Abstract
A model study is conducted on the prediction of the stiffness and fracture toughness of an unidirectional short-fiber reinforced composite containing numerous cracks in the matrix. It is assumed in our model that short-fibers are aligned in the uniaxial loading direction and that cracks in the matrix are perpendicular to the loading axis and are penny-shaped. Then the longitudinal Young's modulus of the composite weakened by those cracks and the energy release rate of a representative penny-shaped crack are com puted by a combination of Eshelby's equivalent inclusion method and Mori- Tanaka's back stress analysis. The interaction between fibers and that be tween fibers and cracks are taken into account by Mori-Tanaka's back stress analysis. Hence our results are valid even for a large volume fraction of fiber and crack.