Modeling of non-uniform composite microstructures

ABSTRACT: The microstructural effects of non-uniform composite microstructures are modeled. Relationships are observed between the degree of non-uniformity and fiber spa-tial information which may be measured via image analysis or derived from Dirichlet cell tessellations. For artifical patterns containing chain-like clustering which simulate com-posite microstructures: (a) the nearest-neighbor distances of random and clustered pat-terns are smaller than those normally estimated by square or hexagonal arrays, (b) in-creased clustering may be associated with increased mean cell volume fraction, cell volume fraction distribution standard deviation, number of cell sides, distribution stan-dard deviation, nearest-neighbor distance distribution skewness, and decreased nearest-neighbor distances and (c) accounting for non-uniform fiber diameters is generally un-necessary, except possibly at low fiber volume fraction or with patterns exhibiting a high degree of chaining. For Nicalon SiC/zirconia titanate composite samples with micro-structures which exhibit clustering, the maximum value of skewness, determined from sub-regions of the sample, correlates with the flexure strength of that sample