AN ANALYSIS OF THE INFLUENCE OF REINFORCEMENT FRACTURE ON THE STRENGTH OF DISCONTINUOUSLY-REINFORCED METAL-MATRIX COMPOSITES

A micromechanical model was developed to study the influence of reinfo rcement fracture on the tensile strength of discontinuously-reinforced metal-matrix composites. The analyses were carried out within the fra mework of the shear lag model, which provides simple expressions for t he average stresses acting on the reinforcement as a function of the m atrix strength and of the reinforcement aspect ratio. The reinforcemen t strength was assumed to follow the Weibull statistics, and in this w ay, the fraction of intact and broken reinforcements can be obtained f or any combination of matrix and reinforcement properties. The overall composite strength was then calculated by assuming that broken reinfo rcements do not contribute to the composite strengthening. The model w as employed to study the influence of various parameters, such as matr ix and reinforcement strength, and reinforcement aspect ratio and size , on the strength of discontinuously-reinforced metal-matrix composite s. Finally, the model predictions were compared with experimental resu lts on several high strength Al alloys reinforced with SiC particulate s.