Number Of Yarns Research Articles

An examination of initial structural degradation in tubular braided composites through region-by-region strain analysis

The objective of this study was to characterize the early structural degradation behavior of tubular braided composites (TBCs) under quasi-static tension through direct quantification of the surface strains developed in their yarn-reinforced and unreinforced (resin-rich) material regions. Kevlar-epoxy TBCs with varying braid angles and numbers of yarns were analyzed through quasi-static testing and stereo digital image correlation (DIC) analysis to understand how the yarn-reinforced and resin-rich regions deformed under tensile loads up to the initiation of structural degradation within the braid structure. Structural weakening was confirmed to initiate in the unreinforced, resin-rich regions of the TBC specimens by way of a normal tensile failure mode, as the strains developed within these regions were the first to deviate from a linear-elastic growth trend and also exceed the expected strain to failure of their constituent material. Through two-way full-factorial ANOVA analysis with a 95% confidence interval, the stress required to initiate degradation within these regions was found to depend significantly upon both the quantity and angular orientation of the preform yarns, the former to a markedly lower extent. The maximum strain accumulated in the resin-rich regions upon their degradation was found to not statistically depend on either of these parameters, affirming that it is purely defined by the strength properties of the constituent neat resin material. To provide conservative and repeatable estimates of the stress to failure in TBC structures, it is recommended that this quantity be estimated from both the global stress-strain data of the entire specimen and the local stress-strain data measured exclusively within its resin-rich regions, with the lower of the two taken. Through these means, the relationship between a TBC’s preform geometry and its stress to failure may be optimally modeled using a polynomial regression trend.

EXPERIMENTAL INVESTIGATION OF THE PERFORMANCE OF A FEEDBACK TENSION CONTROL SYSTEM DESIGNED FOR WARPING MACHINES

This paper presents a research work which investigates experimentally the performance of a tension control system realized by a controlled disc brake. An experimental set-up was established by using a creel with step motor controlled disc brake, laser distance sensor, yarn tension sensor and a 2-unit winding machine. A software was developed in C programming language to read yarn tension and bobbin diameter data and then to control the disc brake by step motor drive. Experimental investigation was carried out with three different cotton yarn counts and unwinding speeds. It was shown that yarn tension changed from full to empty bobbin at a significant amount depending mainly on yarn number and unwinding speed. The feedback tension control system based on adjusting level of braking responded well to short, medium and long term tension variations and enabled unwinding tension control mostly within ±1 cN deviation from the adjusted value.

Improving the stiffness of multilayer 3D woven composites by the integration of shape memory alloys (SMAs) into structures

Shape memory alloys (SMAs) are capable of shape-retaining and stress generation when activated. SMA wires are embedded in laminated composites for improving the properties of the composites. Laminated composites have low through-the-thickness properties and poor delamination resistance. 3D composites are well known for having higher through-the-thickness properties. In 3D woven composites, a set of yarn is in through-the-thickness direction that improves through-the- thickness properties and provides resistance to delamination of layers. As in multilayer 3D woven structures, yarns are distributed from in-plane to through-the-thickness direction, so in-plane properties are reduced with the same number of yarns compared to 2D laminated composites. In this research, SMA wires are embedded into different types of 3D woven structures for utilising stress generation property of SMA wires for improving in-plane properties, specifically stiffness of the composites. Three types of 3D orthogonal interlocking composites: layer-to-layer, through-the-thickness, and modified multilayer interlock structures are fabricated with and without SMA wires. From the tensile test, results show that embedding SMA wires into structures significantly improves the stiffness of the structures due to the stress-induced martensite phase of SMA wire when subjected to load. When these SMA wires are activated, stresses are generated by SMA wires due to phase transformation from martensite to austenite that further gives remarkable higher values of stiffness. This results in a composite structure that has higher in-plane properties due to embedded SMA wire and through-the-thickness properties due to 3D structure of composite reinforcement. The interlocking pattern in the through-the-thickness direction of 3D structures was also found to have an effect on the extent of the improvement in stiffness.

Tensile behavior of fabric-cement-based composites reinforced with non-continuous load bearing yarns

The main aim of this work was two-fold, to study the ability of the fabric within a TRC to carry loads when not all the yarns along the loading direction are continuous and to better understand the role of the transverse yarns when subjected to tensile loading. An excellent correlation was found between the behaviors of the composites and fabrics studied. The load values in stages one and two (while the matrix is still participating in load carrying) were much greater than expected, i.e., not proportionally correlated with the number of continuous yarns. This suggests that during the first two stages of loading, not only the continuous yarns are active and carry the loads, but also the discontinuous (cut) ones participate in load bearing via stress transfer from the transverse yarns and the matrix. Use of an effective ratio between the cross-sections of the yarns and the matrix enables ‘smooth’ tensile behavior, essential in structural elements. A greater matrix cross-section produces a composite with improved tensile stress (at the end of the multiple cracking) which is more ductile and having greater energy absorption but at the expense of a significant drop in load.

Bamboo Charcoal/Quick-Dry/Metallic Elastic Knits: Manufacturing Techniques and Property Evaluations

Protective clothing with electromagnetic shielding effectiveness (EMSE) is a functional textile, which shields electromagnetic waves to protect the human body from the far infrared rays. Traditional EMSE garments primarily use metallic plates for reflecting electromagnetic interference (EMI). However, they also have disadvantages of a heavy weight, easy corrosion, and high production cost. In this study, three different functional yarns are combined, during which the twist number of metallic wires is changed for a better shielding effect. A crochet machine is used to fabricate functional elastic knits with the metallic composite yarns as the warp- and weft-inlaid yarns. The test results show that double (D) functional elastic knits exhibit EMSE of above 20 dB when the EMI are between 1.0 and 3.0 GHz. In addition, the knit structure can improve breaking tensile strength by 170 % and increases bursting strength by 58 %, but undermines the tear strength by 10 %. Although changing twist number of metallic composite yarns does not affect water absorption rate along the weft direction, it helps increasing elastic recovery rate by 3.1 %, water absorption rate along the warp direction by 106 %, far-infrared emissivity by 2.3 %, water vapor transmission rate by 20 %, and air permeability by 6 %.

Experimental investigation of effect of balloon length on yarn tension during unwinding

PurposeYarns of different types are unwound from bobbins in different processes like warping, weaving, doubling and re-winding. It is required that yarn tension remains constant during unwinding in all these processes. Otherwise, it ends with product quality and process efficiency problems. The purpose of this paper is to investigate experimentally the effect of balloon length on yarn tension change with respect to bobbin diameter during unwinding in an attempt to obtain a minimum yarn tension variation.Design/methodology/approachAn experimental set up was built. Bobbin diameter was measured by a laser sensor and yarn tension was measured by a single yarn tension sensor. Both sensor outputs were interfaced to a PC via a DAQ cad. A software program was developed in C programming language to read and record the tension and bobbin diameter simultaneously. Experimental study was conducted with three different balloon lengths for both continuous filament and spun yarns of four different yarn numbers and five different unwinding speeds.FindingsResults showed that yarn tension change with bobbin diameter was affected in different ways with balloon length depending on yarn number, unwinding speed and yarn type.Originality/valueAvailable literature on the effect of balloon length on yarn tension bobbin diameter relation is limited and measurements were generally conducted for three different bobbin diameters. Yarn tension bobbin diameter relation is obtained in this research for at least eight different diameters and more for three different balloon lengths covering practical application ranges. The results obtained can be used in the design of tension control system for warping and winding machines as well as for setting these machines for optimum efficiency.

A simplified constitutive and finite element model of plain weave fabric reinforcements for the biaxial loading

Soft matrices reinforced by textile preforms are considered as flexible composites that can undergo large elastic deformation. The mechanical behaviors of these composites are highly nonlinear, involving both material and geometric nonlinearities. To conduct a finite element analysis studying woven fabric structures, one of the desired approaches is to develop an equivalent continuum model representing the mechanical behavior of the fabric’s unit cell. During large deformation, significant fabric architecture rearrangement occurs. To include this geometrical nonlinearity into a continuum model, it is always a challenge. In this work, the constitutive model of weave fabrics under biaxial loadings has been derived considering the large nonlinear elastic deformations. This model assumes that the fabric consists of monofilaments, where the yarn is treated as a thin isotropic solid bar which follows the sinusoidal shape. The effects of the yarn’s crimp interchange, and bending are considered in the constitutive equations. One of the special advantages to use this constitutive model is that the geometry can be completely defined by the commonly given information for a fabric (i.e., crimps, number of yarns per unit fabric length). Good agreement has been found between predictions and experiments under various biaxial loadings. The theoretical predictions also agree well with FEA simulations of the mechanical behaviors of the unit cell.

Comparison of fabric properties knitted by pin spacer compact and conventional compact yarns

This study examined the influence of pin spacer apparatus attachment on compact yarn quality parameters and physical properties of knitted fabrics manufactured using those 100% cotton compact yarns. Two groups of compact yarns were spun on regular compact yarn spinning frame with and without addition of pin spacer apparatus which is placed at the end of the drawing unit of regular compact yarn spinning frame. Totally eight yarns were spun at four different yarn number levels (Ne 24/1, Ne 30/1, Ne 36/1 and Ne 40/1) and two different spinning conditions (with and without pin spacer apparatus). Spun yarn types were then knitted on the industrial sized plain knitting machine. Knitted fabrics were used in the greige and dyed form to evaluate their bursting strength (kPa), dimensional change, abrasion related mass loss (%), pilling resistance, air permeability (mm/s) and colour difference. Test results were then statistically evaluated and influence of pin spacer attachment on yarn quality parameters and fabric properties was determined. In the frame of this experimental work, attachment of pin spacer apparatus improved compact yarn characteristics especially at yarn evenness, imperfection and hairiness values. In case of knitted fabric properties, it was found that pin spacer apparatus attached compact yarn utilization significantly improved air permeability properties of knitted fabrics.

Experimental Investigation of the Relationship Between the Yarn Tension and Bobbin Diameter in the Warping Process

Yarns of different types are unwound from bobbins in different processes like warping, weaving, doubling and re-winding. A change in yarn tension from a full to empty bobbin causes serious product quality and machine efficiency problems in processes like weaving and winding. This paper investigates experimentally the relationship between yarn tension and bobbin diameter in the warping process. For this purpose, an experimental set up was built with a laser sensor measuring the bobbin diameter, a tension sensor for measuring yarn tension, a bobbin winding unit, PC, and DAQ card. A software program was developed in the C programming language to read and record the tension and bobbin diameter simultaneously. The unwinding speed and yarn number both had a significant effect on the relationship between the yarn tension and bobbin diameter. The effect of the unwinding speed became more pronounced with yarns getting thicker.

A study on the suitability of which yarn number to use for recycle polyester fiber

Recycling and reuse of materials is not new to the textile and apparel industry. Recycling refers to the breakdown of product into its raw materials in order for the raw material to be reclaimed and used in new products. The aim of the study is that the examining the usage of recycle polyester fiber (rPET) in different yarn count and blend ratio and so to determine which count and blend ratio is more suitable for rPET usage. For this aim, 24 yarns containing recycle polyester fiber, virgin polyester fiber and viscose fiber as raw material were obtained in different yarn counts which are Ne 10, Ne 20, Ne 30 and Ne 40, and in different blend ratios. Yarn diameter, density, shape (roundness), unevenness, imperfection, hairiness, and yarn tensile tests were applied to the obtained yarns. The findings obtained by experimental and statistical study show that rPET fiber has usually negative effects on the yarn properties in especially fine yarns due to physical and chemical deterioration caused by contaminants of during re-processing of recycle polyester fiber. Based on the findings it is revealed that the values of unevenness, imperfection, and density increase whereas the values of diameter, hairiness, and tensile decrease from coarse yarns to fine yarns. As a conclusion it is possible to say that rPET fiber is suitable for thick yarns which are especially Ne 10 and Ne 20 as pure and in all blend ratios, and rPET fiber is suitable if it is used in lower ratios than 65% for Ne 30 yarns, whereas it is suitable if it is used in lower ratios than 35% for Ne 40 yarns.

Thermal resistance of viscose socks

Men's viscose socks size 42 were designed and manufactured on an automatic sock knitting machine with a cylinder diameter of 95 mm (3 ¾ inches) which knits with 108 needles. Socks were manufactured of 20 tex viscose yarn, 156 and 220 dtex filament PA 6.6 yarn and 25 tex cotton yarn in multiple plated single jersey structure. The sock cuff contained an interlaced elastane yarn. Sock weight and sock thickness were determined, the height of the sock leg, the length of the sock foot and half of the leg circumference and half of the foot circumference were measured. Thermo physiological sock properties were determined by measuring thermal resistance on a thermal foot manikin. The sock structure under the same knitting conditions depends on the number of yarns, yarn type, the type of raw material (viscose, cotton, PA) and yarn count. Finer yarns provide higher stretchability in the part of the sock leg in the wale direction. The viscose socks with an added coarser cotton yarn and a coarser PA 6.6 yarn had the highest thermal resistance, while the viscose yarns with only an added PA 6.6 yarn had the lowest thermal resistance.

Yarn Tension Change with Respect to Bobbin Diameter in Yarns Including Lycra Component

The yarn is transferred from one bobbin to another in many textile processes. In these kinds of processes like warping, weaving, doubling and twisting, yarn tension change with respect to bobbin diameter has a significant role because it affects product quality and machine efficiency. Yarns including lycra component are widely used in fabric production which are sensible to tension changes. This paper presents an experimental research aiming at determining the relationship between yarn tension and bobbin diameter during unwinding for continuous filament polyester-lycra yarns. For this aim, an experimental research set-up was established representing unwinding from bobbins in many textile processes. Experimental research set-up consists of a winding machine, a creel with single bobbin holder, a laser sensor measuring bobbin diameter, a tension sensor for measuring yarn tension, a PC and a DAQ card. A software program was developed in C programming language to read and record the tension and bobbin diameter simultaneously as a data file. Based on the recorded data, average values of warp tension and bobbin diameter were calculated and relationship between yarn tension and bobbin diameter was obtained in this way. Experimental work was carried out for 3 different yarn numbers (75, 150 and 300 denier) at 5 different unwinding speeds (100, 200, 400, 600 and 800 m/min). The results were compared with the yarns without lycra component and found to be in agreement with theoretical findings in the literature expressing that high elasticity of yarns limited the tension change from full to empty bobbin.

Strength loss of glass yarn during weft knitting

Weft-knitted fabrics from glass yarns present many advantages in technical textile applications. However, due to their stiff and brittle nature; glass fibers can easily be broken during weft knitting process that creates broken fiber ends on the fabric surface, and deteriorates the performance of resultant fabric. In this study, weft-knitted glass fabrics with four different knit architectures, and two different cam settings were produced. Number of yarn ply was also varied as 2- and 3-ply. The effect of all these input parameters on strength loss of glass yarn was examined via measuring virgin and unravelled yarn strengths in loop form. Results showed that knit pattern, cam setting and number of yarn ply did not affect the unravelled loop yarn strength at statistically significant level. On the other hand; unravelled yarns exhibited better loop strength than virgin yarns that was attributed to uniform distribution of fibers over cross sectional area of yarn as a result of knitting process.

Auxetic Yarn Made with Circular Braiding Technology

This paper reports a new type of auxetic yarn made with circular braiding technology to overcome the yarn slippage problem in the conventional helical auxetic yarn structure. Various auxetic yarn structures are firstly produced on a vertical circular braiding machine with 16 yarn carries by changing the number and arrangement of stiff yarn as well as diameter of elastic yarn and core yarn, and then tested under single and repeating tensile conditions. The results show that not only yarn slippage problem could be overcome in the newly developed auxetic yarn structure, but also an early activation and a higher magnitude of negative Poisson's ratio could be achieved. The results also show that all structural parameters including stiff yarn number and arrangement, core yarn, and elastic yarn diameter have an influence on the auxetic effect of the novel yarn structure. Since the new auxetic yarn is produced by using standard braiding manufacturing technique and conventional non‐auxetic yarns, there are few technological barriers for its large‐scale manufacture for practical application.

Mechanical and thermal behaviors of ultra-high molecular weight polyethylene triaxial braids: the influence of structural parameters

Recently, triaxial braids made from ultra-high molecular weight polyethylene (UHMWPE) have been recognized as one of the most popular composite reinforcements in the aerospace and defense fields. To further explore the mechanical characteristics of this material, a detailed experimental study on tensile behavior is reported in this paper. The triaxial braids show a “double-peak” phenomenon in tensile strength and deformation, caused by axial yarns and the in-plane shearing of bias yarns. The evolution of the braiding angle, measured during these tensile tests, is discussed according to the braiding parameters (initial braiding angle, number of axial yarns). Using the high conductivity properties of the UHMWPE material, the temperature caused by inter-yarn friction during tensile tests is also studied. This temperature is related to the evolution of the braiding angle. The temperature increases with the increasing number of axial yarns and decreases with increasing braiding angle. This study provides an experimental database on the influence of braiding parameters on the tensile behavior of triaxial braids.

Stab and puncture resistance of silica-coated Kevlar–wool and Kevlar–wool–nylon fabrics in quasistatic conditions

Stab and puncture resistant body armor is widely used by the law enforcement personnel, security and military in many countries. The primary requirement for the armor is to provide protection against various weapons used in an attack. Comfort properties are given increased importance in many countries and considered the second most important requirement. In this research Kevlar was blended with wool and wool–nylon. The resultant fabrics were coated with silica and their stab and puncture resistance in quasistatic conditions was examined using the universal tensile tester. It was hypothesized that the application of coating will generate higher friction to restrict the lateral movement of yarns, and thus present a higher number of yarns for direct resistance to impact during the attack and dissipating the impact energy, whereas the use of wool and nylon will provide the required ergonomics of wearability and stretch. It was observed that the application of the silica coating helped in improving the resistance to the stab and punctures using weapons such as knife (P1, as specified in NIJ 0115.00), ball and pointed impactors. In the quasistatic tests, the highest value of the maximum resistant force was recorded when the ball was used and the lowest was observed for the knife. Furthermore, the application of coating helped in absorbing impact energy. However, the fabric stiffness increased due to the coating, which will negatively impact the ergonomics and wearability.

Manufacturing techniques and property evaluations of conductive elastic knits

Textiles can have valuable functions in terms of measurement, detection and communication when they are incorporated into functional electronic devices. However, the additional electric circuits limit the flexibility and extensibility, making the wearers uncomfortable and the manufacturing difficult. Therefore, in this study, conductive elastic knits are made of metallic yarns and expected to be used as wearable electronic textiles. In order to retain the flexibility of knits, a crochet machine with jacquard equipment is used to create knit patterns as electric circuits. Regardless of whether it is single-twisted yarn, double-twisted yarn, single-wrapped yarn, or double-wrapped yarn, the metallic wires can be completely covered in polyester filaments. Variations in twist numbers of conductive yarns or knit patterns are beneficial to the tensile strength with a maximum increment of 14%, and changing twist numbers of conductive yarns or knit patterns have a positive influence on the air permeability with a maximum increment of 24%. According to the results of the electric circuit stability test, using double-covered yarns ensures the knits a stabilized electric circuit regardless of the knit pattern.

Air permeability and bursting strength of weft-knitted fabrics from glass yarn. Part I: cam setting and number of yarn ply effect

This study revealed the effect of cam setting and number of yarn ply on air permeability and bursting strength of weft-knitted fabrics from glass yarn. Change in cam setting from loose to tight level increased fiber content, and stitch-density; while it decreased loop length. Fabrics with 3-ply yarn exhibited higher fiber content; lower stitch-density; and longer loop length than fabrics with 2-ply yarn. Cam setting showed more pronounced effect on physical properties of fabric than number of yarn ply. Fabrics knitted via tight cam setting level exhibited less air permeability, and higher bursting strength than fabrics knitted via loose cam setting. Fabrics from 3-ply yarn showed less air permeability and higher bursting strength than fabrics from 2-ply yarn. Loop length, wale density, and fiber content were determined as the most effective physical properties on permeability and bursting strength. A negative correlation was detected between air permeability and bursting strength.

Identification of the elastic constant values for numerical simulation of high velocity impact on dyneema® woven fabrics using orthogonal experiments

Dyneema® fibres and fabrics are widely used for ballistic protection due to its lightweight and super mechanical properties against high strain rate impact, and finite element (FE) simulation and analysis are used to study the response to the impact in parallel to the experimental-based research methods. However, elastic constants of the yarn except the Young’s modulus were difficult to obtain and were basically assigned based on assumptions and approximations in the FE modelling, which caused some inaccuracies. This paper reports a study on the influence of each elastic constant of Dyneema® yarn model in modelling a single layer Dyneema® woven fabric against ballistic impact using the orthogonal experiment method. Orthogonal table L25 (56) was employed to analyse six factors (i.e. E11, E33, ν, G13, G23, and their interactions) with each having five levels. The ballistic modelling results were validated against the experimental results, viz. energy absorption, failure time of the first yarn broken and number of failed yarns. According to the orthogonal analysis, G13 was shown as the most significant in influencing the simulated results, with a confidence level of more than 95%, and ν was the least significant. Through the orthogonal study, the combination of levels of the elastic constants that led to a significant agreement between the FE and practical results was identified.

Carbon/graphene composite nanofiber yarns for highly sensitive strain sensors

In this work, flexible strain sensors were fabricated using carbon/graphene composites nanofiber yarn (CNY)/thermoplastic polyurethane (TPU). These flexible strain sensors exhibit excellent sensitivity and stability because of the continuity, brittleness, and high conductivity of the CNYs. When the number of yarns and substrate thickness were 4 and 129 μm respectively, the average gauge factor value was >1700 under an applied strain of 2%. Meanwhile, the strain sensor showed a high level of stability during 300 stretching–relaxation cycles. Moreover, the strain sensor could accurately detect subtle deformations. The working mechanism of the strain sensor was also analyzed during stretching using a resistance network model; there was very good agreement between the experimental and simulation results. Such flexible strain sensors can be easily incorporated onto the surfaces of textiles, and within electronics, for use in applications such as smart textiles and health monitoring.