Effective mass diffusivity in composites

Gas diffusion is important in composite manufacturing, while moisture diffusion is important for composite performance. In this study, analytical models are developed to predict the mass diffusivity of both square and hexagonal arrays of cylindrical cylinders. These models are able to bridge the gap between continuum calculations via finite differencing of finite element analysis and simple/ trivial models. By breaking the liquid region into zones and making some general assumptions about the diffusion in those zones, simplified models have been developed, which rely solely on the geometry and fiber volume fraction. The models are fairly accurate for a broad porosity range, but specially at low porosity values. A single weight factor is proposed to compensate for the error introduced by the model assumptions. When the weight factor is incorporated, the modified models agree extremely well with the experimental data for the whole porosity range.