Microstructural Effects on Damage Behaviour in Particle Reinforced Composites

This paper discusses the effects of non-uniform, random particle distribution on damage initiation and growth, leading to short cracks and breakage of particle reinforced composite specimens. A multi-scale technique was employed to model and simulate damage. Damage was described at the constituent material level (i.e. micro-level) and the results were compared qualitatively and quantitatively with experimental observation. Both results agreed well. Non-uniform, random particle distribution yielded sporadic crack initiation and growth within a uniform tensile specimen. No local crack propagated beyond a certain size. Breakage of the specimens was not caused by the continuous growth of a single critical crack. Instead, coalescence of neighbouring sporadic short cracks resulted in breakage of the specimens. Computer simulation indicated that random particle distribution affected the strength of the composite significantly, but as expected, not its effective stiffness. However, if there was a pre-existing crack in the specimen before loading, the effect of the random particle distribution on the initial crack and the strength of the composite was almost negligible.