TT2023 MECHANICS OF TEXTILE STRUCTURES ANNA UNIVERSITY SYLLABUS

UNIT I YARN GEOMETRY 9

Basic geometry of twisted yarn – The idealized helical yarn structure. Yarn count and

twist factor. Twist contraction and theoretical calculations. Limits of twists. Real and

idealized yarns. Packing of fibres in yarn – Idealized packing – Derivations from ideal

forms of packing. Packing in actual yarns. Specific volume of yarns. Relation between

Twist, Diameter and Twist Angle.

UNIT II FIBRE MIGRATION 9

Ideal migration – Observation of the paths of individual fibres – Migration in spun yarns.

Characterisation of migration behaviour – Tension variation as a mechanism of migration

– Criteria for interchange of position – Theory of migration – Conditions for migration and

frequency of migration. Forms of yarn twisting – Cylindrical and Ribbon twisting.

UNIT III MECHANICS OF STAPLE FIBRE YARNS 9

Theoretical analysis of yarn geometry – Stress-strain distribution in yarn – Fibre obliquity

and slippage – Influence of fibre length, fineness and friction on fibre slippage and yarn

strength – Yarn breakage. Strength of blended yarns – Hamburger's model. Analysis of

tensile behaviour, Prediction of breakage, Analysis of yarn mechanics by energy

method, Observed extension and breakage of staple fibre yarns.

UNIT IV MECHANICS OF FILAMENT YARNS 9

Theory of extension of continuous filament yarns, Analysis of tensile forces, Stress-strain

relations of the filaments, Effects of large extensions, Filament behaviour at large

extensions, Prediction of breakage, Load-Extension curve near break, Tenacity,

Breaking extension, Initial modulus, Work of rupture.

UNIT V FABRIC GEOMETRY AND DEFORMATION 9

Elements of woven fabric geometry, Peime and Olofsson models. Jamming of threads,

cover factor, crimp interchange in woven fabrics. Modification to Pierce model – Race

track, Saw tooth and Bilinear models. Form factor, degree of set, extension behaviour of

woven fabric, prediction of modulus, tensile properties in bias direction. Geometry of

plain knitted structures, mechanics of nonwoven fabrics.

TEXT BOOKS

1. J.W.S. Hearle, P. Grosberg and S. Backer, Structural Mechanics of Fibres, Yarns

and Fabrics, Wiley-Interscience, New York, 1969.

2. B.C. Goswami, J. Martindale and Scandio, Textile Yarns: Technology, Structure and

Application, Wiley-Interscience, New York, 1977.

REFERENCES

1. J.W.S. Hearle, J.J. Thwaites and J. Amirbayat, Mechanics of Flexible Fibre

Assemblies, Marryland, 1980.

2. R. Postle, S. De Jong and G.A. Carnaby, The Mechanics of Wool Structures, Ellis

Horwood, 1988.