On the Role of Hazard and Particle Failure Statistics on the Variation of Fracture Parameters of Ductile-Brittle Composites

Abstract

The behavior of a simple computer model considering a random distribution of brittle spherical particles in a ductile matrix is examined in order to highlight the intrinsic variations of the fracture conditions due to the probabilistic nature of the particle cleavage. The model is qualitatively supported by experimental data on stress-strain behavior and damage accumulation in an Al-Si alloy with unconnected equiaxed Si particles. It is used to evaluate the effect of the particle failure statistics on the fracture characteristics (strength, ductility, and fraction of cracked particles) and their scatter, which occur to be strongly dependent on the specific shape of the probabilistic law. In particular, it is found that the variations of the fracture conditions may depend non-monotonously on its sharpness, in the case of the well-known Weibull statistics controlled by the value of the respective modulus of the material of hard particles. The existence of a maximum scatter leads to a suggestion that the choice of the reinforcements may influence not only on the average value of the fracture resistance but also on the quality of its prediction.

Keywords

• metal matrix composites
• fracture
• aluminum alloys
• statistical model