Yarn Thickness Research Articles

Characterizing yarn thickness variation by correlograms

The surface evenness and texture are closely related with the irregularity of yarn thickness. Besides, yarn thickness variation has an important role to influence the yarn performance and the textile process efficiency. Thus, the information not only on the yarn thickness, but also on the short- term irregular characteristics that have not been known before is required for enhancing the qualities of textile products. This paper reports the results of a study about the yarn thickness and its variation for various types of yarn on the basis of a new measurement system applying a laser slit beam as a light source. The new method delivers effective information on the irregularity. The analysis of the measured signal confirms that the visual shade created by the yarn doubling and twisting can be measured and the yarn thickness characteristics can be represented by correlograms. Depending on yarn types, correlograms have different shapes and can be approximated to an exponentially decaying function with or without fluctuating magnitude. In addition, the effective information on the yarn irregularity can be influenced by the sampling length interval of the measuring device used for tests.

Measuring Thickness Variations in Fiber Bundles with a Flying Laser Spot Scanning Method

Apparent thickness variations in yarn have a decisive influence on its performance and textile processing efficiency. Yarn thickness has an even more critical influence on the quality of fabrics made from it. This study describes a method for measuring and analyzing the cross-sectional variations of fiber bundles on the basis of a new measurement system consisting of a flying laser spot and a photoelectric sensor. A yarn sample is used to test the feasibility of this measuring system and the usefulness of the results. The analysis shows that the new system has good reproducibility of the measured results and permits extraction of new information on yarn irregularity for shorter wavelengths than conventional devices. Furthermore, the data analysis process can be efficiently automated.

Digital Image Analysis for Fabric Assessment

Conventional methods of fabric inspection are tedious and require close association. In this work, digital image analysis for fabric assessment (DIAFA) is applied to modem and historic fabrics. Fabric images are divided into arrays of pixels with peak intensities distributed over gray scale ranges (histograms) and along constructed lines (line profiles). Fabric cover is measured by segmenting a histogram's B/w pixels, yarn spacing, and yarn thickness from moving point averages by calculating the breadth of a peak corresponding to an individual yarn at half the maximum peak height for a given line profile. The results show very good agreement with known values ( r = 0.919, n = 30, p < 0.01). Fourier power spectra provide facile measurements of yarn parameters in close agreement with the results from line profiling. With DIAFA, a small tool kit is developed to assist in the objective analysis of the structural integrity of fabrics in the museum environment, and it could be very useful in advancing automated fabric inspection.

Carbon composites based on multiaxial multiply stitched preforms. Part 1. Geometry of the preform

Experimental investigation of the internal geometry of a multiaxial multiply carbon reinforcement, stitched by warp-knitting, reveals the general features of this promising class of textile reinforcements. The uniform placement of the fibres is disturbed by the stitching, which creates resin-rich zones in the composite. The shape of the stitching loops, change of the stitching yarn thickness along the loop and statistical characteristics of spacing of the stitching has been studied. These features are covered by a descriptive empirical model of the internal geometry of multiaxial multiply fabrics. The model is implemented in the textile modelling software WiseTex, which serves as a preprocessor for meso-mechanics and permeability modelling.

Energy Approach for Prediction of Mechanical Behavior of 2-D Triaxially Braided Composites Part II: Parameter Analysis

A 2-arcsmodel of 2-D braided composite is developed. Fiber volume fraction is evaluated by this model and compared with experimental results. Predicted valuesof Exx, Eyy, νxy, and νyx by energy approach are compared with results of experiment and other approaches [Reference 1]. Effective stiffness of 2-D braided composite is obtained in a closed form by the analysis of elastic deformation energy in repeat-unit-cell (RUC) of braided composites. Independent parameters of 2-D braided composite are separated from dependent parameters. There are three groups of independent parameters. The first group is yarn geometrical parameters which include filament packing fraction, axial yarn and braiding yarn count number ma, mb, filament diameter df, yarn thickness to width ratio ξ. The second group is composite geometric parameters which include braiding angle Θ and yarn space L. The last group is material constants which include material constants of both resin and yarn. Three dimensional parameter analysis is done by changing any two parametersof yarn space L, braiding angle Θ, count number of axial yarn ma while all other parametersare kept unchanged.

A NEW ELECTRO-MECHANICAL METHOD FOR MEASURING YARN THICKNESS

Abstract Measuring the thickness of a wire using a micrometer is simple, but textile workers cannot use the same technique. The current report describes a possible method of measuring yarn thickness under lateral force using a range of loads. The effect of twist on thickness and compressibility of yarns is studied.

Assessing Yarn Structure with Image Analysis Methods1

This paper presents a system for assessing yarn structure. Image analysis techniques and mathematical methods are used to develop the method of estimating basic structural parameters of yarn thickness, hairiness, and twist. The method provides numerical characteristics of the structure at each point of the yam length. It also provides mean values and irregularity measures of structural parameters for the whole section of the yarn that is analyzed.

Fabric image production system taking account into human feeling. Texture Image Prediction from Kansei Properties with Neural Networks.

In this paper, we discussed a method to quantify the relation between KANSEI properties and physical properties to design an artifact. As a case study, the relation between the visual impressions of fabrics for office chair and those physical properties were i nvestigated using a neural network model. The purpose of this paper is to predict the fabric structural parameters and produce a fabric image from visual impressions. First, to acquire input and output data for a neural network model, a subjective evaluation of fabrics and measurement of their physical parameters were carried out. Thirty-four fabrics were evaluated by 57 subjects using 20 rating scales with the semantic differential method. Four kinds of fabric structural parameters: weave structure, yarn thickness, yarn density ratio of warp to weft, and color of fabric surface, were measured. The relations between the visual impressions and the parameters were formulated using a multilayer neural network. The performance of the neural network model was evaluated by a trend evaluation and a subjective evaluation of predicted fabric surface. Obtained results are summarized as follows.(1) The geometric parameters of fabrics were strongly related to the following visual impressions: luxuriousness, grace, softness, wetness, modern sense, sharpness, roughness and warmth.(2) The color of the fabric is affected by its grace, softness, clearness, wetness, warmth, and sharpness.(3) The fabric images reflected to activity, modern sense, roughness and wetness of fabric can be produced using the neural network. Finally, the system to produce the fabric image from visual impressions was proposed as an application of the neural network. Although th e system predicts a fabric image in the limited region, the system suggests a possibility of design of an artifact that reflects KANSEI properties quantitatively.

Mechanical Analysis of Garabo and Related Experiments.

In Gara-bo spinning, relations among spinning conditions and structural parameters of yarn are very complicated and have not been formulated. when the spinning is in a steady state, some formulae were derived about a relation among the yarn thickness D, the twist rate λ, the established yarn tension T and the fiber density ρp. Namely.where, Ctλ, Ctd and Cdλ are coefficients without relation to T and ρp.Moreover, based upon the essential principle of Gara-bo, a device was developed for the precise measurement by using electronic technology. Through some experiments done with the device, it is ascertained that Ctλ, Ctd and Cdλ can be almost considered as a constant and the theoretical formulae can be used with sufficient suitability.Therefore, when the yarn thickness deviated from the hoped value in spinning process, the compensation quantity of the established tension, which modifies the deviation, can be decided by the formulae.

Experiments of Yarn Forming State of ^|^ldquo;Garabo^|^rdquo; and Consideration from Control Engineering Viewpoint

Some experiments were carried out on Japanese throstle spinning (Garabo)to make clear the mechanism of spinning, especially of self-operated control of yarn thickness. Several factors of spinning such as the equivalent pot weight which determines the control value of yarn tension, the packing density of top in the pot, the winding speed of yarn spun, the rotational speed of pot, were selected as essential factors and their effects on the thickness and the twisting rate of yarn were examined by a test Garabo machine with measuring apparatus developed. Experimental results show that there exists in Garabo system a kind of self-operated control mechanism on yarn thickness, and this mechanism makes possible to form considerably good evenness of yarn in spite of rather simple machine mechanism. We propose the qualitative model of the control mechanism and explain some curious effects of certain factors.

A Study of Factors Affecting Fabric Cover‐shelter Properties

The theoretical analysis indicates that the main factors of cover‐shelter properties of fabrics are cover factor of fabrics, fabric thickness, optical reflectance and absorbance of yarn. With a combination of distances and luminances, 512 experiments have been made to find out the relationship between the least distinguishable distance and reflectance coefficient.

Measurement of Yarn Thickness Change Caused by Tension and Lateral Pressure by Wire Method

Previous studies show that the tensile property of woven fabrics is influenced significantly by the thickness change of yarns at cross-over point of warp and weft yarns when the fabric is subjected to extensional deformation. This thickness change is an important characteristics as well as tensile property of yarns relating to the tensile property of fabrics.A new method, referred to as the wire method, and the modified V-wire method, were used to obtain the data which enable us to predict the yarn thickness change in woven fabrics in extensional state.By the wire method, a yarn specimen is suspended crosswisely on a wire placed horizontally and tension is applied on the yarn to induce the compressional force between the yarn and the wire, and the change of the yarn thickness is measured at the cross-over point. Fabric thickness measurement of biaxially stretched fabric was carried out to confirm that the thickness change obtained by the wire method predicts well the thickness change of the yarn in the fabric in the extension state. The data obtained by the wire method and by the V-wire method agree each other. It is concluded that the wire method is superior to the V-wire method because of its simplicity.

Diffusion and Permeation of Gases in Fiber-Reinforced Composites

Abstract The presence of filler in a matrix phase greatly alters and also complicates the diffusion process, making experimental data very difficult to handle analytically. In this study both diffusion and permeability data were obtained in unfilled cellulose acetate films and cellulose acetate films filled with cheese cloth. Cheese cloth being highly permeable, the permeabilities and diffusivities of gases in the filled films are greater than in unfilled films due to reduced effective film thickness for molecular diffusion. A mathematical model has been developed which considers molecular diffusion to occur in that part of the film having no filler, while diffusion through the low-resistance cheese cloth is approximated by convective flow controlled only by the pressure gradient across the thickness of the cheese cloth yarn. The mathematical model predicts permeability values somewhat lower than experiment at low flow rates, but agrees well with experimental permeabilities at higher rates. The poor agree...

Statistical Analysis of Short-Term Thickness Irregularity of Blended Yarn Caused by Drafting

This article concerns blend irregularity along a yarn composed of two kinds of fibers. Part 1 reported that blend irregularity arose markedly in the drafting process and that it was very similar in characteristics to the thickness irregularity of drafted slivers. Part 2 evaluated the model of the drafting process by means of a block diagram and analyzed it by the simulation method.The present instalment concerns study of the mechanical properties of blended fibers and statistically analyzes shorter-period thickness irregularity and blend ratio irregularity caused by drafting. 1. The distribution of the thickness of a blended yarn and its component in each cross section fit in with the normal distribution or the gamma distribution. 2. Assuming that a thickness irregularity curve is a triangular wave having a period of two times the average fiber length, and that the distribution of thickness of each yarn section fits in with the normal distribution, then the probability density function of the minimum value of thickness along the yarn cut into a constant length which is integer times the period in thickness irregularity can be obtained.

Statistical Analysis of the Tensile Properties of Blended Yarn Having Short-Term Blend Irregularity

In the previous papers, the authors statistically analyzed the short term thickness irregularity and blend ratio irregularity caused by drafting process.This paper has statistically analyzed the tensile properties of blended yarn which has irregularities of yarn thickness and blend ratio with the following results:1. A mechanical model of blended yarn has been obtained.2. Probability density function of the strain under a given tension has been deduced based on the model.3. Probability density function of the strength has been deduced based on the model.4. With the increase in the thickness irregularity and blend ratio iregularity of blended yarn, the mean value and standard deviation of the strain increase. The influence of the thickness irregularity on the strain has been greater than that of the blend ratio irregularity.5. With the increase in thickness irregularity and blend ratio irregularity, the mean value of strength decreases and the coefficient of variations in strength increases.

22—FACTORS AFFECTING THE THICKNESS AND COMPRESSIBILITY OF WORSTED-SPUN YARNS

Yarn-thickness measurements have been made on a range of worsted-spun yarns, apparatus being used whereby loads ranging from I to 100 g could be mechanically applied over a length of 0–5 cm of yarn. A linear relation was found when the logarithm of the load was plotted against the logarithm of the yarn thickness, and this has been used to provide a ‘thickness index’ and a ‘compression index’ for each yarn examined. It has been shown that the two most important factors influencing yarn thickness and compression are the spinning twist and the fibre crimp, these being followed closely by the fibre length. Large differences were observed between the thickness and the compression of yarns spun to the same linear density from a range of different wool qualities, and these were largely due to the combined influence of the fibre crimp, length, and diameter. Considerable increases in yarn thickness and compression were also found between acrylic fibre yarns before and after bulking. Factors exerting less influence...

INFLUENCE OF THE BULKINESS OF NYLON YARN BY TWISTING AND HEAT TREATMNT

Manufacturing condition of the nylon crimped single yarn is investigated. Twisting and heat setting are repeated three times, and the twisting at the first and the third times are limited on giving bulkiness. The temperature of heat setting should be kept lower than 130°C. At the point of strength, elongation and residual torque of the yarn thickness of hnitted fabric. etc., the desirable manufacturing conditions of the yarn are as follows.-First process; 2000t/m twist, 120°CSecond process; 1500t/m over twist, 115°CThird process; 150t/m over twist, 115°C

82—AN INVESTIGATION INTO THE STATE OF A WORSTED YARN AT AN END-BREAK

During the spinning of a l/48s 64s-quality worsted yarn, observations have been made on the physical state of the yarn at the Instant of an endbreak. The values of yarn tension and thickness, and of drafting force and roving thickness, have been measured corresponding to an end-break. It has been concluded that the yarn breaks primarily because of the existence of a thin place generated during the spinning draft. By using a technique for dyeing the ends of fibres, evidence has been produced that, in the case of Fibro, the fibres slip rather than break when a spinning end-break occurs.

17—SOME EFFECTS OF SINUSOIDAL PERIODIC YARN THICKNESS VARIATIONS ON THE APPEARANCE OF WOVEN CLOTH

Sinusoidal periodic thickness variations in weft yarn of wavelength less than twice the width of the cloth cause diamond barring effects. The appearance of plain-weave spun rayon cloths, woven from weft yarn containing periodic thickness variations of known amplitude and wavelength, has been investigated in order to determine the influence of (i) pick spacing, (ii) the ratio of cloth width to wavelength in the yarn, and (iii) the amplitude in the yarn. It is shown that the prominence of diamond barring increases as the amplitude in the yarn increases and that, for a given amplitude in the yarn, it increases as the number of diamonds across the width of the cloth increases. It is also shown that, contrary to what has been generally supposed, the objectionability of periodic thickness variations in weft yarn is little affected by small changes in the ratio of cloth width to wavelength in the yarn. There is some suggestion that, although the cloth width/wavelength ratio to reveal a periodic yarn thickness variation is not critical, the ratio required in order to conceal it is critical. An instrument for the measurement of periodic thickness variations in yarn—the Yarn Period Analyser—is described.

The Relation Between Variation of Density and Thickness of Slivers, Rovings and Yarns

The Relation Between Variation of Density and Thickness of Slivers, Rovings and Yarns