Masako Niwa

3—THE FINITE-DEFORMATION THEORY OF PLAIN-WEAVE FABRICS PART I: THE BIAXIAL-DEFORMATION THEORY

Theories of the biaxial tensile properties, the uniaxial tensile properties, and the shear-deformation properties of plain-weave fabrics are presented in a general form, a simplified stereo-model of the structure of plain-weave fabrics being used throughout these theories. In the first part of this series, the biaxial tensile-deformation theory is presented with the aid of the model, and the forces required to stretch the fabric along the warp and weft directions at the same time are theoretically calculated from the properties of yarns and from the structure of the fabrics. In this biaxial theory, both warp and weft yarns are assumed to be perfectly flexible, and the forces caused by yarn-bending are ignored. The compressibility of the yarn under the action of a lateral compressive force is also introduced into the theory, and it is shown that the compressive properties of yarns have a great influence on the tensile properties of the fabrics.

Fabric Performance in Clothing and Clothing Manufacture

After the performance of clothing fabric in use has been satisfied to some extent, consumers seek better-quality, that is, more comfortable, fabrics. Fabric performance in relation to ‘better fitting to the human body’ is an essential requirement of clothing materials. From the mechanical-comfort viewpoint, textile producers and consumers have evaluated this kind of fabric performance by a subjective method, called handle judgement. For the engineering design of the fabric performance with regard to fabric handle, this subjective method must be analysed to explain what the fabric handle is and how it is judged. In this paper, recent developments in the analysis and standardization of fabric handle, mainly used by experts in textile mills, are first introduced, and then the development of the objective-evaluation system of fabric handle based on fundamental fabric mechanical properties is described. This is a type of expert system, and the translation software from the fabric mechanical data to handle has ...

Objective Hand Measurement of Nonwoven Fabrics Part I : Development of the Equations

Fabric hand evaluation, previously applied to mens suiting, is used here to assess the touch or feel of nonwoven fabrics. In this method, fabric mechanical property parameters are converted by a first conversion equation (equation type I ) to numbers (the hand value or Hv) that express three primary hand values (the Hv) such as stiffness, etc., which are the primary factors characterizing fabric hand. Subsequently, these hand values are converted into a total fabric quality number (the total hand value or THV) by a second conversion equation (equation type II), which should then correlate well with subjective hand. The three primary hand attributes defined pre viously for mens suiting are also assumed to apply to nonwoven fabrics to characterize their hand. Primary hand values for nonwovens were obtained using the same equation as the mens suiting equation with minor modifications. Subsequently, two evaluations were performed—direct application of the mens suiting equation (type II ) to the nonwoven fabrics to derive their THV and construction of a new type II equation for the THV of nonwoven fabrics. Both equations can be used to predict nonwoven THV, but the predictive ability of the new equation is better than that of the previous one, and its prediction error is smaller than that of the subjective judgments made by average individuals. The correlations between THV and mechanical parameters were also examined; MMD, a frictional property parameter, was the most important param eter affecting THV.

Tailoring Process Control

The KESF system, which was developed for the objective measurement of fabric handle, provided precise measurements of fabric mechanical properties in the low-load range, which was enough to apply them to tailoring process control. The joint research of the present authors began in 1975 with the accumulation of a database for the relation between fabric processability and the making-up of mens suits, which had been produced by the industrial line-production system initiated around 1975. Following this development, some pioneering trials of tailoring process control based on fabric objective data were initiated by Ito, and he set this system in practice at his company on a suit-production line. After these trials, similar control systems were initiated into different companies. The engineering of suit manufacture on the basis of objective measurement has now become popular in the tailoring industry in Japan. Some of the essential points of the tailoring-industry control initiated by Ito with the assistance...

38—A FINITE-DEFORMATION THEORY OF THE 2/2-TWILL WEAVE UNDER BIAXIAL EXTENSION

A mechanical model of the 2/2-twill weave is presented in order to investigate the tensile properties of this weave under biaxial extension. The theory predicts that the compressional deformations of the warp and the weft at their cross-over point produce a superior effect on the tensile properties of the weave, especially in the relatively small-extension state. Experimental investigation to examine the accuracy of this theory is also reported, and good agreement between the theory and the experimental result is demonstrated.

Prediction of Fabric Bagging from Mechanical Properties

An objective evaluation method is proposed for predicting the bagging propensity of woven fabrics. The volume of the bagged fabrics was used as a measure of the bagging propensity. Dynamic creep caused by repeated shear deformation under con stant tension was measured in addition to the basic mechanical properties of fabrics. The correlations between the bagging volume of fabrics and their mechanical properties were examined statistically. For stretch fabrics, the bagging volume was correlated strongly with hysteresis behavior in tensile, bending, and low angle shearing defor mation measured after wetting conditioning for 5 hours at 32°C and 90% RH and with the value of the strain at t = 0.1 minutes, &(0.1) from the dynamic creep test. For conventional fabrics, a strong correlation was observed between the bagging volume and the value of the strain &(0.1) as well as the creep rate kd from the dynamic creep test. The equations for predicting fabrit bagging were obtained by statistical analysis of the relationship between the bagging volume of fabrics and their mechanical prop erties.

A guide line for manufacturing “ideal fabrics”

This paper reports the recent progress in the ideal fabrics project that started in 1996. The aim of this project is to initiate the engineered manufacturing of “ideal fabric”. Ideal fabric is the fabric which satisfies the three conditions, good hand, good appearance of suit, and mechanical comfort for wear. The objective evaluation method of these three properties has been developed, and these objective method and fabric mechanics theories are fully applied to this project. Some ideal fabrics have been manufactured as the guideline for manufacturing ideal fabrics in the future. These trial fabrics are now being commercialized to assess the response of consumers.

Clothing engineering based on objective measurement technology

Engineered manufacturing of high quality garments has long been a target of textile technology. There are three main factors for manufacturing high quality garments. They are: the selection of good fabrics for the garments; the process control of garment manufacturing; and the performance and correct adjustment of manufacturing machines such as sewing machines. In recent years, objective evaluation technology of fabric quality has been developed, and many researchers are now moving toward the engineered design of fabric quality based on this objective evaluation technology. The present authors are also conducting research on these three factors on the basis of the development of objective evaluation technology. This paper consists of two parts. The first part is a brief introduction about the investigation of the first and the second factors, which have been investigated by the authors. The second part presents our recent research on seam pucker problems. This problem is a machine‐materials interaction problem, and the mechanical properties of sewing thread and fabric are closely connected in this problem.

29—THE EFFECT OF FIBRE CRIMP ON FABRIC QUALITY

The relation between fibre crimp and fabric quality is investigated for various fabrics of different grades. It is found that fibres taken from fabrics of good quality have a high crimp level and that fibre crimp plays an important role in yarn extensibility, compressibility, and fabric extensibility and improves fabric quality. Correlation between fibre crimp and primary handle is also surveyed, and it is shown that NUMERI (smoothness) and FUKURAMI (fullness and softness) are strongly correlated with the fibre crimp.

Objective Evaluation of the Handle of Blankets

This study develops mathematical equations for an important quality of blankets, good handle, based on the compression and surface properties, thickness, weight, and thermal parameters. The handle of blankets is subjectively evaluated by thirty-nine judges. Two methods are investigated for evaluating the quality of blankets on the basis of these subjective evaluations. The first method uses Equations KN101-W and KN301-W, which were developed for evaluating the quality of mens winter suiting, to predict blanket quality. Equation KN101-W converts the fabric characteristic parameters into primary hand values (HV), then the overall quality value (total hand value or THV) is derived from these primary hand values using Equation KN301-W. The application of these equations to blankets is based on the idea that there may be similarities between the human sensation-based concept of good handle for mens winter suiting and that for blankets. The second method involves a new equation for directly evaluating the THV of blankets from the compression, surface, construction, and thermal properties of the blankets. This second method is based on the idea that the effects of thermal properties on THV must be investigated, although the interrelation of these thermal properties and primary hand is not explained by Equation KN101-W. Some characteristic parameters that are applied to Equation KN101-W may be omitted because they are less important to the THV of blankets. This makes the equation simpler, and applying the equation to blanket design becomes easier. The evaluation equations are investigated to ascertain their ability to predict the handle of blankets.