Plain-knitted Structure Research Articles

Rheological model for studying fatigue of knitted fabric

The plain knitted structure (cotton) generally utilized in the clothing domain has been studied with cyclic loading at diverse fatigue number cycles. Fatigue test induces delayed-elastic and permanent deformation that increase according to cyclic elongation. The delayed-elastic and permanent deformation of tested knit has been discussed based on Burger’s rheological model. This model is suitable to describe the deformation behavior during relaxation of a plain knitted structure. The proposed rheological model permits us to estimate the elastic, viscoelastic and plastic components of the different tested fabrics after fatigue test.

Cut resistant characteristic of weft plain-knitted structure for protective clothing

PurposeThe paper aims to study cut resistant property of basic weft plain-knitted fabric for protective clothing.Design/methodology/approachEffects of fiber materials, fabric direction and knitting technology (sinking-depth) were explored, respectively. Cut process of fabric was tracked and the theoretical analysis was provided to evaluate energy transferring of cutting. Fiber-based cut behavior was observed by SEM images. Deformation energy stored in the loop due to yarn bending was regard as initial elastic potential energy of the fabric, which was related to loop structure.FindingsCut resistance of the fiber material was the dominant factor for cut resistance of weft plain-knitted fabric, while unit loop structure played a critical role in improving cut resistance.Social implicationsCut resistance of the fiber material was the dominant factor for cut resistance of weft plain-knitted fabric, while the unit loop structure played a critical role in improving cut resistance.Originality/valueThe paper provides theoretical support of developing flexible protective clothing.

Investigation into the effect of fabric structure on surface temperature distribution in weft-knitted fabrics using thermal imaging technique

The aim of this paper was to evaluate the surface temperature distribution in several single and double jersey weft-knitted fabrics. Plain knitted fabrics as well as those with, double cross-tuck, cross-tuck, double cross-miss, and cross-miss pattern together with plain rib and interlock structures were under consideration in term of their structural differences. In order to investigate the temperature distribution in produced samples, all the fabrics were placed on a 35?C adjusted hot plate instrument and thermal images were captured by an infrared thermal camera. The results revealed that the presence of tuck stitches in single jersey weft-knitted fabrics increase the air permeability due to the increasing the fabrics? porosity, which in turn leads to decrease their thermal resistance as compared with plain knitted structure. On the other hand, addition of miss stitches in single jersey knitted structures would decrease the thickness of fabrics and improves their heat transfer ability. The obtained results, from rib and interlock knitted structures, suggested their lower heat conductivity in comparison to the single jersey knitted samples.

Basic Studies for Modeling Complex Weft Knitted Fabric Structures Part IV: Geometrical Modeling of Miss Stitches

In this work a model of miss stitch and its effect on the plain knitted fabric structure are introduced for the first time, thus we present a pioneering basic work on knit and miss combinations. Photographs of knitted samples were taken and the assumptions of the model are based on these photographs. A geometrical model of this knit and miss combination is created and the model is drawn to scale. We show that these shapes are found to be exactly the same shapes as observed in real fabrics.

Basic Studies for Modeling Complex Weft Knitted Fabric Structures Part V: Geometrical Modeling of Tuck Stitches

In this work the geometrical model of a tuck stitch and its effect on the plain knitted fabric structure are introduced. The geometrical model of this knit + tuck combination is created here for the first time, being a pioneering basic work on knit + tuck combinations. This model is then plotted using 3DS Max software. It is shown that the obtained shapes are exactly the same shapes observed in real fabrics.

A New Aspect of Geometrical and Physical Principles Applicable to the Estimation of Textile Structures: An Ideal Model for the Plain-knitted Loop

Models of relaxed plain-knit structures proposed by previous researchers suffer from the disadvantage of being based on the arbitrary assumption of some geometrical shape for the knitted loop or subjected to the forces and couples applied to one loop by its neighbors. The work in this series of theoretical studies differs from previous studies. The classical curves that are similar to the knitted-fabric loop shape are considered as a function of an ideal model for a plain-knitted structure. The assumed function is then improved by adopting a buckled-elastic-rod theory, leading to a new equation as the ideal loop configuration. This analysis is presented for two- and three-dimensional models. These models obtain fabric dimensions. The resultant loop configuration is discussed in relation to experimental work previously done on relaxed plain-knit fabrics.

Structural mechanics of knitted fabrics for apparel and composite materials

The importance of fabric biaxial extension, in‐plane compression, shear and bending properties, have been widely recognised by textile scientists and engineers for the evaluation of the three‐dimensional formability and drape of textile materials in apparel products and three‐dimensional preforms. In contrast to woven fabrics where bending and shear properties determine the fabric formability, knitted fabrics have very high formability as a direct result of their easy biaxial extension properties. This ability to form three‐dimensional shapes using the biaxial extensibility of knitted structures enables these knitted textile materials to be utilised for a wide variety of close fitting apparel garments and shaped composite preforms. Some representative biaxial extension curves for the plain knitted structure are described in this paper. These curves illustrate an unusual shape for the load‐extension curve of a textile material arising from the pre‐tension or pre‐stress. The pre‐stress yields an initial high tensile modulus for the structure in contrast to the very low initial modulus characteristic of apparel textiles. Accordingly, for knitted textile materials, it is shown how biaxial extension of the fabric introduces a fabric pre‐stress to maximise the three‐dimensional fabric formability especially when subjected to transverse compression by the resin or matrix in a composite material. Typical uniaxial and biaxial tensile stress–strain curves for knitted fabrics are compared.

Modelling the Load–Extension Behaviour of Plain-knitted Fabric: Part I: A Unit-cell Approach towards Knitted-fabric Mechanics

The objective of the study reported in this paper was to generate new models of the mechanical behaviour of knitted fabrics in quasi-static deformation from an initially relaxed state to the extended state. The problem of extension of a knitted structure is complicated by the combination of non-linear properties derived from both the characteristics of the structure and the properties of the yarn. A model of in-plane deformation of a plain-knitted structure is proposed. To facilitate study of the mechanical properties of the proposed model, standard dimensional parameters of a fabric combined with the geometry and mechanical properties of a yarn are used. With the purpose of obtaining important yarn characteristics for the subsequent evaluation of the model, an advanced analysis of the yarn path in plain-knitted fabric is performed. An algorithm for evaluating the loop geometry from the given fabric dimensions in both course and wale directions and the yarn properties is developed. Kinematic relationships in tensioned fabric are considered. A finite-element approach to the problem of modelling knitted-fabric deformation is proposed in which the knitted structure is presented as a 2D mesh of unit cells.

Structural Mechanics of Knitted Fabrics for Apparel and Composite Materials

The importance of fabric biaxial extension, in-plane compression, shear and bending properties has been widely recognised by textile scientists and engineers for the evaluation of the three-dimensional formability and drape of textile materials in apparel products and three-dimensional preforms. In contrast to woven fabrics where bending and shear properties determine the fabric formability, knitted fabrics have very high formability as a direct result of their easy biaxial extension properties. This ability to form three-dimensional shapes using the biaxial extensibility of knitted structures enables these knitted textile materials to be utilised for a wide variety of close fitting apparel garments and shaped composite preforms. Some representative biaxial extension curves for the plain knitted structure are described in the paper. These curves illustrate an unusual shape for the load–extension curve of a textile material arising from the pre-tension or pre-stress. The pre-stress yields an initial high tensile modulus for the structure in contrast to the very low initial modulus characteristic of apparel textiles. Accordingly, for knitted textile materials, it is shown how biaxial extension of the fabric introduces a fabric pre-stress to maximise the three-dimensional fabric formability especially when subject to transverse compression by the resin or matrix in a composite material. Typical uniaxial and biaxial tensile stress–strain curves for knitted fabrics are compared.

A Study of the Graphical Representation of Plain-knitted Structures Part I: Stitch Model for the Graphical Representation of Plain-knitted Structures

This study is based on the design of s software program to generate a 3-D graphical representation of plain-knitted structures on a computer screen by using the basic fabric parameters, i.e, the yarn diameter, the course-spacing, the wale-spacing, and the stitch length. The mathematical model is set up to establish the basic parameters of plain-knitted structure. The cubic-spline method is applied to describe the central axis of a stitch in a plain-knitted structure. The central axis of a stitch is defined by the control points. The positions of the control points are selected as points where the shape of a stitch is defined and where the geometrical properties of the structures are reflected. The results of this analysis are then compared with practical measurements obtained from an actual plain-knitted structure.

An Energy Analysis of the Mechanics of Weft-knitted Fabrics by Means of Optimal-control Theory: Relaxed-fabric Dimensions and Tensile Properties of the Plain-knitted Structure

An Energy Analysis of the Mechanics of Weft-knitted Fabrics by Means of Optimal-control Theory: Relaxed-fabric Dimensions and Tensile Properties of the Plain-knitted Structure

An Energy Analysis of the Mechanics of Weft-knitted Fabrics by Means of Optimal-control Theory: The Nature of Weft-interlocking in the Plain-knitted Structure — Reply

An Energy Analysis of the Mechanics of Weft-knitted Fabrics by Means of Optimal-control Theory: The Nature of Weft-interlocking in the Plain-knitted Structure — Reply

An Energy Analysis of the Mechanics of Weft-knitted Fabrics by Means of Optimal-control Theory: The Nature of Loop-interlocking in the Plain-knitted Structure

An Energy Analysis of the Mechanics of Weft-knitted Fabrics by Means of Optimal-control Theory: The Nature of Loop-interlocking in the Plain-knitted Structure

An Energy Analysis of the Mechanics of Weft-knitted Fabrics by Means of Optimal-control Theory: Relaxed-fabric Dimensions and Tensile Properties of the Plain-knitted Structure

An Energy Analysis of the Mechanics of Weft-knitted Fabrics by Means of Optimal-control Theory: Relaxed-fabric Dimensions and Tensile Properties of the Plain-knitted Structure

An Energy Analysis of the Mechanics of Weft-knitted Fabrics by Means of Optimal-control Theory: Relaxed-fabric Dimensions and Tensile Properties of the Plain-knitted Structure — Reply

The energy analysis of the plain-knitted structure reported in Part I of this work is further developed by studying the relaxed-fabric dimensions and the fabric tensile properties for extension in the two principal directions of the fabric structure. The relaxed-fabric dimensions are evaluated in terms of the parameters k a, k w and the thickness for fabrics of different tightness of construction and for yarns of different lateral compressibility. The following parameters are also evaluated: inter-yarn distances and inter-yarn forces in the regions of loop-interlocking and length- and width-jamming, the fabric-curling couples, the energies of yarn-bending and lateral yarn compression, and the total energy. Wherever possible, the values of these parameters are compared with experimental results reported in the literature and also with the results of previously reported theoretical models of the plain-knitted structure. The variation of the previously mentioned parameters is studied when a fabric tension is...

34—AN ENERGY ANALYSIS OF THE MECHANICS OF WEFT-KNITTED FABRICS BY MEANS OF OPTIMAL-CONTROL THEORY PART I: THE NATURE OF LOOP-INTERLOCKING IN THE PLAIN-KNITTED STRUCTURE

A general energy analysis formulated for the study of fabric mechanics is applied to the biaxial-deformation properties of the plain weft-knitted structure by assuming quarter-loop symmetry. The basic equations of equilibrium and the boundary conditions for plain-knitted fabrics are derived without assuming any detailed pre-conditions relating to the nature of loop-interlocking. Typical equilibrium solutions for the plain-knitted structure under zero (or very low) tension are presented in this paper in the form of loop shapes and curvatures, continuously distributed forces acting between interlacing yarns, loop-jamming forces, and profiles for the inter-yarn distance within the structure. It is shown that the nature of yarn contact between interlocking loops varies greatly according to such factors as the degree of lateral yarn compressibility and the level and direction of tension applied to the fabric. The dynamic nature of loop-interlocking is discussed in relation to previously published models of the...

35—AN ENERGY ANALYSIS OF THE MECHANICS OF WEFT-KNITTED FABRICS BY MEANS OF OPTIMAL-CONTROL THEORY PART II: RELAXED-FABRIC DIMENSIONS AND TENSILE PROPERTIES OF THE PLAIN-KNITTED STRUCTURE

The energy analysis of the plain-knitted structure reported in Part I of this work is further developed by studying the relaxed-fabric dimensions and the fabric tensile properties for extension in the two principal directions of the fabric structure. The relaxed-fabric dimensions are evaluated in terms of the parameters k a, k w and the thickness for fabrics of different tightness of construction and for yarns of different lateral compressibility. The following parameters are also evaluated: inter-yarn distances and inter-yarn forces in the regions of loop-interlocking and length- and width-jamming, the fabric-curling couples, the energies of yarn-bending and lateral yarn compression, and the total energy. Wherever possible, the values of these parameters are compared with experimental results reported in the literature and also with the results of previously reported theoretical models of the plain-knitted structure. The variation of the previously mentioned parameters is studied when a fabric tension is...

23—A THEORETICAL ANALYSIS OF THE TENSILE PROPERTIES OF PLAIN-KNITTED FABRICS. PART I: THE LOAD-EXTENSION CURVE FOR FABRIC EXTENSION PARALLEL TO THE COURSES

An investigation is described in which, by means of a two-dimensional model of the plain-knitted structure, load-extension curves for extension in the course direction were calculated theoretically. It was assumed initially that the only mechanism of fabric extension was elastic deformation of the loop shape. Account was taken of setting of the yarns into the relaxed-loop shape, but this was found not to have any significant effect on the theoretical load–extension curves. It was found that the intial portions of these curves were almost linear but that the slope could be greatly affected by the occurrence of lateral yarn compression. When yarn compression was taken into account, good agreement was obtained with experimental results for a nylon-monofilament fabric and a series of wool plain-knitted fabrics.

A Theoretical Analysis of the Plain-Knitted Structure

A theoretical analysis was made of the relaxed plain-knitted structure. The analysis differs from previous ones in that no arbitrary geometrical loop shape is assumed and no empirical methods are used. The loop configuration is de rived from consideration of the reaction forces and couples acting within the structure, their magnitude being determined by the yarn displacement necessary for loop interlocking. A minimum-energy structure is shown to exist; this structure is fairly independent of fabric tightness and yarn properties. The actual energy minimum is fairly shallow, so that in practice some difficulty could be expected in obtaining a perfectly relaxed fabric; this would lead to a corresponding spread in experimental values of plain-knitted fabric shape and dimensions. The numerical values of fabric dimensions obtained from the analysis show good agreement with the experimental data reported by other workers.

The Dimensional Properties of Knitted Wool Fabrics

The 1×1 rib and half-cardigan structures, like the plain-knitted structure, are shown to be rationally determinate structures only in the fully-relaxed state; in any other state, their dimensional behavior is dependent on the yarn's physical properties and previous knitting and wet-finishing history. The fully-relaxed state is reached only after the fabrics have been thoroughly wetted-out, hydroextracted, and tumble-dried for 1 hr at 70°C. In this state, the courses and ribs per in. of the 1×1 structure are directly proportional to 1/ L, as predicted by Munden's original theory for the plain-knitted structure, but this theory does not account for the complete dimensional behavior of this structure, as K1 is not strictly a constant. However, K 4 is a constant at 1.76±0.15 and independent of both loop length and yarn count. For the 2X2 rib, no true dimensional stable state is found with wet relaxation and tumble-drying.