http://dx.doi.org/10.5604/01.3001.0012.7747.
Testo completoAbstract (sommario):
Flexible composites from high performance fibres were developed and targeted to replace the wall of existing rigid ceramic Particulate Filters. The composites are made from E Glass fibre webs of different density in the middle, with standard SiC Ceramic fibres webs in in the outer layers, forming a sandwich structure. Different needling densities were applied to form nonwoven composites, and they were stitched diagonally on the surface at specified intervals with continuous glass fibre filament yarn. In total, nine novel flexible composites were developed and evaluated for their structural, surface, mechanical and thermal properties. Based on the results and statistical analysis, the B2 sample is considered to be taken for further research to develop Particulate Matter (PM) filters.
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Hamedi, Naser, e Lars-Göran Westerberg. "Simulation of Flexible Fibre Particle Interaction with a Single Cylinder". Processes 9, n. 2 (20 gennaio 2021): 191. http://dx.doi.org/10.3390/pr9020191.
Testo completoAbstract (sommario):
In the present study, the flow of a fibre suspension in a channel containing a cylinder was numerically studied for a very low Reynolds number. Further, the model was validated against previous studies by observing the flexible fibres in the shear flow. The model was employed to simulate the rigid, semi-flexible, and fully flexible fibre particle in the flow past a single cylinder. Two different fibre lengths with various flexibilities were applied in the simulations, while the initial orientation angle to the flow direction was changed between 45° ≤ θ ≤ 75°. It was shown that the influence of the fibre orientation was more significant for the larger orientation angle. The results highlighted the influence of several factors affecting the fibre particle in the flow past the cylinder.
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Wan, Tao Yu, Mohammad Chowdhury e George K. Stylios. "The Formation and Morphology of PVA Ferrogel Nanofibre by the Electrospinning Process". Materials Science Forum 650 (maggio 2010): 361–66. http://dx.doi.org/10.4028/www.scientific.net/msf.650.361.
Testo completoAbstract (sommario):
Aqueous solutions of polyvinyl alcohol (PVA) with FeCl3 were homogenously mixed and subsequently electrospun; and its characteristics were studied as a function of voltage, tip-target distance and solution flow rate. Fiber mats of (PVA)/FeCl3 composite, in the diameter of 700–1100 nm were prepared by electrospinning. Lower concentrations of solution tended to facilitate the formation of fibres with beads. With increasing concentration, the morphology was improved with smooth and uniform fibres and the increased fibre diameters in the nano range. Spinning voltage also had an important influence on the diameters of the nano fibres, while the collection distance affected fibre diameters. Nano fibres of smaller diameter were formed when lower voltages are applied. The morphology of the electrospun from PVA/FeCl3 nano fibres and their magnetic power was observed and analyzed by scanning electron microscopy (SEM).The fibres produced in this way could potentially be applied to manufacture magnetic sensors, flexible magnets.
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Harlin, Ali, Mailis Mäkinen e Anne Vuorivirta. "DEVELOPMENT OF POLYMERIC OPTICAL FIBRE FABRICS AS ILLUMINATION ELEMENTS AND TEXTILE DISPLAYS". AUTEX Research Journal 3, n. 1 (1 marzo 2003): 1–8. http://dx.doi.org/10.1515/aut-2003-030101.
Testo completoAbstract (sommario):
Abstract Polymeric optical fibre (POF) is used for simple light guide and illumination applications. The polymer optical fibre materials can be utilised in flexible lighting elements which can be combined with textile structures. The POF woven fabrics are introduced as a flexible alternative to lighting elements. Various light-emitting woven fabric and light emission theories has been discussed. Simple polymethyl- metacrylate PMMA and polycarbonate PC fibres have been produced experimentally through single-screw and conical extrusion. The fibre is integrated in woven structures by means of handloom, narrow fabric weaving and Jacquard technology. The manufacturing technology suitable for lightemitting textile applications and its opportunities in textile integration is discussed.
12
Edgerton, V. R., T. P. Martin, S. C. Bodine e R. R. Roy. "How flexible is the neural control of muscle properties?" Journal of Experimental Biology 115, n. 1 (1 marzo 1985): 393–402. http://dx.doi.org/10.1242/jeb.115.1.393.
Testo completoAbstract (sommario):
The issue addressed in this paper is to what extent are selected physiological properties and associated protein systems of muscle fibres controlled or regulated by neuronal systems. One extreme position would be that all muscle proteins are controlled completely by the neural system that innervates the muscle. The opposite position would be that none of the muscle proteins are under neural influence. Although the concept that there is complete neural control of all proteins has generally received more support, it is more likely that there is only partial neural control of some proteins. Identical physiological, morphological and metabolic properties of all muscle fibres within a motor unit would suggest a complete neural control of all protein systems in muscle fibres. However, evidence against this idea is provided by the marked heterogeneity in the activities of two enzymes, alpha glycerophosphate dehydrogenase and succinic dehydrogenase (SDH), and in the wide variations in muscle fibre cross-sectional areas among fibres of the same motor unit in the cat soleus and tibialis anterior.
13
Argyros, Alexander. "Microstructures in Polymer Fibres for Optical Fibres, THz Waveguides, and Fibre-Based Metamaterials". ISRN Optics 2013 (12 febbraio 2013): 1–22. http://dx.doi.org/10.1155/2013/785162.
Testo completoAbstract (sommario):
This paper reviews the topic of microstructured polymer fibres in the fields in which these have been utilised: microstructured optical fibres, terahertz waveguides, and fibre-drawn metamaterials. Microstructured polymer optical fibres were initially investigated in the context of photonic crystal fibre research, and several unique features arising from the combination of polymer and microstructure were identified. This lead to investigations in sensing, particularly strain sensing based on gratings, and short-distance data transmission. The same principles have been extended to waveguides at longer wavelengths, for terahertz frequencies, where microstructured polymer waveguides offer the possibility for low-loss flexible waveguides for this frequency region. Furthermore, the combination of microstructured polymer fibres and metals is being investigated in the fabrication of metamaterials, as a scalable method for their manufacture. This paper will review the materials and fabrication methods developed, past and current research in these three areas, and future directions of this fabrication platform.
14
Jaworski, J. W. "Sound from aeroelastic vortex–fibre interactions". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, n. 2159 (14 ottobre 2019): 20190071. http://dx.doi.org/10.1098/rsta.2019.0071.
Testo completoAbstract (sommario):
The motion of a line vortex moving past a one-dimensional flexible fibre is examined theoretically. A Schwarz–Christoffel conformal mapping enables the analytical solution of the potential flow field and its hydrodynamic moment on the flexible fibre, which is composed of a rigid segment constrained to angular motions on a wedge. The hydroelastic coupling of the vortex path and fibre motion affects the noise signature, which is evaluated for the special case of acoustically compact fibres embedded in a half plane. Results from this analysis attempt to address how the coupled interactions between vortical sources and flexible barbules on the upper surface of owl wings may contribute to their acoustic stealth. The analytical formulation is also amenable to application to vortex sound prediction from flexible trailing edges provided that an appropriate acoustic Green's function can be determined. This article is part of the theme issue ‘Frontiers of aeroacoustics research: theory, computation and experiment’.
15
Yang, Yang, Yongquan Wang, Tao Yao e Xiaojuan Feng. "A flexible carbon fibre-based electrothermal film for fast actuation of shape memory alloy sheets". Smart Materials and Structures 31, n. 4 (10 marzo 2022): 045019. http://dx.doi.org/10.1088/1361-665x/ac5808.
Testo completoAbstract (sommario):
Abstract Two-dimensional shape memory alloy (SMA) structures have great potential in intelligent and highly flexible robots. However, they have challenges in direct electric heating. This paper proposes a solution to heat SMA sheets using carbon fibres as surface heat sources and indirectly transmits Joule heat generated by the carbon fibres to the SMA sheets. The preparation process of the carbon fibre-based thermoelectric composite film is illustrated in this study. The effect of heat source (carbon fibre) distribution on heat transfer characteristics and the temperature field of the SMA surface is simulated. Then, a functional prototype integrated thermoelectric film and flexible SMA is fabricated, and its effectiveness is verified by local and global activation, respectively. The results show that the composite structure can recover deformation rapidly in 2 s with only 0.7 A running current (applied to each carbon fibre). In addition, the local temperature control method can also realize distributed (spatial dimension) and sequential (temporal dimension) control of the structure. The proposed solution is expected to expand further the design and control of complex, intelligent structures with the development of 4D printing technology.
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Broßell, Dirk, Sebastian Wolf, Nico Dziurowitz, Carmen Thim, Asmus Meyer-Plath, Sabine Plitzko, Martin Wiemann et al. "150 The Innomat.Life Extended Fibre Human Risk Banding Scheme". Annals of Work Exposures and Health 67, Supplement_1 (1 maggio 2023): i74. http://dx.doi.org/10.1093/annweh/wxac087.179.
Testo completoAbstract (sommario):
Abstract High aspect ratio materials (HARMs) like multi-walled carbon nanotubes (MWCNTs) show material properties that enable innovative applications but also raise concerns about harmful effects to humans due to their asbestos-like pathogenicity. The fibre-pathological paradigm was established for asbestos and other HARM, linking fibre-specific adverse effects to certain material properties such as fibre length, respirability and bio-persistence. A new risk banding scheme for such hazard- and exposure-related properties is introduced. For each relevant property, we defined descriptors and developed/validated methods for their measurement. Based on results from studies conducted in the project or obtained from literature, we defined quantitative band limits. While the fibre-pathological paradigm acted as a starting point, observations of in vitro effect of nanofibers motivated us to incorporate additional properties. Studying macrophage-fibre interactions led us to highlight the importance of the flexural rigidity of fibres for their uptake by macrophages. Also, the bundling of thin constituent fibres was recognized as a mechanism possibly generating less flexible and, therefore, more harmful inhalable particles with high aspect ratio from harmless precursors. Transformation dynamics of fibres in fluids like the phagolysosomal medium were investigated as well to gain a better understanding about fibre bio-durability. Overall, the risk for humans exposed to HARMs is described by the risk banding scheme in which property bands relevant for the hazard potential were juxtaposed to the respective exposure potential. We present results for a selection of HARMs including multiple MWCNTs with varying properties, TiO2 fibres, SiC whiskers, as well as silver and copper nanowires.
17
Suman, Sanjeev, Gourav Tiwari, Abhay Kumar Jha e Barun Kumar. "Structural Behaviour of Hybrid Fibres Concrete Using Regression Analysis". International Journal for Research in Applied Science and Engineering Technology 11, n. 3 (31 marzo 2023): 173–77. http://dx.doi.org/10.22214/ijraset.2023.49216.
Testo completoAbstract (sommario):
Abstract: The main objective of the current effort is to create hybrid fibre reinforced concrete with improved strength properties, structural behaviour, and structural performance by adding the right dosage amount of hybrid fibre. In this work, it is suggested to employ hybrid fibres of two different types, one of which is Steel fibre, a metallic fibre, and the other is Polyvinyl Alcohol fibre, which has a synthetic foundation. In this way, the concrete gains high tensile strength, flexural strength, and compressive strength due to the inclusion of steel fibre with a high Young's modulus and tensile strength. The steel fibre functions as a crack arrestor, stopping the growth of cracks at the macro level. The microscopic cracks are stopped from spreading by the use of synthetic Polyvinyl Alcohol (PVA) fibre, which is more flexible and ductile, increasing the strength and hardness of the concrete. The objective of the current study is to assess the structural behaviour and strength features of hybrid fibre reinforced concrete. For different mix proportions, such as 0% Steel fibre and 1% PVA fibre, 0.25% Steel fibre and 0.75% PVA fibre, 0.50% Steel fibre and 0.50% PVA fibre, 0.75% Steel fibre and 0.25% PVA fibre, and 1% Steel fibre and 0% PVA fibre by the volume of concrete, the specimens were cast with the addition of hybrid fibres at a total volume fraction of 1%.
18
Bai, S. L., R. K. Y. Li, Y. W. Mai e C. M. L. Wu. "Morphological Study of Sisal Fibres". Advanced Composites Letters 11, n. 3 (maggio 2002): 096369350201100. http://dx.doi.org/10.1177/096369350201100304.
Testo completoAbstract (sommario):
A sisal fibre has microstructures very different from those of synthetic fibres. The special microstructures consist of parallel cells and a cuticle-interface in the form of a continuous network around each cell. The flexible interface and solid cells play an independent role to toughen and strengthen the sisal fibre, respectively. Upon loading, the cell can behave in a brittle or a ductile fashion. The main failure mechanisms of a sisal fibre are the pullout and uncoiling of cells and the debonding of a not very strong interface/cell interface. Therefore, debonding of this interface represents the first initial damage of a sisal fibre composite.
19
WU, JINGSHU, e CYRUS K. AIDUN. "A numerical study of the effect of fibre stiffness on the rheology of sheared flexible fibre suspensions". Journal of Fluid Mechanics 662 (27 settembre 2010): 123–33. http://dx.doi.org/10.1017/s0022112010003885.
Testo completoAbstract (sommario):
A recently developed particle-level numerical method is used to simulate flexible fibre suspensions in Newtonian simple shear flow. In this method, the flow is computed on a fixed regular ‘lattice’ using the lattice Boltzmann method, where each solid particle, or fibre in this case, is mapped onto a Lagrangian frame moving continuously through the domain. The motion and orientation of the fibre are obtained from Newtonian dynamics equations. The effect of fibre stiffness on the rheology of flexible fibre suspensions is investigated and a relation for the relative viscosity is obtained. We show that fibre stiffness (bending ratio, BR) has a strong impact on rheology in the range BR < 3. The relative viscosity increases significantly as BR decreases. These results show that the primary normal stress difference has a minimum value at BR ~ 1. The primary normal stress difference for slightly deformable fibres reaches a minimum and increases significantly as BR decreases below one. The results are explained based on Batchelor's relation for non-Brownian suspensions.
20
Di Giusto, Davide, e Cristian Marchioli. "Turbulence Modulation by Slender Fibers". Fluids 7, n. 8 (28 luglio 2022): 255. http://dx.doi.org/10.3390/fluids7080255.
Testo completoAbstract (sommario):
In this paper, we numerically investigate the turbulence modulation produced by long flexible fibres in channel flow. The simulations are based on an Euler–Lagrangian approach, where fibres are modelled as chains of constrained, sub-Kolmogorov rods. A novel algorithm is deployed to make the resolution of dispersed systems of constraint equations, which represent the fibres, compatible with a state-of-the-art, Graphics Processing Units-accelerated flow-solver for direct numerical simulations in the two-way coupling regime on High Performance Computing architectures. Two-way coupling is accounted for using the Exact Regularized Point Particle method, which allows to calculate the disturbance generated by the fibers on the flow considering progressively refined grids, down to a quasi-viscous length-scale. The bending stiffness of the fibers is also modelled, while collisions are neglected. Results of fluid velocity statistics for friction Reynolds number of the flow Reτ=150 and fibers with Stokes number St = 0.01 (nearly tracers) and 10 (inertial) are presented, with special regard to turbulence modulation and its dependence on fiber inertia and volume fraction (equal to ϕ=2.12·10−5 and 2.12·10−4). The non-Newtonian stresses determined by the carried phase are also displayed, determined by long and slender fibers with fixed aspect ratio λtot=200, which extend up to the inertial range of the turbulent flow.
21
Guo, Li, Azadeh Soroudi, Lena Berglin, Heikki Mattila, Mikael Skrifvars e Hakan Torstensson. "FIBRE-BASED SINGLE-WIRE KEYBOARD -THE INTEGRATION OF A FLEXIBLE TACTILE SENSOR INTO E-TEXTILES". AUTEX Research Journal 11, n. 4 (1 dicembre 2011): 106–9. http://dx.doi.org/10.1515/aut-2011-110403.
Testo completoAbstract (sommario):
Abstract A flexible textile keyboard, using carbon nanotube (CNT) filled polypropylene (PP) composite fibres, is introduced. The identification of input information is achieved by reading the effective resistance of the conductive composite fibre. By using a single wire, a complex matrix is avoided and the interface between textiles and processing electronics is reduced to a minimum. LabVIEW has been used as the output display of the keyboard indicator for testing. This keyboard is fully flexible and washable, which provides opportunities for its integration with etextiles.
22
Wang, Yao, Yuedan Wang, Rufeng Zhu e Dong Wang. "Research progress of fibre-based organic electrochemical transistors". Wearable Technology 2, n. 2 (16 giugno 2022): 67. http://dx.doi.org/10.54517/wt.v2i2.1650.
Testo completoAbstract (sommario):
<p>Organic electrochemical transistors are flexible in design with characteristics such as miniaturisation, biocompatibility and amplification and are one of the rapidly developing research topics in recent years. As an excellent flexible material, fibre has unparalleled advantages in weaving and compatibility with the human body. Combining fibres with organic electrochemical transistors is a promising research direction that has the high sensitivity of organic electrochemical transistor testing and the human body compatibility and flexibility of wearable electronic products. This paper introduces the relevant operating principles, working modes and commonly used channel materials of organic electrochemical transistors. Based on the basic device structure of organic electrochemical transistors, the development and changes of organic electrochemical transistors in recent years are discussed, and the research results of fibre-based electrochemical transistors by researchers focusing on the application of fibre-based organic electrochemical transistors in chemical sensing, bio-sensing and other application explorations are summarized. Finally, this paper visioned the future development trend of fibre-based organic electrochemical transistors.</p>
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Tomar, Pritosh, e P. C. Gope. "Impact Strength Enhancement of PMMA base Denture Material by Fibre Addition". International Journal of Materials Manufacturing and Sustainable Technologies 2, n. 1 (30 aprile 2023): 49–57. http://dx.doi.org/10.56896/ijmmst.2023.2.1.005.
Testo completoAbstract (sommario):
Prostheses used temporarily are flexible based on function. Given the paucity of empirical knowledge flexural strength of temporary resins, choosing the right material for their manufacturing is challenging. Dentures have been reinforced with partial fibres both during the production process and during repairs. Polymer's fiber-rich phase in the denture base can either form a distinct structure or the reinforcing fibres can be dispersed equally throughout the material. In this work, the static three-point flexural strength and modulus of denture base polymer reinforced with various fibre reinforcements were determined. PMMA base material can currently be strengthened by adding fibre reinforcement. The creation of bar-type specimens complied with standard 27 of the American National Standards Institute and the American Dental Association. After being immersed in artificial saliva at 37°C for 10 days, the specimens were broken under 3-point loading with a crosshead speed of 0.75 mm/min in a universal testing machine. The highest breaking weights were expressed in Newton’s. The mean flexural strengths were measured in MPa (n = 10 per group). Results were compared using variance analysis and Duncan's multiple ranges testing (P.05). Impact strength of The Glass and Natural fibre (Jute, Sugarcane, Banana etc.) group with 1% and 0.5% composition respectively composition have the maximum value. This group shows the maximum value of flexural strength, compression strength and tensile strength. The findings imply that fibres that are impregnated or re-impregnated strengthen the denture base polymer more than fibres that are not impregnated. When compared to the same amount of fibre reinforcement placed on the compression side, the fibre reinforcement applied on the tensile side produced much higher values for flexural strength and flexural modulus.
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Obiukwu, Osita, Ignatius Opara e Henry Udeani. "Study on the Mechanical Properties of Palm Kernel Fibre Reinforced Epoxy and Poly-Vinyl Alcohol (PVA) Composite Material". International Journal of Engineering and Technologies 7 (maggio 2016): 68–77. http://dx.doi.org/10.18052/www.scipress.com/ijet.7.68.
Testo completoAbstract (sommario):
The goal of this paper is to determine the mechanical properties of a proposed combined polymer composite which consist of a poly-vinyl alcohol (PVA) matrix and palm kernel fibre reinforced with epoxy. The influence of fibres volume on the mechanical properties of the composites was also evaluated. Composites with volumetric amounts of palm kernel fibre up to 12 % were fabricated and they were arranged in randomly oriented discontinues form. Tensile, impact, flexural and hardness tests were carried out to determine the characteristics of material. The acquired results show that the tensile modulus changes with the fibre content. The strength of coconut fibre reinforced composites tends to decrease with the amount of fibre which indicates ineffective stress transfer between the fibre and matrix. When higher fibre content of 10% was used, the damping peak shows the maximum value for almost all the frequency mode. It was observed that the effects of reinforcing poly-vinyl alcohol (PVA matrix with the palm kernel fibres caused the composites to be more flexible and easily deform due to high strain values and reduction of high resonant amplitude. In general, the mechanical properties of the developed composite showed variation at different test performed. This led to the conclusion that the material is most useful were strength to weight ratio is needed. The optimum percentage of fibre in epoxy resin to obtain the highest tensile properties was found at 10 vol. %. It was also found that fibre, dispersion of fibre and interfacial adhesion between fibre–matrix can affect the mechanical properties of the composites.
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Obiukwu, Osita, Ignatius Opara e Henry Udeani. "Study on the Mechanical Properties of Palm Kernel Fibre Reinforced Epoxy and Poly-Vinyl Alcohol (PVA) Composite Material". International Journal of Engineering and Technologies 7 (16 maggio 2016): 68–77. http://dx.doi.org/10.56431/p-4xufun.
Testo completoAbstract (sommario):
The goal of this paper is to determine the mechanical properties of a proposed combined polymer composite which consist of a poly-vinyl alcohol (PVA) matrix and palm kernel fibre reinforced with epoxy. The influence of fibres volume on the mechanical properties of the composites was also evaluated. Composites with volumetric amounts of palm kernel fibre up to 12 % were fabricated and they were arranged in randomly oriented discontinues form. Tensile, impact, flexural and hardness tests were carried out to determine the characteristics of material. The acquired results show that the tensile modulus changes with the fibre content. The strength of coconut fibre reinforced composites tends to decrease with the amount of fibre which indicates ineffective stress transfer between the fibre and matrix. When higher fibre content of 10% was used, the damping peak shows the maximum value for almost all the frequency mode. It was observed that the effects of reinforcing poly-vinyl alcohol (PVA matrix with the palm kernel fibres caused the composites to be more flexible and easily deform due to high strain values and reduction of high resonant amplitude. In general, the mechanical properties of the developed composite showed variation at different test performed. This led to the conclusion that the material is most useful were strength to weight ratio is needed. The optimum percentage of fibre in epoxy resin to obtain the highest tensile properties was found at 10 vol. %. It was also found that fibre, dispersion of fibre and interfacial adhesion between fibre–matrix can affect the mechanical properties of the composites.
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Allende, Sofía, Christophe Henry e Jérémie Bec. "Dynamics and fragmentation of small inextensible fibres in turbulence". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, n. 2175 (22 giugno 2020): 20190398. http://dx.doi.org/10.1098/rsta.2019.0398.
Testo completoAbstract (sommario):
The fragmentation of small, brittle, flexible, inextensible fibres is investigated in a fully developed, homogeneous, isotropic turbulent flow. Such small fibres spend most of their time fully stretched and their dynamics follows that of stiff rods. They can then break through tensile failure, i.e. when the tension is higher than a given threshold. Fibres bend when experiencing a strong compression. During these rare and intermittent buckling events, they can break under flexural failure, i.e. when the curvature exceeds a threshold. Fine-scale massive simulations of both the fluid flow and the fibre dynamics are performed to provide statistics on these two fragmentation processes. This gives ingredients for the development of accurate macroscopic models, namely the fragmentation rate and daughter-size distributions, which can be used to predict the time evolution of the fibre size distribution. Evidence is provided for the generic nature of turbulent fragmentation and of the resulting population dynamics. It is indeed shown that the statistics of break-up is fully determined by the probability distribution of Lagrangian fluid velocity gradients. This approach singles out that the only relevant dimensionless parameter is a local flexibility which balances flow stretching to the fibre elastic forces. This article is part of the theme issue ‘Fluid dynamics, soft matter and complex systems: recent results and new methods’.
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Gröger, Benjamin, Jingjing Wang, Tim Bätzel, Andreas Hornig e Maik Gude. "Modelling and Simulation Strategies for Fluid–Structure-Interactions of Highly Viscous Thermoplastic Melt and Single Fibres—A Numerical Study". Materials 15, n. 20 (17 ottobre 2022): 7241. http://dx.doi.org/10.3390/ma15207241.
Testo completoAbstract (sommario):
A virtual test setup for investigating single fibres in a transverse shear flow based on a parallel-plate rheometer is presented. The investigations are carried out to verify a numerical representation of the fluid–structure interaction (FSI), where Arbitrary Lagrangian–Eulerian (ALE) and computational fluid dynamics (CFD) methods are used and evaluated. Both are suitable to simulate flexible solid structures in a transverse shear flow. Comparative investigations with different model setups and increasing complexity are presented. It is shown, that the CFD method with an interface-based coupling approach is not capable of handling small fibre diameters in comparison to large fluid domains due to mesh dependencies at the interface definitions. The ALE method is more suited for this task since fibres are embedded without any mesh restrictions. Element types beam, solid, and discrete are considered for fibre modelling. It is shown that the beam formulation for ALE and 3D solid elements for the CFD method are the preferred options.
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Zhou, Xiaodong, Qunfang Lin, Ruohua Xiong, Xinyu Cui e Gance Dai. "Effect of Flexible Polymer Coating on Interfacial Adhesion of Glass Fibre Reinforced Polypropylene". Polymers and Polymer Composites 13, n. 6 (settembre 2005): 619–25. http://dx.doi.org/10.1177/096739110501300607.
Testo completoAbstract (sommario):
Polymer coatings were obtained by using two rubbers, cis-polybutadiene rubber and ethylene-propylene diene monomer and two block copolymer: polystyrene-block-polybutadiene-block-polyvinyltriethoxysilane and polystyrene -block-polyvinyltrietho xysilane. They were used to coat glass fibre surfaces. The effects of the coatings on the interfacial adhesion and thermal cycling resistance of composites were studied by a single-filament fragmentation technique designed to measure the interfacial shear strength of glass fibre reinforced polypropylene. The interfacial shear strength was improved by the rubber coatings, which could graft to silane coupling agents coated onto the fibre surfaces, and could undergo crosslinking under peroxide initiation. The interfacial bond strength was determined by the nature and thickness of the rubber coatings. The interfacial adhesion was also improved when using block copolymers to treat glass fibres. The rubbers and those copolymers having flexible blocks in their chain structures both produced coatings that could relieve the thermal stresses at the composite interface during temperature cycling. The interface between the composites and the flexible polymer coatings had good thermal cycling fatigue resistance.
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S, Murukesan. "Properties of Natural Materials as Alternative to Nylon Bristles – An Exploratory Study for Reduction of Polymer Usage". TEXILA INTERNATIONAL JOURNAL OF PUBLIC HEALTH 11, n. 3 (29 settembre 2023): 56–63. http://dx.doi.org/10.21522/tijph.2013.11.03.art005.
Testo completoAbstract (sommario):
Background: Nylon bristles are the most commonly used type of bristle in toothbrushes, but they have both advantages and disadvantages. Nylon bristles can be too hard or abrasive for some people's teeth and gums. Nylon is not biodegradable and can harbor bacteria if not cleaned properly. Aims: In order to explore the possibility of using natural fibers this study was conducted. Materials and Methods: Twigs of neem, banyan, babool and miswak were purchased as fresh twigs, wiped clean, hammered on a hard wood base to obtain fibers of desired lengths. Physical appearance, Bend Recovery, Folding Endurance and Antibacterial adhesion against B. Subtilis were evaluated. All experiments were performed as triplicate and mean and standard deviation were reported. Results: Digital microscopy showed well defined fibers of fairly constant diameter, apparent from the superimposed scale. Results of bend recovery analysis showed that miswak fibers were flexible and recovery was good. Folding Endurance test showed miswak and banyan were having great folding endurance. Bacterial adhesion with B. Subtilis was heavy in all fibres. The antibacterial activity of four extracts showed that all groups had identifiable antimicrobial activity at 2000 µg concentrations. Conclusion: From results of the study, it can be inferred that miswak is the most suitable material to be used for fabricating bristles in its native form. Keywords: Babool, Banyan, Bristles, Natural Fibres; Neem Miswak.
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Xue, P., Xiao Ming Tao e Keun Hoo Park. "Electrically Conductive Fibers/Yarns with Sensing Behavior from PVA and Carbon Black". Key Engineering Materials 462-463 (gennaio 2011): 18–23. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.18.
Testo completoAbstract (sommario):
In this study, electrical conductive yarns were prepared by wet-spinning technique and a physically coating process. Carbon black (CB) was used to make the fiber gaining electrical conductivity. The electrical conductivity and morphological characteristics of the developed conductive fibres were studied and compared. The results show that linear resistivity of the produced conductive yarns ranges from 1 to a few hundred kΩ per centimeter, mainly depending on processing technique and substrate fibers. It is also shown that the physically coating processes will not significantly affect the mechanical properties of the fibers and yarns. These conductive yarns are lightweight, durable, flexible, and cost competitive; and able to be crimped and subjected to textile processing without any difficulty.
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Kakonke, Grace, Tamrat Tesfaye, Bruce Sithole e Mbuyu Ntunka. "A Novel Method for Rapid Extraction Of Biofibres from Waste Chicken Feathers". Journal of Solid Waste Technology and Management 47, n. 1 (1 febbraio 2021): 31–45. http://dx.doi.org/10.5276/jswtm/2021.31.
Testo completoAbstract (sommario):
South Africa is the biggest chicken meat producer in Southern Africa and generates about 258 million kg of waste feathers. Although some of this waste is beneficiated into animal feed and fertiliser there are problems in adequate digestion of the feed by animals. Consequently, there is a need to find other innovative ways of beneficiating the waste. In this paper, beneficiating of feathers by extraction of fibres for possible conversion into high value products was explored. Three mechanical methods for extracting fibres from feathers were evaluated and the properties of the resultant fibres were studied and compared: they were using a tweezer, a blender, and a novel stripping method using a pulp fluffer. The results revealed that fibres extracted from chicken feathers using a tweezer or a blender had a hollow structure whereas those from the fluffer exhibited pronounced damaging effects on the fibre structure as some barbules were detached from their rami. Fluffer fibres had the highest average length of 16.56 mm followed by blender (16.15 mm) and tweezer (14.84 mm); they were also the most flexible with an aspect ratio of 476.29. The modified pulp fluffer appeared to be a cost-effective and an efficient method of grinding feathers into commercial fibres.
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Williams, Huw. "Marketable fibres need flexible physicists". Physics World 4, n. 5 (maggio 1991): 64–65. http://dx.doi.org/10.1088/2058-7058/4/5/33.
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Plichta, Tomas, Veronika Sirjovova, Milan Zvonek, Gerhard Kalinka e Vladimir Cech. "The Adhesion of Plasma Nanocoatings Controls the Shear Properties of GF/Polyester Composite". Polymers 13, n. 4 (16 febbraio 2021): 593. http://dx.doi.org/10.3390/polym13040593.
Testo completoAbstract (sommario):
High-performance fibre-reinforced polymer composites are important construction materials based not only on the specific properties of the reinforcing fibres and the flexible polymer matrix but also on the compatible properties of the composite interphase. First, oxygen-free (a-CSi:H) and oxygen-binding (a-CSiO:H) plasma nanocoatings of different mechanical and tribological properties were deposited on planar silicon dioxide substrates that closely mimic E-glass. The nanoscratch test was used to characterize the nanocoating adhesion expressed in terms of critical normal load and work of adhesion. Next, the same nanocoatings were deposited on E-glass fibres, which were used as reinforcements in the polyester composite to affect its interphase properties. The shear properties of the polymer composite were characterized by macro- and micromechanical tests, namely a short beam shear test to determine the short-beam strength and a single fibre push-out test to determine the interfacial shear strength. The results of the polymer composites showed a strong correlation between the short-beam strength and the interfacial shear strength, proving that both tests are sensitive to changes in fibre-matrix adhesion due to different surface modifications of glass fibres (GF). Finally, a strong correlation between the shear properties of the GF/polyester composite and the adhesion of the plasma nanocoating expressed through the work of adhesion was demonstrated. Thus, increasing the work of adhesion of plasma nanocoatings from 0.8 to 1.5 mJ·m−2 increased the short-beam strength from 23.1 to 45.2 MPa. The results confirmed that the work of adhesion is a more suitable parameter in characterising the level of nanocoating adhesion in comparison with the critical normal load.
34
GE Ziyang, 葛子阳, 王彦 WANG Yan, 赵慧 ZHAO Hui, 金萍 JIN Ping e 范保存 FAN Baocun. "柔性基体光纤光栅脉搏波传感器特性". ACTA PHOTONICA SINICA 50, n. 12 (2021): 1206002. http://dx.doi.org/10.3788/gzxb20215012.1206002.
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Popel’, S. L. "Structural changes in skeletal muscles in hypokinesia and physical loading in the posthypokinetic period of recovery of rats’ organisms". Regulatory Mechanisms in Biosystems 8, n. 2 (23 marzo 2017): 118–23. http://dx.doi.org/10.15421/021720.
Testo completoAbstract (sommario):
This article reports the study of histo-ultrastructural changes of different structural components of the direct muscle of the thigh of sexually mature male rats over a prolonged period of hypokinesia and subsequent application of physical loading of average aerobic power. Using a light optical, electron microscope (for the exposure of structural transformations of muscle components) and histochemical (for determination of activity of succinate dehydrogenase according to the Nahlas method to identify muscle fibers with different phenotypes) methods, we studied the structural manifestations of adaptation of muscle fibres under prolonged (240 day) hypokinesia and 15–30 episodes of physical loading of average aerobic power in the posthypokinetic period among 55 sexually mature rats. Under prolonged hypokinesis we primarily observed changes in the intramuscular network and morphometric changes in the blood vessels. These data closely correlate with the progression of changes of the subcellular components responsible for energetic and flexible balance of muscle fibres. We found that fast oxygen-glycolytic muscle fibers and their peripheral nervous apparatus are the most sensitive to prolonged hypokinesia. As a result of application of physical loading of average aerobic power, reparative regeneration is intensified, which substantially shortens the period of recovery of structural-functional properties of skeletal muscles in the conditions of hypokinetic disorders. Thus, in prolonged hypokinesia, changes primarily affect the sources of blood supply to skeletal muscles, with the secondary development of reverse processes in muscle fibers and peripheral nervous apparatus with certain morphometric signs.
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Derkowski, Wit, e Rafał Walczak. "Possibilities of Increasing Effectiveness of RC Structure Strengthening with FRP Materials". Materials 14, n. 6 (12 marzo 2021): 1387. http://dx.doi.org/10.3390/ma14061387.
Testo completoAbstract (sommario):
Modern composite materials based on non-metallic continuous fibres are increasingly used in civil engineering to strengthen building structures. In the strengthening of reinforced concrete (RC) structures, the utilisation of externally bonded fibre-reinforced polymer (FRP) composites is only up to 35% because of the pilling-off failure mechanism. This problem can be solved using pre-tensioned composite laminates. Due to more complex behaviour, the strengthening of structures by means of prestressing technology needs a careful design approach and a full understanding of the behaviour of both the materials and elements. The advantages and risks of the presented technology, which may determine the success of the entire project, will be highlighted in the paper. The possibility of using a flexible adhesive layer in carbon fibre reinforced polymer (CFRP) strengthening applications for flexural strengthening of RC elements, as an innovative solution in civil engineering, will also be presented. Parallel introduction of the flexible adhesive layer (made of polyurethane masses) and a traditional epoxy adhesive layer in one strengthening system was investigated in the laboratory tests. This solution was used for the repair and protection of a previously damaged RC beam against brittle failure.
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Harvey, G., A. Gachagan, J. W. Mackersie, T. Mccunnie e R. Banks. "Flexible ultrasonic transducers incorporating piezoelectric fibres". IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 56, n. 9 (settembre 2009): 1999–2009. http://dx.doi.org/10.1109/tuffc.2009.1276.
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Tschannen, Christof, Ali Shalbafan e Heiko Thoemen. "Development of an Electrically Conductive MDF Panel—Evaluation of Carbon Content and Resin Type". Polymers 15, n. 4 (11 febbraio 2023): 912. http://dx.doi.org/10.3390/polym15040912.
Testo completoAbstract (sommario):
Electronics in furniture and construction materials, in particular technologies which allow for a flexible and cable-free connection of electronics in such materials, are gaining broader interest. This study shows a further development of a concept to obtain highly conductive medium-density fibreboard panels (MDF) for furniture application. MDF were produced using two mixing processes (wet and dry) for wood and carbon fibres to investigate the effects of resin type (urea formaldehyde (UF) and polymeric methylene diphenyl diisocyanate (pMDI)) and carbon fibre content on their mechanical, physical, and electrical properties. Overall, wet mixed fibres showed better electrical but reduced mechanical properties. Modulus of elasticity (MOE) and bending strength (MOR) values of 3500 MPa and 35 MPa, respectively, and internal bond (IB) values of 0.45 to 0.65 MPa with electrical conductivities of up to 230 S/m were achieved. The technology has been successfully implemented in a demonstration object showing the application in a small piece of furniture.
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Cardoso, Edivane da Silva Araujo, Viviane Alves Escocio, Viviane Alves Escocio, Elen Beatriz Acordi Vasques Pacheco e Elen Beatriz Acordi Vasques Pacheco. "Flexible composites based on thermosetting resins and lignocellulosic fibers / Compósitos flexíveis a base de resinas termorrígidas e fibras lignocelulósicas". Brazilian Journal of Development 8, n. 1 (25 gennaio 2022): 6592–600. http://dx.doi.org/10.34117/bjdv8n1-446.
Testo completoAbstract (sommario):
Flexible thermoset composites have a wide range of applications, particularly in civil construction, interior design and the automotive industry. The main polymer matrices used for lignocellulosic fiber-based composites are epoxy resin, unsaturated polyester, polybenzoxazine and polyurethane. Many of these resins are synthesized from vegetable oils, whose long chain makes polymers flexible, with the most widely used derived from soybean oil. The main tests Applied to demonstrate the flexibility of the composites and resins were dynamic mechanical analysis, thermogravimetry and flexural strength testing.
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Doyle, Crispin, S. Quinn e Janice M. Dulieu-Barton. "Evaluation of Rugged 'Smart Patch' Fibre-Optic Strain Sensors". Applied Mechanics and Materials 3-4 (agosto 2006): 343–48. http://dx.doi.org/10.4028/www.scientific.net/amm.3-4.343.
Testo completoAbstract (sommario):
Fibre-optic sensors have advantages over existing electrical sensors in many strain and stress monitoring applications. However, bare optical fibres are fragile and packaging techniques must be developed before these sensors can be used more widely. One such method is the Smart Patch, in which the fibre Bragg grating is encapsulated between plies of glass-reinforced epoxy where rugged cables are anchored. This forms a flat flexible patch in which the fibre is protected from mechanical and environmental damage. However, it is important that the mechanical strength of the patch is not achieved at the expense of good strain transfer characteristics. To confirm this, fibre Bragg gratings with acrylate and polyimide coatings were embedded in a glass-epoxy patch that was bonded to an aluminium tensile specimen. An electrical strain gauge was also bonded to the specimen to provide a strain reference. Tests were carried out at different loading rates and at temperatures from -30°C to +80°C. There was good agreement between the fibre-optic sensors and the electrical strain gauge demonstrating that the patch performed in a practically identical manner to the conventional gauges. A second experiment on a representative part of ship structure demonstrated the versatility of the patch.
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Wylie, Sandi, e Ian Calder. "Flexible fibre-optic intubation". Anaesthesia & Intensive Care Medicine 9, n. 8 (agosto 2008): 358–61. http://dx.doi.org/10.1016/j.mpaic.2008.06.012.
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Wylie, Sandi, e Ian Calder. "Flexible fibre-optic intubation". Anaesthesia & Intensive Care Medicine 15, n. 8 (agosto 2014): 358–61. http://dx.doi.org/10.1016/j.mpaic.2014.04.012.
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Sokolova, Vera, e Dmitrijs Sokolovs. "Flexible fibre-optic intubation". Anaesthesia & Intensive Care Medicine 21, n. 9 (settembre 2020): 441–45. http://dx.doi.org/10.1016/j.mpaic.2020.06.001.
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Anjos, Ofélia, António J. A. Santos, Rogério Simões e Helena Pereira. "Morphological, mechanical, and optical properties of cypress papers". Holzforschung 68, n. 8 (1 dicembre 2014): 867–74. http://dx.doi.org/10.1515/hf-2013-0125.
Testo completoAbstract (sommario):
Abstract The pulping properties of cypress species are not known and the present paper aims to filling this gap. Namely, Cupressus lusitanica Mill., C. sempervirens L. and C. arizonica Greene have been submitted to kraft pulping and the pulp properties are compared with those of Pinus pinaster Aiton. and P. sylvestris Watereri as references. Schopper Riegler degree, density, Bekk’s smoothness, tensile index, tear index, burst index, stretch, dry zero-span strength, wet zero-span strength, brightness, opacity and light scattering coefficient have been tested. The pulp yields and delignification degrees of cypress woods were lower than those of the pine references. Fibre length, width and coarseness were statistically different between pines and cypress species and C. sempervirens pulps have corresponding data close to those of pine species. Cypress pulps can be refined much faster than pine pulps. The papers sheets of cypress fibres have, in general, lower mechanical performance than those of pine fibres. Papers from C. arizonica and C. lusitanica are similar and C. sempervirens has intermediate properties being between the other cypress and pine species. However, cypress fibres are relatively short, flexible and collapsible and can be refined with low energy demand, and thus could be incorporated into papers resulting in products with better light scattering and smoothness.
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Andrade-Silva, Ignacio, Théo Godefroy, Olivier Pouliquen e Joel Marthelot. "Cohesion of bird nests". EPJ Web of Conferences 249 (2021): 06014. http://dx.doi.org/10.1051/epjconf/202124906014.
Testo completoAbstract (sommario):
One striking difference between aggregates of flexible frictional fibres and other granular materials like rigid spheres is the effective cohesion of their assembly. While glue or capillary bridges are needed to shape aggregates of spherical particles and build sandcastles, for fibres, no need for glue to build a nest. Here we study an assembly of mono disperse flexible fibres. We first use X-ray microtomography to characterise the geometry of the initial assembly, the number of contact points and mean curvatures of the fibres. Using forcedisplacement measurements, we characterise the macroscopic cohesive strength of the aggregate by varying the geometry of the fibres, the fibres mechanicals properties and the packing of the preparation. Finally, we relate the macroscopic mechanical behaviour of the assembly with the filament reorganisation at the microscopic scale.
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Weissbach, Margret, Marius Neugebauer e Anna-Christin Joel. "Cribellate thread production as model for spider’s spinneret kinematics". Journal of Comparative Physiology A 207, n. 2 (23 gennaio 2021): 127–39. http://dx.doi.org/10.1007/s00359-020-01460-4.
Testo completoAbstract (sommario):
AbstractSpider silk attracts researchers from the most diverse fields, such as material science or medicine. However, still little is known about silk aside from its molecular structure and material strength. Spiders produce many different silks and even join several silk types to one functional unit. In cribellate spiders, a complex multi-fibre system with up to six different silks affects the adherence to the prey. The assembly of these cribellate capture threads influences the mechanical properties as each fibre type absorbs forces specifically. For the interplay of fibres, spinnerets have to move spatially and come into contact with each other at specific points in time. However, spinneret kinematics are not well described though highly sophisticated movements are performed which are in no way inferior to the movements of other flexible appendages. We describe here the kinematics for the spinnerets involved in the cribellate spinning process of the grey house spider, Badumna longinqua, as an example of spinneret kinematics in general. With this information, we set a basis for understanding spinneret kinematics in other spinning processes of spiders and additionally provide inspiration for biomimetic multiple fibre spinning.
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Ponomarev, Andrei B., V. I. Kleveko, O. V. Moiseeva e K. R. Kashapova. "FIBER REINFORCED SAND BACKFILL FOR UNDERGROUND PEDESTRIAN CROSSINGS". Acta Polytechnica CTU Proceedings 10 (15 ottobre 2017): 34. http://dx.doi.org/10.14311/app.2017.10.0034.
Testo completoAbstract (sommario):
Crosswalk is an essential element of the transport system of any city. A priority assignment in any such crossing is to ensure the safety of pedestrians. Underground pedestrian crossings are much safer than crossings at another level, but they lose in attraction when it comes to cost. The cost of the construction of an underground pedestrian crossing often leads to project abandonment. The cost of construction can be reduced through the use of flexible corrugated metal structures instead of ordinary concrete structures. The stress-strain state of the structural shells need to be known to facilitate their rational design. The stress-strain state of flexible corrugated metal shells largely depends on the strength and deformation characteristics of the surrounding soil. Therefore, improving the characteristics of backfill soil is an urgent task in reducing the cost of construction for such tunnels. One way to improve the strength and deformation characteristics of soils is the use of reinforcement. Currently, there are a large number of reinforcement schemes and also associated reinforcing materials. One of the most prospective methods of soil reinforcement is the use of fibre filaments. Fibre reinforced soils have significantly higher strength and deformation characteristics in comparison with unreinforced soils. Numerical modelling of a tunnel shell made out of a corrugated metal structure was undertaken to evaluate the effectiveness of using fibre reinforced sand. Ordinary sand and sand reinforced with polypropylene fibres have been used as soil backfill. The calculation results for a pedestrian tunnel structure involving different strength and deformation characteristics of the backfill soil are presented in this article.
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Yan, Yurong, Weipei Li, Ruitian Zhu, Chao Lin e Rudolf Hufenus. "Flexible Phase Change Material Fiber: A Simple Route to Thermal Energy Control Textiles". Materials 14, n. 2 (15 gennaio 2021): 401. http://dx.doi.org/10.3390/ma14020401.
Testo completoAbstract (sommario):
A flexible hollow polypropylene (PP) fiber was filled with the phase change material (PCM) polyethylene glycol 1000 (PEG1000), using a micro-fluidic filling technology. The fiber’s latent heat storage and release, thermal reversibility, mechanical properties, and phase change behavior as a function of fiber drawing, were characterized. Differential scanning calorimetry (DSC) results showed that both enthalpies of melting and solidification of the PCM encased within the PP fiber were scarcely influenced by the constraint, compared to unconfined PEG1000. The maximum filling ratio of PEG1000 within the tubular PP filament was ~83 wt.%, and the encapsulation efficiencies and heat loss percentages were 96.7% and 7.65% for as-spun fibers and 93.7% and 1.53% for post-drawn fibers, respectively. Weak adherence of PEG on the inner surface of the PP fibers favored bubble formation and aggregating at the core–sheath interface, which led to different crystallization behavior of PEG1000 at the interface and in the PCM matrix. The thermal stability of PEG was unaffected by the PP encasing; only the decomposition temperature, corresponding to 50% weight loss of PEG1000 inside the PP fiber, was a little higher compared to that of pure PEG1000. Cycling heating and cooling tests proved the reversibility of latent heat release and storage properties, and the reliability of the PCM fiber.
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Zou, Ling Chunxian, e Chris Hunt. "A new approach to investigate conductive anodic filament (CAF) formation". Soldering & Surface Mount Technology 27, n. 1 (2 febbraio 2015): 22–30. http://dx.doi.org/10.1108/ssmt-02-2014-0002.
Testo completoAbstract (sommario):
Purpose – This paper aims to describe the development of an approach that uses a flexible substrate to investigate the mechanism of conductive anodic filament (CAF) growth and effect of different material and manufacturing variables. Design/methodology/approach – A new approach using a simulated test vehicle (STV) has been developed to study the CAF phenomena. The STV can be easily built under controlled conditions in the laboratory using different glass fibres and resin powder to investigate the effect of different variables separately on CAF. The advantage of the STV is that CAF can be formed in relatively short period in a controlled way, and CAF growth can be easily identified using a back-lighting under a microscope due to the thin flex material used as the test sample. Findings – STV has been used to investigate a number of effects on CAF formation: different glass fibres, reflow process, acid contamination in drilled holes, desmear process and glass bundle size. The results demonstrate that for finished fibres acid contamination (plating solution) at the electrode was necessary for CAF formation. However, for unfinished glass fibres (loom state and heat cleaned) CAF can be formed without acid contamination. The reflow process significantly increases CAF formation. Running an aggressive desmear process and using large glass fibre bundle also increased CAF formation. Originality/value – This new approach will be of benefit for printed circuit board (PCB) supplier to evaluate CAF performance on different resin systems and glass fibres to provide high CAF resistance quality PCBs. The test period (168 hours) would be much shorter than the traditional CAF testing (1,000 hours).
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Bornemann, Sarah, e Walter Lang. "Considerations and Limits of Embedding Sensor Nodes for Structural Health Monitoring into Fiber Metal Laminates". Sensors 22, n. 12 (14 giugno 2022): 4511. http://dx.doi.org/10.3390/s22124511.
Testo completoAbstract (sommario):
The objective of this article is to present the results of our investigations concerning the environmental conditions that can be expected during the embedding process into fibre metal laminates and the consequences for a sensor node for structural health monitoring. The idea behind this investigation is to determine for which manufacturing conditions the integration of sensor nodes into the material can be done and to identify limits for this. The sensor nodes consist of commercially available integrated circuits and passive components soldered onto an adhesive-less flexible printed circuit board. They are tested under conditions above their specified limits, to find out if they are still working reliably after experiencing 155 min of 180 ∘C and 7 bar of pressure. Apart from occurring temperature damage, the effect of surrounding fibres potentially pushing away the components under the amount of pressure of the manufacturing process, as well as the potential of shorts due to conductive fibers are investigated and suitable solutions to prevent this are evaluated. One experiment exceeding the typical requirements of a fiber metal laminate embedding process for structural components will be conducted at 250 ∘C for 10 h, in order to determine the limits of embedding electronic sensor nodes. This time and temperature combination is expected to cause irreversible damage to the electronic system. Results show that it is possible to integrate electronics into materials under conditions far above their specifications when precautions are taken but also that there are limits that must not be exceeded during the embedding process.