Single Yarn Research Articles

Experimental Investigation of Transverse Loading Behavior of Ultra-High Molecular Weight Polyethylene Yarns

Ultra-high molecular weight polyethylene (UHMWPE) Dyneema® SK-76 fibers are widely used in personnel protection systems. Transverse ballistic impact onto these fibers results in complex multiaxial deformation modes such as axial tension, axial compression, transverse compression, and transverse shear. Previous experimental studies on single fibers have shown a degradation of tensile failure strain due to the presence of such multi-axial deformation modes. In this work, we study the presence and effects of such multi-axial stress-states on Dyneema® SK-76 yarns via transverse loading experiments. Quasi-static transverse loading experiments are conducted on Dyneema® SK-76 single yarn at different starting angles (5°, 10°, 15°, and 25°) and via four different indenter geometries: round (radius of curvature (ROC) = 3.8 mm), 200-micron, 20-micron, and razor blade (ROC ~2 micron). Additionally, transverse loading experiments were also conducted for a 0.30 cal. fragment simulating projectile (FSP) and compared to other indenters. Experimental results show that for the round, 200-micron indenter, and FSP geometry the yarn fails in tension with no degradation in axial failure strain compared to the uniaxial tensile failure strain of SK-76 yarn (2.58%). Whereas for the 20-micron indenter and razor blade, fibers fail progressively in transverse shear followed by progressive strength degradation of the yarn. Strength degradation of yarn occurs at relatively low strains of 0.6–0.7% with eventual failure of the yarn at approximately ~1.8% and ~1.5% strain for the 20-micron indenter and razor blade, respectively. Breaking angles (range of 10°–30°) are observed to have little effect on the failure strain for all indenter geometries.

Nonlinear isogeometric multiscale simulation for design and fabrication of functionally graded knitted textiles

We present a nonlinear multiscale modeling and simulation framework for the mechanical design of machine-knitted textiles with functionally graded microstructures. The framework operates on the mesoscale (stitch level), where yarns intermesh into stitch patterns, and the macroscale (fabric level), where these repetitive stitch patterns are composed into a fabric. On the mesoscale, representative unit cells consisting of single interlocked yarn loops, modeled as geometrically exact, nonlinear elastic 3D beams, are homogenized to compute their effective mechanical properties. From this data, a B-Spline response surface model is generated to represent the nonlinear orthotropic constitutive behavior on the macroscale, where the fabric is modeled by a nonlinear Kirchhoff–Love shell formulation and discretized using isogeometric finite elements. These functionally graded textiles with locally varying properties can be designed and analyzed by parameterizing the stitch value, i.e., the loop length of a single jersey stitch, and the knitting direction as mesoscopic design variables of the macroscopic response surface constitutive model. To validate the multiscale simulation and design approach, numerical results are compared against physical experiments of different tensile loading cases for various grading scenarios. Furthermore, the versatility of the method for the design of functionally graded textiles is demonstrated.

3D angle-interlock woven structural wearable triboelectric nanogenerator fabricated with silicone rubber coated graphene oxide/cotton composite yarn

The fabric-based triboelectric nanogenerator (TENG) with flexibility, diverse structure and energy harvesting aroused widespread concern in recent years for various portable electronics. Herein, a 3D angle-interlock woven (3DAW) structural wearable TENG with high output performance was fabricated with silicone rubber coated graphene oxide/cotton composite yarn. Composite yarn acts the role of energy conversion and it was fabricated to specific 3D woven structure to further improve its electrical properties. The optimal single yarn with a diameter of 2 mm demonstrates open-circuit voltage of 30.8 V and short-circuit current of 1.1μA using constant loading force tapping (~10 N). The obtained 3DAW-TENG reveals the output power of 225 mW/m2 with the area of 5 cm×7 cm, which is more outstanding compared with those of 2D plain structure and 3D double-layer plain structure. The 3DAW-TENG also successfully shows the application in charging small electronics and triggering voltage sensors. It's suggested that the 3DAW-TENG can be a potential candidate for the filed of wearables and self-powered sensors.

Enhancement of the ballistic performance of aramid fabric with polyurethane and shear thickening fluid

Conventionally, the shear thickening fluid (STF) is used to improve the ballistic performance of aramid fabric because its shear thickening property increases the friction of inter-yarns. However, intuitively, enhancing the inter-yarn adhesion is an easier method. In this study, the adhesive polyurethane (PU) was utilized. The aramid fabrics impregnated with STF, the composite of STF and PU (STF-PU), and PU were compared in terms of the resistance to single yarn pull-out, the flexibility of fabric and the high-velocity impact test, respectively. Due to the robust adhesion of PU, comparing with STF/aramid fabric, a small amount of PU within STF-PU could strengthen the resistance of inter-yarn relative motion significantly and decrease mass loading intensively. Meantime, the flexibility had a little compromise due to unique heterogeneous structure in striking contrast with PU/aramid whose flexibility was impaired extremely. When it came to the high-velocity impact test, STF-PU/aramid showed outright advantages over STF/aramid and PU/aramid composite. It was also illuminated that excessively strong resistance to the yarn mobility was adverse for the high-velocity impact. Confidently, this work provides a new avenue in the development of flexible armor.

Pullout behaviors of single yarn and textile in cement matrix at elevated temperatures with varying loading speeds

Textile reinforced concretes (TRCs) have many extraordinary features that make them a future-ready material exposed to complex environmental situations. However, current knowledge related to TRCs under mechanical loading and environmental conditions is not fully explored as compared to conventional fiber reinforced concretes. The present work investigates the quasi-static pullout performance of single-yarn and textile type (AR-glass and basalt fiber) reinforced cement mortars under different temperatures (25 °C, 100 °C, 300 °C and 600 °C). The pullout tests were carried out at loading rates of 0.25, 2.5 and 25 mm/min on an MTS load frame setup. The reinforcement embedded length in the cement matrix was 30 mm. The pullout testing results were evaluated in terms of initial debonding force and maximum pullout (or peak) load, displacement at initial debonding force, and energy absorption. The experimental results indicated that the textile type reinforcement was better than the yarn type reinforcement. The mechanical properties of TRCs were sensitive to loading rate and temperatures. In addition, the scanning electronic microscopy (SEM) images of the fractured samples tested at different loading rates and temperatures highlighted that quasi-static loading rate variations did not affect the fracture pattern. However, the temperature variation highly affected the epoxy resins used for filament bonding or coating in the reinforcements which may critically affect their interfacial performances.

Highly Accurate Wearable Piezoresistive Sensors without Tension Disturbance Based on Weaved Conductive Yarn

Wearable piezoresistive sensors have attracted wide attention for application in human activities monitoring, smart robots, medical detection, etc. However, most of the sensing signals collected from the piezoresistive sensor are triggered by coupling forces, such as the combination of tension and pressure. Thus, the piezoresistive sensor would be incapable of accurately monitoring and evaluating specific human motion due to the mutual interference from tension and pressure, as the tension is difficult to be decoupled or eliminated from the coupling forces. Herein a prestretchable conductive yarn (PCY) sensor with pressure sensitivity but tension insensitivity was introduced to remove the disturbance from tension. The PCY-based piezoresistive sensor is tension insensitive (gauge factor of 0.11) but pressure sensitive (sensitivity of 187.33 MPa-1). The fabric-based pressure sensor assembled with cross-arranged PCY weft and warp revealed magnified pressure sensitivity compared with the single PCY yarn sensor, as well as tension insensitivity to strain and tensile angle. Moreover, it possessed benign cyclicity during 5000 cycles of pressing/releasing. Therefore, the fabric piezoresistive sensor based on weaved conductive yarns is suitable for highly accurate and large area pressure detection, such as monitoring massage intensity of acupuncture points.

Development of helical auxetic yarn with negative Poisson’s ratio by combinations of different materials and wrapping angle

Auxetic materials have negative Poisson ratio which has a multiple ranges of functional applications. The helical auxetic yarn was successfully developed through direct twist system by using core and wrap yarn or filament, which shows Auxeticity when the HAY is stretched in longitudinal direction in response it expand in transverse direction, Helical Auxetic Yarns were developed using various parameters of the core and warp filament, these parameters are wrapping angle (Twist per meter), diameter ratio, and modulus ratio. The strength of Helical yarn was characterized using single yarn strength and Image J software was used for the calculation of poisson’s ratio. According to test results, it is concluded that the core filament of helical auxetic yarn increased its thickness in transverse direction under stress, and a considerable negative poisson’s ratio was calculated. The values of negative poisson’s ratio described that the auxeticity had a direct relation with core filament thickness or diameter and inversely proportional to the linear density of wrap filament, in case of the wrap angle the auxeticity of HAY yarn had an inverse effect with wrap angle. Kevlar/polypropylene combination sample showed maximum auxeticity at a 15-degree angle while Kevlar/nylon combination sample showed minimum auxeticity at a 25-degree wrap angle.

The importance of a variable fibre packing density in modelling the tensile behaviour of single filament yarns

A model able to reproduce the tensile response of single continuous-filament yarns based on parameters derived from geometrical descriptors is presented in this paper. Samples of yarns made of polyester and aramid fibres were scanned at rest using X-ray microtomography, allowing a detailed identification of their fibre orientation distributions for different twists. The variation of the fibre packing density along with yarn extension was characterized by means of additional scans carried out during tensile tests. An analytical model of the tensile response of these yarns, based on the orientation distribution function and the evolution of the packing density identified from microtomography is proposed and validated against experimental results, with good agreements.

Comparison between Conventional Ring and Compact Spinning of some Egyptian Cotton Varieties

The current experiments was conducted at Plant Production Department, Faculty of Agriculture (Saba-Basha) Alexandria University, during 2019 season to evaluate the fiber and yarn properties of combed yarns by compact and conventional ring spun yarns for three Egyptian cotton varieties (Giza 94, Giza 92 and Giza 86) which belong to long staple category under three yarn count (Ne 80’s, Ne 100’s and Ne 120’s). The fiber properties were measured as well as yarn properties by two spinning system were made at Cotton Research Institute under comparable technological condition on RstI Marzoli ring and compact spinning fitted with Olfil system on one frame. The results showed that the compact spinning surpassed than conventional ring spinning in yarn traits i.e. lea count strength product (LCSP), single yarn strength (cN/tex), elongation (%), CV%, thin and thick places, neps, total imperfections and yarn hairiness. as that the compact spinning recorded the higher desirable values for lea count strength product (LCSP) (2900), single yarn strength (cN/tex) (25.39) and elongation (%) (5.03). as recorded the lower desirable values for CV%, thin (16) and thick places (36), neps (68), total imperfections (120) and yarn hairiness (1.60). As well as cotton variety Giza 92 recorded the desirable values for lea count strength product (LCSP) (3030), single yarn strength (cN/tex) (25.24) and CV% (12.08). On the other side, Giza 86 recorded the better values for thin (11) and thick places (21), neps (67), total imperfections (99) and yarn hairiness (1.80). Yarn count Ne 80’s gave the desirable values for above studied traits. The first order and second order interaction were significant differences for all studied traits. From the previous results it could be say that cotton variety Giza 92 under both compact spinning and Ne 80’s recorded the best values for the studied characters. In general, the properties of combed yarns produced with compact spinning system are better than the those with conventional ring spinning system, compact yarns were having better tensile properties, elongation ratio and lower hairiness than conventional ring yarns, that could be due to the elimination of spinning triangle in spinning system, and the decrease from the flight of fibers of structure yarn increase and this leads to higher yarn tenacity and elongation ratio. Also, Compact spun combed yarn was to found to have higher evenness and lower number of total imperfection values (thin places, thick places and neps). If the evenness property of compact yarn can be improved, it will have a potential for improving quality and profitability of cotton yarn manufacturing.

Experimental and analytical analyses of the knitted fabric off-axes tensile test

Determination of mechanical properties and predicting the behavior of knitted fabrics during the manufacturing process and finally in the use is an important part of textile science. In this study the influence of knitted fabric anisotropy on the values of maximum force, corresponding extension and total work when axial tensile forces act on specimens cut at different angles with respect to the course direction of the knitted fabric were analyzed. A plain double weft knit fabric made of single cotton yarns was studied. For different angles of cutting samples, the curves of the relation between the values of the tensile forces and the extension at break were experimentally obtained. The mathematical models obtained were compared with the experimental results, and the corresponding correlation coefficients were calculated.

Toward Accurate Sensing with Knitted Fabric: Applications and Technical Considerations

Fabric sensors have been introduced to enable flexible touch-based interaction. We advance the technical capabilities of a scalable and low-profile knitted capacitive touch sensing system by introducing methods to improve its touch localization accuracy. The sensor hardware design tends toward minimalism by using a single conductive yarn and two external connections located at each endpoint. Fewer connectors simplify the textile system integration, but this comes at the expense of reduced signal information output from the system. The electrical continuity of the sensing element, essential to the process of knitting, also increases the uncertainty of localizing touch. We propose using Bode analysis to measure changes in signal due to capacitive touch, as well as design a new algorithm, MSD, which retains the most significant aspects of the signal in terms of touch location identification. We do not classify location of touch, but focus on an invariant signal representation. To evaluate our methods, we introduce ELD, a distance metric to compute the similarity of pairs of key-presses, generalizable to computing distances of tensors of varying lengths. Our experiments show that the proposed sensing method results in high-fidelity signals. Furthermore, the sparse representation of key-presses produced by MSD significantly increases separability between different touch locations. Possible applications based on these sensors are also illustrated through prototypes and use case descriptions.

Electrical Resistance Sensing of Epoxy Curing Using an Embedded Carbon Nanotube Yarn.

Curing effects were investigated by using the electrical response of a single carbon nanotube yarn (CNTY) embedded in an epoxy resin during the polymerization process. Two epoxy resins of different viscosities and curing temperatures were investigated, varying also the concentration of the curing agent. It is shown that the kinetics of resin curing can be followed by using the electrical response of an individual CNTY embedded in the resin. The electrical resistance of an embedded CNTY increased (~9%) after resin curing for an epoxy resin cured at 130 °C with viscosity of ~59 cP at the pouring/curing temperature (“Epon 862”), while it decreased (~ −9%) for a different epoxy cured at 60 °C, whose viscosity is about double at the corresponding curing temperature. Lowering the curing temperature from 60 °C to room temperature caused slower and smoother changes of electrical resistance over time and smaller (positive) residual resistance. Increasing the concentration of the curing agent caused a faster curing kinetics and, consequently, more abrupt changes of electrical resistance over time, with negative residual electrical resistance. Therefore, the resin viscosity and curing kinetics play a paramount role in the CNTY wicking, wetting and resin infiltration processes, which ultimately govern the electrical response of the CNTY immersed into epoxy.

Effect of finishing chemicals on tearing strength of plain-woven cotton fabric

Purpose This paper aims to assess the relationships amongst the tearing strength of fabrics after each chemical processing stage and after finishing of plain-woven cotton fabric. An effort has been made to study the effect of different finishing chemicals (tear improver) and their different concentrations on the high-density fabric tear strength and its sub-component with respect to the co-efficient of friction value of yarns for all the fabric samples. It also aims to establish a statistical model for prediction of tear strength with identified parameters as yarn–yarn friction co-efficient, yarn pullout force and single yarn strength. Design/methodology/approach In case of woven fabrics, it cannot be assumed that only yarn friction plays the role in deciding fabric-tearing strength. Whether the static or kinetic frictions need to be considered or the linear or capstan frictions have to be analyzed, to incorporate the results of friction analysis in the tearing behavior, need to be assessed. In the present work through a fabrication of yarn–yarn friction measurement, under a synchronized slow speed as that of actual fabric tearing (50 mm/min), has been carried out. After each wet processing stage, surface characteristics of yarns have been changed. Surface of yarns becomes smoother after finishing and rough after dyeing, which affects the co-efficient of friction of yarns, accordingly. Findings After each wet processing stage, the surface characteristics of yarns are changed. Surface structure of yarns becomes smooth after finishing and rough after dyeing, which affects the co-efficient of friction of yarns. For all the fabrics, the weft-way tearing strength is always higher than warp-way tearing strength. It is also observed that yarn pullout force is not the only responsible factor for tearing strength of such fabric. It is because of the combined action of yarn–yarn friction, yarn pullout force and single yarn strength for a given structure. Research limitations/implications A more extensive investigation with respect to concentration as well as further variety of chemicals requires to be identified for the optimum concentration level for each chemical. A mathematical model based on the three parameters as yarn–yarn co-efficient of friction, yarn pullout force and yarn strength for all woven fabric structure to achieve optimum strength level has been established which could be further extended for each fabric structures. Practical implications The problem has been identified from the day-to-day exercise of the commercial textile industry. The whole of the sample preparations have been done in the industry by using commercial machines under standard industrial conditions. The findings have been discussed and suitably introduced in the industry. Originality/value The whole of this paper has been unique in idea origination, sample preparation and execution of tests. The findings are very important for the researchers as well as for textile industry.

Effects of Loading Rate and Temperature on Pullout Response of Basalt Textile–Reinforced Concrete

AbstractThe pullout response of basalt textile embedded in cementitious matrix specimens was investigated under different loading rates and temperatures. Two types of specimens, basalt single yarn ...

Printing electronics directly onto carbon fiber composites: unmanned aerial vehicle (UAV) wings with integrated heater for de-icing

Unmanned Aerial Vehicles (UAVs) are increasingly used to deliver items and gather information in remote areas. As a result, UAVs suffer from ice accumulation on their wings, which drastically affects their flight. However, the UAV industry is still relatively young and, thus, commercial solutions for de-icing on UAVs are limited. The use of carbon fiber composites is becoming increasingly ubiquitous for UAVs as well as many other industries such as military, construction, medical, automobile, sporting goods and aircraft systems. Carbon fiber is commercially available in various forms, including single yarns, braids and weaves, which are similar to traditional textiles. This paper presents a method to create a self-heating composite structure that can be integrated into UAV wings for de-icing by exploiting the thermal and electrical conductivity of carbon fiber. Extrusion printing is used to fabricate electrical contacts directly on the carbon fiber weave. Extrusion printing on textiles faces multiple challenges that are overcome in this paper. A method is presented to extrusion print conductive paste on textiles. Specifically, carbon fiber weaves. This manufacturing method is employed to fabricate carbon fiber-based heating devices, and they are characterized electrically and thermally.

The Role of Textile Products in Fighting the Coronavirus COVID-19

Knowledge about the indigenous traditional woven fabrics of Nigeria reveals the extent the people have advanced in the area of weaving and clothing need. Unfortunately, the indigenous weaving culture faces threat of extinction due to the introduction of machine made fabrics. Here, double twisted and single twisted polyester yarn was used as warp and weft respectively to weave a diaper design for polyester fabric which was used for interior decoration. The diaper weave was produced using a four-shaft hand loom and the steps involved were warping, beaming, heddling or drafting, reeding/denting, tie-up/gaiting, shedding, picking and beating up. The woven diaper polyester was cut and sewn for interior decoration. The diaper twill weave design produced has a front and a back side and was found to be durable, attractive and reliable. Soiling and stains were less noticeable on the uneven surface of the diaper designed twill weave than on a smooth surface, such as plain weaves and as a result makes them suitable for sturdy work clothing, draperies/curtains, durable upholsteries and furnishings. The fewer interlacing in this design as compared to other weaves allow the yarns to move more freely, and therefore they are softer and more pliable, and drape better than most plain-weave textiles. This design also recovers from creasing better than plain weaves do.

A method for evaluating the bond behavior and anchorage length of embedded carbon yarn in the cementitious matrix

This paper presents a method for evaluating the bond behavior of a single carbon yarn embedded in the cementitious matrix. Pullout tests were carried out in which the carbon yarn was progressively pulled out of the matrix. All the pullout specimens with a nominal bond length of 15 mm showed a similar pullout curve that was characterized by an initial ascending part and a descending part followed by a slowly decreasing part, along with the same failure mode due to the slippage of the carbon yarn through the matrix. The proposed method was used to evaluate bond parameters in the trilinear bond-slip relationship, which has been demonstrated to be applicable for describing the carbon yarn-cementitious matrix interface. The reliability of the evaluation method has been substantiated by achieving good agreement between the analytical and experimental results obtained from a wide range of pullout tests. An analytical approach was proposed to directly calculate the anchorage length of all the pullout specimens based on the evaluated trilinear bond-slip relationships, and the calculations were verified against the numerical results. In addition, a parametric study was carried out to investigate the effects of the bond parameters on the carbon yarn’s anchorage length and showed that the anchorage length was influenced most by the local bond strength.

Surface Modification of Flax Yarns by Enzymatic Treatment and Their Interfacial Adhesion with Thermoset Matrices

The aim of this study was to assess the effects of commercially available and relatively inexpensive enzyme preparations based on endo 1,4-β-xylanase, pectinase and xyloglucanase on the thermal (TGA), morphological (SEM), chemical (FT-IR) and mechanical (single yarn tensile tests) properties of flax yarns. The preparation based on pectinase and xyloglucanase provided the best results, resulting in the effective removal of hydrophilic components such as hemicellulose and pectin, the individualization of yarns and increased thermal stability at the expense of a reduction in mechanical properties, depending on the treatment parameters. Single yarn fragmentation tests pointed out an improved interfacial adhesion after enzymatic treatment, with reduced debonding length values of 18% for an epoxy matrix and up to 36% for a vinylester resin compared to untreated flax yarns.

New wicking measurement system to mimic human sweating phenomena with continuous microfluidic flow

Typical liquid moisture management property tests of textiles may not represent human sweating from sweat pores because those methods are conducted with infinite reservoirs or limited, but large amounts of liquid. For this reason, we developed a new method, ‘single-pore wicking evolution apparatus for textiles (SWEAT),’ to investigate how liquid is transported in fabrics based on within-a-yarn and yarn-to-yarn transfer wicking. This measurement system was implemented by supplying continuous liquid flow to a single yarn at a single point within the fabric substrate at a similar flow rate to a single sweat gland (approximately 50 nl/min/gland). In order to mimic the sweating phenomenon, this SWEAT test avoids the flooding liquid stage by controlling flow rate and choosing a diameter of liquid source similar to the pore size of a sweat gland. From microscopic video analysis, we found that the liquid moves along the yarns instead of making a circular wetting area, as observed in standardized tests. With the SWEAT test, we successfully measured the directional wicking rate along an individual yarn, which has not previously been reported. Furthermore, we examined not only liquid movement within-a-yarn but also yarn-to-yarn transfer of liquid because the continuously supplied liquid spills over to the adjacent yarns through the contact points.

Color measurement of single yarn based on hyperspectral imaging system

AbstractThis article proposed a novel approach to color measurement of a single yarn using hyperspectral imaging system (HIS). Due to the size of a single yarn, it is impossible for spectrophotometers to measure its color directly. The HIS can acquire the spectral reflectance of continuous bands within a region of interest on a yarn sample, which can achieve color measurement of a single yarn compared with traditional spectrophotometers. A single yarn is segmented from the background by a spectral matching method through adaptively setting threshold of Fréchet distance values. The spectral reflectance of single yarn is specified by a method that lightness of pixels used as weight. The experiment based on Pantone Cotton Chip Set shows that the interinstrument agreement between the HIS and a standard spectrophotometer Datacolor SF650 has a significant improvement after using the R‐Model, and the average percentage improvement of the color difference is up to 54.99%. The yarn segmentation comparative experimental results show that the proposed method to segment single yarn from background is better in retaining the edge information of the yarn than the modified K‐means clustering method, and the color of the yarn segmented by the proposed method is more similar to the actual color of single yarn.