ON THE SINGLE-FIBER PULLOUT AND PUSHOUT PROBLEM - EFFECT OF FIBER ANISOTROPY

Based on our recent theoretical model of the interfacial debonding and fibre pullout/pushout stresses, an improved analysis including the ef fect of fibre anisotropy has been performed for single fibre pullout a nd pushout. During fibre-matrix debonding the debonded region is consi dered as an interfacial crack and its extension is dependent on a frac ture energy criterion being satisfied. The elastic properties of the f ibre are taken to be transversely isotropic about the fibre axis and t he matrix is assumed to be isotropic. The results show that the maximu m debond stress for fibre pullout and the initial frictional pullout s tress increase as the ratio of the Young's moduli of the fibre between the axial and radial directions E(f)/E(f)r increases, and this is par ticularly so at large embedded fibre lengths. However, in the case of fibre pushout these debond and pushout stresses decrease as E(f)/E(f)r increases.