ELASTIC-PLASTIC FRACTURE BEHAVIOR ANALYSIS ON A GRIFFITH CRACK IN THE CYLINDRICAL THREE-PHASE COMPOSITES WITH GENERALIZED IRWIN MODEL

Abstract

Elastic-plastic stress analysis on a matrix crack interacting with near-by circular inclusions (the fibers) in fiber-reinforced composites has been carried out. The crack is initiated near one of the inclusions, while the effect of other inclusions in the composite is considered through simulating the composite material by the cylindrical three-phase model. To more accurately study the fracture behavior of the crack, plastic zone correction is introduced first time for such a crack-inclusion interaction problem. To determine the plastic zone sizes (PZSs) at the crack tips, a generalized Irwin model is proposed for the current mixed-mode problem where the von Mises stress yielding criterion is employed. With the aid of distributed dislocation method, the physical problem is formulated into a set of singular integral equations and solved through a numerical schism. The effective stress intensity factor (SIF), the PZS, crack tip opening displacement (CTOD) are evaluated accordingly. In the numerical examples, the influence of the crack orientation angle, the fiber/matrix shear modulus ratio, and fiber volume fraction on the fracture behavior of the crack is discussed in detail. It is found that the crack orientation angle has great effect on the normalized values of PZS, CTOD, and effective SIF, while the effects of shear modulus ratio and fiber volume fraction depend highly on the conditions of the inclusion (the fiber) and matrix.