Novel Composite Materials and Structural Test Facilities for Tidal Turbine Blades

This seminar discusses the ongoing work at the University of Edinburgh on the processing, design and testing of thick-section composites for offshore renewable energy structures such as large wind and tidal turbine blades. The potential of ocean renewable energy is tremendous. However, further development of tidal turbine blades is required due to the harsh marine environment, large cyclic forces and high cost of installation. Heat-activated, single component epoxy powders are widely used in the powder coating industry due to their low cost, long out-life, and minimal VOC emissions. They can be formulated to achieve low viscosities at elevated temperatures and then cure rapidly while producing a relatively small total exothermic reaction. The potential to use these materials as a resin matrix for glass-fibres has been identified for manufacturing thick section parts in which it is often difficult to control the heat of cure e.g. the root sections of wind and tidal turbine blades. Numerical simulations of the heat transfer, consolidation flow and cure process can allow for a better understanding of the manufacturing process, and how thick sections can be processed more efficiently with epoxy powders. Carbon fibre reinforced polymers are also promising materials for marine applications; hence, it is vital to understand fully their material properties and failure mechanisms. The effect of water immersion on the properties of glass and carbon-fibre reinforced composites is discussed and a novel tape-line for production of low cost carbon and basalt fibre prepreg and semi-preg materials is presented.

The development of tidal energy is being delayed by the absence of suitable test facilities for lifetime fatigue testing of composites blades, the prime movers in the technology. A typical tidal turbine blade will see 10 million loading cycles in a 15-20 year lifetime, which will take over 3 years to fatigue test in current facilities. The FASTBLADE facility to be constructed at Rosyth Dockyard, Fife, funded by the EPSRC and the University of Edinburgh, will use novel hydraulic technologies to accelerate the testing of these structures by a factor of 10, reducing the lifetime fatigue testing time to only 4 months, which will make the facility unique in the world. Other applications that need accelerated hydraulic-fatigue testing include bridge sections and aircraft wing boxes.