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Fick's diffusion law is applied to a one-dimensional diffusion case in which moisture diffuses through both surfaces into a composite laminate submerged in water. The advancing boundary model is adopted to study the moisture diffusion depth and also the moisture content distribution in the laminate. The major contribution of this work is establishing the procedure to obtain the required parameters for quantifying the depth of diffusion and the moisture content distribution which are related to the induced real-time hygric strain and important to the design of a composite structure that is to be used in a marine environment. [ABSTRACT FROM AUTHOR]

The moisture expansion of composites exposed to humid air was investigated. Tests for moisture expansion were performed on carbon/epoxy laminates exposed to humid air of different relative humidity levels and temperatures. The expansion strain data were employed to derive the material's diffusivity and the saturated expansion strain. The result indicated that the saturated expansion strain is about proportional to the level of humidity and inversely proportional to absolute temperature. An algorithm was then employed to track moisture expansion of a laminate in air with varying humidity level based on the diffusivity and the saturated expansion strain. The theoretical predictions were confirmed experimentally. [ABSTRACT FROM AUTHOR]