间隔层结构参数对纬编间隔织物压缩性能的影响

采用4根16.6tex(150D)涤纶低弹丝为表面纱,0.10、0.12mm涤纶单丝为间隔丝,在机号E14的电脑横机上通过改变间隔丝的集圈方式、直径及密度编织了12种不同结构参数的纬编间隔织物;测试了织物的压缩性能,从应力-应变曲线、压缩功和压缩回弹性三方面考察了间隔丝的3个参数对纬编间隔织物压缩性能的影响。结果表明对于表面纱为低弹涤纶丝的间隔织物,在一定范围内间隔丝的集圈隔针距及直径的减小和间隔丝密度的增加可使织物具有更好的抗压能力;压缩功和压缩回弹性基本上随间隔丝集圈隔针距及间隔丝直径的增加而降低;而间隔丝密度的增加大都使织物的压缩功提高及压缩回弹性降低。     

高速经编机梳栉横移运动的优化设计

为改善梳栉横移运动,减小横移冲击,通过分析梳栉横移运动的工艺特性,运用机械运动学理论,选用适合高速凸轮机构的组合正弦加速度运动规律作为梳栉横移驱动曲线,研究影响横移运动特征值的4个因素：织针针距、横移针距数、经编机主轴转速和横移允许主轴转角。分析结果表明,可通过增大横移允许主轴转角的方法来优化横移运动,即在确保横移安全可靠的条件下导纱针横移提早起始点,延后结束点,增长实际横移时间,从而显著改善高速经编机梳栉横移的运动性能。     

经编机梳栉横移曲线特性改善方法

通过对KS型经编机的成圈过程及梳栉的横移运动进行分析,运用机械运动学理论,针对KS型经编机梳栉横移运动曲线,对梳栉横移过程进行分析,得出影响横移运动规律特性值的因素,包括横移针距数、针距、编花凸轮转速以及横移的凸轮转角。分析得出,可通过增大梳栉允许的横移主轴转角对横移运动进行优化,让梳栉横移的时间提早开始,推迟结束,并确保横移的安全,避免导纱针和织针相撞或擦断纱线。通过优化设计,高速经编机梳栉横移的运动性能得到改善,提高了机器运转速度。     

经编工艺基础讲座(五)——花板链条式横移机构中花板的形状和尺寸

经编机在编织过程中,导纱梳栉除在针间作摆动外,还要在针前和针后作横向移动。针前横移通常为一个针距,而针后横移运动的大小可以是一个针距、两个针距或者更多,这取决于织物的组织结构。在每个成圈横列编织过程中,针背垫纱横移的针距数过大,将影响机器的运行速度。考虑到织针的刚度,针背横移允许的最大针距数,一般     

新型纬编间隔织物及其复合材料的冲击性能

开发了一种双层V形(三角形)间隔层纬编间隔织物(WKSF)编织工艺，并在STOLL电脑横机上编织双层V形与双层U形WKSF,分别研究了两种织物的横向和纵向断裂拉伸性能。通过试验得到拉伸载荷-位移曲线。结果表明，双层V形间隔结构织物的横向拉伸性能优于双层U形间隔结构。同时研究了浸渍剪切增稠液(STF)的WKSF(STF-WKSF)冲击行为。通过冲击载荷-位移与能量吸收-位移曲线可知，在相同的冲击速度下，STF-WKSF比纯WKSF具有更低的峰值力和更高的能量吸收，STF可以有效提高织物的抗冲击性能；在不同的冲击速度下，双层V形结构的STF-WKSF比双层U形结构具有更好的缓冲性能。双层V形STF-WKSF可以用作人体局部缓冲保护材料。     

多弹性支承-轴向运动导纱梳栉的振动模型

针对经编机导纱梳栉由于弯曲振动造成导纱针与舌针摩擦的问题,基于连续梁理论从静态和动态方面建立了导纱梳栉的振动模型。通过能量法获得导纱梳栉的振动方程,通过边界条件和连续性条件获得导纱梳栉的特征方程和模态函数。在静态情况下,研究了不同材料和支承刚度对导纱梳栉固有频率和振型的影响;在动态情况下,研究了轴向速度、加速度和横移时间对导纱梳栉固有频率的影响。研究结果表明,材料和支承刚度对导纱梳栉振动的影响显著,而速度、加速度和横移时间的影响较小。研究结果可为减小导纱梳栉的弯曲振动和优化经编机的横移系统提供参考。     

Karl Mayer推出FC 20/16型经编机

FC20/16型经编机是编织网眼窗帘的机型。该机的主要特点是提花机构采用了新开发的通丝提吊式提花梳概念。通丝提吊式提花梳由细钢丝-提花梳栉及与之相连接的导纱片组成,由特殊的异形横移机构引导。每个异形横移机构可带8把提花梳,而两个异形横移机构组成一组。这种概念的优点就是在一定的空间内可容纳更多的提花梳栉和横移行列,同时减少了移动量。结合新的传动概念能更好地发挥这种优势,这种传动概念指的是伺服传动,它能使提花梳栉的最大横移距离达到180m m,而过去只能达到47m m。尽管横移距离增大,针距的精确度仍非常高,而且不需要经常保…     

贾卡经编织物编织技术(七)

提针式贾卡起花是利用贾卡装置,按花纹要求,由通丝直接将贾卡导纱针上提,从而使其引导的纱线的横移垫纱针距数发生变化的一种起花方法。如图100所示。贾卡梳栉始终作两针距针背横移。因此,图中左边的五枚贾卡导纱针,因处于原来的高低位置,它们引导纱线作两针距横移垫纱。而在右边的三枚贾卡导纱针,按花纹需要,受贾卡通     

经编间隔织物的缓压性能

为探究经编间隔织物的缓压性能与结构参数之间的量化关系,从理论上分析了经编间隔织物压缩过程中人体受力与间隔织物之间的相互作用机制,以及人体所受压强与其结构参数之间的关系,获得间隔丝直径、间隔丝排列密度以及间隔织物的厚度等结构参数与间隔织物缓压性能的规律方程。采用自行设计球形压头对不同结构参数的间隔织物样品进行压缩实验,验证分析间隔织物的缓压性能与这3个主要影响因素之间的关系,并得出了各自的回归方程。研究结果表明,间隔织物压缩过程中人体所受压强与间隔丝直径呈幂函数变化,与织物的厚度和间隔丝的排列密度分别呈反比和正比函数关系。     

纬编间隔织物/聚氨酯复合材料的制备与压缩性能

采用不同的3种集圈连接距离、3种间隔丝直径和3种间隔丝排列密度共制备了7种不同结构参数的纬编间隔织物。使用一步发泡工艺制备纬编间隔织物/聚氨酯复合材料,研究了织物结构参数对复合材料压缩性能的影响。结果显示:织物厚度大、间隔丝直径大和间隔丝排列密度大的复合材料有更大的抗压应力和更好的抗压性能。     

Impact resistance behaviour of silicone coated warp knitted spacer fabrics used for protective clothing

This paper aims to analyse the effect of coating, fabric layers and structural parameters on the impact resistance behaviour of warp knitted spacer fabrics used for protective clothing. For this purpose, six warp knitted spacer fabrics were produced by varying thickness and mesh structure and were coated with a silicone substrate. A drop-weight impact tester was used to determine the impact resistance characteristics of the samples. The results indicate that, the impact resistance properties of warp knitted spacer fabrics can be improved considerably by coating as reducing approximately 10 kN of the peak transmitted force. Also, the structural parameters such as fabric thickness and mesh structure have significant effects on impact resistance behaviour of the samples. The fabrics with higher thickness and smaller size mesh on the outer layers have better impact resistance properties. Additionally, the lamination of spacer fabrics can effectively improve the impact resistance characteristics of the spacer fabrics. The warp knitted spacer fabrics can be used as an energy absorbing material for body protection by varying their structural parameters, fabric lamination and/or by coating.     

衬垫用经编间隔织物的压陷性能

为获得具有良好支撑性和压力分布的衬垫用经编间隔织物,对不同规格的经编间隔织物的压陷性能进行研究。在双针床拉舍尔经编机上,通过改变织物纵密、间隔丝垫纱角度、间隔丝直径以及脱圈板距离,试织了13种经编间隔织物试样。测试了试样的压缩应力与应变曲线,并以25%和65%压陷硬度和支撑因子作为评价织物压陷性能的指标。探讨间隔丝密度、垫纱角度和直径以及织物厚度对经编间隔织物压陷性能的影响。研究结果指出：织物屈服阶段是研究织物压缩性能的重要阶段;通过各种结构参数的合理配置,可以获取具有理想压缩特性的经编间隔织物衬垫材料。     

纬编间隔床品面料的结构及性能分析

采用3.3 tex涤纶单丝为间隔纱,8.3 tex涤纶和2.2 tex氨纶交织为表层,制备4种不同密度、厚度及间隔纱连接方式的纬编间隔织物。分析织物组织结构和编织工艺,并测试力学性能和热湿舒适性能,分析面料厚度、密度与各项性能关系,用数学模糊分析法对面料进行综合分析。结果表明,间隔纱连接方式对面料拉伸断裂性和顶破性有一定影响,对透气透湿性无明显影响;厚度、密度较小且间隔纱交叉连接的织物综合性能最好;选择床垫面料时考虑厚度、密度及间隔纱连接方式对面料性能影响。     

三维横编间隔织物的编织工艺及其性能

为开发适合不同应用领域的曲面复合材料,采用新型三维曲面间隔结构,在电脑横机上用芳纶纱编织了带有双层罗纹连接中间层的横编间隔织物,探讨了编织步骤和编织工艺。在此基础上通过在间隔织物纬向的2个表层衬入芳纶增强纱,改进了织物的力学性能。通过调整编织程序,开发出不同曲率的间隔织物。在英斯特朗电子万能材料试验机上测试有增强纱和无增强纱织物的横、纵向拉伸性能,比较分析这2种织物的应力应变曲线。结果表明,在其他条件相同时,有增强纱的三维横编间隔织物横向、纵向拉伸应力增加明显,变形较少,织物尺寸稳定。     

Permeability and impact properties of warp-knitted spacer fabrics for protective application

An experimental investigation was carried out to study the effect of interlining material on the comfort and dynamic deformation characteristics of body armour. Suitable plies of interlining materials were selected based on the fabric comfort properties and the impact resistance specified for ballistic application. Kevlar woven fabric was used to block the projectile, and the spacer fabric was used as an interlining material to ensure wearing comfort and for imparting impact resistance. The yarn denier of the middle and bottom layers of the spacer fabrics was maintained constant, and three different deniers were used for the face layer. Three different plies of spacer fabrics were analysed by means of thermophysiological comfort properties to select the suitable interlining material for body armour. The experimental results confirm that the number of plies of spacer fabrics has significant influence on the ballistic armour characteristics than the face layer denier as proved by two-way ANOVA. The substantiated spacer fabric was used as an interlining material, and the depth and area of deformation were analysed. The research findings demonstrated that the three-plied warp-knitted polyester spacer fabric produced better results than single- and five-plied spacer fabrics. One-way ANOVA and Turkey’s HSD also confirmed the influence and interaction of different plies of spacer fabrics.     

Application of warp-knitted spacer fabrics in car seats

Polyurethane foam is commonly used as padding in car seats despite some problems concerning comfort and recycling. Compared with polyurethane foam, textile seat padding is easier to recycle; so textile padding is a good candidate to substitute foam padding as regulations on recycling have become more stringent on car manufacturers. With the available textile option, warp-knitted spacer fabrics are likely a good substitute for polyurethane foam as padding in car seats. Warp-knitted spacer fabric structures can be designed to be quite flexible in a variety of thicknesses. Warp-knitted spacer fabrics can be very resilient and may display good breathing properties. The current work presents a study on the application of warp-knitted spacer fabrics as cushion in car seats. The results show that, relatively to polyurethane foam, warp-knitted spacer fabrics demonstrate better recovery to compression, thermal properties and breathability. Furthermore, warp-knitted spacer fabrics retain their original thickness for longer time and can be easily recycled.     

An analysis of the bending rigidity of warp-knitted fabrics: a comparison of experimental results to a mechanical model

This study focuses on the bending rigidity of warp-knitted fabrics as a function of knit structure (underlaps length), density (wale and course spacing) and yarn bending properties. Seven standard warp-knitted fabrics are produced with three different densities (Tricot, Locknit, three and four needles Satin, Reveres Locknit, three and four needles Sharkskin). The bending rigidity of the fabrics is measured using a Kawabata evaluation system and an automatic cyclic bending tester. Results show that the bending rigidity increases for the fabrics with a higher density and underlaps length of the front and back guide bars. In addition, a new mechanical model for the bending behaviour of warp-knitted fabrics using an energy method is presented. In this model, the knitted loop structure is assumed to consist of a series of straight and skew yarns simulating legs and underlaps while considering a rigid region lying in the direction of bending. Experimental results show that there is a reasonable agreement between the calculated and measured values for both wale and course directions.     

曲面三维横编间隔织物复合材料的压缩性能

为研究曲面三维横编间隔织物增强复合材料的压缩性能,为后续低速冲击及剩余强度的研究提供实验数据,制作了满足要求的试样。将三维横编间隔织物织成平面与曲面2种,再分别制成2组不同曲率的复合材料。将不同曲率增强复合材料置于电子万能材料试验机上测试其压缩性能,分组比较其载荷与位移的曲线关系。结果表明：在其他条件相同时,不论是平面间隔织物复合材料还是曲面间隔织物复合材料,横向压缩载荷峰值都明显高于纵向;同组复合材料随着织物样片曲率的增大,压缩载荷峰值也呈逐渐增大趋势。     

Theoretical and experimental investigation of tensile properties of net warp-knitted spacer fabrics

Abstract

This work aimed to investigate the tensile behavior of net warp-knitted spacer fabrics using the experimental and theoretical approaches. Tensile behavior of the warp-knitted spacer fabrics is one of the fundamental parameters which rarely considered in the literature. Therefore, the net spacer fabrics were made with three different variables (fabric thickness, size of meshes, and the position of meshes of the outer layer with respect to each other) in order to study the effects of structural parameters on the tensile behavior. A 2D net-fabric which used for the outer fabrics was made for in-depth considerations and also the comparison between the 2D fabrics and spacer fabrics. The initial linear elastic modulus of the 2D fabrics and the initial linear elastic modulus of the spacer fabrics were selected for the assessment of the tensile characteristics. First, a mechanical model was developed based on the geometrical structures and material properties of the 2D fabrics using energy method and Castigliano’s theorem. Then, the effects of spacer yarns on the tensile behavior of spacer fabrics were taken into account. The latter model was proposed using the bending theory of a curved bar. Experimental data were compared with the values obtained from the theoretical approaches and the end results showed that the developed models can predict the modulus reasonably. Moreover, the results indicated that the tensile behavior of the spacer fabrics are independent of the position of the holes in the outer layer whilst the fabric thickness and size of meshes affect the tensile modulus.     

An experimental investigation into structure and properties of 3D-woven aramid and PBO fabrics

Three-dimensional (3D) fabrics are the focus of recent developments due to their versatile physical, structural attributes, and application scopes. These fabrics can be manufactured in various architectures which offer a great deal of opportunity to modify the weight, physical and mechanical properties, and cost of the various products. The potential usage of 3D woven fabrics in the ballistic protection applications was the main motivating factor of this research work. Thus, interest has been focused to investigate the structure and properties of 3D woven orthogonal fabrics with aramid fiber and PBO fiber in comparison with 2D fabrics. The investigation of ballistic properties of these fabrics showed that 3D woven fabrics are superior in terms of breaking load and energy absorption as compared to those of 2D woven fabrics. The specific ultimate tensile strength of 3D woven fabric was observed to be lower than 2D fabrics, which may be due to less number of load bearing yarns in the loading direction. The crimp percentages of the load bearing tows in 3D fabric are very less than that of 2D fabrics. Owing to the higher values of work at peak and load at peak, in knife penetration test, it is revealed that 3D fabrics offer better protection than 2D fabrics.