Prediction of microscopic interface crack onset in fiber-reinforced composites by using a multi-scale homogenization procedure

A two-scale method able to carry out a macroscopic failure analysis of a compositestructure in presence of microscopic mixed mode interface crack initiation, is proposed. The methodis able to accurately predict local failure quantities (fiber/matrix interfacial stresses, energy releaseand mode mixity for an interface crack) in an arbitrary cell from the results of a macroscopichomogenized analysis. Microscopic crack initiation is thus analyzed by using a coupled stress andenergy failure criterion in term of these local quantities. Numerical results are obtained for a planestrain model of a locally periodic fiber-reinforced composite material subjected to shear loading andcharacterized by initially undamaged fiber/matrix interfaces. Predictions for the critical load factorand interface crack length at crack onset obtained by the proposed model are compared with thoseobtained by means of a direct simulation.