Characterisation and water aging of composite materials for tidal turbine blades

It is widely acknowledged that Ireland has access to some of the richest tidal energy resources in the world. The technology required to efficiently and economically extract tidal energy is dependent on the current choice of... [ view full abstract ]

It is widely acknowledged that Ireland has access to some of the richest tidal energy resources in the world. The technology required to efficiently and economically extract tidal energy is dependent on the current choice of tidal turbine blade construction materials, namely fibre reinforced polymer composites. The lifespan and economic viability of these devices is constrained, in part, by the degradation of the blade materials due to prolonged sub-sea immersion. To represent a worthwhile investment, it is expected that the turbines will remain operational for periods of time of up to 20 years. This work aims to investigate water ingress in four polymer composite materials commonly used to construct ocean energy devices. 3-D X-ray CT (computed tomography) is used to characterise the voids, resin-rich areas and other manufacturing defects present in each materials. These defects are believed to significantly alter the rate of seawater diffusion, as well as the total uptake of seawater at saturation. The materials are then exposed to accelerated water aging in order to determine the rate of water uptake. Comparisons are then made between the materials based on the initial material characterisation and the results of the aging experiment. The material micro-structure, as well as the matrix material, are shown to strongly influence both the water uptake rate and total water uptake.