The objective of this study was to investigate new models for the mechanical behaviour of knitted fabrics in quasi-static deformation from an initiallyrelaxed state to the extended state. In order to do so a mechanism for plain knitted structure deformation in plane was proposed, implemented and tested on a range of real samples. The problem of extension of a knitted structure is complicated by the combination of non-linear properties derived from both the characteristics of the knitted structure and the properties of the yam. To obtain a solution to this problem a finite-elementtechnique was used to evaluate the proposed model. The proposed model of mechanical behaviour of knitted fabrics is an analogue of the thin membrane problem in mechanics. The model developed is applicable to a wide range of mechanical problems where it is possible to assume that fabric is a thin membrane with zero bending rigidity. To facilitate the mechanical properties of the proposed model, standard dimensional parameters of fabric and yam combined with the mechanical properties have been used. With the purpose of obtaining important yam characteristics for the subsequent evaluation of the model, an advanced analysis of the yam path in plain knitted fabric was performed. An algorithm for loop geometry from the given fabric dimensions in course and wale directions and yam properties were developed. In order to implement the algorithms developed during this investigation complex software was written. This software allows simulation of the mechanical behaviour of different plain knitted structures under various loading and boundary conditions. At the approval stage of the model, a number of fabric samples were produced and tested; models of real samples have been simulated and compared with experimental data. The model used could be developed further to extend the application to tackle complex 3D deformation and to simulate a range of different knitted structures.

This thesis is concerned with issues arising from the fit of bras. An investigation was carried out into the pressure and sensations caused by wearing a bra and the influence of these on bra fitting issues. The literature review revealed that there has been only. a small amount of research into the topic of the fit of bras, and certainly not enough to effect any !' marked improvement. There are still maJiy women who are not satisfied with the bra they are wearing, and who, furthermore, find it is difficult to obtain a satisfactory fit, and this especially so in the case of large-sized women. Previous research has shown that pressure is a very important factor in bra fitting, as is also the wearer's perception of the comfort of the bra, and these have a direct bearing on issues of breast health. The whole field of the fitting of bras requires more scientific and technical research. This study employed survey and experimental research methodology to investigate bra pressure and the sensations influencing bra fitting issues. The investigation revealed that the design of the survey is satisfactory. The use of pressure test equipment, Bra Sensor, and ,' the sensation evaluation method utilizing the Borg CRIO Scale are appropriate. The statistical data analysis methods used to obtain the results were shown to be reliable. The results obtained from the survey of the wearers' sensations caused by wearing a bra revealed some basic information about the subjects and their bra-wearing habits and a general picture of pressure, discomfort and pain sensations. Further, through an in-depth analysis of the data from the pressure and sensation tests, general characteristics of wearers' sensations in the bra were concluded, the relationships between the pressures and the sensations were established, the factors which influence the sensations were discussed. Analysis was also carried out within the different groups of subjects.

The manufacture of conventional textiles usually involves either weaving or knitting. The author and his colleagues have devised a completely new technology for textile fabric construction involving the use of simple elements. These elements are basically similar in shape to sewing machine needles which interact with each other in such a way that yarns 'stitch-knit' themselves together to produce a fabric. As a result of this unique interaction the number of loops produced is doubled when compared to the time cycle of a conventional knitting action. Further enhancement of at least doubled fabric production rates should accrue from the dual effects of decreased yarn tensions and the lowered dynamic disturbing forces of the simplified knitting element manipulating system. A survey has been made of the looped-type textile manufacturing processes and the most appropriate groups have been enumerated in order to form a basis of comparison for the novel process. A basic study (including computer aided graphics) of probable textile structures, that could be produced by this technology, has revealed a substantial range of novel fabrics. These fabrics have been analysed and possible uses for them are suggested. A powered research-rig has been designed and constructed on which the important yarn manipulation characteristics have been determined. This experimentation has facilitated a more positive yarn pick-up to be evolved. As a result of this, more practicable design tolerances may be given for the manufacture and setting-up of the manipulative elements. Moreover, narrow-width novel fabric samples have been produced from spun-staple yarns at rates exceeding the current commercially available maximum, thereby substantiating the earlier predictions. Finally, the new technology and its resulting products are appraised and design proposals for a prototype machine are made; it is hoped that this will be offered to industry in due course for further development and potential exploitation.

The air-jet texturing (AJT) and intermingling (INT) processes are two applications of air jets used to modify the structure of synthetic multifilament yarns. The modification is performed by high-speed jets, which are created by purpose designed nozzles. The present work experimentally investigates the interrelation between properties of the yarn produced and air flow and the nozzle geometry in order to gain an improved understanding of the AJT process. Firstly, a number of industrial AJT nozzles were selected for detailed analysis. undisturbed flows created by these nozzles are investigated by means of total pressure measurements and shadowgraphy. The effect of nozzle geometry on the AJT process is investigated by using a series of systematically designed nozzles. A number of geometrical parameters of cylindrical type AJT nozzles are specified for successful texturing, after assessing performance of the nozzles by stabilising zone tension and the properties of yarns produced. It is found that large exit length and slightly diverging main duct are beneficial for texturing. Also the trumpet shaped exit profile is found to be necessary for adequate texturing. Low tilt angle of air inlet hole is recommended. Effect of wetting on AJT is investigated with special reference to yarn-to-yarn and yarn-to-metal friction. It is found that when the supply yarn is treated with water interfilament friction prior to the nozzle is reduced, but increased slightly in the texturing area. The former may make relative movement of filaments easier. The latter is considered to be one of the ways through which wetting improves the process, since it assists anchoring the loops in the yarn. Subsequently high-speed cine-photograpy is deployed to visualise the AJT process inside and around exit area of the nozzle. The nozzle used has rectangular cross-section and one glass wall, which allows to see inside the main channel. It is found that for successful texturing loop formation and fixing the loops are both necessary. The INT process is investigated by using again several systematically designed nozzles with reference to correlation between nip frequency and nozzle geometry. Rectangular nozzles are found to be performing adequately, depending on their dimensions. The nozzles with area ratio smaller than unity perform adequate intermingling. It is also found that small aspect ratio is benefical in terms of nip frequency. A better understanding of the INT is achieved by means of SEM, high speed video and cine-photography and yarn tension measurements. The yarn is found to be necessary to run constantly against the incoming flow to reduce missing nips.

The thesis presents a detailed analysis of the effects of one-sided access z-direction reinforcement, ‘tufting’, on the morphology and mechanical performance of the resulting MVR-444 epoxy matrix/carbon fibre fabric composites. The dry fabric architectures used are pseudo-UD, twill woven fabric and non-crimped fabric (NCF). They are tufted with a range of commercial tufting threads, using KSL KL150 tufting head mounted on a 6-axis robot arm. The main focus is on the use of a twisted carbon fibre thread, at areal tufting densities of 0.5% and 2%. The composite plates are prepared via Resin-Transfer- Moulding (RTM) route, making it possible to control the plate thicknesses. The morphological features characteristic of tufted, cured composites are described and categorised. The global and local fibre volume fractions are measured and simple models proposed that connect local increase with local fibre deviation and presence of resin rich surface loop layers. It is shown that the balance of in-plane and out-of-plane properties in tufted composites is highly dependent on the tufting parameters, but also on the fabric architecture, with the NCF option seeming the most attractive. Overall, the stiffness of tufted materials is not affected and the drop in in-plane strength of any realistic geometry combinations is below 20%. ‘Thread-less’ tufting experiments prove that the drop is not caused by fibre breakage from the passage of the needle alone. Digital image correlation (DIC) techniques is used to map out the strain field distributions during mechanical testing, increasing the accuracy of crack tip location in Mode II delamination cracking studies and confirming the mode mixity changes during deformation of tufted structures. Single-tuft experiments provide the experimental data that are required for the development and validation of analytical models. A finite element unit cell model is developed to predict in-plane elastic and failure behaviour of tufted UD and NCF composites incorporating the critical meso-structural features of fibre deviation and increased fibre volume fraction. The thesis also contains an overview of the tufting technology and some detailed information on recent manufacturing developments that were required to obtain the controlled quality specimens used in the study. A demonstration structural element was produced, in the form of a tufted omega-stiffener. A standard pull-off test demonstrates the superior load carrying and energy absorbing capacity of this strengthened structure. Details of robot programming, additional single tuft bridging results, test fixture design, derivation of the analytical bridging model and additional publications are given in appendices to the main body of the thesis.

The work presented in this thesis applies the high resolution derivative technique developed in this laboratory to a study of the structure and water absorption of viscose, dicel and tricel films, prepared in a pure form by techniques develope d during the course of this work. These three materials provide a means of following how progressive acetylation (from 0% in viscose to 88.3% in dicel to 98.3%'in tricel) influences structure and water absorption. A controlled Temperature and Relative Humidity cell was developed to standardize experimental conditions and to enable reproducible spectra to be recorded especially in spectral regions where temperature sensitive hydrogen bonding occurred. The use of the call enabled structural and/or water absorption properties of these materials to be observed by changing the temperature or Relative Humidity at which spectra were recorded; or by observing annealed sample spectra at a standard temperature. Experiments were undertaken to determine the existence of chain folding in viscose, dicel and tricel films. The results of these experiments support the existence of chain folding in viscose and the nature of the fold is discussed in detail. A,T,R, absorption spectra of the film surfaces were recorded in an attempt to study water absorption at surfaces and these spectra were correlated where possible with stereoscan tracings of the surfaces of the films. Evidence is presented from the results of the work in this thesis for the involvement of CH groups in hydrogen bonding.

Attention is focused on the range of literature which has contributed to the developing awareness of the theoretical principles governing the geometry of pattern. A means by which textile and other surface patterns can be classified by reference to the symmetry characteristics of their underlying structures is developed, and shown to be an objective, systematic and reproducible means of providing meaningful, standardised descriptions of regular geometric patterns. The potential of the classification system as a worthwhile analytical tool is explored through its application to groups of textile patterns from four distinct cultural settings: traditional Javanese batiks; traditional Sindhi ajraks; Jacquard woven French Silks (Autumn, 1893); Japanese textiles produced during the Edo period (1604-1867) using a variety of patterning techniques. Data are tested to establish firstly, if the patterns from different cultural settings show different symmetry preferences; secondly, if the symmetry preferences associated with a given culture are maintained over the passage of time, in the absence of external pressures for change; thirdly, if techniques of manufacture have any bearing on the symmetry preferences associated with a given culture.

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This research has investigated the modification of cotton fabric in order to improve the crease resist and liquid repellency properties. The project has involved studying the interaction of crease resist finishes and fluorochemical finishes and their subsequent durability to laundering and abrasion. Since the surface chemistry of fluorocarbons and detergents is vitally important to the effectiveness of the finishes, surface analytical techniques, such as, X-ray Photoelectron Spectroscopy (XPS) and Secondary Ion Mass Spectrometry (SIMS) have been utilised. A number of poly carboxylic acids (zero-formaldehyde) were examined, in combination with sodium hypophosphite (SHP) in order to impart high crease recovery to cotton fabrics. Butane tetracarboxylic acid (BTCA) has been shown to be the best crease resist agent for crosslinking cotton fabric with SHP, giving a similar high fabric crease recovery performance and whiteness index to the traditional formaldehyde based crease agents. In addition BTCA treatment offers higher tensile/tear strength compared to fabric treated with dimethylol dihydroxyethylene urea (DMDHEU). Subsequent UV irradiation of the fabrics significantly improved the initial whiteness of the crosslinked cotton fabrics. Treatment of Jarosol sulphur dyed cotton fabrics with BTCA and SHP resulted in improved washfastness due to "locking" the dye inside the fibre. In combination with the UV absorber, CIBATEX UPF, the poor lightfastness of the dyeing system was improved significantly.