加捻金属丝纱线的制备及其弯曲刚度

为降低高刚度、高模量、低延伸性金属丝纱线的弯曲刚度以便于针织物的编织,分别采用传统的转杯纺纱机和管绞机对不同线密度的镀金钼丝单丝进行加捻,借助三维视频显微镜和纯弯曲试验仪分析了2种加捻工艺及单丝线密度对加捻前后纱线外观形貌以及弯曲刚度的影响。结果表明:与转杯纺得到的金属丝纱线相比,采用管绞机加捻得到的纱线外观紧密均匀且平直光洁,存在较少的残余扭矩,管绞机更适合用于对刚性纱线进行加捻;在纱线线密度相同的条件下,单丝线密度与纱线的弯曲刚度成正比,可通过降低纱线中单丝的线密度来降低纱线的弯曲刚度,从而增加纱线的柔软性使其更易于编织。     

聚丙烯单丝在拉舍尔经编机上的编织性能探讨

聚丙烯单丝模量高、抗弯刚度大、断裂伸长率低，所以编织性能较差，尤其是直径较大的单丝。文章研究了聚丙烯单丝的拉伸、压缩、弯曲和摩擦等力学性能，并在拉舍尔经编机上进行了编织试验，在此基础上提出了改善和提高聚丙烯单丝编织性能的方法。     

T形截面三维编织复合材料细观结构分析及弯曲性能预测

根据矩形组合截面三维编织复合材料四步法编织原理,分析了T形截面编织物的纱线运动规律,按照载纱器的水平运动规律确定了纱线的空间运动轨迹,并用控制体积法建立T形截面交接区域的特殊细观结构模型。在假设纱线截面为椭圆形等理想状态下,建立了编织工艺参数之间的数学关系。运用弯曲刚度合成法预测了T形截面三维编织复合材料的弯曲性能,用MatLab编写了弯曲模量的计算程序。结果表明：弯曲模量随编织角的增大而减小,随纤维体积含量的增加而增大,三维五向T形截面梁的弯曲性能优于三维四向的。最后将预测结果与实验结果进行比较分析,结果证实用弯曲刚度合成法预测T形截面三维编织复合材料的弯曲性能是可靠的。     

三维编织复合材料T型梁的低温场弯曲性能

为研究三维编织复合材料T型梁低温环境下的弯曲力学性能,以指导耐低温抗弯曲三维编织复合材料结构设计,采用真空辅助树脂传递模塑成型工艺制备不同筋高高度三维编织复合材料T型梁,自制低温环境箱,与MTS 810.23型材料测试系统相结合测试三维编织复合材料T型梁在不同低温下的弯曲力学性能。结果表明:随测试温度的降低,三维编织复合材料T型梁载荷增加,位移增大,能量吸收增加;随筋高高度的增加,三维编织复合材料T型梁载荷增加,位移减小,能量吸收增加,抗弯刚度增强;三维编织复合材料T型梁由较高温度下不同程度的屈服断裂转变为低温下的脆性断裂,随着筋高高度增加,失效模式由弯曲失效转变为剪切失效。     

温湿度对苎麻纱强伸性能的影响

探究了在不同温湿度下苎麻纱强伸性能的变化规律.分别测试了纱线在不同温度和注水量下的强力与伸长,计算得出弹性模量值,并进行纱线力学性能随温度和注水量变化的实验.实验结果表明:随温度升高,浸湿的苎麻纱强力下降,但相对于干燥状态下的强力,其下降趋势小的多,伸长先保持不变后逐渐下降;苎麻纱的弹性模量在50℃浸湿状态下达到最小,弯曲刚度也达到最小,在针织机上弯纱成圈时更容易.研究苎麻纱线的强伸性能,为苎庥纱线高效高质编织提供参考.     

三维四向编织复合材料刚度的细观力学设计

为了实现工程应用中三维编织复合材料的灵活设计,合理优化纤维束结构参数使得三维编织复合材料宏观刚度达到要求。基于非连续介质力学方法建立桁架结构单胞模型,采用有限元法预估复合材料的有效弹性模量,以材料质量最轻和刚度要求为目标,选用遗传算法优化细观结构参数。对纱线线密度和编织节距长度的优化结果验证,实验表明,桁架单胞模型结合遗传算法可以为满足弹性性能要求的三维编织复合材料快速地找到最优的细观结构参数。     

用于热塑复合材料的混合纱织造性能

研究了由玻璃纤维和丙纶纤维组成的包芯编带纱、摩擦纺纱、空心锭子包缠纱以及玻璃纤维纱的织造性能。在设计的实验条件下,经过100次摩擦后,包芯编带纱表面只出现少许毛羽,纱线强力基本没有变化;摩擦纺纱的包覆纤维被完全剥离,纱线强力下降60%;空心锭子包缠纱在摩擦70次左右发生断裂;玻璃纤维纱产生大量的断丝,强力下降52%。三维织造实验表明,包芯编带纱具有优良的可织造性能,而上述其它的纱线难以进行织造加工,特别是难以织造高密织物和三维织物。     

纸页的损伤力学

损伤力学是近２０年发展起来的一门新的学科。它是材料与结构的变形与破坏理论的重要组成部分。一、损伤力学的研究内容材料的内部有许多孔隙和微裂缝，在一定外部载荷下，微裂缝会不断地扩展，使材料的强度和刚度等力学性能下降，这些导致材料和结构力学性能劣化的微观结构变化称为损伤。结构材料中的损伤，有的是在制造和加工过程中产生的，称为初始损伤；有时是在外力作用下或环境因素影响下发生和演变的；有的是在自然状态下就是一种疏松介质，这类材料受力时，会在体内产生弥散裂纹。这些以孔洞或微裂纹形式表现的材料损伤，将在载荷、…     

涤纶微细旦空变丝与低弹网络丝织物披裂性能研究

本文研究和分析了涤纶微细旦空变丝和低弹网络丝的织物中，其长丝种类，单丝细度，纱线变曲刚度，纱线表观直径对织物披裂性能的影响。实验结果表明，微细旦变形纱随着其单丝细度的减小，其纱线表观直径和弯曲刚度明显下降，用其织制的织物交织阻力变小，织物易破裂，低弹网络纱织物与空变纱织物相比，由于其纱膨松性好，表观直径大，交织阻力较大，不易破裂。     

长丝纱的结构与织物的基本力学性能,表面性能的研究

本论文通过实验调查了常见的精梳毛型短纤维纱线、化学长丝仿毛的空气变形纱、低弹网络丝、长丝与短纤维的ｓｉｒｏ型复合纱和并捻型复合线的结构差异给织物的基本力学性能及表现性能造成的差异，发现其注要差异表现在织物的抗弯刚度及其弯曲滞后常数、抗剪切刚度及其剪切滞后常数、厚度方向的压缩性能、织物表现摩擦系数的平均差不匀率，并探明了纱线的结构种类与这些织物性能相关的具体规律。     

短纤纱动态拉伸性能

短纤纱的拉伸强力通常是评定纱线质量的重要指标。纱线拉伸强力在纺纱后道的大部分工序中(如整经、机织和针织)起着重要作用,因此对其精确的评定方法在工业生产中很重要。通过分析动态拉伸性能的定义和所用到的拉伸仪器,以环锭纺、转杯纺、喷气纺和摩擦纺的短纤纱的动态拉伸性能测试为例,做了几项有关理论和实验的工作,探讨了研究短纤纱动态拉伸性能在工业生产中的重要性,同时也总结出影响动态拉伸性能的因素有材料、纺纱参数和测试方法等,得出短纤纱静态和动态强力的关系。     

Coating of conductive yarns for electro-textile applications

Conductive yarns are used for integration of sensors and other electronic devices with textile fabrics through weaving, knitting, braiding or embroidery processes. In the lifetime of the textile also several washing cycles might occur. These processes involve rubbing which may lead to displacement of conductive fibres, causing short circuiting between the neighbouring conductive fibres. Also the textile products made with conductive fibres may have to work in the presence of water, where the exposed conductive fibres can get short circuited. In this work, an attempt has been made to protect silver-coated polyamide yarns with polypropylene (PP). This is done through wrapping the PP staple fibres around the silver-coated polyamide yarns through friction spinning and melting the PP sheath fibres in an oven. The influence of twist in the conductive yarns, amount of PP coating and the oven temperature during coating process on the tenacity, electrical insulation in the presence of water and flexibility properties of the coated yarns are studied. The PP coated yarns with plied conductive yarn in the core provide better flexibility but need higher amount of coating to provide complete electrical insulation in the presence of water as compared to those yarns with single conductive yarn in the core.     

Finite element analysis of monofilament woven fabrics under uniaxial tension

Mechanical behavior of woven fabrics under tensile load is complex because their deformation could result from the combined effects of tension, compression, bending, and shear. In this study, the tensile behavior of woven fabrics is simulated using finite element method. The input parameters are the mechanical properties of constituent yarns obtained from tensile and friction coefficient tests and the geometry of woven fabric repeating unit. First, a 3D geometric model of the repeating unit based on Pierce’s model was built using computer-aided design tools. Then, finite element analysis which incorporates material properties, frictional contact, and periodic boundary conditions was implemented using ANSYS. A non-linear mechanical behavior was defined. Frictional contact algorithm for the cross-sectional zone of the repeating unit and periodic boundary conditions to the contour of the repeating unit was implemented. Numerical simulation data and experimental data were compared, which showed good agreement.     

Bending and tensile properties of cotton/metal wire complex yarns produced for electromagnetic shielding and conductivity applications

Recently, there has been a growing interest in protective textiles that are produced in order to reduce detrimental effects that arise from electric and magnetic fields on biological organisms and particularly on human health. The main goal of this investigation is to develop conductive metal-based yarns with desirable properties. For the purpose of this study, by using copper and stainless steel wires and cotton yarns, core spinning technique was applied in order to manufacture hybrid yarns in modified ring spinning machine. Physical behaviour of complex yarns consisting of cotton yarn and metal wire was evaluated by investigating bending rigidity, tensile and hairiness properties of the samples.     

Influence of cyclic tensile straining parameters on the tensile characteristics of compact yarn

It would seem that previous tensile fatigue studies in yarns using the cyclic loading and extension principles were carried out with limited sets of variables and levels. To get a clear understanding of the tensile fatigue behaviour of yarns and in order to study the yarn damage under the influence of cyclic tensile straining, an investigation on the influence of various cyclic tensile straining parameters, extension level, extension rate and straining cycles at five different levels, on the tensile breaking load and breaking extension characteristics of compact yarn of count 14.75 Tex has been carried out. The extension level of 8 mm, the extension rate of 400 mm/min and the number of straining cycles of 2500 have resulted in the maximum drop in the breaking load and extension values of the yarn which are 30.4 and 40.25% lower than the average breaking load and extension values of the unstrained yarn.     

制服类面料低负荷下的力学性能对服装成形性的影响

通过KES系统研究了不同织物密度和后整理工艺调整对织物经纬向在低负荷下的拉伸、弯曲、剪切性能的影响,制作了曲面造型,分析了不同性能的织物曲面造型的难易程度.研究表明,面料在低负荷下的力学性能,尤其是剪切性能直接影响了面料制成服装的成形性.且同一种织物存在最佳工艺配制点,超过这个点后,某一类型服装造型的成形性显著降低.织物经、纬向的弯曲和剪切性能相互影响显著,经密或纬密变化将同时导致经向和纬向2个方向上的弯曲和剪切性能变化,而经、纬向拉伸性能则相互影响较小.对于制服类面料,尤其是适体性的制服类面料,应该注意到织物在低负荷下的力学性能,并进行规范.     

The electromagnetic shielding properties of some conductive knitted fabrics produced on single or double needle bed of a flat knitting machine

In recent years, the use of electrical and electronic devices has grown rapidly. These devices cause electromagnetic interferences, which could threaten human life. In order to solve this problem, intensive research to develop textile surfaces having electromagnetic shielding properties continues. In this paper, we study textile surfaces knitted with conductive copper and stainless steel wires wrapped with acrylic yarns and also core yarns produced by using conductive yarns to test the electromagnetic shielding properties of the fabrics. It was concluded that the knitted structure of the fabrics affected the electromagnetic shielding effectiveness (EMSE). Besides, the fabrics knitted on a double needle bed of the knitting machine with higher amounts of conductive yarns and unit weights could not provide the targeted improvement in the EMSE values with respect to the fabrics produced on a single needle bed of the knitting machine.     

棉/Ti3C2导电纱制备及其电容式压力传感器的性能

为了探究类石墨烯二维结构材料(MXene)与天然纤维的结合效果,及其所得导电纱线在柔性电容式传感器中的应用情况,以一种新型二维过渡金属碳化物Ti₃C₂为导电材料、以棉纱为基体纤维,实现了导电纱线的连续化制备;然后以此导电纱线为电极、以横编间隔织物为介电层,设计了一款电容式压力传感器。研究了处理时间对纱线微观形貌、结合效果以及导电性能的影响;分析了该压力传感器的力学性能与电容特性。实验结果表明:随着处理时间的延长,Ti₃C₂材料与棉纱复合得到的纱线电导率可达0.872 S/cm;制备的传感器压缩回复性好、电容特性显著,灵敏度最高达到0.028 kPa^-1,能在150 ms内对压力快速响应,200次压缩循环中展现了良好的耐久性与稳定性。     

Study of tensile properties of plain-woven fabrics in all-directional using energy method,Part I: theoretical study

Abstract

In the first part of this series, a new mechanical parameter, that is, “Comprehensive Tensile Modulus (CTM)” is introduced and modeled to show the tensile behavior of plain-woven fabrics in the initial linear elastic region of the force-elongation curve subjected to tensile load and extended it simultaneously in all directions. Considering the initial load-extension behavior of fabrics, a mathematical-mechanical model is presented to predict the CTM of fabrics in the initial linear elastic region using Castigliano’s theorem. Based on the generated model, the initial sample length, dimension of the load imposed region, the geometrical shape created in the plain-woven fabric sample during tensile, the structural specification of these fabrics such as yarns sett, yarns crimp in fabric and mechanical properties of yarns such as bending rigidity in both warp and weft yarns affect in the comprehensive tensile modulus of fabric. In order to verify the conformity and accuracy of the model, a preliminary test was conducted on the prepared samples based on a novel tensile test method developed to measure load-extension curve of the fabric samples under the proposed loading condition. A reasonable agreement was found between theoretical and experimental results.     

机织针织复合织物与多层双轴向纬编织物拉伸性能对比

选用玻璃纤维作经纱、纬纱和高强涤纶作针织纱分别编织机织针织复合(CWK)织物和多层双轴向纬编(MBWK)织物,测试两种织物的横向、纵向的拉伸性能,分析比较拉伸负荷和位移特征曲线。研究表明：在拉伸过程中,CWK织物MBWK织物均先由其中的经纱或纬纱,在较低的伸长下,承担较高的负荷,直至经纱或纬纱断裂,然后由针织结构,在较高的伸长下,承担较低的负荷,直至针织结构破坏;经纱和纬纱以交织形式衬入针织结构中,使得CWK织物的轴向的拉伸强度稍低于MBWK织物,但起到一定的“预牵伸”作用,可使针织纱对经纱和纬纱捆绑效果更好。