An experimental study of water diffusion in carbon/epoxy composites under static tensile stress

Abstract

The coupling between tensile stress and water diffusion in composites represents a major issue in many marine applications. Even if these two behaviours are well documented as separate subjects, there are still very few data on fully coupled mechanisms. The aim of this study is to understand what governs the coupled behaviour, by investigating the water diffusion in carbon/epoxy. The coupling is first evaluated on neat resin samples to characterise the matrix behaviour. Then the study focuses on composites with two types of woven fibre orientation: one at ±45°, in order to understand the coupling effects on materials loaded away from the reinforcement direction and another quasi-isotropic to obtain properties along the fibres. For each material the same approach was applied: first, the tensile behaviour, damage development and water diffusion were studied uncoupled. Then, semi-coupled effects were investigated. The final part of the paper combines both behaviours as fully coupled phenomena

Ageing effects after ozone and water immersion on tensile strength at room and high temperatures of carbon/epoxy F8552 laminates

“…Mansouri and collaborators 24 experienced temperature aging as water absorption is an important parameter in the degradation of composites, which influences the elastic properties of the composite laminates, and consequently the stiffness of the whole composite structure. Humeau and collaborators 27 tested water immersion combined with mechanical loading and this coupling caused large effects on tensile strength which led to premature failure.…”

Performances, challenges and opportunities in strengthening reinforced concrete structures by using FRPs – A state-of-the-art review

“…Because, if polymers are exposed to moisture conditions for a long time, their properties may be changed to some extent, which may or may not be possible to recover after drying. Generally, plasticization, swelling, hydrolysis and differential stress may develop owing to moisture uptake [95,96]. Swelling of a polymer is proportional to its moisture content and increases with increasing relative humidity [97].…”

“…whereas CFRP exhibits sufficient resistance [9,96]. In GFRP, moisture extracts the ions from the glass fibres and a change in the fibre structure takes place and fibrillation increases when aramid fibres absorb moisture [99].…”

Degradation and Damage of Composite Materials in Marine Environment

“…Humeau et.al. [45] performed experimental research of water diffusion in carbon/epoxy composites subjected to static tensile stress. This research emphasizes the lack of experimental data and analytical theories for fully coupled behaviour of the water absorption/diffusion process and mechanical stress.…”