This work was carried out within the framework of the WEAMEC – CEAUCOMP project – and with funding from the CARENE.
Marine renewable energy (MRE) structures are simultaneously subjected to severe environmental conditions (water or humid air) and continuous mechanical loadings during their lifetime. These parameters accelerate the damage development  and it appears important to build effective predictive models which should take into account the coupled representative operating conditions of the MRE structures.
The aim of this study is to have a better understanding of the coupling between the diffusion of water and the mechanical behaviour of composite materials used in marine energy conversion systems, through both a regular campaign of uncoupled tests and also innovative experiments where creep is performed in water.
Many studies have been conducted on the impact of water diffusion on the resulting properties of composite materials, [2,3]. For instance, the hygroscopic swelling leads to significant mechanical strains and internal stresses which may cause premature damage. However, few studies have focused on the coupled phenomena. Indeed, the absorption of water has multiple effects on composite materials such as decreases of Young’s modulus or glass transition temperature for instance  which have a direct impact on the mechanical behaviour of the studied material. Thus, there is a coupled relation between the mechanical state and the absorption of water that needs further investigation.
A first experimental campaign has been performed on both epoxy and CFRP samples to study the diffusive and mechanical behaviour at different states of ageing, for different humid conditions, written below in the table 1.