Multi‐scale analysis of diffusion of fluid in sandwich composites

This study presents a multiscale analysis for describing the fluid diffusion in polymeric sandwich composites, comprising of glass‐epoxy fiber reinforced polymer (FRP) skins and polyurethane foam core. The multiscale framework includes the unit‐cell micromechanics model for determining the overall diffusion behavior in the FRP skins by incorporating different diffusivities of the fiber and matrix and the diffusion model for foam core. In addition, multiscale diffusion tests have been conducted for the sandwich composites, FRP skins, foam core, and epoxy resin. The specimens were immersed in deionized water at 50°C. The capability in predicting the overall diffusion behavior of sandwich composites while recognizing the different diffusion processes of the constituents is not only beneficial for designing polymeric sandwich composites with desired performance but also enhances understanding on the durability of polymeric sandwich composites. POLYM. COMPOS., 40:3520–3532, 2019. © 2019 Society of Plastics Engineers