Fiber Yarn Research Articles

New Approach for Processing Recycled Carbon Staple Fiber Yarns into Unidirectionally Reinforced Recycled Carbon Staple Fiber Tape.

This study describes a novel process in which staple fiber yarns made from recycled carbon fibers (rCFs) and polyamide 6 (PA6) fibers are further processed into semi-finished tape products in a modified impregnation and calendaring process. In this process, the staple fiber yarns are heated above the melting temperature of the polymer, impregnated, and stretched to staple fiber tapes (SF tapes) in the calendaring unit. SF tapes with different degrees of stretching and/or repasses were produced. The individual width and thickness were measured in line by a laser profile sensor. From these tapes, preforms were manually laid and processed into laminates in an autoclave. The important physical properties of the unidirectionally reinforced laminates made of the tapes were compared with organic sheets wound from staple fiber yarns. With increasing stretching, both the fiber orientation and mechanical properties improved compared to the organic sheets made from unstretched staple fiber yarns. An improvement in fiber orientation relative to the process direction from 66.3% to 91.9% (between ±10°) and 39.1% to 71.6% (between ±5°), respectively, was achieved for a two-stage stretched tape. The tensile and flexural moduli were increased by 15.2% and 14.5%, respectively.

Challenges in Manufacturing of Hemp Fiber-Reinforced Organo Sheets with a Recycled PLA Matrix.

This study investigates the influence of a hot press process on the properties of hemp fiber-reinforced organo sheets. Plain-woven fabric made from hemp staple fiber yarns is used as textile reinforcement, together with a recycled poly-lactic acid (PLA) matrix. Process pressure and temperature are considered with three factor levels for each parameter. The parameter influence is examined based on the B-factor model, which considers the temperature-dependent viscosity of the polymer, as well as the process pressure for the calculation of a dimensionless value. Increasing these parameters theoretically promotes improvements in impregnation. This study found that the considered recycled polymer only allows a narrow corridor to achieve adequate impregnation quality alongside optimal bending properties. Temperatures below 170 °C impede impregnation due to the high melt viscosity, while temperature increases to 185 °C show the first signs of thermal degradation, with reduced bending modulus and strength. A comparison with hemp fiber-reinforced virgin polypropylene, manufactured with identical process parameters, showed that this reduction can be mainly attributed to polymer degradation rather than reduction in fiber properties. The process pressure should be at least 1.5 MPa to allow for sufficient compaction of the textile stack, thus reducing theoretical pore volume content to a minimum.

Numerical Modeling of Kevlar/Jute Fiber and Hybrid Composite Pressure Vessels

In this study, nine composite overwrapped pressure vessel (COPV) models (type IV) have been developed to analyze their burst pressure performance using the ultimate tensile strength (UTS) from experiment and the von Mises stress profile from finite element ABAQUS simulation. The four-layer jute-reinforced PV shows almost five times lower burst pressure than Kevlar-based PV, indicating the inherent vulnerability of using pure jute. However, for the hybrid jute/Kevlar alternate combination, JKJK shows strength improvement over a jute PV by almost two times. Other jute hybrids with glass and aluminum foil show very comparable performance when compared to jute PV. Both yarn and braided-type jute fiber exhibit similar operating conditions, indicating that the preparation type of jute fiber is invariant to pressure performance. However, COPVs woven with 90° cross-oriented jute fibers are found to have the most degraded strength, highlighting that fiber orientation remains an important optimization factor in designing PVs with hybrid composite wraps.

Experimental Investigation on Tensile Strength of Twisted Ramie Fiber Yarns

Natural fibers as reinforcement can be an alternative material with an environmentally friendly profile. The aim of this work is to determine the potential of Indonesian Ramie fiber, as a reinforcing material in cement mortar, by exploring new twisting ideas for natural fibers and the impact of twisting techniques on tensile strength. Long fibers are arranged in four cross-sectional areas and also in different numbers of constituent layers, as 2 ply and 3 ply. The spinning process contributes to the final yarn result which the process is carried out in the same direction for each ply, but to unite each ply it is necessary to rotate the direction of rotation and the direction of the single fiber yarn (opposite way). Twisted Ramie fiber yarns were tested for tensile strength using the Universal Testing Machine (UTM). It showed that comparing at the same weight of 24 gr twisted yarn, 3 ply twisted yarn shows the highest tensile strength value as much as 110,32 MPa than 2 ply as much as 96,56 MPa that indicates that the number of ply affects the tensile strength of the yarn.

A mesoscopic constitutive model for woven fabrics with large deformation

The meso-structure of woven fabrics plays a pivotal role in enabling significant deformations. To precisely characterize the deformation behavior of woven fabrics, a mesoscale model based on their meso-structure is developed. In this model, the fiber yarn is represented as a Timoshenko beam with fluctuations described by the shape function. A novel approach is proposed to establish the relationship between the macroscopic mechanical response and the infinitesimal strain of the beam, employing the principle of virtual work. The shearing behavior of woven fabrics is characterized by considering friction energy dissipation and transverse compression among fiber yarns. The general applicability of the proposed model is validated through its application to glass fiber woven fabrics and jute fiber woven fabrics. The model parameters are determined through uniaxial tensile and bias-extension experiments. The accuracy of the model is verified using bias-extension and picture frame experiments. The results demonstrate that the proposed model can effectively simulate the large deformation of woven fabrics.

Micro-computed tomography imaging and segmentation of the archaeological textiles from Valmarinniemi

ObjectiveArchaeological textiles represent a variety of structures and materials, often subject to post-depositional effects such as dirt and decay. In this study, we examined textiles in 3D with high-resolution micro-computed tomography (μCT) imaging and studied the internal structures and patterns of textiles. In addition, nanoscale CT was used to identify fibre material. DesignTwo tablet-woven textile fragments and a plain-woven textile were excavated from a late medieval burial site in Valmarinniemi, Finland. Two textiles were scanned with μCT imaging and one with nanoscale CT imaging. Image segmentation was performed to study the internal structural components of the fabrics, yarns, and fibres. ResultsThe tablet-woven ribbon and plain-woven textile were imaged and visualised in 3D using high-resolution μCT and nanoscale CT imaging. 3D μCT images together with segmenting showed the structure of the woven textiles and how warp and weft intertwine. Nanoscale CT imaging of plain-woven fragment showed individual fibres and provided information in identifying the fibres as cotton. ConclusionsHigh-resolution μCT and nanoscale CT enabled the examination and identification of archaeological textiles in 3D. Thus, μCT imaging brings added value to the study of archaeological textiles with a precise method to study internal structures that otherwise would be invisible or difficult to examine and evaluate yarn and individual fibre geometry in a way that is less laborious and time-consuming than conventional methods.

Gentamicin Release Study in Uniaxial and Coaxial Polyhydroxybutyrate-Polyethylene Glycol-Gentamicin Microfibers Treated with Atmospheric Plasma.

The skin is the largest organ and one of the most important in the human body, and is constantly exposed to pathogenic microorganisms that cause infections; then, pharmacological administration is required. One of the basic medical methods for treating chronic wounds is to use topical dressings with characteristics that promote wound healing. Fiber-based dressings mimic the local dermal extracellular matrix (ECM), maintaining an ideal wound-healing climate. This work proposes electrospun PHB/PEG polymeric microfibers as dressings for administering the antibiotic gentamicin directed at skin infections. PHB-PEG/gentamicin fibers were characterized before and after plasma treatment by Raman spectroscopy, FTIR, and XRD. SEM was used to evaluate fiber morphology and yarn size. The plasma treatment improved the hydrophilicity of the PHB/PEG/gentamicin fibers. The release of gentamicin in the plasma-treated fibers was more sustained over time than in the untreated ones.

Mineral-impregnated carbon-fiber based reinforcing grids as thermal energy harvesters: A proof-of-concept study towards multifunctional building materials

This proof-of-concept study demonstrates for the first time the fabrication of a multifunctional reinforcing grid-building material within a thermoelectric element generator (TEG) configuration. Commercially available carbon fiber yarns, which possess inherent Seebeck coefficient (S) values of −2.5 μV/K (n-type) and +7.4 μV/K (p-type), were thoroughly investigated prior to their impregnation with a geopolymer (GP)-based suspension. The resulting hardened mineral-impregnated carbon-fiber (MCF) reinforcements were subsequently tested regarding their physicochemical and mechanical properties. Afterward, individual MCFs were employed as n-/p-type thermoelements to assemble a grid-like TEG consisting of five serially interconnected junctions. The TEG-enabled reinforcing grid exhibited a voltage output of 1.8 mV, corresponding to a generated power of 22.3 nW upon exposure to an in-plane temperature difference (ΔT) of 50 K. Multifunctional building materials are envisaged to exploit thermal gradients on a large-scale during their service lifetime, contributing towards zero energy consumption constructions.

Investigation on the off-axis tensile failure behaviors of 3D woven composites through a coupled numerical-experimental approach

Computational models with high precision and efficiency are in urgent need for the damage analyses of 3D angle-interlock woven composites which are widely accepted in composites industry. A novel concurrent multi-scale damage evolution modeling scheme is established based on a meso-scale representative volume cell (RVC) model and the multiphase finite element method to characterize the off-axis tensile response of carbon/epoxy composites. Modified Puck criterion and maximum shear stress criterion are adopted for fiber yarns. Parabolic yield criterion is adopted for the matrix. The fiber breakage, the inter-fiber fracture and matrix cracking are considered at mesoscopic level. To validate the proposed multi-scale damage model, off-axis tensile test is conducted with the help of 3D Digital Image Correlation (DIC) method. A reasonably good agreement is achieved between numerical predictions and experimental observations. Furthermore, the validated damage model is used to predict the tensile response of the composites considering full range on-axis and off-axis angles.

Use of Yarn and Carded Jute as Epoxy Matrix Reinforcement for the Production of Composite Materials for Application in the Wind Sector: A Preliminary Analysis for the Manufacture of Blades for Low-Intensity Winds.

The development of wind turbines for regions with low wind speeds imposes a challenge to the expansion of the corresponding energy generation capacity. The present work consists of an evaluation of the potential carded jute fiber and jute yarn to be used in the construction of a wind blade for regions of low wind intensity. The fibers used were supplied by Company Textile of Castanhal (Castanhal-Para-Brazil) and used in the study without chemical treatment in the form of single-filament fibers and yarns with a surface twist of 18.5°. The composites were produced through the resin infusion technique and underwent tensile and shear tests using 120-Ohm strain gauges and a blade extensometer to obtain the Young's modulus. In the analysis of the results, the ANOVA test was applied with a 0.05 significance level, followed by Tukey's test. The results showed that long, aligned jute fibers can be a good option for laminated structures applied in composites for small wind turbine blades.

Sustainable biobased epoxy thermosets with covalent dynamic imine bonds for green composite development

The widespread use of thermoset composites has raised great environmental and economic awareness, due to the lack of recyclability of the resins and fibres. This work is focused on the development of a sustainable, recyclable and reprocessable epoxy vitrimer by using an epoxidized linseed oil resin and a vanillin derived Schiff base as dynamic hardener. Different epoxy:dynamic hardener ratios have been employed, analyzing its influence in the final physico-chemical properties of the thermoset resin. The reprocessability and the recyclability of the vitrimers have been demonstrated. This work also describes the manufacturing and characterization of greener composites obtained with these vitrimers and flax yarn fibres. A good adhesion between the fibres and the vitrimer is observed. Moreover, the characterization of developed composites indicated that their thermal and mechanical properties allow their use in lightweight engineering applications. Finally, chemical recyclability and compostability of the flax fibre vitrimer-based composite have been demonstrated.

Experimental and Numerical Analysis of Axial Behavior of Triaxial Woven Fabric Confined Concrete Columns

Continuous efforts are being made to improve plain concrete compressive strength and ductility by applying carbon, glass fiber, or hybrid-reinforced epoxy resin composites. The investigation centers on analyzing the axial compressive strength and strain, compressive stress–strain behavior, failure morphology, and crack evolution of the reinforced cylinders. Besides the experiments, non-linear finite element analysis was performed using the finite element (FE) package ABAQUS 2021. The test results indicate that carbon fiber triaxial woven fabric (TWF-C) confinement result in the most significant improvement of 118% in compressive stress than the concrete specimens. On the other hand, glass fiber triaxial woven fabric (TWF-G) confinement shows the highest enhancement of 161% in ductility. The mechanical properties of the sample utilizing glass fiber as the weft yarn and carbon fiber as the warp yarn (TWF-GC2) exhibit superior improvements of 22% in compressive stress and 8% in axial strain compared to the sample using glass fiber as the warp yarn and carbon fiber as the weft yarn (TWF-CG2). Samples with glass fiber as weft yarn show gradual cracks during loading, while carbon fiber as weft yarn show instantaneous damage. The numerical finite element models accurately predict the experimental results of the tested specimens in this study. There were 1.2~3% and 5~10% discrepancies for compressive stress and axial strain, respectively, between experimental and FE results. Overall, the results suggest that Triaxial woven fabric confinement is a valuable technique to improve the strength and strain of concrete and that the type of fibers used could be tailored for appropriate performance characteristics.

A critical review on recent developments and solutions in the high-speed ring spinning process

Twist plays an important role in textile technology, particularly in the production of staple yarn structures. Due to the higher yarn quality and flexibility of the process, most short staple fiber yarns are produced in the ring spinning process in comparison to other high-speed spinning processes, such as rotor or air jet spinning. To impart twist in the yarn, the ring/traveler system, rotor and air jet nozzle are used in the ring, rotor and air jet spinning processes respectively. However, the productivity of the ring spinning process is limited significantly due to the frictional heat generated between the ring and traveler, especially at higher angular spindle speeds, which is crucial for the spinning of man-made fibers. This paper aims to describe the recent developments and solutions for increasing productivity in the ring spinning process in a systemic way. To reduce the friction, different topologies and surface modifications in the ring/traveler system were made to increase the angular spindle speed of maximum 23,000 rpm. To eliminate the friction, the twisting element was made of an air bearing or magnetically elevated rings were developed by replacing the ring/traveler system completely, thus permitting a higher angular spindle speed of up to 50,000 rpm. Further approaches deal with cap, loop and nova spinning or Nu-Torque technology to reduce yarn tension or residual torque in the yarn, respectively. The results of the presented work reveal the potential of different developments, especially in the field of twisting system, so that the productivity of ring spinning can be increased drastically.

Improving the structural integrity of foam-core sandwich composites using continuous carbon fiber stitching

This study aims to improve the structural integrity of foam-core sandwich structures by embedding carbon-fiber/epoxy stitched reinforcements with fiber-volume fraction (Vf) as high as 55 %. Sandwich panels with 1.5 mm thick carbon fiber skins and 30 mm thick PVC foam-core were stitched with 0, 12 k and 24 k carbon fiber yarns. X-ray computed tomography (CT) was utilized to determine the “as-manufactured” quality of the stitched panels. Flatwise-, edgewise-compression and 3-point bending tests were conducted with in-situ 3D Digital Image Correlation (DIC) to record the deformation and analyze the structure’s mechanical response. It was observed that compared to non-stitched samples - under flatwise compression loading, the reinforced samples with a stitch Vf of 0.34 and 0.55 showed an increase in stiffness and strength by 130 % and 163 %, and 29 % and 53 %, respectively. For edgewise-compression and 3-point bending loading cases, stiffness and strength of stitched samples showed an increase of ∼20 % over the benchmark. Using DIC, X-ray CT and a fractography analysis, the external and internal damage as well as failure mechanisms were evaluated. Analytical solution was employed to understand the parametric influence of the stitch Vf and stitch density per unit area in pursuit of an optimized sandwich structure.

Tensile behaviors of nanoporous phenolic composites reinforced by 3D needle-punched preforms with different weave patterns

Needle-punched preform reinforced nanoporous phenolic composite (NPC) is a cost-effective lightweight ablative material for thermal protection systems. It consists of a needle-punched preform composed of alternating stacked fiber felt and stacked woven fabric, which plays a crucial role in the thermal insulation efficiency and mechanical properties. Herein, needle-punched preforms with different types of fabrics, including plain, twill, and satin, are deliberately designed for the reinforcement of NPC, and their tensile properties and fracture mechanism are investigated through experimentation and the CT image-based finite element method. At the same preform density, the composite with plain fabric exhibits the highest tensile strength of 146 ± 6.3 MPa, a tensile modulus of 8.2 ± 0.2 GPa, and an elongation of 2.1 ± 0.1%, due to having the highest number of crossover points and the largest undulation of fiber yarns. Furthermore, the CT image-based simulation reveals the failure mechanism of NPC. The von mises stress of woven fabric is higher than that of fiber felt, which demonstrates the woven fabric is the main load-bearing structure and determines the mechanical of composite. These results will provide useful guidance for the structural design and optimization of needle-punched preform reinforced composites.

A multiscale deep learning model for elastic properties of woven composites

Time-consuming and costly computational analysis expresses the need for new methods for generalizing multiscale analysis of composite materials. Combining neural networks and multiscale modeling is favorable for bypassing expensive lower-scale material modeling, and accelerating coupled multi-scale analyses (FE2). In this work, neural networks are used to replace the time-consuming micromechanical finite element analysis of unidirectional composites, representing the local material properties of yarns in woven fabric composites in a multiscale framework. Leveraging the fast multiscale data generation procedure, we presented a second neural networks model to estimate the elastic engineering coefficients of a particular weave architecture based on a broad range of dry resin and fiber properties and yarn fiber volume fraction. As an outcome, this paper provides the user with a generalized, neural network-based approach to tackle the balance of computational efficiency and accuracy in the multiscale analysis of elastic woven composites.

Thermoresistivity of Carbon Nanostructures and their Polymeric Nanocomposites

AbstractCarbon nanostructures such as carbon nanotubes, graphene, and its multi‐layer derivatives exhiibit temperature‐dependent electrical conductivity. They can form percolated networks inside polymers, which render electrical conductivity to nanocomposites. Upon the formation of a percolated network, thermal energy applied to the material drives structural changes of the network, which manifest as changes in electrical conductivity. This principle is used to develop smart materials with self‐sensing temperature capabilities. This critical review covers past and present research on the electrical response to temperature (thermoresistivity) of carbon nanostructures and their polymeric nanocomposites. It covers few‐ and multi‐layer graphene, carbon nanotubes, carbon‐nanostructured arrays and fibers (yarns). The mechanisms driving the thermoresistive response of individual nanostructures, their arrays, and of their polymeric nanocomposites are addressed. The role of the nanostructured filler on the thermoresistivity of polymer nanocomposites depends on its morphology and concentration. For low filler concentrations, thermal expansion of the polymer may dominate over the inherent thermoresistivity of the filler. For high filler concentrations, or for densely packed arrays of carbon nanostructures, the inherent (quantum) thermoresistive response of the nanostructures becomes dominant. The review addresses recent progress in the field, highlights current issues, synthesizes published data, and provides outlooks and insights into future directions.

Improved ballistic limit velocity from filament-wound fibres as composite cover on ceramic tiles

Hard armour plates are used in body armour for protection against high-velocity threats. The strike face often consists of a single ceramic tile that is covered by a sheet material made of a high-tenacity fibre-composite material. During impact, the ceramic will fracture but at the same time cause erosion and fragmentation of the hard core of the projectile. The composite cover is there to improve the ballistic performance by partly maintaining the integrity of the fracturing ceramic. In this study, a new production method where glass fibre yarns were filament-wound around an alumina tile in a unidirectional 0°/90°lay-up, was investigated. Ballistic testing was conducted with a 7.62 mm armour piercing projectile. The new target design gave a remarkable increase in the V50ballistic limit velocity by as much as 16% compared to a traditional design where a glass fibre fabric was wrapped around the tile. A higher degree of fragmentation of the projectile steel core after perforation was also observed. The high degree of fibre alignment in the filament-wound composite, as opposed to the more wavy fibres in the fabric, is believed to be the main reason for the higher ballistic performance.

Damage Monitoring of Braided Composites Using CNT Yarn Sensor Based on Artificial Fish Swarm Algorithm.

This study aims to enable intelligent structural health monitoring of internal damage in aerospace structural components, providing a crucial means of assuring safety and reliability in the aerospace field. To address the limitations and assumptions of traditional monitoring methods, carbon nanotube (CNT) yarn sensors are used as key elements. These sensors are woven with carbon fiber yarns using a three-dimensional six-way braiding process and cured with resin composites. To optimize the sensor configuration, an artificial fish swarm algorithm (AFSA) is introduced, simulating the foraging behavior of fish to determine the best position and number of CNT yarn sensors. Experimental simulations are conducted on 3D braided composites of varying sizes, including penetration hole damage, line damage, and folded wire-mounted damage, to analyze the changes in the resistance data of carbon nanosensors within the damaged material. The results demonstrate that the optimized configuration of CNT yarn sensors based on AFSA is suitable for damage monitoring in 3D woven composites. The experimental positioning errors range from 0.224 to 0.510 mm, with all error values being less than 1 mm, thus achieving minimum sensor coverage for a maximum area. This result not only effectively reduces the cost of the monitoring system, but also improves the accuracy and reliability of the monitoring process.

Biomimetic construction of 3D needle‐punched CF/PEEK composites based on ladybug forewing structure for directional reinforcement

Abstract3D needle‐punched CF/PEEK composites are a kind of composites with promising applications in multiple fields, such as implant materials, but their mechanical properties in the Z‐axis and interlaminar are still weak at present. In this study, a bio‐inspired reinforcement structure based on ladybug forewing was developed to achieve directed reinforcement of 3D needle‐punched CF/PEEK composites. Carbon fiber yarns were stitched into the 3D needle‐punched CF/PEEK preforms according to the set structure, and the bio‐inspired CF/PEEK composites were obtained after hot pressing. The interlaminar and in‐plane mechanical properties of the composites were investigated at different stitch lengths. The results showed that the addition of the bio‐inspired structure greatly improved the interlaminar shear strength of the composites, reaching 111.30 MPa, an enhancement of 95.06%. The in‐plane mechanical properties, including tensile, flexural, and compression, were also significantly improved to different degrees. The “structure‐effect” relationship in the bio‐inspired CF/PEEK composites was investigated, and the effectiveness of such a bio‐inspired reinforcement structure was demonstrated. This new reinforcement strategy provides a new idea for the improvement of the mechanical properties of multi‐stage carbon fiber‐reinforced thermoplastic resin matrix composites.Highlights The in‐plane and interlaminar mechanical properties of composites were simultaneously improved. Up to 95.06% improvement in interlaminar shear strength. A novel bionic strategy of directional reinforcement was developed. The “structure‐effect” relationship in the composites was investigated.