NON-FICKIAN MOISTURE DIFFUSION IN POLYMERIC COMPOSITES

This article concerns the effects of non-Fickian water diffusion in fiber-reinforced polymeric composites. The departure from classical diffusion is attributed to the time-dependent response of the polymer, akin to viscoelastic mechanical response. The purpose of the present work is to propose a methodology to reduce non-Fickian moisture weight gain data in a manner which enables the evaluation of the diffusion coefficient and moisture profiles across the thickness of composite laminates. The evaluation of those moisture profiles is essential to the computation of residual stresses within composite laminates. It is demonstrated that in some circumstances the non-Fickian moisture profiles result in residual hygro-thermal stresses which differ by about 25 % from predictions based upon classical diffusion.