Total porosity,theoretical analysis,and prediction of the air permeability of woven fabrics

Air permeability is one of the most important properties of textile materials that ensure their comfort. For many materials for technical applications (filters, sails, vacuum cleaners, parachutes, etc.), this is one of the main properties that determine their quality. The air permeability of woven textile fabrics depends on many parameters of fabric. Thus, the determination of air permeability of woven fabric is highly complex and difficult. In this study, we attempted to establish a theoretical model for the porosity and predicted the air permeability of woven fabrics. A theoretical model was created to predict the total porosity and the air permeability of a fabric structure depending on the geometrical parameters such as pore size, warp density, weft density, fabric thickness, number of yarn, diameter of yarn, and fiber density. For the purpose, a theoretical model of porous systems on D’Arcy’s law was used, and the validity of the model was confirmed by experimental results using 100% cotton and 97/3 cotton/lycra woven fabrics. Since the amount of air passing through both the pores between yarns and the interstices in the fibers constituting the yarn structure was calculated, theoretical values of air permeability were obtained very close to the experimental values.     

Mathematical model to predict vertical wicking behaviour. Part II: flow through woven fabric

The aim of the paper is to develop a mathematical model to predict vertical wicking behaviour of woven fabric. The first part of this series (Part I) has dealt with the mathematical model for predicting vertical wicking through yarn. In this part a model has been proposed to predict vertical wicking of the woven fabric, based on the developed yarn model. In order to model the flow through woven fabric along with the vertical flow through liquid carrying threads, the horizontal flow through transverse threads has also been taken into account. A simplified fabric geometrical concept (inclined tube geometry) and Peirce geometry for plain woven fabric have been used to define the fabric structure. Warp and weft linear density, fabric sett and yarn crimp have been considered in the fabric modelling. The theoretical wicking values of the yarn and fabric made from that yarn have been compared. Experimental verification of the model has been carried out using polyester and polypropylene fabrics. The model is found to predict the wicking height with time through the yarns and fabrics with reasonable accuracy.     

舒弹丝机织物透湿性能的分析

选用60／40舒弹丝棉试织了具有不同紧密度和不同组织的18种机织物。通过对18种机织物进行透湿性能测试,采用SPPS因子分析法,探究舒弹丝棉机织物结构参数对透湿性能的影响规律。由因子分析得到的综合评价函数可以预测舒弹丝棉织物的透湿性,便于在生产中控制织物的结构参数。     

棉织物透气性能的BP神经网络预测研究

采用BP神经网络技术建立和训练反映织物结构参数与织物透气性能之间关系的三层神经网络模型，可预测织的透气性能，比较预测值和试验值，表明用神经网络方法预测织物透气性能有相当的准确性，从而在一定程度上实现用神经网络预测织物的透气性能。     

机织物透气性预测的投影寻踪回归模型

针对机织物透气性预测中存在非线性建模困难的问题,选择机织物总紧度、厚度、面密度及平均浮长等结构参数作为机织物透气性预测的影响因素,建立机织物透气性预测的投影寻踪回归模型.对模型训练样本的拟合值及检验样本的预测值以相对误差的均值及标准差为指标进行分析,并与BP神经网络及多元线性回归模型进行对比.结果表明,投影寻踪回归模型...     

Regression model for predicting the air resistance of fabric made from doubled yarns and with different weave structures

The purpose of the investigation is to model the effect of doubled yarns produced from conventional and compact yarns in three different combinations and weave structures on the air resistance of fabrics. A series of woven fabrics differing only in weave structures and having the common count and fabric sett was produced from three types of doubled yarns, namely compact/compact, conventional/conventional and compact/conventional. The hybrid combination was produced principally to reduce the cost of manufacturing doubled yarns. Essential data for the fabrics such as CFF (crossing over firmness factor), FYF (floating yarn factor), FFF (fabric firmness factor), mass per unit area, thickness and porosity were determined. Air resistance was determined by performing the standard test KES-F8 API. Analysis of the results in respect of fabrics produced from the compact/compact, conventional/conventional and conventional/compact yarns shows a strong correlation between the air resistance, porosity, CFF, FYF, FFF, mass per unit area and thickness (R = conventional/conventional 0.97, compact/compact 0.861, conventional/compact 0.974) and the generated statistical models have given the satisfactory prediction of air resistance. Among the parameters, thickness exerts a strong influence on the air resistance. It is concluded that in order to predict air resistance, a number of parameters are needed and any conclusion which has been drawn using only CFF and FYF should be treated with caution. Also the possibility of cost saving as a result of using hybrid doubled yarn has been pointed out.     

Acoustic performance of woven fabrics in relation to structural parameters and air permeability

This work deals with the study of the acoustic characteristics of woven fabrics in relation to fabric structural parameters and air permeability. In order to achieve the objectives of the research, sound absorption coefficient of woven fabric samples was determined via impedance tube method. Samples with various pick densities and yarn twist were used. The effect of fabric thickness was analyzed using three and six layered test samples. Results showed that, while for all samples the minimum values of sound absorption were observed at frequency bands of 250 and 2000?Hz, the maximum sound absorption occurred at the frequency of 1000?Hz. Results also indicated that fabrics woven at pick density of 30?thread/cm exhibited higher sound absorption than fabrics woven at other pick densities. It was found that, noise reduction coefficient of three and six layered samples, woven at low pick densities showed significant increases in comparison to those woven at high pick densities. It was also established that samples woven with lower weft yarn twist absorb sound wave more efficiently. It was concluded that fabric air permeability can be used as a criterion of sound absorption behavior of woven fabrics.     

Development of mathematical model to predict vertical wicking behaviour. Part I: flow through yarn

Theoretical models have been proposed in this article (Parts I and II) to predict the vertical wicking behaviour of yarns and fabrics based on different fibre, yarn and fabric parameters. The first part of this article deals with the modelling of flow through yarn during vertical wicking, whereas the second part deals with the modelling of vertical wicking through the fabric. The yarn model has been developed based on the Laplace equation and the Hagen–Poiseuille’s equation on fluid flow; pore geometry has been determined as per the yarn structure. Factors such as fibre contact angle, number of filaments in a yarn, fibre denier, fibre cross‐sectional shape, yarn denier and twist level in the yarn have been taken into account for development of the model. Lambertw, a mathematical function, has been incorporated, which helps to predict vertical wicking height at any given time, considering the gravitational effects. Experimental verification of the model has been carried out using polyester yarns. The model was found to predict the wicking height with time through the yarns with reasonable accuracy. Based on the proposed yarn model, a mathematical model has been developed to predict the vertical wicking through plain woven fabric in the second part of this article.     

Role of filament cross-section in properties of PET multifilament yarn and fabric. Part I: Effect of fibre cross-sectional shape on transmission behaviour of fabrics

The transmission property of a fabric is a key factor that affects clothing’s comfort and decides the functional potential of clothing. The dependence of filament cross-section with varying shape factor (SF) on air, moisture and thermal transmission behaviour of fabric is determined in case of polyester multifilament woven fabrics. The linear density of each filament is kept identical for all 12 cross-section shape filaments. The SF of filament cross-section is an important factor which remained the prime factor to influence the transmission behaviour of fabric samples directly in many cases. Other indirect factors that influence the transmission behaviour of fabrics when the SF is identical are yarn structure, inter-fibre and inter-yarn space. Twelve different novel cross-sectional shapes are considered to make the multifilament woven polyester fabrics. The fabrics made from multifilament yarns having different SFs show that relative moisture vapour permeability and air permeability decrease with the rise in SF. Wickability increases with the rise in the SF of a filament cross-section. Multilobal, hexalobal and plus shapes were made a part of novel cross-sectional shapes in order to develop fabrics of higher comfort index.     

Investigation on permeability and moisture management properties of different denim fabrics after repeated laundering

The physiological comfort determined by air permeability and moisture management properties of fabrics is influenced by various constructional parameters of the fabric which give woven fabric a porous structure. Evaporation of sweat during wear has the potential to cool the body besides restricting the additional weight of sweat being absorbed by the fabric. In this study, comfort characteristics of denim fabrics with different weft yarn of cotton, polyester and core spun Lycra have been discussed. Effect of enzyme washing and repeated laundering on air permeability, moisture management and drying rate has also been discussed. It was observed that air permeability and water vapour permeability of unwashed denim fabrics with cotton weft yarn are significantly higher than the fabric with polyester and Lycra cotton weft yarns. The wetting time is higher for cotton and Lycra cotton yarn fabrics. One-way transport index is highest for Lycra cotton weft fabrics and lowest for fabrics with polyester weft. Fabrics with polyester weft yarns show highest spreading rate, spreading radius and drying rate due to better wicking and hydrophobic nature of polyester fibres.     

应用纱线序列图像的电子织物构建

为检测纱线条干均匀性对织物外观的影响,在纱线条干图像测量的基础上,提出了一种基于纱线序列图像的电子织物的构建方法。通过建立织物组织变化模型和光照模型,将纱线直径值与基元组织点外观灰度纹理分布相结合,构建电子织物外观数学模型。实验中通过将采集的纱线序列图像进行图像分割和形态学运算等处理,获取纱线直径数据,代入到构建的织物外观数学模型中,实现基于纱线序列图像的电子织物的模拟并且相关参数可调。通过选择合理的织物结构参数,提出的电子织物模型能够真实的反映纱线条干均匀性对织物外观的影响,准确预测布面效果。     

Geometrical modelling of angle warp interlock fabrics

A geometrical modelling approach has been developed which predicts all the necessary geometrical parameters for multilayer angle warp interlock weaves. The model requires tow and weaver data as input and gives fabric thickness, warp and weft crimp angle, areal weight and fibre volume fraction (FVF) as outputs. In order to validate the model we have woven three angle warp interlock woven reinforcements, having same number of total layers, on a conventional loom, using carbon multifilament tows in warp and glass multifilament tows in weft. The depth of the binder (maximum number of layers traversed by the binding warp in vertical plane) was maximum for the first variant (5). The binder tow traversed all the five layers so that this variant is termed as through-the-thickness angle interlock. For the second variant it was reduced to an intermediate level (3), whereas for the third one it was minimum (2) so as to conceive a layer-to-layer interlock structure. The geometry of such woven reinforcements can be categorised in terms of crimp amplitude and cross-sectional shape of the warp and weft tows. These two vary with the structure of the woven fabric and weaving parameters, ultimately influencing the areal weight, size of the unit cell and FVF of the fabric reinforcement. Results obtained show that the modelling approach can be successfully applied to calculate necessary fabric geometry parameters from minimum number of manufacturer and weaver data.     

Effect of structural parameters on thermal protective performance and comfort characteristic of fabrics

In an attempt to understand the influence of basic structural parameters of fabrics on thermal protection and comfort, present study mainly focuses on analyzing effect of fabric weaving pattern and fabric weight. Fabric samples of three basic weaving patterns (plain, twill, and satin) and three different weights were prepared. Air permeability of the developed fabric samples was measured. Thermal protective performance of fabrics against radiant heat and flame exposures of two different intensities were measured. Spectral transmission behavior of fabrics was also studied. It was observed that for same fabric weight, protective performance and air permeability of satin woven fabrics were better as compared to the fabrics of other patterns. Protective performance increased and air permeability decreased as fabric weight increased for each type of woven structure included in this study. A new structural parameter is proposed which primarily influences the protective performance of fabrics exposed to either radiant heat, flame, or combined convective/radiant heat exposure.     

紧密机织物高气压下面外变形的机制

为指导设计新型防护面料,依据其防护过程,探索了紧密机织物在高气压下面外变形的机制。结合能量理论和板壳理论,建立了紧密机织物在高气压下面外变形的系统能量平衡方程(机制模型),从能量最小化的角度预测织物变形后的最大变形量和变形轮廓曲线。通过自行搭建的织物变形仪测量了2类不同紧密程度的机织物面外变形情况。结果发现织物变形程度与其弹性模量呈负相关性,随后对织物变形的实验值与理论预测值进行了比较,发现二者之间的误差小于20%。从而证明该数学模型可较为精确地用来预测其他紧密机织物高气压下的面外变形。     

Effect of structural parameters of porous yarns and fabric on air permeability and moisture transfer of double-face woven fabrics

In this study, effect of fabric structural parameters of double-face woven fabrics including kind of porous yarn namely micro-porous yarn and hollow yarn, hole size of hollow yarn, percentage of these yarns in double-face woven fabric structure, and finally weft density on air permeability and moisture transfer of woven fabrics was evaluated. These yarns were produced by using water-soluble continuous polyvinyl alcohol filaments as core part for hollow yarns and as doubling yarn in micro-porous yarn. Results revealed the effect of kind of porous yarn, hole size of hollow yarn, and weft density on air permeability and moisture transfer of woven fabrics. The percentage of porous yarns as weft did not show obvious trend. Analysis of variance was used to study the effect of these variables on air permeability and moisture transfer of double-face woven fabrics statistically.     

圣麻涤混纺机织物的性能研究

为研究圣麻涤混纺织物的性能,测试了混纺织物的抗弯性、折皱回复性、透气性与导湿性、织物的表面摩擦性能、抗起毛起球性、光泽度等,结果表明,所设计的圣麻涤混纺织物有良好的爽身、透气、柔软性,适合制作服用面料.     

Finite element analysis of bias extension test using an orthotropic hyperelastic continuum model for woven fabric

In this paper, an orthotropic hyperelastic model of woven fabric has been developed. The model is coded in Abaqus/Explicit using subroutine Vumat. The work reported here covers the influence of the ratio between shearing and tensile rigidities of woven fabric on stress and strain fields. Numerical results from bias extension tests on samples of three aspect ratios are compared to those predict by the theory. This study proved that the shearing deformation depends not only on the specimen dimensions but also on the ratio between shearing and tensile rigidities of woven fabric.     

气流槽聚棉麻混纺织物的风格评价及其工艺研究

本文以30个棉麻混纺织物为样本,通过KES-FB风格仪测试织物的16项性能指标,运用主因子分析法,得到评价织物风格的5个主因子:紧密厚实因子,变形因子、拉伸匀整因子、丰满因子、弯曲压缩回复因子及其决定因素。结合探讨汉麻纤维前处理、纺纱、浆纱、织造等四个关键工序的技术改进和优化,通过定量结合定性的分析来科学系统地指导气流槽聚棉麻混纺织物的产品开发。     

Influence of graphene oxide concentration and dipping cycles on electrical conductivity of coated cotton textiles

The electrical conductivity of cotton fabrics is enhanced by coating with graphene in aqueous phase by a suitable process. Two different types of fabrics viz. woven and knitted structures of same GSM are used as substrate. The fabrics are dipped in dispersed graphene oxide (GO) solution and then GO-enriched fabric samples are subjected to a reduction process for in-situ conversion of the added GO to electro-conductive graphene. The concentration of GO solution and number of dipping cycles influence the graphene add-on and electrical resistivity of the fabrics. The change in surface resistivity, thickness, air permeability, porosity and water vapour permeability of the fabrics after the treatment has been evaluated. Comparisons have been made between the woven and knitted fabrics for all these properties to understand the effect of fabric structure.