Analysis of Dependence of Volume Fraction and Micropore Shape on Fracture Toughness by the Equivalent Inclusion Method

Abstract

Effects of microstructure on fracture toughness were investigated. Using the equivalent inclusion method, the change in Gibbs' free energy was caluculated for a relatively large body containing a main crack and many spherical micropores (or penny-shaped microcracks). Applying the Griffith's fracture criteria to the model, the effects of micropores (or microcracks) on fracture toughness were formulated. The fracture toughness decreased with the increase in volume fraction of micropores (or microcracks). Furthermore, the fracture toughness of a body with microcracks, depended on the volume fraction more remarkably than that with micropores. The tendencies of the experimental results reported previously, were explained by this theoretical analysis.