Effect of particle distribution on initial cracks forming from notch tips of composites with hard particles embedded in a soft matrix

Abstract

This paper studied the size of a so-called initial crack occurring at a notch tip caused by strain concentration in a particulate composite. The composite had hard and strong particles embedded in a soft and weak matrix material. Therefore, the crack formed in the matrix material but not in particles. This study discusses a computational model and a criterion to predict lengths of initial cracks. The predicted results agree well with average values obtained from the experiments. However, the experimental data showed scattering. In order to understand such scattered data, the effect of particle distribution on the initial crack size was studied numerically. The study showed that a variation in particle volume fraction did not affect the crack length as long as the specimen had a uniform particle distribution. However, a local variation of particle distribution in a specimen had a significant effect on the initial crack length confirming the scattered data. The size of the localized zone was about 2 mm or less which was the smallest size of the specimen to represent the smeared homogeneous properties of the composite material.