44—ASPECTS OF SEAM-STRENGTH PREDICTION: PART II

Physical and mathematical models of strength behaviour to explain the angle-of-bias effects postulated in Part I are further examined and various modifications suggested. Comparison between experimental results on a wide range of woven fabrics and theoretical predictions with the basic model and its modifications is made, and a good fit between experimental results and theoretical predictions is found and described.     

43—THE INFLUENCE OF COTTON-SPINNING MACHINERY ON THE RANDOM IRREGULARITY OF SLIVERS AND YARNS PART I: THEORETICAL CONSIDERATIONS

The regularity of slivers and yarns is analysed by the mathematical and experimental method of system analysis. After the mathematical background has been sketched, appropriate parameters are defined, and a mathematical model—in the statistical sense—is developed. Special considerations concerning the effect of ‘doubling’ conclude the paper.     

44—A METHOD OF WEAVE-CODING. PART I

In the light of recent discussions on weave-coding methods, a coding method based on the binary system is suggested. Systems of numeration are discussed, and a method of compacting weave-repeat diagrams into octal and sedecimal numbers is developed. Examples are given of various weaves coded by this method. Further developments of the system are suggested, to deal with more complex weaves.

The system described is intended particularly for mechanical-recording methods and any future automatic-weaving devices.     

53—HIGH-INTENSITY DRYING OF TEXTILE FIBRES. PART IV: PREDICTION OF THE DRYING TIME FOR TEXTILE ASSEMBLIES

The physics of drying a bed of loose textile fibres is discussed in relation to methods of predicting the drying times. An empirical method developed by other workers for predicting the drying times for flax stalks is reviewed and its applicability to loose fibres examined theoretically. It is concluded that, although the method is strictly applicable to the drying of non-absorbent fibres, it is also relevant to the drying of wool under industrial conditions. The experiments reported confirmed this expected deduction. A few observations covering the intended range of application should make it possible to predict the drying times for any combination of variables within the range.     

48—SOME ASPECTS OF WORSTED-YARN STRUCTURE. PART I: THE SINGLE-FIBRE MECHANICAL STATE IN YARNS PRODUCED ON HIGH-DRAFT SPINNING SYSTEMS

An account is given of an investigation of the mechanical state of single wool fibres in some worsted yarns, spun on a high-draft spinning system, by the radioactive-tracer-fibre technique. By means of this technique, it is shown that, whereas the main fibre-strain-inducing parameter is the insertion of twist into the yarn, a significant, if small, amount of this strain occurs as a result of the drafting process.     

24—ANALYSIS OF THE DRY-RELAXED KNITTED-LOOP CONFIGURATION: PART I: TWO-DIMENSIONAL ANALYSIS

Models of the relaxed plain-knit structure proposed by previous workers suffer from the disadvantage of being based on the assumption of some geometrical shape for the knitted loop and are not derived from equilibrium considerations of the forces and couples applied to one loop by its neighbours. In the work described in this paper, the dry-relaxed knitted-loop configuration is considered as a function of a system of localized forces and couples acting on the loop at the interlocking points in the fabric. The assumed system of forces and couples is derived from physical considerations of equilibrium and loop symmetry.

In this paper, the loop is assumed to be plane (or two-dimensional), and its shape is analysed as a function of the forces acting in the plane of the fabric. The resultant loop configuration is discussed in relation to experimental work previously done on relaxed plain-knit fabrics. The analysis is to be extended to three dimensions in Part II.     

69—THE MECHANICS OF SELF-PLYING STRUCTURES. PART I: MONOFILAMENT STRANDS

Analyses of the mechanics of self-plying structures developed for monofilament strands are presented, and an account is given of the experimental verification, by means of the use of rubber strands in simple twisting and plying experiments, of theoretical predictions of the extent of self-plying twist on the basis of monofilament pre-twist and filament properties.     

13—THE BIAXIAL LOAD-EXTENSION BEHAVIOUR OF A MODEL OF PLAIN WEFT-KNITTING—PART I

An analysis is presented of a model of plain weft-knitting subjected to uniaxial loading in either direction and also to biaxial loading. For each case, calculated load–extension curves, which are given for a range of values of fabric tightness, illustrate biaxial fabric deformation. Each curve shows a marked dependence of fabric modulus on the prevailing jamming conditions. In particular, where jamming in the direction of the application of the load is present, the relaxed fabric behaves as a pre-stressed structure. Whereas uniaxial loading leads ultimately to a state of single jamming with near-constant moduli, biaxial loading may lead to a more complex situation, which is outlined in the paper.     

7—YIELD-TESTING OF GREASY-WOOL CORE SAMPLES: PART I: AN IMPROVED SAMPLE WASHER OF NOVEL DESIGN

The increasing volume of yield-testing of greasy wool indicates the need for equipment that has a greater rate of handling samples and is more automatic than that employed in methods in current use. New washer equipment has been developed in which samples are washed by being dispersed and circulated around a long pipe by a special pump; the arrangement ensures thorough treatment of the whole sample and facilitates complete collection after washing. Released dirt is removed continuously from the system during washing. After being washed, the sample is discharged directly into a can, dewatered by suction, and dried in the same can by forced convection of hot air. Experimental prototypes have been built and have been extensively tested in a commercial testing laboratory.

When the washer is used in a conventional yield-testing arrangement with one operator, samples can be handled at a rate of 20 samples/hr, and the total time required to process a sample to obtain a washing-yield value is about 25 min. It is intended that the rate of testing will be 30 samples/hr when the equipment is used as a section of a Wool-base Analyser.     

50—SOME ASPECTS OF WORSTED-YARN STRUCTURE. PART III: THE FIBRE-PACKING DENSITY IN THE CROSS-SECTION OF SOME WORSTED YARNS

Measurement of the fibre-packing density in the cross-section of a range of wool worsted yarns indicates that these are slightly hollow at the core, with the maximum packing density occurring about one-quarter of the yarn radius from the yarn axis. A comparison of these results with those obtained on cotton-viscose rayon yarns by other workers is also made.     

49—SOME ASPECTS OF WORSTED-YARN STRUCTURE. PART II: THE MECHANICAL STATE OF SINGLE FIBRES LEAVING THE DRAFTING ZONE

An investigation is described in which a novel method of constraining drafted material between transparent adhesive tapes was used to show that, whereas the main single-fibre strain-inducing parameter is the insertion of twist into a yarn, a significant amount of this strain occurs as a result of the drafting process. The differences in behaviour during drafting of the leading and trailing ends of fibres are also demonstrated.     

33—THE DYNAMICS OF THE FALSE-TWIST PROCESS PART I: THE PROCESS SURVEYED

The changes experienced by a yarn during its progress through the falst-twist-texturing system are examined. The relations involved, between twist, tension, and torque, and the process parameters, are shown to be those of a feedback system, and the dynamic operation of the process is considered, in a general way, by using this concept.     

35—THE AGEING OF WOOL. PART I: AGEING AT VARIOUS TEMPERATURES

Experiments are described in which the stress-relaxation and recovery behaviour is investigated for Lincoln-wool fibres in bending as a function of the ageing time at temperatures of 20, 40, and 60°C. It is found that, at any temperature, the effect of increasing the ageing time by one decade is to shift the stress-relaxation curve by one decade to longer stress-relaxation times. Furthermore, the three sets of curves corresponding to the three temperatures are proportional to one another, although a marked decrease in stiffness occurs with increasing temperature. The recovery curves, which are independent of temperature, are successfully predicted from the stress-relaxation-moduli data by using the equations of generalized linear viscoelasticity.     

19—A STUDY OF NEEDLED FABRICS PART I: EXPERIMENTAL METHODS AND PROPERTIES

Methods of producing a fibre web for needle-punching on a laboratory machine are described: a parallel-laid card web was suitable for most purposes, though a cross-laid web was less anisotropic. Methods of operation and testing are described; the effects of specimen shape and size on tensile-test results were studied. The effects of web weight and structure were investigated, and experimental results are given: heavier-weight fabrics show much greater consolidation on needling.     

36—FINITE-ELEMENT ANALYSIS OF YARNS PART I: YARN MODEL AND ENERGY FORMULATION

The finite-element method is applied to derive alternative governing equations for Carnaby and Grosberg's continuous-filament-yarn model. This is shown to give a reasonable simulation of the stress–strain curves of wool yarns when tested at a short gauge length. The finite-element analysis used here is based on the principle of virtual work, and, because of the large deformations occurring, non-linear continuum mechanics are used to describe the configuration of the model.     

15—THE MEASUREMENT OF TORQUE IN CONTINUOUS-FILAMENT YARNS PART I: EXPERIMENTAL TECHNIQUES

A torsion-balance apparatus, incorporating a photopotentiometer device and developed to study the torsional-hysteresis and torque-relaxation behaviour of both monofilament and multifilament yarns under conditions of constant tension, is described. Differences in the shape of the torsional-hysteresis curves are studied for nylon monofilament and multifilament yarns, these differences in shape are related to friction effects and to the mechanical properties of the constituent filaments.     

60—AN INVESTIGATION OF THE TAPER OF COTTON FIBRES. PART I: THE EXPERIMENTAL DETERMINATION OF TAPER

In this study, an attempt is made to define and estimate cotton fibre-end taper. On the basis of fibre profiles obtained on single fibres and bundles, a few concepts for estimating taper were considered, namely, (i) the variability of the ribbon width or linear density of the fibre along its length, (ii) the length of the thinner part of the fibre with respect to an arbitrarily chosen value, (iii) the angular width of the fibre at its tip, and (iv) the relative linear densities at the two ends with respect to the mid-portion.

A critical analysis of the data obtained on seven cottons of varying fibre properties indicates that the taper parameters are dependent on the length group of the fibres but that the taper estimated on fibres belonging to the modal length can be used to characterize a cotton.     

28—THE BENDING BEHAVIOUR OF A HELICAL FILAMENT PART I: THE RIGIDITY OF THE HELIX

The large-scale bending of a helical filament is considered. It is shown that, in many cases likely to be of interest in textile applications, the bending rigidity of the helix calculated from small-deflexion theory provides a good approximation to the large-deflexion case. The cross-section of the deformed helix and the position of the neutral axis are also discussed.     

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.     

33—WITHDRAWAL FORCES IN THE PROCESSING OF WOOL SLIVERS: PART I: THE DETERMINATION OF WITHDRAWAL FORCE

Apparatus is described by means of which the force necessary to withdraw a tuft of fibres from a sliver inserted in pins can be measured. An account is given of the use of this apparatus in investigations of withdrawal-force variations for different sliver weights and withdrawal speeds.