Three-dimensional water diffusion and modelling of flax/shape memory epoxy composites

Current applications of mass diffusion in composite structures with natural fibres reinforcements focus on the development of large thickness, balanced laminates, and long diffusion times. Hygromorph composites are, however, thin in thickness and possess slender shapes with unbalanced laminate designs, together with higher moisture diffusion speeds. This work proposes a new three-dimensional inverse identification diffusion method based on extracting the diffusion parameters from each direction in hygromorph composites made of the shape memory epoxy and aligned long flax fibres. The proposed methodology is particularly suitable for slender hygromorphs composites, because the in-plane moisture diffusion is non-negligible in those cases. The method proposed here also helps the understanding of the moisture diffusion and associated mechanical deformations in general hygromorph adaptive morphing structures made of natural fibre-reinforced unbalanced composites.