Prediction of the thermo-elastic properties of knitted structural composites using FEM

It is a very important and complex task to estimate the thermo-elasticproperties of a textile structural composite. In this paper, the finite element method (FEM) wasused for the prediction of the orthotropic thermo-elastic properties of a composite reinforced byglass fiber knitted fabric. In order to define the final 3-D configuration of the loop reinforcingstructure, the interactions between the adjacent loops, the large displacement and the contactelements without friction were considered. The values predicted were compared with the experimentalresults.

A MICRO-MECHANICAL MODEL OF KNITTED FABRIC AND ITS APPLICATION TO THE ANALYSIS OF BUCKLING UNDER TENSION IN WALE DIRECTION:MICRO-MECHANICAL MODEL

The typical micro-knitting structure of knitted fabric,which makes it very different from woven fabric,is described.The tensile tests of knitted fabric are reported.The deformations of the micro-knitting structures are carefully studied.The study indicates that when a knitted fabric sheet is subjected to a tension along w-direction an extra compressive stress field inside loop in c-direction is induced.The extra stress field is also determined through analysis.Finally,a micro-mechanical model of knitted fabric is proposed.This work paves the way for the simulations of buckling modes of a knitted fabric sheet as are observed in experiments.

Tensile Properties of Weft Knitted Fabric Reinforced Composites

Seven kinds of weft knitted fabrics from glass fiber yarns were used as reinforcement to make fabric/epoxy composite laminates. Tensile tests were carried out to examine and compare the mechanical properties in course and wale direction of these composites. On the basis of experimental results, attempts have been made to analyze some main factors influencing stress-strain curve, ultimate tensile strength and initial elastic modulus of specimens.

Investigation on the Dimensional Properties of Relaxed Plain Knitted Fabrics

A geometric model of relaxed plain-nitted fabric isproposed.A method based on the model for predictingthe loop length from the course spacing,wale spacing offabric and the diameter of yarn is deduced,as well as a computer program is developed to graphically represent the structures of plain knitted fabric with various struc-tural parameters.

Wet Permeability and Moisture Vapor Transmission Characteristics of Soybean Knitted Fabrics

Wet permeability of fibrous assembly is mainly influenced by the properties of liquid and the configurations of the fiber which consist of diameter of fiber, twist angle and fiber alignment in a yarn. It can be seen from experimental results that the knitted fabric made of soybean (SB) fiber has goodproperties both in wet permeability and vapor transmission so that the knitting technology and fabric characteristics can be improved.

Study on How to Design Knitted Fabric Pattern with Mathematical Theory

To improve design capabilities for the knitted fabric pattern,a preliminary study is carried out for the design method.Based on mathematical theory,pattern could be created automatically by computer with inputting different parameters for mathematical functions.The knitted fabric simulation is realized by M1 CAD pattern preparation system of STOLL Company.In the pattern,different color unit is replaced by obverse stitch with different color,or by obverse stitch and reverse stitch with the same color separately,after that the effects of knitted fabrics could be simulated.Designing with this method,it would not only help to acquire a great of diversity patterns,but also improve design efficiency and save cost.

Finishing Effect on Warmth Property of Cotton/Kapok Blended Knitted Fabric

Nowadays,more and more natural or functional fibers are being investigated due to their utilization in thermal underwear.Kapok fiber is one of the natural cellulosic fibers whose source is the kapok plant. It has hollow body and sealed tail,which exhibits desirable features required for functional textiles of this nature. In this study,cotton / kapok( 80 /20 by mass) blended yarn with two types of yarn size 18. 5 and 14. 8 tex,respectively are knitted into plain stitches. The fabrics are undergone with an optimal preparation plan according to orthogonal design. Then,after dyeing and softening,fabric properties including thermal and water-vapour resistances, wicking property, pilling behaviour, and surface morphology,are tested and scrutinized for their candidacy for thermal underwear. The results showed that cotton / kapok blended fabrics have good thermal resistance which is significantly higher than those of cotton / modal blended fabrics,and the same water vapour resistance compared with cotton / modal blended fabrics which are normally used as underwear. Cotton / modal blended knitted fabrics has better pilling grade than cotton / kapok blended fabrics. Meanwhile, the cotton / kapok blends fabrics have good wicking property. Collectively,it was concluded that cotton / kapok blended fabric was appropriate for thermal underwear. However,the main limitation of these fabrics is their pilling properties.

A micro-mechanical model of knitted fabric and its application to the analysis of buckling under tension in wale direction:buckling analysis

With the aid of the micro-mechanical model of knitted fabric proposed in Part 1 we analyze the buckling of a knitted fabric sheet when it is subjected to a tension along the wale direction. The large deformation of the fabric sheet in the critical configuration is considered and, to avoid possible deviation due to the approximation of the theory of thin plate, the three-dimensional theory of instability is used. The fabric sheet is considered as a three-dimensional body and all boundary conditions are satisfied. It is shown that the buckling of the fabric sheet is possible, two buckling modes and the corresponding buckling conditions are obtained, but only the flexural mode is physically possible as observed in experiments.

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.

Flexural Properties of Weft Knitted Fabric Reinforced Composites

Several different kinds of weft knitted fabrics from glass fiber yarns were used as reinforcement to make fabric/polyester composite laminates. Flexural tests were carried out to examine stress- deflection process and compare the mechanical properties in course and wale directions of these composites. The experimental results indicate that the numbers of load-bearing yarn in course and wale direction and the fabric density are the main factors influencing the ultimate tensile strength and initial elastic modulus of specimens.

A Distributed Online Custom System for Knitted Sweater

A new application of Sun ONE architecture — an online custom system for Knitted Sweaters is presented, which links sweater design, manufacturing and sales in different places to share information through the Internet.The framework and characteristics of J2EE and Sun ONE are analyzed. Having studied the requirements of the online custom system for knitted sweaters, the paper presents a detailed and original system design based on J2EE technology and Web Services. This paper also gives descriptions on how to assemble and deploy the whole system under the Sun ONE architecture.

Research on the Dyeing Properties of Silk-like Knitted Fabric of Ultra-fine Polyester Fiber

In this paper, dyeing processes of silk-like fabric of ultra-fine polyester fiber are studied through orthogonal experiment, dyeing properties (K/S value, L* value, and C* value) of the fabric are tested under different dyeing conditions (pH value, time, and bath ratlo), and optimum dyeing conditions are arrived at through analysis.

The Application of Fractal to Design Knitted Sweaters

Pattern design is very important for knitting industry. Fractal theory is adopted to create image automatically, which is applied to design knitted sweaters. Based on Mandelbrot set(M-set), image could be generated automatically by visual basic (VB) program. Plenty of wonderful patterns are created by the following methods: selecting any parts of the image and magnifying, extending generalized M-set, editing the selected images with photoshop. The edited pattern is used to set on any parts of clothes to show fashion effect. Actual knitted structure is simulated by knitting CAD software. The results show that the fractal theory has greater potential applications in knitted pattern design, and it deserves further research.

Web-Based Interactive Simulation of Weft Knitted Fabric

In order to realize parametric simulation of three-dimensional(3D)fabric structure based on web,a 3D model describing a plain knitted fabric,in which the cross-section of the yarn is circular shape and the path of the yarn is cubic B-spline curve,is proposed in this paper.With this model,the 3D simulation of the loop and of the basic structures of the knitted fabric is realized by using Virtual Reality Modeling Language(VRML).The virtual simulation scene is suitable for network transmission with freely available VRML browsers and can be translated,scaled and rotated quite arbitrarily.By using Java and External Authoring Interface(EAI)technology,the web-based interactive simulation platform of weft knitted fabric is established.The user can input type of structures,basic fabric parameters,and yarn colors interactively to obtain a more realistic simulation result in real-time.A new approach is provided to imitate the knitted fabric 3D appearance on network.

Modeling Locking Angle of the Multi-layered Biaxial Weft Knitted Fabric in Shear Deformation

This paper introduces the construction of the multi-layered biaxial weft knitted fabric （MBWK fabric） and studies the locking angle of this kind of fabric. Moreover, a locking angle model of the MBWK fabric is established for the first time according to its unique construction. Two kinds of locking angles are considered under different restraint conditions: the locking angle θ1 controlled by the inserting yarns and the locking angle θ2 controlled by the stitch yarns. It is concluded that the ultimate value of the locking angle θ is the larger one of the two angles.

Development of Warp Knitted Products on RSJ Machine

Products made by Raschel Jacquard(RSJ)high-speed jacquard warp knitting machine are used in ornament and apparel fabrics.However,most products are produced according to the existing samples.The capability of creative design is not enough at home.In this paper,based on the basic features,the knitting methods and the working principles of warp knitting jacquard machines,the rules for manufacturing jacquard products are summarized.The article provides the new thoughts for the development of fabrics,such as the pattern design,changing the cams,power-net and a special technology of without pillar,which were obtained from the practices in a factory.

Investigation of Different Washing Effects on Physical and Mechanical Properties of Cotton Knitted Garments

This paper deals with three types of washing (enzyme, softener, Silicone) effects on 100% cotton Single Jersey T-shirt, Slub Single Jersey T-shirt, Double Lacoste (5% Lycra) Polo shirt, Single jersey CVC (T-shirt) and PC single Jersey (T-shirt). Typical industrial washing procedures and techniques were followed and then physico-mechanical properties were analyzed under standard condition. It is observed that after washing, weight of each garments has increased from 5% to 36%;stitch length of the constituted fabric has decreased from 1% to 10% approximately;CPI has increased 23% for CVC fabric only for enzyme treatment and for other process it has a little bit or no wash effects. Same effects found for WPI except 100% cotton and Double Lacoste. Shrinkage property both for lengthwise and widthwise remains the same except CVC and Double Lacoste knitted garments and spirality has almost unchanged except 100% cotton and slub fabric. Both the dry and wet rubbing properties have improved after any types of wash except 100% cotton on Silicone wash. Water absorbency property has increased;pH of all the samples is under controlled and lies between 4.5 and 5.0. But there is no significant change of colorfastness to wash and stain after these washing treatments.

Comparative Study of Polypropylene Non-Woven Surgical Mask and Locally Manufactured Woven and Knitted Fabrics Facial Masks

The outbreak of coronavirus has led to an increase in the demand for facemasks globally. Unavailability of appropriate polypropylene non-woven fabrics face masks as a result of inadequate supply to satisfy the growing population has brought about the manufacturing of locally fabrics masks to augment or substitute standard medical class facemasks. The study aims at analyzing airflow of these locally manufactured fabrics to determine possible means of transmitting the virus as well as establish comfort of the user of these masks. Standard polypropylene non-woven, woven and knitted fabrics were considered for the study. Air permeability test was conducted on these fabrics using Frazier Air permeability tester. Depending on the property significant variation in the textile fabrics, polypropylene non-woven is widely accepted for facial masks. Nevertheless, this study illustrates that woven and knitted fabrics have more open structures, which allow a high rate of air penetration and so may require two or three layers to prevent antimicrobial or antiviral potential.

Prediction of Buckling of Plain Knitted Fabric Sheets Subjected to Simple Shear in Wale Direction

Knitted fabric is very different from woven fabric due to its more complicated knitting structures. The buckling of knitted fabric sheets subjected to simple shear in the wale direction is investigated analytically in consideration of the large deformation of fabric sheet in critical configuration. The theory on instability of finite deformation is applied to the analysis. All the stress boundary conditions of knitted fabric sheet are satisfied. An equation to determine the buckling direction angle is derived. It is shown that there are two possible buckling modes, flexural mode and barreling mode. The buckling condition equations for the flexural mode and barreling mode are also obtained respectively. Numerical illustrations reveal that only the flexural mode can actually occur and the barreling mode cannot, which agrees with the experimental observations. For a permitted buckling mode on margin boundaries, the critical value of shear amount and the buckling direction angle can be determined.