Fiber Configuration Research Articles

Investigation on impact properties of different type of fibre form: hybrid hemp/glass and kenaf/glass composites

Abstract Natural fibre reinforced polymer composites have high potentials to be used in a variety of applications due to its environmental friendly and biodegradability capabilities. The purpose of this study is to evaluate the effects of core fibre type, core thicknesses, and fibre configurations on the impact behaviour of hybrid natural fibre reinforced polymer (FRP) composites. The samples were made of kenaf, hemp and glass mat fibers, and polyester used as matrix resin. These samples were fabricated using a combination of hand lay-up and vacuum bagging systems. The Instron Dynatup 8250 was used in accordance to ASTM D7136. The results showed that the highest impact properties were in hemp hybrid composites. For fibre arrangement, system (1/4/1) in which kenaf, hemp and glass mat were arranged in outer layer (as skin) resulted a higher energy absorbed compared to system (2/2/2) in which kenaf, hemp and glass mat were arranged in middle layer (as core). The impact properties increased with the increasing of core thickness. These findings are significant for possible applications of natural/synthetic fibre reinforced polymer hybrid composites in the fields of vehicles, biomedical, transportation and other specific application could have benefited for further study in hybrid composite material improvement.

Water stable and matrix addressable OLED fiber textiles for wearable displays with large emission area

Organic light-emitting diode (OLED) fibers with favorable electroluminescence properties and interconnectable pixel configurations have represented the potential for wearable electronic textile displays. Nevertheless, the current technology of OLED fiber-based textile displays still leaves to be desired due to several challenges, including limited emission area and lack of encapsulation systems. Here we present a fibrous OLED textile display that can attain a large emission area and long-term stability by implementing addressable networks comprised of integrated phosphorescence OLED fibers and by designing multilayer encapsulations. The integrated fiber configuration offers decoupled functional fiber surfaces for an interconnectable 1-dimensional OLED pixel array and a data-addressing conductor. Tailored triadic metal/ultrathin oxide/polymer multilayer enables not only the oxygen/water permeation inhibition but also the controllable conductive channels of dielectric antifuses. Together with reliable bending stability, the long-term operation of OLED textiles in water manifests the feasibility of the present device concept toward water-resistant full-emitting-area fibrous textile displays.

Cost-Effective Fiber Optic Solutions for Biosensing.

In the last years, optical fiber sensors have proven to be a reliable and versatile biosensing tool. Optical fiber biosensors (OFBs) are analytical devices that use optical fibers as transducers, with the advantages of being easily coated and biofunctionalized, allowing the monitorization of all functionalization and detection in real-time, as well as being small in size and geometrically flexible, thus allowing device miniaturization and portability for point-of-care (POC) testing. Knowing the potential of such biosensing tools, this paper reviews the reported OFBs which are, at the moment, the most cost-effective. Different fiber configurations are highlighted, namely, end-face reflected, unclad, D- and U-shaped, tips, ball resonators, tapered, light-diffusing, and specialty fibers. Packaging techniques to enhance OFBs’ application in the medical field, namely for implementing in subcutaneous, percutaneous, and endoscopic operations as well as in wearable structures, are presented and discussed. Interrogation approaches of OFBs using smartphones’ hardware are a great way to obtain cost-effective sensing approaches. In this review paper, different architectures of such interrogation methods and their respective applications are presented. Finally, the application of OFBs in monitoring three crucial fields of human life and wellbeing are reported: detection of cancer biomarkers, detection of cardiovascular biomarkers, and environmental monitoring.

Effect of Fiber Geometry on Fracture and Fatigue of Composite Hydrogels

Abstract Hydrogel-based biomedical applications are under rapid development. These applications usually demand hydrogels to have high toughness and high fatigue threshold. Recently, various fiber-reinforced composite hydrogels have been developed to meet this challenge. However, the effect of fiber geometry on the fracture and fatigue of composite hydrogels is still elusive. Here, we use a model composite hydrogel to study the influence of fiber width, fiber spacing, and fiber configuration on these properties. It is found that the toughness of the composite hydrogel does not increase monotonically with the fiber width or fiber spacing, but presents a peak. This is because the variation of fiber width and fiber spacing not only affects the volume of fiber in the fracture process zone but also influences the dissipated elastic energy density in that volume, which is affected by the stress concentration. The peak is a consequence of the trade-off between these two factors. Our study further shows that the shape of the fiber network affects the stress concentration in the fiber dramatically, thereby leading to a huge difference in the toughness and fatigue threshold of the composite hydrogels. This work highlights the importance of fiber size as well as the shape of fiber networks on the mechanical properties of composite hydrogels. It may help the design of tough and fatigue-resistant stretchable composite materials.

Dynamic Heterochromatin States in Anisotropic Nuclei of Cells on Aligned Nanofibers.

The cancer cell nucleus deforms as it invades the interstitial spaces in tissues and the tumor microenvironment. While alteration of the chromatin structure in a deformed nucleus is expected and documented, the chromatin structure in the nuclei of cells on aligned matrices has not been elucidated. In this work we elucidate the spatiotemporal organization of heterochromatin in the elongated nuclei of cells on aligned nanofibers with stimulated emission depletion nanoscopy and fluorescence correlation spectroscopy. We show that the anisotropy of nuclei is sufficient to drive H3K9me3-heterochromatin alterations, with enhanced H3K9me3 nanocluster compaction and aggregation states that otherwise are indistinguishable from diffraction-limited microscopy. We interrogated the higher-order heterochromatin structures within major chromatin compartments in anisotropic nuclei and discovered a wider spatial dispersion of nanodomain clusters in the nucleoplasm and condensed larger nanoclusters near the periphery and pericentromeric heterochromatin. Upon examining the spatiotemporal dynamics of heterochromatin in anisotropic nuclei, we observed reduced mobility of the constitutive heterochromatin mark H3K9me3 and the associated heterochromatin protein 1 (HP1α) at the nucleoplasm and periphery regions, correlating with increased viscosity and changes in gene expression. Since heterochromatin remodeling is crucial to genome integrity, our results reveal an unconventional H3K9me3 heterochromatin distribution, providing cues to an altered chromatin state due to perturbations of the nuclei in aligned fiber configurations.

Finite element analysis of the effect of longitudinal debonding on stress redistributions around fibre breaks in randomly packed fibres

One of the challenges in longitudinal strength models of unidirectional composites is to comprehensively simulate the stress redistribution around a broken fibre. This redistribution is affected by the interfacial debonding of the broken fibre from the matrix. In the present work, a novel approach using finite element modelling is developed that considers all primary contributors to the longitudinal debonding in randomly packed fibre configurations. The parametric study revealed that a larger friction coefficient, interfacial fracture toughness and interfacial shear strength shorten the debond length and increase the stress concentration factor (SCF) on the neighbouring intact fibres. The magnitude of the SCFs strongly depends on the local fibre volume fraction, the radial distance between the intact fibres and the broken fibre, and the debond length. Incorporating interfacial debonding considerably reduces the SCF overpredictions by the well-bonded models. The presence of a matrix crack, encircling the broken fibre, locally increases the SCFs in the adjacent intact fibres and marginally shortens the debond length of the broken fibre. By incorporating these results into a strength model, the influence of the longitudinal debonding and co-existing matrix cracks on failure strain of unidirectional composites can be further tuned.

Bulging of inflated membranes made of fiber reinforced materials with different natural configurations

In this article, we study the inflation and bulging of fiber reinforced hyperelastic membranes in which fibers are symmetrically arranged in two helically distributed families that are mechanically equivalent. The isotropic ground substance behavior is described by a neo-Hookean model and the mechanical behavior of fibers is described by the so-called standard reinforcing model. The two constituents, fiber and matrix, may possess different natural configurations to account for different characteristics. For example, in collagenous soft tissue synthesized collagen fibrils are integrated at a certain distribution of pre-stretches, or fibers may be crimped, and different natural configurations of the constituents can be used to model these mechanisms. In addition, fibers are taken to be dispersed with respect to a mean fiber direction within their respective fiber families. It is shown that the arrangement and the natural configuration of fibers have a strong effect on bulging of inflated cylindrical membranes. The modeling at hand can be used to understand the mechanical behaviour of arterial soft tissue and the formation of aneurysms.

Manipulation of breather waves with split-dispersion cascaded fibers

A stabilization scheme is proposed for the dynamics of breather waves induced by the coherent-seed modulation instability based on manipulation of phase-space trajectory. Theoretical and numerical analysis show that carefully dispersion- and nonlinearity-managed cascades of fiber configuration allows the system evolution to be stabilized around an elliptic center point, forming stable pulse trains with ultrahigh contrast efficiently. We also demonstrate that the scheme proposed works equally well for near-separatrix dynamics. Our results provide an alternative means to control the unsteady nonlinear waves by abruptly changing the waveguide properties.

A Comparative Study of the Use of Concrete Mix Using Jute Fibers

Abstract: The character of fiber reinforced concrete can be changed by the variation of certain factors. these factors are the geometric configuration of fibers, type and. quantity of fibers, , dispersal, direction, and concentration of the fibres Portland cement concrete is assumed to be a relatively. Brittle material .When non-reinforced concrete is exposed to tensile stresses. This is likely to fracture and fail. Since the start of the nineteenth century, studies were conducted. to reinforce concrete by using fibres. After the reinforcement of concrete by fibers, it becomes a composite group in which the fibres endures the tensile stresses. When concrete is reinforced by. using fiber in the mixture, it further increases the tensile strength of the composite system. Research has revealed that. The strength of concrete may be improved greatly by the adding of fibers Keywords: Fiber, jute fibres, NDT Mix design, design mix

Phenol Deterioration in Refinery Wastewater through Advanced Electrochemical Oxidation Reactions Using Different Carbon Fiber and Graphite Electrodes Configurations

Phenol Deterioration in Refinery Wastewater through Advanced Electrochemical Oxidation Reactions Using Different Carbon Fiber and Graphite Electrodes Configurations

Hinged Adaptive Fiber-Rubber Composites Driven by Shape Memory Alloys-Development and Simulation.

Adaptive structures based on fiber-rubber composites with integrated Shape Memory Alloys are promising candidates for active deformation tasks in the fields of soft robotics and human-machine interactions. Solid-body hinges improve the deformation behavior of such composite structures. Textile technology enables the user to develop reinforcement fabrics with tailored properties suited for hinged actuation mechanisms. In this work, flat knitting technology is used to create biaxially reinforced, multilayer knitted fabrics with hinge areas and integrated Shape Memory Alloy wires. The hinge areas are achieved by dividing the structures into sections and varying the configuration and number of reinforcement fibers from section to section. The fabrics are then infused with silicone, producing a fiber-rubber composite specimen. An existing simulation model is enhanced to account for the hinges present within the specimen. The active deformation behavior of the resulting structures is then tested experimentally, showing large deformations of the hinged specimens. Finally, the simulation results are compared to the experimental results, showing deformations deviating from the experiments due to the developmental stage of the specimens. Future work will benefit from the findings by improving the deformation behavior of the specimens and enabling further development for first applications.

Insights from the IronTract challenge: Optimal methods for mapping brain pathways from multi-shell diffusion MRI

Limitations in the accuracy of brain pathways reconstructed by diffusion MRI (dMRI) tractography have received considerable attention. While the technical advances spearheaded by the Human Connectome Project (HCP) led to significant improvements in dMRI data quality, it remains unclear how these data should be analyzed to maximize tractography accuracy. Over a period of two years, we have engaged the dMRI community in the IronTract Challenge, which aims to answer this question by leveraging a unique dataset. Macaque brains that have received both tracer injections and ex vivo dMRI at high spatial and angular resolution allow a comprehensive, quantitative assessment of tractography accuracy on state-of-the-art dMRI acquisition schemes. We find that, when analysis methods are carefully optimized, the HCP scheme can achieve similar accuracy as a more time-consuming, Cartesian-grid scheme. Importantly, we show that simple pre- and post-processing strategies can improve the accuracy and robustness of many tractography methods. Finally, we find that fiber configurations that go beyond crossing (e.g., fanning, branching) are the most challenging for tractography. The IronTract Challenge remains open and we hope that it can serve as a valuable validation tool for both users and developers of dMRI analysis methods.

Dual U-shaped fibers refractometer with enhanced sensitivity based on the coupling effect

Numerous methods have been reported to further enhance the sensitivity of U-shaped fiber optic sensors towards external refractive index variation. This paper introduces a variant U-shaped fiber structure, which is inspired by the U-shaped and twisted fiber configurations. The U-shaped passive-active fiber arrangement consists of two fibers placed in a concentric semicircle manner and is expected to yield higher sensitivity than single U-shaped structure due to the multiple modulations at the boundaries of the fibers. This configuration is also beneficial in terms of its simple fabrication process (i.e. no twisting) and compact-size. Ray tracing analysis was performed, and the simulated data corroborates with the experimental data. Moreover, the sensor sensitivity is enhanced by a factor of around 1.55, 1.48 and 2.90 for bend ratios of 6, 12 and 17, respectively. In addition, the sensor demonstrated good sensing stability, which eliminates the intense signal fluctuation problem caused by the inconsistent gap between the fibers. Ultimately, the U-shaped passive-active fiber provides a promising route towards developing a low-cost, portable, and sensitive sensor, and allows the incorporation of a mixture of transducer coatings for further improvement in the sensing performance.

Manufacturing and axial compression performance of a novel composite cylindrical shell

AbstractIt is challenging and expensive to manufacture composite cylindrical shells with characteristics such as large diameters and lengths and 0°‐fibers for applications such as bridge piers and wind power columns. In this study, a new type of cross section configuration of inner annular block and outer annular continuous fiber is proposed, and a low‐cost method is established First, the inner assembly block is pulled and extruded, and then, the outer continuous prestressed fiber is wound as the mold to apply annular compressive stress to the inner tube. Axial compression tests were carried out with Φ104 × 8 mm glass fiber‐reinforced polymer(GFRP) tubes made of pultruded standard blocks without integral forming, without external winding carbon fiber, and with an external winding layer. The results show that the mechanical properties of the pipe produced via piece‐assembling followed by winding are better than those produced via piece‐assembling without an external winding layer, which has mechanical properties similar to those of a one‐time forming member. Based on the obvious deterioration of mechanical properties, composite cylindrical shells with large diameters and lengths and 0°‐fibers can be produced at low costs.

Low velocity impact and compressive response after impact of thin carbon fiber composite panels

Impact damage of laminated composite structures continues to be a challenging problem. The complexity of damage morphology, the sequence of damage events, and multiple damage modes pose significant challenges when it comes to design for damage tolerance. In an effort to reduce some of the complexity, a systematic experimental study was conducted to understand the sequence of damage during impact of a thin composite plate. Two configurations of carbon fiber reinforced epoxy composite panels were impacted with increasing impact energies. Digital image correlation (DIC), using high speed camera, was performed to measure plate deflection and strain evolution during the impact event. Detailed post impact measurement and imaging were conducted to quantify the extent of damage and delamination. Compression after impact (CAI) tests were conducted to ascertain the post impact compressive load carrying capability of the panel. The results of the experiments indicate a sequence of damage from back surface splitting, delamination and then impact surface compressive failure. Correlations were also found between impact energies, panel configuration and damage type and morphology. The data thus generated is useful for validating computational models for impact damage and CAI. An approach to performing such validation is also provided in this study.

Assessing the potential of highly permeable reverse osmosis membranes for desalination: Specific energy and footprint analysis

The ultra-permeable membranes (UPMs) are expected to reduce the specific energy consumption (SEC) of desalination, but the potential of UPMs in hollow fiber configuration has not been well quantified. Herein, we analyse the SEC and footprints of UPM modules in three feed salinities: seawater reverse osmosis (SWRO), brackish water RO (BWRO) and low-pressure RO (LPRO). Through the modelling the fluid dynamics and mass transport of RO systems, we find that a tripling in spiral-wound SWRO membrane permeability (based on the current value of 1 L m−2 h−1 bar−1; LMH/bar) could result in 16% decrease in SEC. Contrastingly, the quadrupling of hollow fiber SWRO membrane permeability (based on the current value of 0.25 LMH/bar) could reduce the SEC by 23%. According to our analysis, hollow fiber and spiral-wound SWRO membranes with permeabilities up to 1 LMH/bar and 3 LMH/bar, respectively, can reduce the SEC of seawater desalination. On the other hand, membranes with permeabilities up to 9 LMH/bar and 12 LMH/bar can lead to SEC savings in BWRO and LPRO desalination, respectively. This study provides a general guidance to RO membrane researchers on the permeability upper-limit of which UPMs could bring about SEC and footprint savings at a system level.

Disentangling the variability of the superficial white matter organization using regional-tractogram-based population stratification

Each variation of the cortical folding pattern implies a particular rearrangement of the geometry of the fibers of the underlying white matter. While this rearrangement only impacts the ends of the long pathways, it may affect most of the trajectory of the short bundles. Therefore, mapping the short fibers of the human brain using diffusion-based tractography requires a dedicated strategy to overcome the variability of the folding patterns. In this paper, we propose a fiber-based stratification strategy splitting the population into homogeneous groups for disentangling the superficial white matter bundle organization. This strategy introduces a new refined fiber distance which includes angular considerations for inferring fine-grained atlases of the short bundles surrounding a specific sulcus and a subtractogram distance that quantifies the similitude between fiber sets of two different subjects. The stratification splits the population into groups with similar regional fiber organization using manifold learning. We first successfully test the hypothesis that the main source of variability of the regional fiber organization is the variability of the regional folding pattern. Then, in each group, we proceed with the automatic identification of the most stable bundles, at a higher granularity level than what can be achieved with the non-stratified whole population, enabling the disentanglement of the very variable configuration of the short fibers. Finally, the method searches for bundle correspondence across groups to build a population level atlas. As a proof of concept, the atlas refinement achieved by this strategy is illustrated for the fibers that surround the central sulcus and the superior temporal sulcus using the HCP dataset.

Effect of graphene nanoplatelets on mechanical and impact properties of an aramid/glass-reinforced epoxy composite

Abstract This study aims to characterize and evaluate the effects of graphene nanoplatelets (GnPs) added to the epoxy matrix and the fiber stacking sequence on the mechanical and impact responses of carbon/aramid hybrid composites. For this purpose, Aramid/Glass/Aramid and Glass/Aramid/Glass stacking sequences as well as full Aramid and Glass fiber configurations were used in an epoxy matrix with various contents (0.1, 0.25, 0.5 wt%) of GnPs. Tensile and flexural tests were conducted per mechanical characterization and low-velocity impact (LVI) tests with 30 J impact energy were performed by a drop-weight impact test. According to results, aramid fiber location has a significant effect on the peak load values, absorbed energy, and displacement of the hybrid composites. In addition, the inclusion of 0.25 wt% GnPs into the epoxy matrix increased the LVI properties of pure glass and hybrid fiber-reinforced composites. However, the incorporation of GnPs into the epoxy matrix caused a deterioration in the LVI properties of the aramid fiber-reinforced composite plates. Moreover, the best increase in the mechanical properties of pure and hybrid fiber-reinforced composites was obtained by adding 0.1 and 0.25% wt% GnPs into the epoxy matrix.

Monitoring industrial acoustics with distributed acoustic sensing

True-phase distributed acoustic sensing (DAS), a technique which uses low-power laser pulses to monitor along-fiber strain in optical cable, has proven useful in many geophysical research areas, including down-hole monitoring in oil/gas extraction, near-surface characterization, detecting and locating regional and global earthquakes, urban monitoring. Most of the geophysical applications to date, however, have focused on recording elastic waves propagating through solid media. In this work, we explore the response of DAS for recording acoustic propagation in air, as a function of fiber type and configuration, over frequency bands useful for monitoring industrial environments. We also present methods of creating simple fiber-composite sensing units for improving sensitivity, and strategies for combining solid-earth and acoustic monitoring to create an effective seismoacoustic array with a single DAS interrogator.

Design and Modeling of a Compound Twisted and Coiled Actuator Based on Spandex Fibers and an SMA Skeleton

Twisted and Coiled Actuators (TCAs) are a class of new artificial muscles for flexible actuations. However, conventional TCAs based on nylon fibers commonly require high driving temperature, which limits their applications. Although the TCAs based on spandex fibers can produce high strain under low driving temperature, their output force is low. In this work, a Compound TCA (CTCA) based on spandex fibers and an SMA skeleton is developed. The spandex fibers are spirally wound on the surface of the SMA wire with large number of spiral turns, and the SMA skeleton forms a coil, which can produce additional contraction force for the CTCA owing to the shape memory effect of the SMA wire. To obtain the designated CTCA configuration, a new double twisting fabrication process is proposed, i.e., twisting of spandex fibers followed by twisting of the pre-twisted spandex fibers and an SMA wire together. The CTCA will form a compound twisted fiber configuration, which has the merits of low driving temperature, high strain, and high output force. The influence of the fabrication parameters on the stroke and output force of the CTCA is investigated experimentally. The effect of temperature on the thermal expansion coefficient of spandex fibers is quantified through experiments. It is found that pre-stretching of spandex fibers significantly enhances its thermal expansion behavior. Based on the geometrical parameters and the materials properties of the CTCA, a static model that describes the displacement of CTCA with respect to the temperature and load is established. Experiments under different loads are conducted to verify the accuracy of the static model. Simulation and experimental results show that the proposed CTCA achieves superior performance, with the maximum contraction strain of 46.8% and the maximum output force of 4 N at 80 °C driving temperature.