Effect of Knitting Process on Elastic Property of Polyethylene Terephthalate (PET)/Polybutylene Terephthalate (PBT) Warp Knitted Fabric

This study investigated the elastic elongation and elastic recovery of the elastic warp knitted fabric made of polyethylene terephthalate( PET) and polybutylene terephthalate( PBT)filament. The effect of knitting parameter on the elasticity of PBT /PET warp knitted fabric was analyzed. The increase of drawing density( from 16 to 26 courses per centimeter( CPC)) on machine resulted in the decrease of elongation at the weft direction. But,the elongation at the warp direction fluctuated as drawing density increasing. The yarn run-in speed influenced the elongation of PET /PBT warp knitted fabric as well. When the yarn run-in speed of GB1( front bar) was kept a constant,the increase of GB2( back bar) yarn run-in speed caused the gradual enhancement of the elastic elongation at the warp direction,but the different trends of the elastic elongation at the weft direction. When yarn run-in speed of GB2 was kept a constant,the increase of GB1 yarn run-in speed enlarged the elastic warp elongation from 104.16 to 124.97 mm,while the weft elongation decreased from 110.34 to 98.03 mm.Eventually yarn run-in speeds of GB1 and GB2 were retained at1 360 and 1 170 mm / rack respectively under 20 CPC drawing density. It could not only balance the two directions of elongation but also reach the highest elongation at both directions( 126. 32 and115.88 mm) under 100 N tension. These results provide a better understanding of characteristics of PET / PBT warp knitted fabric,and its elastic elongation and recovery behavior for development and effective applications.

Performance of Flexible Warp Knitting Metal Mesh with Notch

Three different kinds of notch involving single edge notch （ SEN）, double edge notch （ DEN ） and central notch （ CEN ） were preset in flexible warp knitting metal mesh, and the tensile properties of notch samples were tested. Three kinds of notch samples＇ sensitivity were investigated through different notch lengths. Then failure process and tensile properties were contrasted and analyzed between intact and notch samples. Experiment and analysis results showed that positive Poisson＇s ratio effect gave rise to obvious waist binding and special inverted triangle loading area. All samples were sensitive to three kinds of notches. And notch sensitivity was closely related to notch form and notch length. The notch procession obviously deteriorated the mechanical properties of flexible warp knitting metal mesh. Sample with different notch lengths and breakage locations determined different tensile strengths that sample could bear. The fitting function of waist binding track satisfied the parabolic equation.

Positions of Guide Eyes in Circular Warp Knitting Machines

The special lapping requirements were pointed out and the safe range to fix the guide eyes on the circular guide unit was determined by means of Locus Formulas of Warp sections in lapping movement, which were carried out on installing prototype machine. Based on the calculations of the force components acting on lapping points, the positions of the guide eyes in chain overlapping could be used to determine the safe range that could meet the requirements for tricot overlapping. The safe range can ensure the successful lapping and the multi-guide unit designing in circular warp-knitting machines.

4th China Warp Knitting Design Awards held successfully

On August 27, 2008, the Fourth Haining·China Warp-Knitting Design Awards Press Release and Signing Ceremony was held in Shanghai.

The Road of Meili Warp Knitting Cluster

The Town of Meili, Changshu is an old town that owns thousands years of history. The symbol of this small town in Jiangnan is the Tower of Jusha from South Song Dynasty. From the nineties of last century, Meili has begun her story as a leading industry cluster of warp knitting. Meili Town owns 46 warp knitting enterprises, and more than 560 family workshops, more than 1,800 sets of different kinds of warp knitting machineries. More than 70% of the domestic warp knitting machineries is bought by Meili town. The main products include more than 30 kinds of plush. The annual production capability reaches 10 tons and annual output reaches four billions. More than 30 companies sell their products to Russian, South Africa, Nigeria, Romania and Middle East. Meanwhile the development of the industry activate doubling, slitting, brushing, dyeing, gigging, home textile, apparel and other related industry. The town of Meili now owns a complete industrial chain from raw materials to warp knitting, finishing and final products.

OPTIMAL SETTING-UP OF KNITTING ELEMENTS AND ITS EFFECT ON TENSION VARIATION

The dynamic yarn tension variations during knitting cycle are very difficult to control and be-come one of barriers to knitting on modern warp knitting machine.Examination of experimentaldata and theoretical analysis show that the relative position of spring rail to knitting elements suchas needle,guide as well as their displacement has noticeable effect on tension variation so that theknitting condition can be much improved by rearrangement of the knitting elements and theirmovement within a knitting cycle.

Effect of Run - in Ratios on the Mechanical Properties of Two - Guide Bars Warp - Knitted Fabrics

Warp knitting technology gets rapid development at present and becomes one of the most important parts of the textiles.But it is less known how the parameters of warp knitting technology affect the mechanical properties of warp-knitted fabrics.This paper presents discuss a research on the relationships between run-in ratio and mechanical properties of the two-bar warp-knittedfabrics through the measurement and analysis of the mechanical properties of various samples with different run-in ratios.The optimal run一in ratios for the reasonable mechanical properties are obtained from above dis-

Application of Bi-axial Warp Knitted Structures in Concrete Constructions

The warp knitted bi-axial directionally oriented structure (D. O. S. ) reinforcement substrates applied to building construction are discussed in comparison to woven fabrics. One of usage barriers of reinforced cement with gloss-grid is its sensitivity to alkali existed in the cement which will lead to the reduction of its service-life. The tests show that the treatment by sol-gel method to protect the composite from alkali corrosion is effective. Then two formulae of sol-gel solution are also recommended here for application.

In-plane Tensile Behaviors of Bi-axial Warp-Knitted Composites under Quasi-static and High Strain Rate Loading

The in-plane tensile behaviors of bi-axial warp-knitted(BWK) composites under quasi-static and high strain rates loading were experimentally analyzed in this article. The tensile tests were conducted along warp direction( 0°) and weft direction( 90°) at quasi-static rate of 0. 001 s^(-1) and high strain rates ranging from 1 450 to 2 540 s^(-1),respectively. It is found that the significant strain rate sensitivity can be observed in the stress-strain curves of BWK composites. The fracture morphologies of BWK composites demonstrate that the tensile failure modes are shear failure and fiber breakage under the quasi-static testing condition while interface failure and fibers pullout are at high strain rates.

Computer-aided Pattern Design of Multi-bar Warp Knitted Fabrics

To meet the development trend of multi-bar warp knit-ting machine towards high-speed,advanced technologyand computer control and the requirements of variousproducts with small quantity,there are many researcheson the computer-aided pattern design of multi-barwarp knitted fabrics.In terms of the special propertiesof the computer-aided pattern design of multi-barwarp knitted fabrics,the Object Oriented Program(OOP)programming-Object Windows class Library(OWL)programming is selected.According to thecharacters of the OWL programming,various functionsare defined.Pattern design and technical parameters canbe output,which offers a great convenience for the fac-tory.

The Mechanical Behaviour of Rubber Hose Reinforced with Warp Knitted Fabric

A new process for the rubber hose reinforced with warp knitted fabric was introduced, and the relation between the inside pressure and the radial expansion ratio of four kinds of rubber radiator hose reinforced with warp knitted fabric was investigated. The result showed that the bursting pressure and the radial direction expansion ratio of the hose could meet the requirement of ISO4081 for auto radiator hose. A new model was built up to analyse the relation between the inside pressure and the radial expansion ratio of the hose based the reinforced fabric structure parameters and yarn properties.

Influence of Wires Properties on Warp-Knitted Loop Geometry in Plane Based on Theory of Elastic Rod

Based on classic theory of elastic rod,the warp-knitted loop geometry in plane is independent of yarn properties,while there is a certain gap between the geometrical model and the actual fabrics.According to this problem,further analysis of loop geometry is done based on the theory of elastic rod with theoretical calculation and experiments.The theoretical analysis found that the distance between the contacted points at the loop root affected the loop geometry,and the distance was affected by the ratio of bending rigidity and the friction between yarns.The experiments,forming simple loop by taking the yarn as an elastic rod,found that the bending rigidity affected the loop geometry.Then the relationships between warp-knitted loop geometry in plane of metallic fabrics and wires properties were studied.The results show that metallic fabrics are more suitable for the theory of elastic rod;the friction and bending rigidity of wire yarns affect the loop geometry in plane.Also,the elongation of yarn affects the loop geometry in the actual warp-knitted fabric.

Research on Tearing Property of Reinforced Plastic Film with Bi-axial Warp Knitted Fabric Skeleton

The specification of laid-in and warp yams,thedensity of fabric and the specification of groundyam are of great importance when the bi-axialwarp knitted fabric being knitted.In this paper,the tearing property of the reinforced plastic filmwith bi-axial warp knitted fabric skeleton istested and analyzed.The resuits show thatamong the three factors,the specification of laid-in and warp yam has the greatest influence onthe tearing strength of the reinforced plastic film,while the rest of them has secondary and lesseffect respectively,and there is exponential re-lation between the tearing strength of the rein-forced plastic film and the number of yams in thedirection of force.

3D间隔织物/改性空心微珠复合材料吸声性能研究

将3D经编间隔织物加入到空心微珠增强聚氨酯基复合泡沫塑料中,制备出新型3D间隔织物/改性空心微珠复合材料,并对所加入微珠进行界面改性,以改善其与聚氨酯基体的界面结合及吸声性能。采用阻抗管传递函数法对4种具有不同规格的试样进行吸声系数测试,对试验结果分析可知,改性后微珠在一定程度上提升此种新型复合材料的吸声性能,改性S60微珠增强的复合材料样品吸声性能更优。此外,该复合材料在中低频率下的吸声系数要小于高频率下的吸声系数。

填充物的力学性能对坐垫舒适性影响的仿真分析

将经编间隔织物和不同密度的海绵材料作为坐垫的填充物,通过分析坐垫上的人体体压分布情况,深入探讨坐垫的整体舒适度。首先,选择中密度海绵(28 kg/cm^(3))、高密度海绵(50 kg/cm^(3))及新型弹性材料经编间隔织物,分别对其进行力学性能实验。随后,采用有限元仿真法,对三种材料分别进行单轴压缩仿真,分析得出拟合度最高的本构模型;对经编间隔织物材料进行微元变形仿真,分析该材料变形量、压强、厚度三者关系的数学模型。最后,建立弹性坐垫和中国50百分位男性的人体臀部(软组织+骨骼)仿真复合模型,分析臀部与垫面的体压分布数据,并利用体压测试仪验证仿真数据的有效性。结果发现:仿真结果显示,中密度海绵、高密度海绵及经编间隔织物体压-应变拟合度最高的本构模型选低密度泡沫较合适;经过MATLAB进行二次多项式拟合可得出经编间隔织物的变形量、压强、厚度三者之间的数学模型;经编间隔织物弹性坐垫垫面的峰值比中密度海绵弹性坐垫垫面的体压峰值大,比高密度海绵弹性坐垫垫面的体压峰值小,整体垫面体压分布情况较海绵坐垫更均匀;体压测试仪验证仿真数据与实际测试数据小于5%,表明仿真实验可行。研究表明,经编间隔织物比海绵材料具有更好的支撑性和压力舒适性。这些实验结果以及虚实结合的方法可为未来弹性坐垫产品的材料选择及开发提供参考。

芳纶/玻纤经编复合材料的力学性能研究

研究芳纶/玻纤混杂纤维双轴向经编复合材料的力学性能。以芳纶/玻纤混杂纤维双轴向经编织物为增强体,将№1⁃695⁃3K A环氧树脂与№1⁃695⁃3K B固化剂混合,基于真空辅助树脂传递模塑技术制作复合材料,并与同状态下玻纤经编复合材料对比,研究两种复合材料在拉伸性能、弯曲性能和低速冲击性能上的区别。结果表明:与玻纤经编复合材料相比,芳纶/玻纤经编复合材料沿纱线加载方向的拉伸强度和弯曲强度分别提升了约20%和26%,最大冲击载荷提高了约45%。认为:芳纶/玻纤经编复合材料具有更好的力学性能,可替代玻纤经编复合材料用于工程领域。

间隔织物-羊毛角蛋白气凝胶复合材料研究

采用羊毛角蛋白制备有机气凝胶,存在结构不稳定、力学性能较差等问题。为提升材料的性能,通过还原C法从废旧羊毛中提取R-角蛋白并制备角蛋白气凝胶,将特殊的三维立体结构经编间隔织物引入气凝胶中,开发出经编间隔织物增强废旧羊毛角蛋白气凝胶复合材料,并对废旧羊毛的溶解率、提取率以及材料的密度、力学及隔热性能进行测试与分析。结果表明,通过还原C法得到的羊毛溶解率为89.4%,R-角蛋白提取率为72.6%。复合材料的密度不超过28.23 mg/cm^(3),具备传统气凝胶低密的优良特性,同时经编间隔织物与角蛋白气凝胶原位复合后,材料的压缩性能显著提升,并仍具有良好的隔热性能。

经编间隔织物增强亚麻纤维/硅橡胶复合材料的压缩性能

通过将亚麻纤维/经编间隔织物与软质硅橡胶进行复合,制备8种具有不同结构参数的经编间隔织物增强亚麻纤维/硅橡胶复合材料试样。对复合材料进行平板压缩试验,探讨经编间隔织物结构参数、亚麻短纤维长度和质量分数对复合材料压缩性能和压缩能量吸收性能的影响。结果表明:由结构正切值较低的间隔织物和较长的亚麻短纤维制成的复合材料具有较好的抗压缩能力;亚麻短纤维质量分数过高时,复合材料内部摩擦增加,材料压缩性能降低,亚麻短纤维质量分数过低时,则无法有效增强复合材料的压缩性能。基于Spence不变量本构理论建立压缩状态下复合材料的细观压缩力学理论模型,对其压缩性能进行模拟分析与预测,结果表明,所建立的细观压缩力学理论模型可有效模拟20%形变内复合材料的压缩演化过程。

基于Spline算法经编间隔织物的仿真建模

现阶段大多建模方法得到的模型保形性差,且缺少光照处理。文章提出一种基于Spline插值算法的建模方法,该方法保证曲线经过所有控制点,在三维空间上建立与实际织物基本相同的空间曲线,解决了以往所得模型保形性差的问题,并且通过VC++以及OpenGL开发工具,可以加上环境光照渲染、纹理处理等,使仿真模型更为写实,得到的仿真模型可以节省人力和物力及时间,能够在短时间内为设计人员提供更为准确的设计思路和方案。

基于线圈结构的双针床经编毛绒织物三维仿真

为实现高效率、低成本双针床经编毛绒织物开发,在分析了双针床经编毛绒织物形成及运动规律的基础上构建了垫纱数码数学模型、穿经数学模型,由数学模型自动生成垫纱运动轨迹。探讨了成圈及衬纬结构形成的毛绒织物的编织规律及其工艺,在研究其线圈结构及毛绒形态的基础上,建立了理想状态下的成圈及衬纬毛绒线圈模型,结合毛绒仿真关键因素及生成工艺参数,利用C#和JavaScript程序设计语言在Visual Studio平台上进行编程,实现了双针床成圈型及衬纬型毛绒织物的三维仿真。通过与实物图对比,验证了该模型可以真实模拟实物花色效果,仿真效果相似度高,可有效解决毛绒花型设计局限性的问题,降低设计难度和生产成本,解决设计周期长的问题,提高了生产效率,使双针床经编毛绒织物的应用得到广泛推广。