Localized stress redistribution after fibre fracture in brittle matrix composites

A model is detailed that describes the redistribution of stress, after individual fibre failure, amongst the intact reinforcing fibres of a ceramic matrix composite. The load drop carried by a single fibre when it breaks is balanced by extra loads in the intact fibres which are calculated using elastic solutions and variational mechanics. The magnitude of stress redistribution is shown to follow a d(-m) relationship, where d is the distance from the broken fibre and m depends on the fibre volume fraction and a non-dimensional parameter that normalizes the influence of the stress and the elastic properties of the composite. The model has been applied to two composites, SiC/SiC and CAS/SiC. It is shown that the stress redistribution is localized in both composites, the stress increments in the closest intact fibres being more than one order of magnitude greater than predicted by the assumption of global stress redistribution. (C) 1997 Elsevier Science Limited.