Macrocrack propagation

Propagation phase During this phase, macroscopic cracking and macrocrack propagation result in fatigue failure, and the physical data that may quantify the material s damage state can be more easily obtained. 

At intermediate concentrations of fibres (10 and 20 wt%), fracture initiates first by the formation of a frontal damage zone (microvoids at fibre ends, fibre decohesion, microrupture of the matrix) and then by a stable growth of microcracks and their junction into a macrocrack which propagates catastrophically (types 2 and 2 loading curves in Table II, associated with Figures lOA and IOC, lOD respectively). 

The destruction of a brittle matrix consists of initiation and propagation of microcracks caused by local tensions. With increased load or imposed deformation, the dispersed microcracks are transformed into a system of macrocracks. Then, one or more major cracks divide the element into separate parts and the continuity of the element disappears in conjunction with a rapid decrease in bearing capacity. 

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