Crack Tip Plasticity in Unidirectional Metal Matrix Composites

Abstract

This paper presents the results from shear lag analysis of a unidirectional metal matrix composite (MMC) containing a central crack and extensive crack tip matrix yielding. The specimen is subjected to a uniaxial tensile load parallel to the fiber axes while the crack is normal to the fibers. The emphasis has been on studying the effect of crack tip damage on the stress concentration and fracture behavior of a unidirectional MMC such as Boron/Aluminum. Since the stiffness of the fiber is very large compared to that of the matrix it is assumed that the fiber carries all the axial load while the matrix transfers load between and amongst fibers by shear. Results show that the fiber stress concentrations at the notch are significantly higher for a finite width plate than those of an infinite plate and the maximum stress concentration does not occur along the crack plane in the presence of matrix yielding.