Page 86 - Fiber Fracture

FORMS OF FIBRE FRACTURE 71

Fix. 13. (a) Final stages of’ wear: multiple splitting leads to rounded ends. Wool/polyester jacket. (b,c) ‘Di-
rect’ breaks of nylon after a few cycles of severe biaxial rotation testing. For further explanation, see Fig. 1.

Hearle et al. (1998), which also contains a full list of references. The SEM pictures were
reduced from about 40,000 in UMIST files, plus some from other sources, to about 1500
in the Atlas, and to 54 in this paper. More information on stress distributions in twisted
and bent fibres is given by Morton and Hearle (1993).
Finally, although it is of more academic than practical interest, the complicated
modes of deformation that can occur in fibres are shown by some breaks in the biaxial
rotation test with a high angle of wrap round the pins. This generates high torque forces
and probably some heating. Bulbous zones of disorientation are formed and ‘direct’
breaks occur in a few cycles in very curious forms, Fig. 13b,c.

REFERENCES

Ansell, M.P. (1983) The degradation of polyester fibres in a PVC-coated fabric exposed to boiling water. .I.
Textile Inst., 74: 263-271.
Bunsell, A.R. and Hearle, J.W.S. (1971) A mechanism of fatigue failures in nylon fibres. J. Mater: Sci., 6:
1303-1311.
Goswami, B.C., Duckett, K.E. and Vigo, T.L. (1980) Torsional fatigue and the initiation mechanism of
pilling. Textile Res. J., 50: 481-485.
Hearle, J.W.S., Lomas, B. and Cooke, W.D. (1998) Atlas of Fibre Fracture and Damage fo Textiles.
Woodhead Publishing, Cambridge.
Holmes, S.A. (1996) Surface defect geometry/tensile failure relationships of aminolyzed poly(ethy1ene
terephthalate) fibers. Texfile Res. J., 66: 214-21 8.
Morton, W.E. and Hearle, J.W.S. (1993) Physical Properties of Textile Fibres. Textile Institute, Manchester.
Oudet, Ch. and Bunsell, A.R. (1987) Effects of structure on the tensile, creep and fatigue of polyester fibres.
J. Mater: Sci., 22: 4292-4298.
Schoppee, M.M. and Skelton, J. (1974) Bending limits of some high modulus fibers. Textile Res. J., 44:
968-975.