采用ABAQUS的粘胶机织物拉伸力学性能仿真

为预测织物拉伸性能,采用有限元方法对织物拉伸力学进行数值模拟分析。在实测织物几何结构参数的基础上,借助纺织建模软件Texgen建立了织物模型;利用有限元软件ABAQUS模拟织物拉伸环境,设置材料属性、相互作用和边界条件,得到织物拉伸变形后应力分布云图以及拉伸时应力—应变曲线图等数值模拟结果;最后通过织物拉伸强力测试实验对数值模拟结果进行了验证。结果显示：模拟所得应力—应变曲线和实验所得拉力—伸长曲线上升趋势大致相同;模拟所得最大拉伸应力与实验所得拉伸应力平均误差为3.03%,证明了采用ABAQUS有限元软件模拟粘胶织物拉伸力学性能的是可行的。     

针刺滤布生产中纤维、针布和刺针的选配

为了提高针刺非织造布产品品质,从针刺滤布用原料纤维、梳理用针布及刺针选配三个方面进行了详细阐述。指出:纤维是针刺非织造布基本原料,其物理性能指标直接影响最终产品的质量;在生产前首先应掌握原料纤维的物理性能指标、优缺点及影响最终产品的关键点,并针对纤维、设备及具体工况条件制定工艺;梳理工艺在非织造布生产中十分关键,它又是通过针布来实现的,所以应根据所加工的原料品种、纤维性能、各辊筒尺寸及工艺参数,纤网克重及纤网杂乱要求等具体参数选择合适的针布规格及配置参数;刺针型号及刺针品质直接决定产品质量,应根据原料纤维细度,针刺工艺、工序作用具体选择刺针,同时刺针使用厂应和制造厂密切配合、交流,不断修正、提高刺针质量以适应生产需要。     

Study on needle punched jute nonwoven as an artificial medium for germination of seed: Effect of bulk density

A uniform, porous, and bulky mechanically entangled fibrous sheet, i.e., needle-punched nonwoven, from eco-friendly and natural, low-grade jute fiber, has been designed and engineered to use as an artificial medium for germination of seed in place of soil. Needle-punched nonwoven fabrics of different bulk densities have been prepared from low-grade jute. Bulk densities of needle punched nonwoven fabric can be changed due to change of punch density, area density and depth of needle penetration. In this case, bulk densities of fabric have been achieved by varying the punch densities only, keeping the area density and depth of needle penetration same/ unaltered. As per experimentation, 500 g/m² area density needle punched nonwoven with 0.116 g/cm³ bulk density shows the best quality of germination. This bulk density has been achieved using 160 punches/cm² and 13 mm depth of penetration as per the system applied and fiber used. It may be a good alternative as a medium of cultivation. The design of the bed is also proposed in the article. It is observed that in this artificial system, cultivation can be made in hostile condition and plant growth is better than that in soil. Its moisture-holding capacity and temperature control of medium help in better agriculture. This is highly applicable in the regions where soil is either not available or not suitable for cultivation.     

基于ABAQUS的筒状纬编针织物拉伸力学性能模拟

为更好地了解筒状纬编针织物抵抗拉伸变形的能力,基于对织物试样尺寸测量得到的几何结构参数,借助Rhino 3D建模软件建立了纬编针织物线圈模型和筒状纬编针织物模型;同时利用有限元分析软件ABAQUS在单位线圈和筒状织物2个方面研究了筒状纬编针织物的纵向拉伸性能;对织物拉伸过程进行有限元模拟和实验验证,并对针织物拉伸过程中纱线形变和应力分布进行探讨,将有限元仿真结果和拉伸实验结果进行对比分析。结果表明:筒状针织物纵向拉伸时,发生线圈转移和纱线伸长现象,其形变和应力变化的有限元分析结果描述准确,应力-应变数值计算结果与实验结果的差异在8%以内,证明有限元仿真的可行性。     

Nonwoven Production from Waste Rice Straw by Using Enzymatic Method

ABSTRACT

In this study, the nonwoven fabric is produced by rice straws to utilize agricultural organic waste. Rice straws dried after harvest are pretreated with NaOH, pectinase enzyme and wetting agent. Washed and softened fibers are cut at 4–5 cm staple length, blended in carding engine with cotton at 9/1 ratio. By carding band and needle punch process nonwoven fabric is obtained. SEM, EDX and FTIR analyses are applied on the fabric. Product’s inspection verified that pretreatments provided smoothness, removed noncellulosic substances, and decreased hydrophobic structure. Thus, a new nonwoven material to be used in textile is produced.     

A finite element approach to the modelling of fabric mechanics and its application to virtual fabric design and testing

This work presents a detailed finite element approach for textile fabrics for mechanical analysis and simulation by combining yarn properties, inter-yarn interaction and fabric structures. The fabric geometries are generated using the TexGen geometric modelling schema developed at the University of Nottingham. This geometric model of the fabric is interfaced with a mechanics modelling environment, ABAQUS, to predict its mechanical properties. The major advantages over other approaches are that all issues arising from textile mechanics modelling are considered, physically measured data are used as inputs and the traditional requirement of user intervention during model creation is removed. The developed model and its implementation are validated using the Kawabata Evaluation System for Fabrics on commercial fabrics subjected to variety of external loadings. The presented validation shows good agreement between the simulations utilising the finite element model and the experiments. The modelling approach is used as a virtual fabric design/testing system which allows designers to input yarn details and geometric fabric structures and to predict how the performance of the fabric depends on textile structures and basic material properties. The virtual testing shows that fabric mechanical performance depends in a complex way on structural parameters, geometric data and loading conditions due to the interaction between various deformation mechanisms. The virtual testing also shows that the bending and shear properties are very sensitive to the cross-sectional shape of the yarns, which need to be modelled accordingly in order to obtain good mechanical predictions.     

Investigation on filtration properties of polyester needle-punched dust filter

Abstract

In nonwoven filter fabrics, virgin polyester fibre is mostly used. Therefore, this study has been conducted with the use of virgin polyester fibre and recycled polyester fibre which is obtained after recycling of post-consumer bottle flakes to reduce the cost of filter fabric. The study is concerned to examine the effect of fabric GSM (grams/m²), needling density and depth of needle penetration on filtration efficiency and also to see the suitability of recycled polyester fibre in place of virgin polyester fibre. The study has shown that the increase in fabric weight resulted in increase in the filtration efficiency percentage. The increase in the depth of needle penetration resulted in increase in the extent of filtration efficiency initially; subsequently, it decreased. Similar trends were observed in case of both recycled polyester filter fabrics and virgin polyester filter fabrics. Though the filtration efficiency of filter fabrics prepared from virgin polyester fibre was slightly higher, the filtration efficiency of fabrics prepared from recycled polyester fibre was lower by only 2 to 3 per cent due to close difference in values of molecular weight (Mw) and polydispersity index (PDI). Therefore, looking to the filtration efficiency percentage, it may be suggested that recycled polyester fibre can be used in place of virgin polyester fibre for the manufacturing of needle-punched nonwoven filter fabrics.     

织物折皱回复性能的研究

把毛织物看成是具有内摩擦约束的弹性条，利用能量分析的方法对毛织物在折皱回复时的回复力与变形的关系进行了分析，通过；简单的模型及公式将织物在回复过程中的重要性质表征出来，理论与实测结果基本吻合。     

An Investigation of the Penetration Force Profile of the Sewing Machine Needle Point

The distributions of the tangential and radial stresses acting on the yam of a fabric during sewing as the sewing needle is inserted into the fabric have been discussed by means of the mechanical principles of elasticity. The influence on the needle penetration force caused by the shape of the cross section and the profile curve at the needle point has also been investigated. It is suggested that five parameters. i.e., the mechanical properties of the textile material k, the variation ratio y' of the needle radius, the contacting arc length θ. the frictional coefficient μ and the sewing machine speed v are the main factors that determine the penetration force of the sewing needle. The variation ratio y', or the slope at any point of the needle profile, is the most important factor for needle design. Depending on the analysis of the forces acting on the needle surface, an optimum profile curve has been obtained. If this curve is used as a new sewing needle profile, the penetration force can possibly be reduced by up to 20%.     

8—AN ANALYSIS OF THE YARN TENSIONS DEVELOPED DURING TUFTING: PART I. CUT-PILE TUFTING

An attempt has been made to analyse the yarn tensions developed during tufting. The input yarn tensions were measured on a Venor carpet-sample-tufting machine and related to the characteristics of the machine. Estimations were made of the maximum tensions developed during insertion of tufts into the backing fabric by measuring the upward force on a needle during tufting and relating this to the input tension.

Measurements on commercial tufting machines indicated, that the tension patterns developed in the yarn delivered to the needles were similar to those of the Venor machine and that an approximation to the maximum tensions developed during tuft-insertion could be realized by using the data obtained from the Venor-machine experiments.     

Finite element analyses of tensile impact behaviors of co-woven-knitted composite from unit-cell approach

This paper reports finite element analyses of tensile impact behaviors of co-woven-knitted (CWK) composite from a unit-cell model. A unit-cell model was established to characterize the microstructure of the CWK composite. A vectorized user-defined material subroutine was written and connected with commercial finite element analysis (FEA) software package ABAQUS to calculate the tensile failure of the CWK composites. The FEA results were also compared with the experimental results of the CWK composites under high strain rate tension obtained from the split Hopkinson tension bar apparatus. The comparisons indicate that the FEA results agree well with the experimental results. The failure mechanisms of the CWK composite under the different strain rates are also discussed.     

复合载荷下不同结构编织人工韧带的有限元分析

为探究不同结构编织人工韧带试样在人体正常步态中受到复合载荷加载时的应力分布以及摩擦损耗情况,使用有限元分析法进行数值模拟,基于纱线在空间中的螺旋轨迹以及交织规律,采用MatLab计算空间离散坐标点,并导入至Solidworks中建立试样三维模型。在ABAQUS中赋予试样材料属性、边界条件和接触摩擦属性,最后计算有限单元解。结果表明:有限元模拟曲线和实际测试曲线具有较高的一致性;施加外部载荷时,规则编织试样应力在2个方向的纱线上分布较为均匀,而三向编织试样应力主要集中于轴纱,且需要抵抗更多纱线之间的摩擦作用。该研究可为人工韧带的优化设计提供理论参考。     

Investigation of electromagnetic shielding effectiveness of needle punched nonwoven fabrics with staple polypropylene and carbon fibres

Conductive needle punched nonwoven fabrics are developed from staple polypropylene (PP) and varying weight fractions (10, 20 and 30 wt.%) of staple carbon fibres. A fibrous webs of staple PP and carbon fibres were formed at a wool-type carding machine, and these webs subsequently bonded on needle punching machine with 132 punches/cm² and 13.5 mm needle penetration depth. The electromagnetic shielding effectiveness (EMSE), absorption and reflection characteristics of as-produced needle punched nonwoven fabrics were determined using a network analyser as specified in ASTM D4935-10 in the frequency range 15–3000 MHz. The surface resistivity measurements were carried out in accordance with ASTM D 257-07 standard. These results indicate that the EMSE values increase incrementally with frequency in the 15–3000 MHz range. The nonwoven sample with 30 wt.% carbon fibre showed the lowest surface resistivity of 3.348 kΩ and corresponding highest EMSE of ~42.1 dB in the 3000 MHz frequency range. In comparison, the highest EMSE values from 10 to 20 wt.% staple carbon fibre were found to be 15.6 and 32.2 dB in the 3000 MHz frequency, respectively. It was observed that the absorbance and reflectance curves of each nonwoven fabric move at opposite directions to each other. It was found that as the amount of carbon fibre in the nonwoven fabric increases, absorbance values decrease, but reflectance values increase. The resultant nonwoven fabric samples are expected to be used as garment interlining after thermal bonding and wall interlayer in the future.     

Ranking fibre and process parameters affecting thermal resistance of needle-punched blankets using neural network model

In this paper, an artificial neural network (ANN) model has been designed to predict the thermal resistance of needle‐punched blankets. Web‐laying (parallel‐ and cross‐laid), fibre fineness, fibre degree of hollowness, fabric weight, depth of needle penetration and needle punch density are considered as input parameters to predict the thermal resistance of needle‐punched nonwoven blankets. In order to reduce the dependency of the results on a specific partition of the data into training and testing sets, three‐way cross validation tests were performed, that is, total data were divided into training and testing sets in three different ways. The predicted thermal resistance correlated well with the experimental thermal resistance. The relative contribution of each parameter to the overall prediction of the thermal resistance was studied by carrying out a sensitivity analysis of the test data set. The results of sensitivity analysis show that web‐laying is the most important input parameter, followed by depth of needle penetration, fabric weight, degree of fibre hollowness, needle punch density and fibre fineness.     

Study on Some Functional Properties of Mesta Needle Punched Nonwoven Fabrics Using Central Composite Rotatable Design

The combined effect of two structure forming process parameters i.e. punch density and needle penetration on properties of Mesta needle punched nonwoven fabric has been studied using central composite rotatable design. As properties are structure dependent, the relationship between compressional behavior and other functional properties was studied. It was observed that compressional (α) and recovery (β) parameters are well correlated with tensile, air permeability and thermal insulation value of Mesta needle punched fabric. The regression equations were also suggested. Therefore, the α and β may be used for indirect approximation of these properties with reasonable accuracy.     

An investigation into the effects of fiber architecture on the mechanical behavior of woven preforms

This study attempts to analyze the behavior of different types of woven composite preforms (i.e. plain, twill, and satin) under distinct loading conditions. To this end, fabric elements are modeled using discrete finite element approach. Different loading scenarios such as intra-ply shear, in-plane tension, and simultaneous intra-ply shear and in-plane tension loads are applied to the fabric elements. TexGen software is utilized to develop the geometric model of the fabric elements. Subsequently, the geometric model is exported to ABAQUS FE package and mechanistic analyses are conducted. The FE results reveal that under the same loading conditions, the in-plane tensile stress induced in plain weave elements has the minimum value compared to twill and satin elements. Having said that, the intra-ply shear resistance of the plain element is larger than the other weave types. What’s more, the behavior of the fabric elements under simultaneous intra-ply shear and tension loading scenarios are studied that discloses almost the similar response for all weave types.     

地毯簇绒机簇绒针传动机构运动分析

 地毯簇绒过程中簇绒针的力学和运动性能制约了主轴转速的提高,影响着整个机械系统的振动特性,而簇绒针的运动性能直接取决于传动机构的设计。根据地毯簇绒运动的工作原理,设计了由曲柄摇杆机构和曲柄滑块机构组合而成的簇绒针传动机构,并对传动连杆机构的运动进行了数学分析;应用ADAMS仿真软件对不同曲柄参数条件下的传动机构进行运动分析和比较,着重对簇绒针刺入底基布时的运动和受力状况进行讨论,确定了曲柄的最优设计值。分析结果已应用到DHT-200地毯簇绒机的设计实践中。     

地毯簇绒过程针梁受力测试与工艺分析

为分析地毯簇绒机主轴执行机构的受载情况,提出一种间接测试主轴系统末端执行机构受力的方法,完成主轴1转内针梁推杆的受力和不同主轴转速下针梁的受力测试。测试结果表明,随着主轴转速的提高,针梁推杆受到的冲击越加明显,针梁推杆受到的拉力随之变大,并且拉力的变化也趋于激烈,而针梁受到的最大压力随主轴转速变化不大。为此,提出在工艺上采用将喂纱时刻逐次提前、适当减小底布张紧程度的方法来改善主轴系统的受载情况。测试结果也为进一步计算分析主轴等效力矩提供实验依据。     

簇绒地毯织机耦联轴系的铰链间隙对毯面绒高的影响

为给高质量簇绒地毯的开发提供设备保障,针对运动副铰链中存在间隙的问题,以3处易磨损的铰链间隙,基于虚拟样机ADAMS软件得到不同间隙下簇绒针的位移、速度、加速度及铰链支反力,从而根据针位移分析铰链间隙对毯面绒高的影响。再以铰链点坐标及杆长为设计变量,以铰链副间的冲击力和针行程最小为优化目标,对该簇绒针机构进行多目标优化,得到最优的铰链坐标及杆长,将铰链间隙对绒高的影响降到最低。     

无土栽培用废棉非织造布基质的设计开发

以无土栽培基质所要求的物理性状为依据,采用棉纺厂落棉,根据Design-Expert软件设计的实验方案,利用非织造布针刺技术,生产了17种非织造布基质。采用响应曲面法,建立针刺工艺参数与基质主要物理性状和草坪综合评价的数学模型,并进行拟合优度检验,实现了基质针刺工艺的最优化。研究表明废弃棉纤维能够作为无土栽培基质的原料,生产的非织造布基质有利于水分的吸收、排放、通气及根系的伸长和结构的稳定。