Meso-scale finite element modeling of moisture diffusion in 3D braided composite

Abstract This paper presents a meso-scale finite element approach on moisture diffusion of 3D braided composite (3D-BC). Firstly, meso-scale geometric configurations for both surface region and interior region of 3D-BC are constructed, and modifications of cross sections of fiber bundles in surface region are made to achieve the equivalent fiber volume fraction there. Then a mixed integral point element (MIPE) model is proposed which can discretize 3D-BC with uniform element mesh. Thus the difficulty of element discretization for 3D-BC introduced by its complicated local braided architecture is avoided. This meso-scale FE model is used to simulate moisture uptake test of a carbon fiber/epoxy matrix 3D-BC. A particular accelerating of moisture uptake during early period observed in the test of this 3D-BC is characterized by the proposed model. Influences of braided layer number and braided angle on moisture diffusion are also investigated by using this model.