Behavior Of Yarns Research Articles

A viscoelastic-plastic model for the core of various close-packings of multifilament polyamide-6 yarns

Different forms of close-packed yarns can be produced by varying the number of monofilaments in the core region, ranging from one to five. Numerous efforts have been made to model or simulate the mechanical response of close-packed yarns; however, previous studies have predominantly focused on one or two monofilaments in the core. In this study, we propose an analytical approach that combines a geometrical model with an artificial neural network (ANN) to predict the tensile behavior of close-packed yarns containing 2 to 5 monofilaments in the core region. The novelty of this hybrid model lies not only in accounting for more than two monofilaments in the core but also in extending the prediction range from elastic to viscoelastic-plastic behavior. Validation of the proposed method showed excellent agreement between experimental and theoretical results. Numerical simulations further confirmed that the results align with theoretical predictions, demonstrating the model’s accuracy in predicting the tensile behavior of close-packed yarns. This modeling approach has the potential to significantly improve the understanding and modeling of textile structures.

Strain sensing of structural composites by integrated piezoresistive CNT yarn sensors

This work presents the development of piezoresistive strain sensors for the next-generation airframe parts. The sensors consist of polyetherketoneketone (PEKK) coated thermoplastic filaments with a continuous carbon nano-tube (CNT) yarn reinforcement fully integrated into the structural thermoplastic CFRP laminates. PEKK coating improves the piezoresistive behaviour of CNT yarns by increasing internal stress transfer. When consolidated in a laminate, the CNT sensors have a gauge factor of 10.5 and 12 for 0.2 % tensile and compressive deformations, respectively. The CNT sensors were calibrated and compared with commercial strain gauges at the coupon level and demonstrated high sensitivity in three- and four-point bend tests.

Characterization of pressure-dependent nonlinear bending behavior of yarns and its application in modeling the compression of 2D woven fabrics

This paper investigates the pressure-dependent nonlinear bending behavior of yarns, which is essential for the application of the virtual fiber modeling (VFM) method in the mechanical analyses of fabrics. An experimental method, along with a theoretical model based on classical beam theory, is presented to characterize the varying bending stiffness of yarns under different pressures. A tailored beam user element is then developed, incorporating the nonlinear bending behavior and combined with a truss element to create a physics-based virtual fiber formulation. Utilizing this formulation, the original kinematic VFM method is extended for modeling the mechanical response of 2D woven fabrics under compression. The predicted results of the proposed model closely match the reported experiment, demonstrating the significance of introducing the nonlinear bending behavior of yarns. This method can be a valuable tool for the fabric compression process and generating realistic mesoscale geometries for textile composites.

Modeling of mechanical behavior of Agave sisalana fiber's yarn using the design of experiments method

The aim of this study is to propose a model for predicting the mechanical properties of natural sisal yarn based on mechanical strength of used fibers, unit twist of yarn and its density. To achieve this, a complete factorial design modelling method was used, based on a design of experiments approach, which is recommended today because of the ease it offers in taking into account the most complex phenomena. It was developed on the basis of laboratory tests. The model obtained predicts mechanical strength and elasticity modulus of sisal yarn, based on control parameters such as fiber strength, unit twist and yarn mass. This model is currently one of the most accurate tools for predicting and optimising the mechanical properties of sisal yarns. The iso-surface curves represented by this model, can be used to obtain the strength and elasticity modulus of sisal yarn during manufacture, by varying the optimum control parameters. This model is an original tool that can be recommended to the spinning and sisal fiber composite manufacturing industries and others, as it saves time and materials and ensures precision in the manufacture of yarns according to the field of application, thereby contributing to safety in use.

Dynamic Behavior of Twisted UHMWPE Yarns

Twisting is an effective method to reduce defects during fabric weaving and improve the impact resistance of the armor material. This study examined the dynamic behavior of twisted ultra-high molecular weight polyethylene (UHMWPE) yarns. Material characterization was conducted using three-dimensional X-ray tomography and scanning electron microscopy (SEM). Dynamic mechanical experiments were carried out on the twisted yarns using a Kolsky bar, with the yarn's failure process captured in real time through high-speed imaging. Additionally, the digital imaging correlation (DIC) technique was used to calibrate the strain measured by the Kolsky bar. Post-fracture analysis was performed using SEM. The effects of twisting extent, strain rate, and gauge length on the dynamic behavior of twisted yarns were studied. It was observed that all twisted yarns underwent elongation, shrinkage, fiber breakage, untwisting, and yarn rupture. Furthermore, as the twisting degree and strain rate increased, and the gauge length decreased, the fracture area became more concentrated. The tensile strength peaked at a twisting degree of 250 t/m and decreased thereafter. Moreover, twisting was found to alter the sensitivity of the yarns' stress–strain curves and tensile properties to the strain rate and gauge length.

VISUALIZING SPUN YARN DEFORMATION: INSIGHTS FROM OPTICAL INSTRUMENTATION

This article presents a comprehensive analysis of key quality indicators for spun yarns, focusing on yarns with a linear density of T=20 (Ne=30) tex produced on both simple and compact ring spinning machines. Through the utilization of optical instrumentation, various parameters including relative breaking strength (Rkm), strength, elongation at break (E %), and hairiness (H %) were meticulously examined to evaluate yarn quality. The study delves into the assessment of yarn unevenness (CV %) as a crucial quality metric, aiming to provide insights into the deformation characteristics of spun yarns. By employing advanced optical techniques, such as high-resolution imaging and precise measurements, the deformation behaviour of yarns under different spinning conditions is elucidated. The findings shed light on the influence of spinning machine type on yarn quality parameters, revealing nuanced differences in strength, elongation, and hairiness between simple and compact spinning processes. Additionally, the analysis highlights the correlation between yarn deformation and overall yarn quality, emphasizing the significance of understanding deformation mechanisms in optimizing textile manufacturing processes. Through a rigorous examination of these quality indicators, this research contributes valuable insights into the intricate dynamics of spun yarn deformation and its implications for textile production. The utilization of optical instrumentation offers a novel approach to visualize and quantify yarn deformation, providing a deeper understanding of the factors influencing yarn quality and performance in industrial settings.

Micromechanical Modelling of the Deformation Mechanisms of Friction-Spun Yarn from Recycled Carbon Fibres

The growing use of carbon fibre-reinforced polymers (CFRP) results in an increased amount of CF waste from offcuts or end-of-life components. A promising method to reuse the waste fibre materials in a structural component with excellent mechanical properties is the processing of recycled CF (rCF) and thermoplastic fibres into hybrid yarns. Spinning of friction spun yarns consisting of more than 90% rCF and containing almost no thermoplastic fibres that are suitable for thermoset composites, currently leads to high fibre damage and low yarn quality and is, therefore, addressed in this project. The technology is reported in another paper. One of the limiting factors for drapability of textiles is the stretchability of continuous fibres and draping of the semi-finished textile products for complex geometries is still error-prone. Friction spun yarns exhibit significantly higher yarn elongations due to sliding mechanisms between the fibres. The deformation properties of friction spun yarns are significantly influenced by fibre-fibre interactions and depend on a variety of process and material parameters. In the following, micromechanical finite element models of the spun yarns are created by using beam elements. Monte Carlo method is used to model local variabilities in the yarns. The models are then used to simulate yarn behaviour under deformation and to investigate the influence of various process parameters.

Highly stretchable, durable, and reversibly thermochromic wrapped yarns induced by Joule heating: With an emphasis on parametric study of elastane drafts

Abstract Highly stretchable thermochromic wrapped yarns, which employ elastane filament (EF) as core, stainless steel wire, and thermochromic polyester filament as the first and second winding, was prepared, and the effect of elastane draft upon yarn properties was investigated. It was found that the elastane draft played an essential role in determining the final yarn behavior, and the optimized elastane draft parameter was 2.5 using Technique for Order Preference by Similarity to Ideal Solution. It is a distinctive configuration of yarn’s constituents and the EF draft that are responsible for the exceptional stretchability of yarns, and it showed mechanical robustness following cyclic stretch. Importantly, the yarn exhibited rapid, durable, and reversible color conversion when subjected to cyclic voltage, cyclic abrasion, and alkali. Finally, a flower-shaped pattern was fabricated by embroidering yarn onto an elastic substrate as a proof-of-concept, and no obvious variation of color fidelity was observed during the stretch.

Study on the wear characteristics of carbon fiber yarns under the influence of multifactor coupling on braiding carriers

AbstractReducing the wear of carbon fibers on braiding carriers is the key to manufacturing high‐performance carbon fiber composite prefabricated parts. In this study, a new analytical model is developed to describe the local friction behavior of yarns on braiding carriers. The degree of yarn wear is characterized by calculating the gray value of carbon fiber hairiness and observing the micro‐surface morphology of carbon fibers. The wear characteristics of carbon fiber yarns under the multi‐factor coupling influences of yarn tension, unwinding speed, and guiding element characteristics were considered. The results show that increases in unwinding angle and unwinding speed both increase the wear of carbon fiber yarns. Eliminating the effect of unwinding angle can reduce the yarn hairiness by more than 60%, alleviate the yarn tension fluctuation by more than 70%, and improve the yarn tension stability by more than 75%. Meanwhile, the relationship between the wrapping angle between the yarn and the yarn bobbin, the unwinding angle, and the yarn tension was established according to the Capstan Equation. A method is proposed to improve the characteristics and spatial position of the guiding elements to obtain more intact yarn and low‐damage yarn surfaces.Highlights A new analytical model for local friction of carbon fibers is developed. The friction‐wear‐fracture mechanism of carbon fiber yarns is constructed. Characterize the degree of yarn wear from a macro and micro perspective. Wear characteristics of carbon fiber yarns under multi‐factor coupling.

Characterization of viscoelastic properties of yarn materials: Dynamic mechanical analysis in the transversal direction

Abstract Warp knitting creates very challenging dynamics due to its high production speeds. On the one hand, this makes it method of choice for many products in various fields. On the other hand, not all materials are suitable for such high productivity. With the current generation of machines being limited to only achieve their maximum speed of around 4,400 min−1 with highly elastic yarns, it is desired to gain a deeper insight into yarn behavior in such highly dynamic environments. Among other influences, resonance effects gain high significance as they may result in high loads on the used materials; therefore, yarn breakages interrupt the production and decrease the quality of the product. To extend the material choice, especially high-performance fibers, for high productivity, a deep understanding of the intrinsic properties of the yarn is required. In particular, the viscoelastic properties are of importance. This study proposes a method to determine these characteristics using the dynamic mechanical analysis method. For the purpose of finding the damping in the transversal direction to the yarn axis, the variant of free oscillation is chosen. For the trials, a high-speed camera is suspended above a testing rig. On this rig, a yarn sample is clamped and then displaced from its rest position. The resulting oscillation is recorded and later extracted from the video. From the decrement of the maxima of the amplitude and corresponding time intervals, the damping factor is determined. It decreases with higher initial deflection. Summarised the developed trial setup proved suitable for the determination of the viscoelastic properties in transversal direction.

CREEP AND ELECTRICAL PROPERTIES OF CARBON NANOTUBE YARNS FOR LONG-TERM APPLICATIONS

One of the primary challenges to turning CNTs into commercial applications is the feasibility to manufacture macroscopic structures that mirror the extraordinary properties of individual CNTs. CNT yarns (CNTY) are an alternative to overcome this challenge. However, most yarn-like structures are exposed to dynamic systems, like creep and/or fatigue, and limited studies are published predicting their behavior. Therefore, the current study aimed to assess the behavior of CNTYs under creep situations and establish a relationship with their electrical properties. Five layers of CNTs were drawn from the MWCNT forest, placed one on top of the other, and scrolled into a 250 mm yarn, that was later twisted to 2000 twists m−1. Afterward, these CNTYs were densified with acetone. Creep experiments were performed with a sustained load of 50, 70, and 80 % of the YBL. The yarn behavior seen during creep experiments was unexpected, which, although partial breakage of the yarn was seen, it sustained the creep load much for longer periods. The mechanism proposed for the phenomenon includes CNT alignment and void elimination at first, followed by partial CNT sliding, with breakage of van der Waals forces. As the creep load continues, CNTs are able to rebind to their neighbors and recover their strength before total failure. Mechanical gripping due to friction is also occurring between nanotubes which favors a strength increase. This behavior indicates that there is a regeneration of van der Waals forces occurring among the CNTs, which recovers the strength of the yarn under constant load, increasing creep lifespan. The time to failure obtained under creep load is about 9, 10, and 11 days to failure for CNTYs at 50, 70, and 80 % of YBL, respectively. Raman results showed that ID/IG ratio remained the same after mechanical loads, which indicates that no structural modification is seen in the CNTs when static and/or dynamic mechanical systems are imposed on the yarn. The electrical conductivity of a CNTY is improved after the mechanical tests, increasing by 5.9 and 6.7% after static tensile and creep, respectively. The improvement of electrical conductivity is attributed to densification, which leads to an enhancement of the intertubes contact area among the nanotubes within the yarn.

Evolution of stiffness in flax yarn within flax fiber reinforced composites during moisture absorption

This study aims to investigate the evolution of stiffness in flax yarn within flax fiber reinforced composites (FFRCs) during moisture absorption, focusing on the influence of moisture content on the microstructure of flax fibers. To characterize the hygroscopic mechanical behaviors of flax yarns in FFRCs, the hygroscopicity and tensile properties of dried and impregnated flax yarns were tested at various humidity levels. A multi-scale modeling approach was utilized to simulate the stiffness in flax yarn within FFRCs, encompassing the modeling of cell wall layers of the flax elementary fiber, flax elementary fiber and twisted flax yarn. Specifically, the variation trends of the microfiber angle (MFA) in the S2 layer and the stiffness degradation of the combined amorphous matrix (CAM) with respect to relative moisture content (RMC) were proposed and determined through simulation and inversion calculation. The study reveals that the MFA in the S2-layer is the most crucial parameter affecting the longitudinal elastic properties of flax yarn in FFRCs, while the stiffness degradation of the CAM significantly influences the transverse elastic properties. Finally, this study establishes a relationship between the overall stiffness of flax yarn in FFRCs and the RMC. This relationship provides a parameter foundation for accurately predicting the mechanical properties of FFRCs during moisture absorption.

Electromechanical Properties of Silver-Plated Yarns and Their Relation to Yarn Construction Parameters.

For signal transmission and sensing in stretchable structures for human motion monitoring or proprioception of soft robots, textiles with electronically conductive yarns are a promising option. Many recent publications employ silver-plated yarns in knits, braids, wovens for strain or pressure sensing purposes as well as heating fabrics or twisted string actuators. Silver-plated yarns are available in a wide range of base materials, yarn counts and twists. These structural properties significantly influence the electrical and electromechanical behavior of such yarns. However, until now little research has been carried out on the yarns themselves. To close this research gap, several variations of a single yarn type are electromechanically characterized. Additionally, tensile tests with synchronous resistance measurements are performed. From these measurements, sensor metrics are derived and calculated to compare the different variants quantitatively.

Characterization of the Viscoelastic Properties of Yarn Materials: Dynamic Mechanical Analysis in Longitudinal Direction

Warp knitting is a highly productive textile manufacturing process and method of choice for many products. With the current generation of machines running up to 4400 min−1, dynamics become a limit for the production. Resonance effects of yarn-guiding elements and oscillations of the yarn lead to load peaks, resulting in breakage or mismatches. This limits material choice to highly elastic materials for high speeds, which compensate for these effects through their intrinsic properties. To allow the processing of high-performance fibers, a better understanding of the viscoelastic yarn behavior is necessary. The present paper shows a method to achieve this in longitudinal yarn direction using a dynamic mechanical analysis approach. Samples of high tenacity polyester and aramid are investigated. The test setup resembles the warp knitting process in terms of similar geometrical conditions, pre-loads, and occurring frequencies. By recording the mechanical load resulting from an applied strain, it is possible to calculate the phase shift and the dissipation factor, which is a key indicator for the damping behavior. It shows that the dissipation factor rises with rising frequency. The results allow for a simulation of the warp knitting process, including a detailed yarn model and representation of stitch-formation process.

Analysis of the transverse compressive behavior of cotton yarns and fabrics

The inherent complexity of textile preforms and a high degree of consistency in dry fabrics and yarns present a number of modeling challenges, including uncertainty in geometrical characteristics under external loads, non-elastic deformations of fibrous media, and multiple deformation modes at the fiber and yarn scales. The prediction of the compaction reaction for different preforms is still possible thanks to the direct measurements of yarn compaction. The data are checked against compression stress-thickness curves that were produced by compacting yarns and preforms. The yarn and fabric compaction model given in this article demonstrates the final characteristics of woven preforms. The yarn compaction curve exhibits asymptotic hardening with a restricted compaction state attained at high compression stress and as the limit deformations are being approached. The yarn count, yarn fiber volume ratio, and the spinning method all affected the compression modulus. The transverse compression behaviour of yarns and fabrics was studied both analytically and experimentally. Mechanisms of fabric compressibility have been found to be reliant on both fabric and yarn specifications of warp and weft Young’s modulus. Investigations were made into the fabric’s fiber volume fraction under compression stress. When producing composite with low fiber volume fraction preforms, it may be more efficient to use more compression, according to research on the link between compressive stress and fabric volume fraction. The relationship between the compressive stress and fabric volume fraction was investigated, as well as the value of maximum compression stress.

Characterization of the dissipative large deformation bending response of dry fabric composites as occurs during forming

Bending rigidity is known to play a significant role in the formability of composite fabrics, as it can affect wrinkles formation and reduce the mechanical properties of the final part. However, measuring the highly nonlinear dissipative bending behaviour of unconsolidated fabrics undergoing large deformation, is an ongoing challenge. In this article, a customized setup is employed to capture the bending as well as reverse bending responses of unconsolidated fabrics under large deformation (up to ±90o bent angle). As a test case, a typical fiberglass fabric that is thick and has high areal density, as well as a carbon fiber fabric with lesser thickness and lower areal density are considered and compared. In addition, the response of the fabrics was compared to that of individual yarns, suggesting that the interlaced architecture and the dissipative behavior of yarns affect the effective bending rigidity, along with the ensuing hysteresis effects during loading/unloading. Furthermore, when the unconsolidated fabrics were oriented off-axis relative to the bending axis, the bending rigidity interacted with the in-plane trellising (reach to maximum of 3.3o shear at full bent angle), suggesting that the classical laminate theory would not apply to capture shear-bending coupling in dry fabrics.

Numerical and Experimental Investigation on Bending Behavior for High-Performance Fiber Yarns Considering Probability Distribution of Fiber Strength

The performance of fiber-reinforced composite materials is significantly influenced by the mechanical properties of the yarns. Predictive simulations of the mechanical response of yarns are, thus, necessary for fiber-reinforced composite materials. This paper developed a novel experiment equipment and approach to characterize the bending behavior of yarns, which was also analyzed by characterization parameters, bending load, bending stiffness, and realistic contact area. Inspired by the digital element approach, an improved modeling methodology with the probability distribution was employed to establish the geometry model of yarns and simulated bending behavior of yarns by defining the crimp strain of fibers in the yarn and the effective elastic modulus of yarns as random variables. The accuracy of the developed model was confirmed by the experimental approach. More bending behavior of yarns, including the twisted and plied yarns, was predicted by numerical simulation. Additionally, models revealed that twist level and number of plies affect yarn bending properties, which need to be adopted as sufficient conditions for the mechanical analysis of fiber-reinforced composite materials. This efficient experiment and modeling method is meaningful to be developed in further virtual weaving research.

Dynamic mechanical properties and ageing studies of coir-sisal yarn reinforced polypropylene commingled composites

This work investigates the dynamic mechanical properties (DMA) and ageing behavior of coir-sisal yarn reinforced polypropylene commingled composites. Moreover, the fibres were subjected to various chemical treatments and their effects on DMA and ageing studies were investigated. DMA reveals that the chemical treatment, especially MAPP treatment, enhances the storage and loss modulus values on the other hand it diminishes the mechanical damping coefficient (tan δ) of the composite. Diffusion studies indicates that treated composites shows a much lower apparent percentage weight gain compared to other treated ones. Solar ageing studies shows that accelerated solar ageing deteriorated tensile strength and modulus of PP/coir-sisal yarn composite.

Developing a rheological model for predicting stress relaxation behavior of cotton-covered elastane core-spun yarns

Developing a rheological model for predicting stress relaxation behavior of cotton-covered elastane core-spun yarns

Influence of displacement rate in the tensile testing of dry yarns for composite materials used in masonry strengthening

One of the most recent strengthening techniques of masonry structures involves fibre-reinforced polymer (FRP) grids as internal reinforcement of mortar plasters to produce what is normally referred to as Composite Reinforced Mortar (CRM) systems. The behaviour of such systems relies on the performance of the FRP grids which in turn depends on the properties of their constituents (fibres and resin).By comparing results of tensile tests at different displacement rates on glass fibre yarns, the effects of the strain history on the strengths exhibited by such products is here investigated. Further tensile tests were then performed on glass FRP grids made of the same previously analysed yarns in their warp direction and the influence of the displacement rates again studied.The analysis of the results of the performed experimental activity allows studying the influence of strain rates on the mechanical properties and failure behaviour of both yarns and their relative composites.