Law of Critical Yarn Diameter and Twist Influence on Yarn Characteristics

An attempt is made to define the physical connotations of the aesthetic concept of bulk. In a review of the past usage of this term, it is shown to have originated as a purely aesthetic description of certain properties of fabrics, particularly hosiery fabrics. The linking of bulk to the physical measurement of specific volume is traced, and the wide acceptance of specific volume as the physical equivalent of bulk is demonstrated to be false. By the use of factor analysis techniques, sensory bulk is shown to be related to fabric thickness and to be entirely independent of fabric specific volume, weight, and cover.

Section: Y Arll Propertiesmentioning

confidence: 85%

The Characterization of Bulk

Brown

1969

“…Using the 10 measured values of 8 and d, average values were obtained by taking the arithmetic mean of 8 and the root mean square value of d. The RMS value was chosen because d' appears in Equation 1.…”

Section: Calculation Of Valuesmentioning

confidence: 99%

Relations between Specific Volume, Count, and Twist of Spun Nylon Yarns

Hearle

Merchant

1963

Measurements of count, twist, and diameter were made on 500 specimens from 20 spun nylon yarns, covering counts from lOs to 40s and twist factors from 2 to 8, and used to study the specific volumes of these yarns. I t was shown that in hard-twisted yarns the packing was about 7% less effective than in an ideal ring structure. In soft-twisted yarns, the specific volume was much greater. The effect of tension on yarn diameter was investigated in preliminary tests. The correlation between twist t and count N was also considered, and the constants k and m in the relation t = kNm were calculated. The value of m was shown to vary with twist factor in a way which could be explained by the torque-twist relations of yarns. the specific volume of spun nylon yarns as a function of count and twist. The relation between count and twist in irregular yarns is also considered.where l' = length of yarn in twist tester, cm; d, = fiber diameter, mm.Equation 5 incorporates the correction for fiber thickness suggested by Schwarz [8J. Experimental Method Measurement of Yarn ParametersThe specific volume 'lI cmt/g of a yarn specimen is given by: .The twist factor is related to the count and the turns per inch t, which can be calculated either from the surface twist angle 8 or from the total number of turns t' in the specimen. The relations are:(4)(2)'lI = 7rd 2ljO.4 w N = 5.905(ljw) C = t/Nt t = 2.54t'/I' = 25.4 tan 8/7r(d -d,)where d = yarn diameter; mm; 1 = specimen length, em, as cut; w = mass of specimen, mg, as cut.The yarn may be characterized by its cotton count N and its twist factor C. The former is given by:

“…The relationships between physical properties and both the tensile property and geometry of the cross-section of a yarn have been widely investigated [11][12][13][14][15][16][17][18]27]. Barella [19] measured the yarn diameter under different tensile loads using a projection microscope. Carvalho et al [20] measured the yarn diameter employing coherent optical signal processing.…”

Section: Introductionmentioning

confidence: 99%

Continuous measurement of apparent Poisson’s ratio for yarn based on omni-directional diameters

Takatera

Arichi

Peiffer

et al. 2016

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.