Multiphysics Modeling of the Hygro-Mechanical Behavior of Heterogeneous Materials

The present chapter investigates the modeling of the hygro-mechanical behavior of composites used in marine environment. The purpose of the proposed models is to analyze the effect of water absorption on a composite structure through mechanical quantities such as stress fields. The case of non-Fickian diffusion processes is first addressed with the Langmuir model allowing representing anomalies of diffusion. The elastic constitutive equations thus depend on the moisture content involving a hygroscopic strain field. The capabilities of the model are shown with a numerical study on a composite material. Second, we propose to introduce couplings between the water diffusion and the mechanical states. To achieve this, we mix the classical Fick model with the free volume theory and implement the model in a finite element software. A numerical study regarding the impact of such coupling on a pure resin case is carried out. We finally propose to take into account the uncertainties sometimes observed on the experimental data which enable the characterization of the diffusion properties. Some of the material properties of the hygro-elastic model thus become random and are modeled with random variables. The propagation of these uncertainties is made with a stochastic spectral approach based on polynomial chaos expansions. The efficiency of the proposed technique is shown with a numerical application involving a polyamide neat resin.