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Re-entrant structures are known to perform an auxetic effect. It was aimed in this paper to investigate the Poisson's ratio of the woven pique structures because of the re-entrant lozenge effect of the weave. Sound absorption, air permeability, and synclastic properties of the fabrics concerning the auxetic properties of pique structures were also examined. In evaluating the synclastic behavior, the drape ability and bending rigidity of the fabrics were assessed. Pique weave fabrics were subjected to tensile tests, and the changes in fabric unit cell at different tensile strains were observed in the warp and weft directions. Experimental results showed that the auxetic effect was produced in the warp direction. A high negative Poisson's ratio (NPR) was obtained in cotton pique fabrics under low elongation values. It was observed that the yarn floating lengths and the yarns intersecting region widths forming the re-entrant lozenge pattern had effects on fabrics' NPR.

Bu çalışmada çekme kuvveti sebebiyle dokuma kumaşlarda gerçekleşen boyut değişikliklerinin ölçülmesi amacıyla dairesel Hough dönüşümü tabanlı bir görüntü işleme yöntemi geliştirilmiştir. Bunun için farklı yapısal parametrelere sahip dokuma kumaşlar üzerine iğneler yerleştirilerek, kumaşlar çözgü doğrultusunda çekme işlemine tabi tutulmuştur. Bu esnada 30 saniye süresince 5’er saniye aralıklarla alınan kumaş görüntüleri bilgisayara kaydedilmiştir. Kumaş görüntüleri üzerindeki iğneler arası mesafeler hem el ile çizim yöntemiyle hem de dairesel Hough dönüşümü tekniği kullanılarak geliştirilen görüntü işleme yöntemiyle ölçülmüştür. İki ölçüm yöntemi ile elde edilen sonuçlar incelendiğinde sonuçlar arasındaki sapmanın %1’den düşük olduğu görülmüştür. Tüm ölçümler hesaba katılarak hesaplanan ortalama yüzde sapma değeri ise yalnızca %0,26’dır. İki ölçüm yöntemi ile elde edilen sonuçlar arasındaki korelasyon katsayısı değeri 0,99 hesaplanmıştır. Geliştirilen görüntü işleme temelli ölçüm yöntemi, dokuma kumaşların gerilme altındaki boyut değişikliklerini kolay, hızlı ve doğru olarak ölçebilmektedir. In this study, a circular Hough transform based image processing method has been developed to measure the dimensional changes of woven fabrics due to tensile force. For this purpose, needles were placed on woven fabrics with different structural parameters and the fabrics were pulled in warp direction. In the meantime, fabric images taken at intervals of 5 seconds for 30 seconds were recorded on the computer. The distances between the needles on the fabric images were measured both by hand drawing method and by image processing method developed using the circular Hough transform technique. When the results obtained from the two measurement methods were examined, it was seen that the deviation between the results was less than 1%. The average percentage deviation calculated by considering all measurements was only 0.26%. The correlation coefficient value between the results obtained by the two measurement methods was calculated as 0.99. The developed image processing based measurement method can measure the dimensional changes of woven fabrics under stress easily, quickly and accurately.

This study evaluates the effects of different aqueous borax solutions on the morphology, mechanical, thermal and chemical properties of regenerated cellulose fiber woven fabric reinforced hydrogel ...

Fast and facile one-step preparation of paraffin/polyacrylonitrile hybrid nanofibers via single needle (uniaxial) electrospinning system was studied. As-spun paraffin/polyacrylonitrile nanofibers were used for thermal hysteresis enhancement of paraffin actuators. Solid paraffin with the melting point of 32, 58, 89 and 114°C were employed for the preparation of the paraffin/polyacrylonitrile nanofibers. Differential scanning calorimetry measurements revealed that the melting point of the paraffin in paraffin/polyacrylonitrile hybrid nanofiber was clearly detectable and the melting entalpy coming from the paraffin part gradually increased from 9.6 to 101.5 J/g with the increase in the melting points of the added same amount of paraffins in paraffin/polyacrylonitrile nanofibers. When both calorimetric and weight loss measurements were considered, the paraffin which has the melting point of 32°C was found to be suitable to produce hybrid nanofibers paraffin actuator. Therefore, this hybrid nanofiber was selected for the application in paraffin actuators for e-vehicle battery cooling systems where the battery temperature must be kept between 15 and 35°C. Paraffin compound of the paraffin actuators was prepared with a mixture of pure paraffin and paraffin/polyacrylonitrile nanofiber with the wt.% of 2.5, 5, 7.5 and 10. In the hysteresis measurements, the hysteresis value at 3 mm stroke was successfully enhanced as 1.7, 3.4, 11.9 and 15.3% sequentially for the samples produced with the above ratios. Beyond hysteresis enhancement, the phenomena of thermal percolation threshold effect and thermal conductivity contrast ratio effect in nano scale were emprically exposed on opening and closing behavior of the paraffin actuator.

One-step and rapid preparation of natural fiber woven fabric reinforced hydrogel composites via simultaneous dissolution and crosslinking of polyvinyl alcohol (PVA) yarns in the fabric was reported. In this regards, PVA/Cotton (C), PVA/Flax (F) and PVA/Wool (W) blended woven fabrics were prepared for the manufacturing fabric reinforced hydrogel composites. The hybrid woven fabric reinforced fabrics were treated with different concentrations of borax solutions. Aqueous borax solutions were used to alter the PVA yarns in the fabric into cross-linked structure in order to enhance mechanical performance of the hydrogel composite. Morphological investigation of hydrogel composites in a dried form was carried out by scanning electron microscopy (SEM) imaging. The chemical characterization of aqueous borax treated samples was examined by fourier-transform infrared spectroscopy (FTIR) measurements. Mechanical performances of the hydrogel composites were observed by tensile measurements. Thermogravimetric analysis (TGA) was conducted to characterize thermal stability of hydrogel composites. The results revealed that natural fiber woven fabric reinforcement significantly enhanced the mechanical strength of hydrogel composites, and wool fabric reinforced composite had better mechanical performance than its cotton and flax counterparts. Due to the low mechanical properties of hydrogels in general, the prepared fabric reinforced hydrogel composites could be used in hydrogel applications where mechanical strength is critically important.

Polyvinyl alcohol (PVA)/cotton (Co) woven fabrics were produced by constructing Co as warp yarns and PVA as weft yarns in the fabric structure. As-prepared PVA/Co fabrics were treated with borax/water solution. Because of the simultaneous dissolution and gelation of PVA yarn in the fabric and transformation of PVA molecules into cross-linked gel structures, gel penetrated among the yarns in the matrix form and hence Co yarn-reinforced composite hydrogels were obtained. The retention time of water by composite hydrogels was first increased and then decreased by increasing borax concentration in the cross-linker solution. With yarn reinforcing, the tensile strength of hydrogel structure significantly increased. Mechanical properties of hydrogel composites were very variable depending on water content in the structure and tensile strength tremendously increased when water evaporated from the structure. Thermal and chemical characterizations of yarn-reinforced hydrogel composites were conducted in addition to swelling and mechanical analysis to investigate the performance of the hydrogel composites.

In this study, the auxetic performance and various physical properties of fabrics woven with braid yarn were examined. Fabrics were woven in plain weave with conventional warp and braid weft yarn. Experimental results showed that fabrics woven with braid weft yarn exhibited an auxetic behavior by giving Negative Poisson's Ratio (NPR) up to a certain elongation value under tension in the warp direction. In addition, it was observed that the NPR of fabric was affected by the thickness of the braid yarn and the tightness (compactness) of the fabric. It was found that the use of braid yarn in woven fabric improved various physical properties such as tensile strength, thermal resistivity and abrasion resistance. Use of braid yarns increased the tensile strength in the weft direction where braid yarns were used, increased thermal resistivity values at the fabric woven with thick and bulky braid yarns and also increased abrasion resistance.

Iplik gerginlik sensorleri laboratuvarlarda arastirma amacli oldugu gibi endustriyel uygulamalarda da oldukca yaygin olarak kullanilmaktadir. Orme, bobinden sagim, bobine sarim ve cozgu hazirlama gibi bircok tekstil prosesinde iplikler prosesin dogasi ve mekanizmalarin hareketinden dolayi tekrarli zorlamalara maruz kalirlar. Bu durum iplik gerginliginde tekrarli degisimlere sebep olur ve gerginlik sinyali frekansi proses hizina bagli olarak degisir. Bundan dolayi gerginlik sensorunun iplik gerginliginde meydana gelen en kucuk bir degisimi dahi algilamasi ve gurultu olarak isimlendirilen daha yuksek frekansli degisimleri sinyalden uzaklastirmasi gerekmektedir. Bu makale iplik gerginlik sensorlerinde kullanilan genel teknikleri incelemekte ve daha sonra direnc esasli yuk hucreleri kullanarak gerginlik sensor tasarim ve gelistirilmesini aciklamaktadir. Sensor gelistirilip uretildikten sonra 800 m/dak’ya kadar iplik hizlarinda gerginlik olcumleri gerceklestirilmekte ve olculen gerginlik sinyalleri analiz edilmektedir. Calisma kapsaminda gelistirilen sensor ile bir ticari iplik gerginlik sensoru ile es zamanli yapilan gerginlik olcumleri karsilastirilmakta ve gelistirilen gerginlik sensorunun yuksek hizlarda daha hassas bir gerginlik olcumu yapabilmesi icin yapilmasi gereken iyilestirmeler oneri olarak verilmektedir.

Purpose Yarns 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/approach An 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. Findings Results 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/value Available 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.

Özet:Bu çalışmada %100 akrilik, poliester(PES)/akrilik ve pamuk/akrilik karışımlı dokuma kumaşların boncuklanmaözellikleri incelenmiş, kontrollü olarak üretilen deneysel kumaşlarda pamuk vepoliester ipliklerin akrilik iplikler ile birlikte kullanılmasının, atkısıklığının, örgü tipinin ve atkı iplik numarasının kumaşların boncuklanmaözelliklerine etkisi araştırılmış ve istatistiksel olarak değerlendirilmiştir.Çalışmasonucunda %100 akrilik, poliester/akrilik ve pamuk/akrilik karışımlı dokumakumaşlarda atkı sıklığının boncuklanma oluşumuna istatistiksel olarak etkisininolmadığı, örgü tipinin boncuklanmaya etkisinin olduğu en fazla boncuklanmanınsaten örgülü kumaşlarda en az boncuklanmanın ise bezayağı örgülü kumaşlardaoluştuğu tespit edilmiştir. En az boncuklanmanın pamuk atkılı kumaşlarda, enfazla boncuklanmanın ise poliester atkılı kumaşlarda oluştuğu, atkı tipininboncuklanmaya istatistiksel olarak etkisi olduğu görülmüştür. Akrilik vepamuk/akrilik kumaşlarda atkı iplik numarasının boncuklanmaya istatistikselolarak etkisi bulunmamıştır., In thisstudy, pilling behavior of acrylic (%100), polyester (PES)/acrylic andcotton/acrylic woven fabrics is studied. For this purpose, the effect of weftdensity, weave type, weft yarn count and use of acrylic yarns with polyesterand cotton yarns in experimental fabric samples on pilling behavior isinvestigated and statistically evaluated.After assessment ofthe results, it is shown that weft density has no statistically significanteffect on pilling behavior of %100 acrylic, polyester/acrylic andcotton/acrylic fabrics. But fabric weave is found to have a significant effectwith highest effect obtained with sateen weave and the lowest with plain weave.Cotton weft fabrics produce the lowest amount of pilling while it isencountered at highest amount in polyester weft fabrics. Hence the type of weftyarn shows a statistically significant effect on pilling. On the other hand,the effect of weft yarn number on fabric pilling is not found to bestatistically significant.

Bu çalışmada %100 akrilik dokuma kumaşların hava ve su buharı geçirgenliği özelliklerine atkı iplik numarası, atkı sıklığı ve örgü tipi değişiminin etkisi incelenmiş ve istatistiksel olarak değerlendirilmiştir. Çalışmada iki farklı numara atkı ipliği ile üç farklı örgüde kumaş üretilerek iplik numarası ve örgü tipi değişiminin etkisi, bezayağı örgülü kumaş yapılarında ise 3 farklı atkı sıklığı kullanılarak atkı sıklığı değişiminin etkisi değerlendirilmiştir. Çalışma sonucuna göre, akrilik dokuma kumaşlarda atkı sıklığı arttıkça hava ve su buharı geçirgenliği azalmaktadır. Bezayağı örgünün hava geçirgenliği dimi ve saten örgülü kumaş yapılarına göre daha düşük bulunmuştur. Kalın atkı ipliği kullanılan kumaşlarda daha yüksek su buharı geçirgenliği elde edilmiştir.

Cotton-woven fabric-reinforced polyvinyl alcohol-based hydrogel composite was produced by constructing cotton as warp and polyvinyl alcohol/cotton hybrid and polyvinyl alcohol yarns as weft yarns in the fabric structure. As-prepared polyvinyl alcohol/cotton fabrics were treated with different concentrations of aqueous borax and glutaraldehyde crosslinking solutions. Polyvinyl alcohol molecules were transformed to crosslinked gel structure after the treatments. Since cotton yarns kept their yarn structure in the fabrics, woven fabric-reinforced hydrogel composites were obtained. Chemical analysis to investigate crosslinking was conducted by attenuated total reflection–Fourier transform infrared spectroscopy spectra analysis, and the results revealed that a proper crosslinking of polyvinyl alcohol molecules in polyvinyl alcohol yarns occurred by using both borax and glutaraldehyde as crosslinkers. Thermal stabilities of the samples were observed via thermogravimetric analysis measurements. Even though borax crosslinking increased the thermal stability, glutaraldehyde crosslinking did not have a significant effect on the thermal stability of hydrogel composite. Crystalline microstructural analysis was carried out with X-ray diffraction measurement. Tensile properties of the samples by focusing on the crosslinker ratio and water contents in the hydrogel composites were performed. The results revealed that tensile properties of hydrogel composite tremendously increased with fabric reinforcement. Also, breaking force gradually increased when the hydrogel composite structure released the water from its structure at both borax and glutaraldehyde samples. Since the produced fabric-reinforced hydrogel composites have high strength, they are promising candidates as hygroscopic materials for planting and erosion control at inclined terrains.

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.

In this study, a circular Hough transform based image processing method has been developed to measure the dimensional changes of woven fabrics due to tensile force. For this purpose, needles were placed on woven fabrics with different structural parameters and the fabrics were pulled in warp direction. In the meantime, fabric images taken at intervals of 5 seconds for 30 seconds were recorded on the computer. The distances between the needles on the fabric images were measured both by hand drawing method and by image processing method developed using the circular Hough transform technique. When the results obtained from the two measurement methods were examined, it was seen that the deviation between the results was less than 1%. The average percentage deviation calculated by considering all measurements is only 0.26%. The correlation coefficient used to determine the strength of the relationship between the results obtained by the two measurement methods was calculated as 0.99. The developed image processing based measurement method can measure the dimensional changes of woven fabrics under stress easily, quickly and accurately., Bu çalışmada çekme kuvveti sebebiyle dokuma kumaşlarda gerçekleşen boyut değişikliklerinin ölçülmesi amacıyla dairesel Hough dönüşümü tabanlı bir görüntü işleme yöntemi geliştirilmiştir. Bunun için farklı yapısal parametrelere sahip dokuma kumaşlar üzerine iğneler yerleştirilerek, kumaşlar çözgü doğrultusunda çekme işlemine tabi tutulmuştur. Bu esnada 30 saniye süresince 5’er saniye aralıklarla alınan kumaş görüntüleri bilgisayara kaydedilmiştir. Kumaş görüntüleri üzerindeki iğneler arası mesafeler hem el ile çizim yöntemiyle hem de dairesel Hough dönüşümü tekniği kullanılarak geliştirilen görüntü işleme yöntemiyle ölçülmüştür. İki ölçüm yöntemi ile elde edilen sonuçlar incelendiğinde sonuçlar arasındaki sapmanın %1’den düşük olduğu görülmüştür. Tüm ölçümler hesaba katılarak hesaplanan ortalama yüzde sapma değeri ise yalnızca %0,26’dır. İki ölçüm yöntemi ile elde edilen sonuçlar arasındaki korelasyon katsayısı değeri 0,99 hesaplanmıştır. Geliştirilen görüntü işleme temelli ölçüm yöntemi, dokuma kumaşların gerilme altındaki boyut değişikliklerini kolay, hızlı ve doğru olarak ölçebilmektedir.

This study presents the effects of a novel plied yarn structure consisting of different yarn components and yarn twist levels on the Poisson's ratio and auxetic behavior of yarns. The plied yarn structures are formed with bulky and soft yarn components (helical plied yarn [HPY], braided yarn, and monofilament latex yarn) and stiff yarn components (such as high tenacity [HT] and polyvinyl chloride [PVC]-coated polyester yarns) to achieve auxetic behavior. Experimental results showed that as the level of yarn twist increased, the Poisson's ratios and the tensile modulus values of the plied yarns decreased, but the elongation values increased. A negative Poisson's ratio (NPR) was obtained in HT–latex and PVC–latex plied yarns with a low twist level. The plied yarns formed with braid–HPY and braid–braid components gave partial NPR under tension. A similar result was achieved for yarns with HT–latex and PVC–latex components. Since partial NPR was seen in novel plied yarns with braided and HPY components, it is concluded that yarns formed with bulky–bulky yarn components could give an auxetic performance under tension.

The rapid development of technology in textile industries has been improving textile finishing properties such as durability, water replants and breathability. Enset is effectively un-utilized agro-waste fiber composed of cellulose, hemicellulose and lignin, which are resemblance to banana fibers. This paper was focused on the utilization of enset waste materials for the production of nano fiber. Enset nano fiber (ENF) was fabricated by defibrillation of raw fibers from the surface of enset woven fabrics into micro and nano-scale fibers by -amylase enzyme treatment and mechanical hammering. Instead of sandwiching the nanofiber mats between conventional woven fabrics, in this research work, nanofiber mats were manufactured on the surface of the conventional woven fabrics. This top-down nanofabrication approach is simple, cost-effective and environmentally friendly manufacturing technique of nanofiber woven fabric structures. Fiber characterization was done by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). The surface area, pore size and pore volume of enset nano fiber was analyzed by Brunauer, Emmett and Teller (BET). The test results revealed that nano fiber fabrication was significantly affected by used enzyme concentration and applied mechanical power. Enset micro fiber was formed when 10 % (w/v) concentration of α-amylase enzymatic treatment was applied while enset nano fibers were formed when the enzyme concentration was increased to 15% - 20 % ( w/v). The FTIR results revealed that hemicellulose and lignin were effectively removed and fine fibers were defibrillated from the crystal structure of enset woven fabrics. The SEM microscopic image also confirmed the formation of the enset nano fibers ranges from 63-650 nm.

Noise is an unpleasant sound generated from high level sound source, which is a major concern on the residential areas and disturbed comfort, safe activity performance and human health. Now a days, most people are interested on light weight, having good mechanical strength and biologically degradable as well as compostable products. The aim of this research work was characterized the acoustic properties of new alternative ecological composite materials using low cost and light weight agro waste resources. The sound absorption performance of enset fabric and its composite were determined using two microphone transfer mechanism with impedance tube method. The porosity and void structure of enset fibers were studied by scanning electron microscope (SEM) for analysis of enset fabric/enset fabric composite sound dissipation mechanism. The sound absorption coefficient of enset fabric reinforced green composite had a value of 0.9 at critical frequency of 4500 Hz. The test result revealed that, enset fabric had better sound absorption capacity than commercially used glass fabric and had a promising potential to substitute flax in ecofriendly automobile and construction sectors with a wide range of acoustic absorbing frequencies, 3000 Hz - 6000 Hz.

Purpose Sectional warping is the most widely used warp preparation process in weaving. Winding all warp sections with the same length and same tension is a key factor for a good quality warp preparation. It is required that winding thickness (increase in radius due to warp winding) remains the same within and between warp sections. The purpose of this paper is to investigate winding thickness variations within and between warp sections, which can lead to quality problems in woven fabrics. Design/methodology/approach A measurement system is developed and then an experimental investigation into winding thickness variations is carried out. Winding thickness is measured with respect to number of drum revolutions using a laser sensor with 20 microns resolution. The number of drum revolutions and drum angular position are measured by an incremental encoder. Both sensors are mounted on an industrial sectional warping machine. A real-time software written in C programming language collects and records the data for all sections of warp with respect to drum number of revolutions and then results are evaluated to determine winding thickness variations. Findings Results show that warp sheet thickness starts with a higher value and it decreases up to around 30 drum revolutions and then it remains constant or decreases very slightly which can be considered as insignificant from practical point of view. Warp sheet thickness (i.e. thickness of one warp layer) fluctuates within each section up to 10 percent CV with five drum revolutions average warp sheet thickness. There are also warp sheet thickness variations between warp sections up to 3 mm. Originality/value Considering the short of practical research results on winding thickness variations in the literature, results of this study will be an original contribution to understanding winding thickness variation level. Also, results presented in this paper can be used to develop control algorithms for thickness control in sectional 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.

Objective: Classical phenylketonuria (PKU) is on inherited disorder of amino acid metabolism. Since treatment at an early stage is the most important factor effecting prognosis of the disease, the disease is screened with newborn screening program in our and in many countries as well. The basis of treatment is a life-long phenylalanine-restricted diet. In this study, we aimed to evaluate the effect of phenylalanine-restricted diet on anthropometric parameters of patients with the diagnosis of phenylketonuria

Sectional warping is the most widely used warp preparation method in weaving, as it enables warping from all kind of yarns with color or type repeat. The quality of warping is directly dependent on the precision of motion control of machine mechanisms. This paper presents a mathematical analysis of motions of a sectional warping machine. Experimental work is also carried out on industrial sectional warping machines. It is shown that the results of mathematical equations derived for motions of a sectional warping machine match well with experimental results and they can be used for computer control of a sectional warping machine.

Step precision winding is a widely used bobbin winding method in industry, especially for dyeing bobbins. It is important to adjust winding parameters in an optimum way to obtain optimum hardness variation and best dyeing performance. Main winding parameters are winding pressure, crossing angle and yarn tension. This paper presents a research investigating the effect of main winding parameters on hardness distribution in radial and longitudinal directions of bobbins wound with step precision winding. Bobbins are produced from Ne 30/1 and Ne 10/1 cotton yarns. Bobbin hardness is measured by a new instrument called UNITORQ, which enables the measurement of relative bobbin hardness in radial and longitudinal directions with small increments of distance. It is found that crossing angle affects mainly longitudinal hardness variation while radial hardness variation is determined and affected in a large variation interval by winding tension. Winding pressure is seen to have no significant effect on winding hardness distribution in both radial and longitudinal directions but it determines bobbin hardness level together with winding tension and crossing angle.

This paper presents an approach for the kinematic design of a rapier drive mechanism containing a spatial mechanism and analyses rapier motion curve. Kinematic design and analysis equations are derived and then the link lengths of the spatial mechanism are calculated in order to satisfy the critical rapier positions inside and outside the shed. In this way, the portions of one loom revolution, during which the rapiers are inside and outside the shed, are determined. The rapier motion curve is obtained by using kinematic analysis equations. It is shown that the position of the oscillating link in the spatial mechanism and the loom main shaft angle at which the rapier enters the shed have the most significant effect on the rapier motion curve. The gear ratio has also some effect on the rapier motion curve. Different rapier motion curves are obtained by changing these parameters and the suitability of these curves for rapier motion is discussed.

In this paper, the effect of weaving machine settings on weavability limits of air-jet looms was investigated by weaving plain weave fabrics with polyester warp and weft yarns. For this purpose, firstly, weavability limits were determined for 16.7 tex weft by setting back-rest height, total warp tension, frontshed angle and shed closing time at different levels without changing the properties of warp. For each machine setting, weft density was increased gradually until reaching the weavable limit. During the experiments, weaving continuity, unfavorable effects interrupting this continuity, negative changes on fabric and yarns were observed. In the mean time, the warp yarn tension and cloth-fell distance were measured. Later, the weaving with 7.8 and 33.3 tex wefts was carried out at the settings required to produce a weave at the maximum weft density for 16.7 tex weft. The maximum weavable weft densities were determined for these two weft yarns. Finally, the obtained maximum weft densities and cover factors with three different weft yarns were compared with the results obtained from theoretical equations of Pierce, Love and Brierley. It was found that the warp tension had the most significant effect on the weavability limits. Changing shed adjustment from the zero level of the back rest to higher values, increased the weavability limit slightly, but increasing the shed asymmetry further did not have a significant effect on the weavability limit. The shed closing time had some effect on the limit. But this was less than the effect of the warp tension. Changing the front shed angle did not have any effect on weavability limits. © 2011, SAGE Publications. All rights reserved.