A relationship between dry-relaxed warp-knitted fabric structure and curling distance

This study provides us information about relationship between curling and knitted structure and density of two-guide bar warp-knitted fabrics. Five standard warp-knitted fabrics are produced with three densities (Tricot, Locknit, three-needle Satin, Reveres Locknit and three-needle Sharkskin). Certain cut lengths of sample fabrics in both wale and course direction are analyzed through image processing to define curling value. A mechanical model, a function of fabric structure and yarn parameters, is also suggested to predict the curling force. The results of experimental and theoretical results show a greater curling value for course-wise cut in comparison to that of wale-wise in all warp-knitted structures and densities. The lowest curling value is found for three-needle Sharkskin structure in both directions and all densities.     

针织西服面料的挺括风格研究

为探讨针织面料在西服开发应用的要求与标准,寻找能够用于西服开发的针织面料,分别从弯曲长度、折皱回复性、悬垂性3个方面对针织面料的挺括风格进行量化分析。借助实验仪器以及数据处理得到弯曲刚度、折皱回复角、静态悬垂系数3项性能指标,以机织西服面料为参考标准,对针织面料的挺括风格进行研究分析。结果表明:6路变化罗马组织是较为适合针织面料开发西服的组织结构,其结构稳定性优于12路小提花组织以及变化间隔组织,降低纵向弯曲刚度与横向弯曲刚度的差异;织物厚度增加0.1 mm,折皱回复程度提高10%;织物密度控制在110~130线圈/(5 cm)时,悬垂程度达到机织西服面料的60%以上;6路变化罗马组织配合高织物密度能够使针织面料的挺括风格达到机织西服面料的80%。     

The influence of two bar warp-knitted structure on the fabric tensile stress relaxation Part II: (locknit,satin, loop raised)

When strain is applied constantly, there is a decreased stress with time in viscoelastic materials, which is called stress relaxation. During the manufacture and application of clothing and footwear, materials experience various long-lasting deformations, and relaxation process in materials arises. Thus, with theoretical and experimental study of the factors affecting stress relaxation, the ability to design and produce appropriate clothes will be increased. In the first part of this research, we studied the stress relaxation behavior of warp-knitted structures which have longer underlaps in back bar (reverse locknit, three- and four-needle sharkskin, and queens’ cord). Following the previous research, the aim of this study was to investigate the effect of fabric structure, strain percentage, and course density on the stress and stress relaxation of the warp-knitted structures which have longer underlaps in front bar (locknit, three- and four-needle satin, and loop raised). The results reveal that the fabric structure, strain value, and fabric density are important factors affecting the stress and stress relaxation percent of the fabrics. By increasing the strain and the length of underlap in the front guide bar, stress and stress relaxation percent will be increased. Also, fabrics with higher course density show higher stress and stress relaxation percent. Among the mechanical models used to describe the stress relaxation behavior of the fabrics, the three-component Maxwell’s model with parallel-connect nonlinear spring showed the best agreement with the experimental stress relaxation curves of the analyzed fabrics.     

基于图像处理的织物弯曲性能测试方法

织物的弯曲性是体现织物柔软变形能力的重要指标,但关于织物弯曲性的研究大多集中在理论分析而非测试方法。针对这种情况,本文提出一种简便的、可同时测多块织物或多个角度的织物弯曲性能的测试方法--水滴法,并给出了其具体的使用方法以及评价指标--水滴宽度、水滴长度、水滴面积及抗弯系数。最后将20块织物的4项水滴法指标与抗弯长度及抗弯刚度进行对比分析,得出：水滴法中的4项指标与斜面法中的抗弯长度与抗弯刚度相关性从大到小依次是水滴面积、抗弯系数、水滴宽度和水滴长度,且这四者与抗弯长度及抗弯刚度都具有高度线性相关关系。这说明文中作为尝试和探索提出的利用水滴法测试织物弯曲性能是可行的。     

Theoretical and experimental analysis of bending rigidity of plain and twill woven fabrics

The study of bending behavior of woven fabrics is an important issue in textile scientific researches and its industrial applications. Different behavior of fabrics such as drape, comfort, and handling can be understood by this study. Bending rigidity of fabric depends on several factors such as weave geometry, bending rigidity of yarn, and yarn density. In this study, estimation of bending rigidity of woven fabric with different twill and plain structures, have been carried out using energy method. Generally, the woven fabric structure is divided into three different section lengths i.e. rigid, semi-rigid, and flexible sections. Thereafter, bi-component and tri-component models for predicting bending behavior of plain and twill woven fabric have been presented. Then, bending properties of fabric based on Shirley apparatus as well as weight per area as a physical property were measured. Good agreement between measured and predicted values, validated our theoretical models for obtaining bending rigidity, except considerable differences observed between experimental and predicted values using bi-component model of plain fabric. Therefore, using assumptions in calculation of the ratio of rigid section length to flexible section length (R₁), the modified model of plain fabric has been proposed.     

组织结构对涤纶经编织物卷边性的影响

为减少织物卷边对后道工序带来的影响,对各把梳栉的组织结构配置以及牵拉密度的选择进行了探讨。以55.5 dtex 24 f涤纶全牵伸丝(FDY)为原料,生产出7种不同组织和4种不同牵拉密度的两梳经编织物,对其卷边量进行测试,并结合显微镜下的线圈图进行分析。结果表明：随着牵拉密度的增大,经编织物横、纵向卷边量均不断减小,其中牵拉密度对横向卷边的影响要明显大于纵向卷边;两梳同向编织的织物横向卷边性要明显好于反向编织;当前梳组织不变,增加后梳延展线长度时,织物的横、纵向卷边量均不断减少,尤其是横向卷边量下降明显;而当后梳组织不变,增加前梳延展线长度时,织物的横、纵向卷边量均不断增加。     

Analysis of warp-knitted fabric structure. Part III: theoretical study on initial modulus of warp-knitted fabrics (reverse locknit,three- and four-needle sharkskin)

In the second part of this series, tensile properties of tricot structure were investigated. Then derived model was extended to locknit and satin as first group of fully thread two-needle bar warp-knitted fabrics. In the present study, tensile properties of second group of these warp-knitted fabrics, i.e. reverse locknit and three- and four-needle sharkskin, are considered using energy method and Castigliano’s theorem. For this purpose, the difference between the tensile properties of first and the second group of warp-knitted fabrics is attributed to the movement space and friction of back bar underlaps. Similar to previous part, free-body diagrams of elements are drawn to show the relative magnitude and direction of all forces acting upon an object in a given situation. Finally, the initial modulus of second group of warp-knitted fabrics is obtained.     

An explanation of warp knitted fabric deformation under uni-axial tension by a novel index as shape ratio

Although the Poisson’s ratio (PR) can predict the deformation of engineering materials under uniaxial tension, but seems that it cannot predict well the deformation of structures such as fabrics. It can be attributed to the lack of continuity among constituent elements that leads to some distortion of them during tension. Therefore, the PR is not a suitable tool to explain precisely the deformation of structures such as fabrics. For this reason, a new geometrical index was defined to quantify the deformation of fabrics in order to use instead of PR. This index named shape ratio is obtained by division of the variation of squared perimeter to the area of a printed square on the fabric under uniaxial tension. To check the defined index, warp-knitted fabrics with various structures such as Tricot, Locknit, and Three- and Four-needle satin were produced and tested using tensile tester. The results show that shape ratio can predict the deformation of warp-knitted fabrics as an orthotropic structure rather than the PR.     

常用高性能纱线弯曲刚度的测量和表征

由于轴向织物增强薄壳体复合材料越来越成为研究的热点课题。衬纱是轴向织物的重要组成部分,弯曲变形是织物变形的主要形式,因此,衬纱的弯曲刚度对织物的三维成型性能有着重要影响。本文借助KES织物风格仪,通过测量最大弯矩值M_max和拟合斜率值s,表征四种常用高性能纱线的弯曲刚度。实验结果表明：在相同线密度下,高性能纱线的弯曲刚度大于传统纱线的弯曲刚度,四种高性能纱线的弯曲刚度由大到小依次是碳纱线、玻璃纱线、高强聚乙烯纱线、芳纶纱线;高性能纱线的弯曲刚度受纱线中单丝的排列、聚集状态影响,并且随着进入角度的增加而减小。     

用蝴蝶结法测试毛织物弯曲性

针对现有织物弯曲性测试需要用多块试样才能得到多个测试结果的现状,提出一种既简便又节约面料的预测毛织物弯曲性的方法蝴蝶结法。详细阐述了用蝴蝶结法测试织物弯曲性的实施步骤及采用的表征参数:蝴蝶结面积、宽度、高度和角度。以18块毛织物为研究对象,用新方法与传统方法进行对比测试分析。结果表明:新方法中的4个参数与毛织物的抗弯刚度都具有较好的相关性,且越硬挺的毛织物形成的蝴蝶结角度、宽度和面积越大,高度越小,其中蝴蝶结面积与抗弯刚度的相关性最高;用蝴蝶结法建立的蝴蝶结面积与织物抗弯刚度的关系式可预测毛织物的抗弯刚度。     

Analysis of bending properties of worsted wool yarns and fabrics based on quasi-three-point bending

Abstract

The bending behavior of worsted wool yarns and fabrics plays a crucial role in handling and performance of end-use textiles. Hence, the fabric/yarn bending properties were studied based on a quasi-three-point bending model by means of the theoretical modeling and the corresponding measuring method. By means of the formula and the measured curves, the curve of bending rigidity and the curvature of a fabric or a yarn can be calculated so as to characterize the bending behavior more precisely than in the previous work. All the experiments on the fabric/yarn bending rigidity have been conducted for both the worsted wool fabrics and the corresponding yarns procured from the fabrics, with the same apparatus bending evaluation system of fabric and yarn, which was developed independently. The measured results of bending rigidity and curvature curve show good correlation with the bending moment and the curvature relationship of the theoretical modeling, and the comparisons of bending rigidity among KES-FB2 (Kawabata Evaluation System for Fabrics-2 pure bending tester), FAST-2 (Fabric Assurance by Simple Testing-2 bending meter), and the independently developed apparatus show that the three systems exhibist reasonably high correlations. It is confirmed that the new apparatus and the theoretical model are both viable and precious. Meanwhile, the theoretical relationship between the yarns and the fabrics has also been discussed, and the theoretical analysis of the bending behavior between the yarns and the fabrics is helpful in selecting a better theoretical model of the fabric-to-yarn bending rigidity ratio.     

轴向经编针织物的设计与仿真

为了解决轴向经编针织物计算机辅助设计方面的不足并且最终实现其快速设计,本文针对轴向经编针织物的CAD设计与仿真功能进行了研究。在深入了解轴向经编针织物生产工艺的基础上,采用实验的方法测量了织物结构的尺寸,建立了轴向经编针织物的CAD设计模型,其中包括地组织模型和铺纬组织模型;重点研究并建立了轴向经编针织物的纱线与线圈的二维仿真模型,以及玻璃纤维衬纱、线圈的三维仿真模型;以Visual C++ 为开发工具,并且结合OpenGL（Open Graphics Library）图形库,最终在WKCAD4.0系统中实现了轴向经编针织物的CAD设计与仿真功能。     

Relations between Fabric Structure and Friction: Part II: Weft Knitted Fabrics

Abstract

In the earlier part of the series (Jeddi et al., 2003) the authors defined a new index for the structural asperity of woven fabrics and found the relationship between this index and fabric frictional parameters. In this part, the authors develop this definition for weft knitted fabrics and introduce a ‘Fabric Structural Asperity Index’ (FSAI) for interlock gating of knitted structures. This index, which can be explained as the ratio of miss stitches to the total number of needles in a structural knit cell, shows a good relation with frictional resistance parameters of the course over course direction of motion.

The experimental results show that the static and dynamic frictional resistances of the course over course motion are higher than the wale over wale motion. The values of frictional forces for different structures have no statistical difference in the wale over wale direction of motion. This paper also studies the effectiveness of the structural cell stitch length and fiber content on the frictional behavior of the fabrics.     

Investigation into the curling behavior of single jersey weft-knitted fabrics and its prediction using neural network model

This research investigates the effect of fiber, yarn, and fabric parameters on curling phenomenon of single jersey weft-knitted fabrics which is interpreted to have curling surface in both course and wale direction. Taguchi’s experimental design is used to estimate the optimum process conditions and to examine the individual effects of all controllable factors on curling one by one. The controllable factors are blending ratio of polyester to cotton fiber, yarn twist and count, fabric structure, knit density, and relaxation time. Results show that fabric structure and knit density have the most dominant effect on the fabric curling. The optimum conditions of minimum curling values were also determined. Finally, the curling surface in course and wale direction as a two features of curling phenomenon was predicted using artificial neural network which selects scale conjugate gradient learning algorithm based on process parameters of single jersey weft-knitted fabrics. Our findings confirm the good capability of artificial neural network algorithm to predict these features.     

影响竹浆纤维针织物起毛起球性的因素

为深入分析竹浆纤维针织物起毛起球性的影响因素,根据7种竹浆纤维纬平针针织物的基本结构参数和起毛起球性的测试结果,应用灰色关联分析法对织物基本参数与起毛起球性之间的关系进行了定性和定量分析.结果显示:对起毛起球性的影响程度依次为织物的面密度、纵密、厚度、纱线线密度、氨纶含量、织物横密和竹浆纤维含量;含氨纶纯竹浆纤维针织物...     

成圈型贾卡经编针织物仿真探讨

文章从贾卡基本提花原理入手，对贾卡导纱针的偏移情况进行了说明；：介绍了两针技术、三针技术和四针技术等选针技术的成圈型贾卡织物组织结构；根据贾卡意匠图叙述了在进行仿真前需作的贾卡意匠信息处理；并通过线圈结构模型和纱线仿真过程最终实现织物仿真。     

玻璃纤维多轴向经编织物增强复合材料弯曲性能的研究

通过测试玻璃纤维多轴向经编织物增强复合材料的三点弯曲全载荷—挠度曲线 ,研究了不同树脂基体和不同增强体取向对复合材料弯曲性能的影响。     

A novel approach for simulation of curling behavior of knitted fabric based on mass spring model

Edge curling is a unique property of knitted fabrics which affects on fashion such as using upper and side curling in cloth design. The purpose of this research is to present a new method to simulate drape behavior of knitted fabric considering difference between single and double jersey knitted fabrics. To this point, at first the bending and torsion moments that applied on the fabric edges and caused curling in single knitted fabric are determined. Also it demonstrated that these moments will be neutralized in double knitted and as the results, leads to a non-curling structure. Then, using the mass spring model, curling shape in fabric wale and course directions are simulated. To show efficiency of the proposed model, real 3D shape of single knitted fabric is compared with experimental results. Also, using the proposed model, the drape behaviors of single and double jersey knitted fabrics hanging from two fixed corners with different properties are simulated and then extend to simulation of skirt. Results of simulation are compared with 3D shapes of actual drape behavior in fabric samples which are achieved by depth camera. The simulated results show good agreement with 3D shapes of actual fabrics.     

丝织物抗弯刚度仪的原理和研制

丝织物抗弯刚度仪是采用高精度测力传感器和位移传感器，并据纺织总会“织物弯曲试验方法”的原理研制而成的。该机设计合理，测试精度同，操作简易，使用方便能检测各种真丝与仿真丝织物的弯曲刚性。文章着重介绍了电路设计与工作原理。     

经编间隔织物的冲击性能

为探讨间隔织物在一定冲击能量下对人体(支撑物)的保护性能。采用的原料为在拉舍尔双针床经编机上编织的6种不同结构(不同间隔丝梳栉横移针距、间隔丝直径和织物厚度)的间隔织物。分析了不同织物在一定冲击能量下的应力、能量和能量吸收效率特征。实验结果表明,随着间隔丝梳栉横移针距数的减小、间隔丝直径的增大,冲击产生的应力峰值减小,吸收的能量和能量吸收效率峰值增加,但间隔丝过于接近垂直的织物容易发生倒伏,不利于人体保护。较厚的织物产生的应力峰值小、吸收的能量多,中等厚度的织物能量吸收效率峰值高。刚度或厚度大的织物由于产生的应力峰值小有利于人体保护,但在选择织物结构时还需考虑人体穿着的舒适性。