A novel method to determine the moisture concentration in composite laminates

A novel experimental method based on Fick's diffusion law is developed to determine the distribution of moisture concentration of a composite laminate immersed in water. This method can be applied to a technique of measuring coefficients of moisture expansion of composite laminates. The technique is based on measuring the curvature of a [0n/90n] antisymmetric crossply laminate, introduced by the in-plane unbalanced interlaminar resultant forces. The interlaminar resultant forces can be related to the local hygric expansion along the thickness of the laminate via lamination theory. The hygric expansion is proportional to the moisture concentration by the coefficient of moisture concentration. The technique has been verified to be valid for [02/902] and [05/905] graphite/epoxy. The results agree with the measurements reported elsewhere.