We proposed a new method of measuring apparent Poisson's ratio for yarn and developed a new tensile tester equipped with a digital micrometer that can measure the yarn's omni-directional diameter annularly while the yarn is elongated. Values of apparent Poisson's ratio were obtained from the longitudinal and transverse strains continuously. The mean diameter measured omnidirectionally was used to calculate the transverse strain for each longitudinal strain. We tested five spun yarns, one mono filament yarn and two filament yarns and obtained values of apparent Poisson's ratio against longitudinal strain for all samples. Apparent Poisson's ratio was not constant for spun and filament yarns while it was constant for monofilament yarn. When the longitudinal strain was low, apparent Poisson's ratios of ring spun yarns and filament yarns were large owing to the fiber packing density. As the longitudinal strain increased, apparent Poisson's ratio gradually decreased. Furthermore, we approximated the relationship between apparent Poisson's ratio and the longitudinal strain using a power function. The apparent Poisson values can be used in the simulation of fabrics.

Purpose The purpose of this paper is to create a fabric retrieval system for designers that is based on a database that includes designers’ criteria and Kansei (sense and feeling) information, designed for the selection of a fabric from a wide range in e-commerce. Design/methodology/approach The database included sensory expressions for each type of fabric taken from fashion journals and values of smoothness, softness, luster and thinness (referred to as Kansei values) for each fabric. The Kansei values were determined by a Japanese expert designer using standard fabric samples of a fabric type. The system uses two search methods to find the desired type of fabric: a category search method and a free word search method. After finding appropriate types of fabric, the user further narrows down the fabrics of the selected type to more suitable fabrics using the Kansei values. The validity of the Kansei values and the effectiveness of the system were verified by 11 professional designers from Japan and Sweden. Findings The Japanese and Swedish designers were satisfied with the fabrics retrieved for specific items and found that the system was effective. The Kansei values were similar among fashion designers and shown to be effective for fabric retrieval. Originality/value The system will allow designers to find appropriate types of fabric and to narrow their search for fabrics among selected types to find candidate fabrics easily and quickly with their Kansei values and experience without technical knowledge of fabrics.

The effect of yarn torsional rigidity was verified on the Cooper model for fabric bending rigidity in any direction. We made five cotton fabrics with different weft densities and prepared three commercial fabrics as experimental samples. The torsional rigidity of yarn from the bobbin and that of yarn directly extracted from fabric were measured with a yarn torsional tester. The bending rigidity of yarn from the bobbin was measured using the same pure bending tester as used in fabric bending testing. The bending rigidity of thin fabric was calculated using torsional rigidities of yarns extracted from the fabric and showed better agreement with the experimental values than that calculated using the torsional rigidity of yarn from the bobbin. Indeed, measurements showed that the torsional rigidity of yarn from the bobbin was appreciably higher than the torsional rigidity of yarn from the fabric. This is due to the crimp in the yarn. The fabric bending rigidity can be predicted using the Cooper model with torsional rigidities of yarns extracted from the fabric.

We investigated the distinctive characteristics of jean fabrics (denim fabrics obtained from jeans) and compared the physical properties and the hand. We used 13 kinds of jean fabric from commercial jeans and 26 other fabric types. The physical properties were measured using the Kawabata evaluation system, and the fabric hand was evaluated by 20 subjects using a semantic differential method. To characterise the hand of jean fabrics compared with other fabrics, we used principal component analysis and obtained three principal components. We found that jean fabrics were characterised by the second principal component, which was affected by feelings of thickness and weight. We further characterised the jean fabrics according to ‘softness & smoothness’ and ‘non-fullness’, depending on country of origin and type of manufacturer. The three principal components were analysed using multiple linear regression to characterise the components according to the physical properties. We explained the hand of fabrics including jean fabrics using its association with physical properties.

The effect of crimp on torsional rigidity of monofilament and cotton spun yarns was studied. Two kinds of polymeric monofilament yarns and four kinds of cotton spun yarns were examined. Different crimps were applied to the yarn using original crimp setting equipment. To fix the crimp, the polymeric monofilaments were treated with heat and the cotton spun yarns were treated with steam. The test samples were then produced following two protocols: with or without the application of weight. The yarn torsional rigidities with crimp were measured using a torsional measurement device and were compared with those without crimp. Almost no weight was applied to the cotton spun yarns to preserve the crimp during testing. The results with and without the application of weight were compared. For the monofilament yarns, the torsional rigidities of the crimped yarns had a linear relationship with the crimp ratio. For the cotton spun yarns, the torsional rigidities of the crimped yarns were smaller than those of the straight yarns. The smaller the yarn count, the smaller the yarn torsional rigidity. The effect of crimp on torsional rigidity differed according to the yarn counts. There was almost no difference in crimped yarn torsional rigidity between the straightened and non-straightened yarns after crimp setting. Therefore, there is a possibility that the change in yarn properties could have resulted from the bending of the fiber during crimp setting and not from the shape of the crimp afterwards.