RESEARCH NOTE SHEARING PROPERTIES OF THE SKEWED WOVEN FABRICS

Abstract This experimental work deals with the effects of skewness on the shearing properties of the worsted woven fabric. Shearing properties of 160 samples are measured by two methods (KES and concentrated loading methods) and the results are compared. Both methods show a positive correlation between skewness and shear rigidity indicating, as the skewness goes up the shear rigidity also increases. Correlation between shear rigidity evaluated by KES and skewness was 0.725, but new parameter (EML) extracted from the concentrated loading curve (Extension at 200 gram-load) showed more sensitivity to fabric skewness and gave a higher correlation (-0.866) to it. In other words, the concentrated loading method shows the relationship between skewness and the shear rigidity (G)

Effects of Kevlar® 29 yarn twist on tensile and tribological properties of self-lubricating fabric liner

Yarn twist in textile technology is an important characteristic since it considerably affects the properties of knitted or woven fabrics. Many researchers have investigated the effect of staple-spun yarn twist on the properties of the yarns and fabrics. However, the effects of twist level of Kevlar® 29 filament yarn on the properties of yarn and its resin-impregnated self-lubricating fabric liner are not fully known yet. In this study, we have investigated the effects of Kevlar® 29 twist level on the tensile and tribological properties of the fabric liner (Kevlar® 29/polytetrafluoroethylene fabric-resin composite). Two unexpected findings about the effect of yarn twist have been observed, namely (1) asynchronous twist effect on the yarn’s and the liner’s tensile strength and (2) dissimilar yarn twist effect on the liner’s performance. These findings are mainly attributed to the synergic contributions of the yarn twist and strength and the interaction of the resin with the yarn orientation in the woven fabric structure of the liner

A new method to evaluate low-stress shearing behaviour of woven fabrics

333-338The ability of extraction and concentrated loading methods for measuring the shearing properties of woven fabrics has been studied. Forty light weight woven fabrics of different varieties have been tested by three methods, viz KES, extraction and a new suggested method, and the results compared. Correlation between the KES quantitative parameters and the measured features extracted from the curves of extraction and new methods indicates better ability of the new method to measure the shearing properties. It is observed that the buckling zone of fabrics is the key point to evaluate the shearing rigidity. In addition, the new method is capable of yielding the effect of changing production parameters

Wpływ kierunku skrętu przędzy na właściwości mechaniczne tkanin

This work deals with the role that twist directions at the contact point of warp and weft play in the mechanical behaviour of fabrics. Two sets of 100 percent combed cotton yarns (20 tex) of different twist directions (Z & S) and six twist levels were produced and then used as wefts on an old type Dornier loom (weft insertion of 120 picks/min), in which the warp was 100% combed cotton yarns with 870 Z twist per meter. Hereby we obtained two sets of fabrics in which the warps were all the same but the wefts were different in the twist directions and twist levels. Then the fabrics were compared with respect to the yarn pullout (two adjacent yarns were pulled out at the same time), the fabric formability (product of bending rigidity and reverse value of initial modulus) and fabric buckling (200-g tensile concentrated force was applied to the fabrics). The results show that the yarn pull-out force, fabric formability and fabric buckling force were greater in the fabrics in which the warp and wefts were unidirectional in the twist directions. In addition, in the group in which the warp and weft twist directions were the same, the maximum pull-out force, maximum formability and maximum buckling force belonged to the fabrics in which the nesting angle was around zero.W pracy rozważono wpływ skrętu na właściwości mechaniczne wzajemnie krzyżujących się przędz osnowy i wątku. Wyprodukowano dwa zestawy przędz bawełnianych o rożnych kierunkach skrętu (Z i S) i rożnych jego wartościach. Uzyskano tkaniny o jednakowej osnowie i wątkach o różnym kierunku skrętu i jego wartościach. Następnie tkaniny badano oceniając efekt wyciągania nitek, odkształcalność i wyboczenie tkaniny. Wybrane parametry badano przy różnej wzajemnej konfiguracji skrętów osnowy i wątku

Wytrzymałość na ścieranie przędz krzyżujących się pod kątem prostym

This paper investigates yarn abrasion behaviour based on the yarn structure, twist factor and fibre alignment at the rubbing contact points (twist direction at contact points). First yarns arranged at right angle (utilized with a high resolution camera) were introduced on a yarn abrasion tester and then the abrasion behaviour of the ring (R) and open-end rotor (O.E.) spun yarns were compared and analysed. Comparison of the yarns indicates that the abrasion resistance thereof is affected by the twist factor in a way that as the twist increases, the yarn on yarn abrasion cycles to failure follows the same trend as the effect of twist on the yarn strength (first an increase and then a decrease); that is, yarn on yarn abrasion resistance increases up to a certain degree (a=140 in ring spun yarn and a=156 in open-end rotor spun yarn), and then as the twist increases, the yarn on yarn abrasion resistance decreases. It also shows that the yarn abrasion cycle to failure is lower when the fibre alignments of the contact yarns are in the same direction. Close observation of the yarn rubbing also indicates that as the fibres are removed from the outer layers, the rotor spun yarn shows higher yarn on yarn abrasion resistance; that is, moving from the outer side to the interlayer of the rotor spun yarn, the relative yarn on yarn abrasion resistance (abrasion cycles to failure/yarn count) increases. This phenomenon indicates the fact that in open-end rotor spun yarn the compactness of the interlayer fibres are higher than the compactness of the outer layer fibres.Analizowano różne właściwości mechaniczne przy zrywaniu lnianych przędz łączonych różnymi węzłami, stosując test na rozciąganie dla czterech węzłów o różnej strukturze - węzeł prosty, zwykły, tkacki i rybacki. Zastosowano cztery próbki: 50 tex (A - bielona, B - surowa) i 68 tex (C - bielona, D - surowa), każda wyprzędziona z lnu. W pracy przedstawiono wartości siły zrywającej, wytrzymałości przy zerwaniu, wydłużenia przy zerwaniu, pracy do zerwania oraz jednostkowej pracy do zerwania dla przędz łączonych węzłami. Ponadto, przeanalizowano współczynnik retencji dla siły zrywającej, wydłużenia przy zerwaniu i pracy przy zerwaniu. Stwierdzono, że wytrzymałość przędz łączonych węzłami zależy w dużym stopniu od struktury węzłów, podczas gdy przędze surowe i bielone wykazały podobne właściwości wytrzymałościowe

Nowy typ dysz lejkowych dla oceny mechanicznych właściwości tkanin metodą ekstrakcji

Current methods of mechanical property evaluation of fabrics such as the KESF and FAST systems employ several testing devices for measuring tensile, shearing and bending characteristics separately. In this research a new facile and efficient extraction method for simultaneous estimation of different mechanical properties using a funnel-shape nozzle is introduced. The tensile, shearing and bending properties of 84 woven fabric samples were measured using standard methods and subsequently circular specimens of these fabrics were extracted through the funnel shaped nozzle. Sixteen different parameters were graphically selected from the force-displacement curves obtained, and the correlation between these parameters with the experimental mechanical properties was calculated. Finally stepwise multiple linear regression analysis was applied to acquire the best equation for predicting the mechanical properties of the fabrics. Our findings revealed that the shear stiffness and tensile strength can be objectively evaluated by measuring the initial slope (S1) and maximum load (Pmax) on the load-displacement curve. The maximum load in the 4th zone (Fmax) of the graph was introduced as an objective measure of the bending rigidity and tensile module in the warp direction. The area of curve (A) can be used for objective evaluation of bending rigidity in the weft and bias directions.Obecnie stosowane metody oceny mechanicznych właściwości płaskich materiałów tekstylnych takie jak KESF i FAST wykorzystują rożnego rodzaju urządzenia dla pomiaru i niezależnego określenia charakterystyk rozciągania, ścinania i zginania. W pracy przedstawiono nową wydajną metodę równoczesnej oceny kilku mechanicznych właściwości materiałów przy zastosowaniu dyszy o lejkowatym kształcie. Dla przeprowadzenia badań przygotowano 84 próbki tkanin, które sprawdzono standardowymi metodami, a następnie przeciągnięto przez lejkowatą dyszę rejestrując jednocześnie charakterystyki siły w funkcji wydłużenia. Z tych wykresów wyznaczono 16 parametrów, które skorelowano z uzyskanymi poprzednio właściwościami tkanin oraz poddano analizie statystycznej. Wykazano, że sztywność ścinania i wytrzymałość na rozciąganie można obiektywnie określić z początkowego nachylenia charakterystyki siła-wydłużenie. Maksymalna siła w 4-tej strefie wykresu została skojarzona ze sztywnością zginania i modułem rozciągania w kierunku osnowy. Powierzchnia pod krzywą może stanowić obiektywną miarę w sztywności zginania w kierunku wątku i kąta rozciągania 45 stopni

Measuring and modelling the effect of base zone on sound absorption of persian rug

The aim of this study is to investigate the role of base zone on rug sound absorption and to predict the acoustic behavior of typical Iranian rugs using a mathematical model. For this purpose, four rug samples (1.5 cm thickness) were produced with different base structures, so that the base warp yarns are divided into two equal groups and arranged from each other at a different adjustable distance (0.0, 0.1, 0.2 and 0.3 cm). Sound absorption measurements were carried out using an impedance tube. Then, in order to focus on the base zone and to separate the piles contribution from the global rug sound absorption, the pile yarns were shaved from all samples and the non-piled samples were measured again. The five-parameter model of Johnson-Champoux-Allard (JCA model) was fitted to experimental data, assuming the rug is a two-layer (pile + base zone) porous absorber. The agreement between the model and the experiments is satisfactory. This optimized model can be used to predict the sound absorption coefficient of Iranian rugs. The results indicate that the rug base plays an important role in the overall rug sound absorption and that the air gap between the two groups of warp yarn improves the rug sound absorption