INFLUENCE OF REINFORCEMENT FRACTURE ON THE CYCLIC STRESS-STRAIN CURVEOF METAL-MATRIX COMPOSITES

The cyclic stress-strain curve of a 2618 Al alloy reinforced with 15 v ol.% SiC particulates was measured through the incremental step method in the naturally aged and peak-aged conditions. The mechanical respon se was also simulated by means of the finite element analysis of a uni t cell to determine the average stresses acting on the matrix and on t he reinforcements during cyclic deformation. The stresses on the reinf orcements were used to calculate the fraction of broken reinforcements by assuming that the reinforcement strength follows the Weibull stati stics. Then the cyclic stress-strain curve, including the influence of reinforcement fracture, was obtained by neglecting the load carried b y broken reinforcements. Finally, the predictions of the model (the cy clic stress-strain curve and the fraction of broken reinforcements) we re compared with the experimental results.