Size effects in the fiber pullout test

In this paper, a numerical simulation method is used to study the effect of specimen size on interfacial behavior of the specimen in fiber pullout tests. Interfacial shear stress and normal stress are analyzed for different sizes of the test specimen. The interface between fiber and matrix is assumed to be bonded perfectly. For simplicity, all materials are assumed to be linear and elastic solids, and the effects of thermal residual stress and friction between crack faces are ignored. The effects on interfacial behavior of both length of the fiber embedded in the matrix and thickness of the matrix around the fiber are studied using the finite element approach. Furthermore, the effect of the specimen size on the interfacial crack growth is also studied by way of energy release rate. The study shows that the size of the test specimen can influence interfacial stresses and fracture characteristics dramatically.