Tom Cassidy

The Simulation of the Geometry of a Two-component Yarn Part II: Fibre Distribution in the Yarn Cross-section

This paper considers the distribution of fibres in yarns and discusses the development of a model for the simulation of fibre distributions; the concept of ‘virtual location’ within the cross-section domain, which may contain a fibre, is introduced. The distribution of fibres in real yarns is compared with computer-generated distributions. The distributions predicted by using the model demonstrate all of the properties of the real yarns considered.The change in the fibre distribution caused by compressive forces is considered, and a model to describe the behaviour of real yarns is proposed.

Modelling of Two-component Yarns Part I: The Compressibility of Yarns

This paper considers the compression properties of yarns. A model is proposed which predicts the behaviour of yarns in compression; the model takes account of the structural characteristics of yarns and the finite dimensions of fibres. A device is described which has been successfully used to measure the effects of compression forces on the dimensions of yarn cross-sections.A comparison between the theoretical behaviour of yarns and experimental results demonstrates the good predictive ability of the theory.

An Application of Queuing Theory to Modeling of Melange Yarns Part I: A Queuing Model of Melange Yarn Structure

A queuing model of staple fiber yarn is presented that enables the modeling and a better understanding of fiber migration in a yarn. The model provides a fine yarn structure where the migrational behavior of fibers is associated with the behavior of customers traveling across an open network of queuing systems to get services. Based on this analogy, the underlying mathematical foundation of the queuing theory is used for the modeling of yarn structure and properties. The model uses yarn technical specifications including yarn linear density and twist level, fiber linear density and length distribution, together with specific parameters such as fiber packing density distribution and migration probabilities. The model can be used for modeling a wide range of structurally different yarns; examples include marl, mottle and melange yarns, yarns with different levels of hairiness, and yarns produced by various spinning systems. The model can be used for 3D simulation of yarns in computer-aided design systems for textile design and for the prediction of mechanical properties of yarns.

An application of queuing theory to modelling of melange yarns. Part II: A method of estimating the fibre migration probabilities and a yarn structure simulation algorithm

A queuing model of staple yarn structure was presented in Part I of this work, where the migration behaviours of fibres were simulated by the movement of customers in a Markovian network of queuing systems. Part II of the series proposes (i) a multi-dimensional minimization method for estimating the migration probabilities of fibres based on the analysis of the distribution of number of fibres in yarn cross-sections; (ii) a yarn structure simulation algorithm which uses the migration probabilities of fibres, yarn technical specifications (e.g. linear density and twist) and colour composition to produce a realistic three-dimensional image of a melange yarn. The result is a high quality three-dimensional image of a melange yarn showing its fibrous structure as well as the formation of hairiness. Due to the generic nature of the model and the simulation algorithm, this approach can be applied to a wide range of yarns including ring-spun or open-end spun yarns of solid shade or produced from melange blends. Further improvements to the proposed model are discussed including the application of inhomogeneous Poisson process and the analysis of energy relationships which govern the migration behaviour of fibres.

The influence of woven stretch fabric properties on garment design and pattern construction

Tensile properties of various woven stretch fabrics were measured. The extension, residual extension and elastic recovery under repeated tests were evaluated. The measurement of a female body was taken in five different postures and five patterns produced. These were combined to produce one pattern which allows for optimum movement. This pattern was then modified by taking into account the extension and recovery properties of the stretch woven fabric. Garments produced using a traditional method of pattern production and the new modified pattern for both woven and woven stretch fabrics were compared by 40 experienced fashion and textile designers with regard to appearance and visual fit during movement.

Modelling of Two-component Yarns Part II: Creation of the Visual Images of Yarns

This is the second part of a two-part series. It introduces a method for simulating a two-component yarn based on the compression model described in Part I. A quadrilateral mesh is employed to generate the over-all yarn appearance from a wire-frame model with texturing and light reflection applied to the surface. Comparison with other simulated yarns using different models and with real yarns show that the simulated yarns using the method described in this paper are more accurate and yield an improved visual representation of real yarns.

An Evaluation of the Effect of Different Yarn-spinning Systems on the Handle of Fabrics Part I: A Comparison of Ring-spun and Mule-spun Woollen Yarns

An investigation is reported in which simple rib-knitted fabrics were constructed from lambswool yarn spun on ringframes and mules. The mechanical properties of these fabrics were then measured on the Kawabata range of instruments, and primary hand values (stiffness, smoothness, and fullness/softness) were calculated. The fabrics were also subjectively assessed by a panel of judges for differences in handle. Both the objective measurements and the subjective measurements detected differences in handle between the fabrics. The fabrics constructed from mule-spun yarns were found to be less stiff and smoother in handle.

Cultural reinvention for traditional Korean bojagi

This article introduces the idea of cultural reinvention for cultural textile products. Fundamentally, the term ‘cultural products’ consists of culture and product. Culture means a symbol of a particular time and society. Cultural products can be thought of as artefacts produced by and for a specific cultural group. However, commercial needs and desires may and often do mean that although the form and style of the artefact may remain, it can be produced by other cultural groupings. This article builds an understanding of the term cultural reinvention through the historical and modern consideration of tartan as a case study. It then provides a taxonomy of traditional and cultural Korean textiles and identifies possible strategies for the cultural and commercial reinvention of bojagi textiles. A website has been developed as a design marketing tool to allow consumers to learn about and create their own bojagi designs. This website has been evaluated by five focus groups.

The measurement of plain weft-knitted fabric stiffness

A new instrument and a test method are presented in this paper that can evaluate the stiffness of plain weft-knitted fabrics. The WIRA Instrumentation Tester can measure torsion data for various flexible fibre assemblies whilst they are being twisted. The torsional properties of two types of fabrics, namely nonwoven and knitted fabrics, were analyzed. Then, comparisons between bending rigidity and torsional rigidity have been conducted using FAST-2, Shirley, Heart Loop and the new WIRA method for the assessment of fabric stiffness. The results show high correlation between bending rigidity and torsional rigidity in assessment of nonwoven fabric stiffness; they also reveal that the WIRA tester and torsional rigidity are more suitable for characterizing the stiffness of plain weft-knitted fabrics than the other test methods.

Advances in the CAD Simulation of Textile Yarns

A project aimed at the 3D simulation of textile yarns from technical specifications was begun in 1993 and attracted support from both industry and research councils to enable the formation of a multi-national team of researchers to come together in the UK. Considerable progress has been made particularly in the simulation of knitting yarn and plain knit fabric. In recent times the team has tackled the problem of simulating mixture coloured yarns sometimes called melange. This has necessitated a more complicated model of yarn structure based on queuing theory which is outlined at the end of the paper. References are provided for readers who wish to learn more of the various theories and models that have been used throughout the course of this project.