High tensile strength characteristics of strong interfacial filament/
matrix bonding can be combined with the high fracture toughness of
weak interfacial bonding,when the fibers are arranged to have alternate
sections of high and low shear stress. Such weak and strong bonds can
be achieved by appropriate intermittent coating of the fiber [25], or
mixing coated and non-coated filaments. The strong regions ensure
that the filament is picked up, weak areas randomly dispersed along
the running crack path serve to blunt them, by producing pull-out
length with an associated large contribution to toughness.