Numerical modeling of moisture diffusion in an unidirectional fiber‐reinforced polymer composite

The durability of a fiber‐reinforced polymer (FRP) composite is dependent on the diffusion of water or corrosive media in them. In this paper, the finite element method (FEM) is adopted to investigate the effects of neighborhood filaments in cell model process, as well as the fiber volume fraction, fiber arrangements and fiber in contact on the moisture diffusion in FRPs. The diffusivity coefficient determined by the modified predicted theoretical model is larger than the FEM results. The filaments affect the moisture diffusion process significantly within the 1.2∼1.4 times of the fiber radius, while the fiber arrangement plays a slight effect relatively. In addition, the tortuosity of the diffusion path owing to the fiber contact is found to play a dominant role on the moisture diffusion. The diffusivity coefficient of the water in the fiber‐resin interphase zone is much smaller than that of the matrix, due to the effect of the existence of the carbon fibers. For the current CFRP system, the diffusivity of resin matrix is 1.12 × 10−7 mm2/s and the diffusivity coefficient of the water in the interphase is only 25% of that of the matrix. POLYM. COMPOS., 40:401–413, 2019. © 2017 Society of Plastics Engineers