STRESS TRANSFER IN THE FIBER FRAGMENTATION TEST .2. MULTIPLE FIBER COMPOSITES

The micromechanics of stress transfer has been analysed in a multiple- fibre composite which was subjected to uniaxial tension. The model com posite was treated as a three-cylinder assemblage, which consisted of a central fibre, a matrix annulus and a composite medium. Analytical s olutions have been derived for all major stress components for the com posite with fully bonded fibre-matrix interface. A parametric study wa s performed on a carbon fibre-epoxy matrix composite. The result sugge sts that the principal effect of a stiff composite medium surrounding a discontinuous isolated fibre due to the high fibre volume fraction a nd stiff matrix, is to reduce the efficiency of stress transfer over t he central potion of the fibre, while promoting the fibre-matrix inter face shear stress concentration at the fibre end region. Practical imp lications of this observation with respect to fibre fragmentation and interfacial debonding are discussed.