Sea Water Ageing of Composites for Ocean Energy Conversion Systems: Influence of Glass Fibre Type on Static Behaviour

Abstract

Composite material components will be an essential part of ocean energy recovery devices, and their long term durability in sea water must be guaranteed. Despite extensive experience for boat structures and wind turbines few data exist to design structures subjected to a combination of mechanical loads and sea water immersion. This paper presents the first results from an experimental study, performed jointly with fibre manufacturers, and a resin supplier, to fill this gap. The experimental study is completed by numerical modelling to simulate the coupling between water absorption and mechanical behaviour. Sea water ageing is shown to result in a drop in quasi-static mechanical properties and a change in flexural mode from compression to tension at longer ageing times, which is consistent with results from the numerical simulations.

Characterization of sea water ageing effects on mechanical properties of carbon/epoxy composites for tidal turbine blades

“…A thorough understanding of the fatigue behavior of the moving parts (example: turbine blades) is therefore essential. A previous study [7], [8], has highlighted the sensitivity of durability to the choice of components (fibre, resin, surface treatment of fibres). That work was carried out on thin composites reinforced by glass fibres.…”

Water‐induced degradations in MWCNT embedded glass fiber/epoxy composites: An emphasis on aging temperature

“…Offshore oil platforms are also a potential thrust application area of glass fiber reinforced polymer (GFRP) composite . In addition, GFRP is also being used in oil and water pipelines, water storage tanks, desalinization plants, tidal, and wind turbines in sea …”

“…1 In addition, GFRP is also being used in oil and water pipelines, water storage tanks, desalinization plants, tidal, and wind turbines in sea. 2 Epoxy has been commonly used as a matrix material in structural load-bearing FRP components due to its superior strength, stiffness, and thermal and chemical resistance. 3,4 Ingression of environmental moisture/water in epoxy-based materials is undesirable and very often limits its utilization in naval applications.…”

Evaluation of the durability of composite tidal turbine blades

“…The influence of water on composite properties has been studied for many years and is now reasonably well understood [6][7][8]. Studies of ageing in sea water are less frequent, but some data are available [9][10][11][12][13]. Many marine structures are not highly loaded however, so there has been little interest in cyclic loading during immersion, nor of the influence of wet ageing on fatigue performance.…”

“…COMSOL MULTIPHYSICS software was used throughout, as it is well suited to coupled modelling problems, both at a material level (water diffusion coupled with mechanical loading) and at a structural level (fluid/structure interactions). For example, at a specimen level, the dog-bone geometry was modelled, and a coupled model with strength versus weight gain input data enabled a flexural failure mode transition from compression to tension to be predicted [13].…”