Effect of Specimen Width on the Fracture of Unidirectional Metal Matrix Composites

This paper presents the results from shear lag analysis of a finite-width, unidirectional metal matrix composite (MMC) containing a central crack and crack tip matrix yielding. The specimen is loaded in uniaxial tension parallel to the fiber axes while the crack is normal to the fibers. The emphasis has been on studying the effect of specimen width 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. The governing equations consist of a system of coupled integral equations which are solved by a numerical quadrature technique. The parameters considered in obtaining the numerical results include the crack length, specimen width, plastic zone size, and the ultimate strength. Results show that the fiber stress concentrations at the notch, as well as at the specimen edges, are significantly higher than those obtained by an infinite plate solution. © 1992