Influence of the material inhomogeneity effect on the crack growth behavior in fiber and particle reinforced composites

Abstract

If a crack grows through a material with variations in Young’s modulus, a variation in the crack driving force occurs at a constant loading. Recent papers have shown that this material inhomogeneity effect has a great influence on the crack growth behavior and the fracture toughness of the materials. The purpose of this paper is to investigate the material inhomogeneity effect in fiber- or particle reinforced materials where the crack circumvents the particles and grows only through the homogeneous matrix material. A finite element study is performed under application of the configurational force concept. The particles cause a spatial variation of the crack driving force, quantified by the near-tip J-integral, Jtip. Characteristic parameters of the Jtip-variation are determined as a function of the composite geometry and the matrix and particle properties. The study is made for a regular arrangement of particles, but the results can be also applied for composites with arbitrary particle locations. Implications for the fracture toughness of the composite are worked out. The validity limits of the numerical results and the deduced analytical expressions are discussed.