COMPOSITES 2023

Full-Scale Fatigue Test of a Composite Tidal Blade

  • Lopez Dubon, Sergio (The University of Edinburgh)
  • Vogel, Christopher (University of OXford)
  • Garcia Cava, David (The University of Edinburgh)
  • O'Bradaigh, Conchur (The University of Edinburgh)
  • McCarthy, Eddie (The University of Edinburgh)

In session: - Fatigue

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Fatigue testing of tidal turbine blades requires the cyclical application of loads without matching the natural frequency of the blade due to their high stiffness and associated thermal issues of composite materials at those frequencies (i.e., 18Hz cycles). To solve this, loading the blades with an auxiliary system is necessary; in most cases, a hydraulic system tends to be highly energy demanding and inefficient. To solve this, loading the blades with an auxiliary system is necessary; in most cases, a hydraulic system tends to be highly energy demanding and inefficient. In 2020, a new turbine blade fatigue test standard was published, IEC TS 62600-3:2020 [1], which codifies a test method for full-scale tidal blades, and in 2022, the new FastBlade facility at Port of Rosyth, Scotland [2], was opened, which has the capability to deliver accelerated lifetime fatigue testing of a full-scale tidal blade and other long slender structures. Using real on-site collected data, a series of equivalent target loads were defined and used in FastBlade to prove an efficient way to perform fatigue. They used a regenerative digital displacement hydraulic pump system and saved up to 75% compared to a standard hydraulic system. During the test, a series of measurements were performed on the blade response and Fastblade itself, showing exciting results on the mechanical behaviour of a blade and best testing practice for FastBlade. The blade withstood 20 years (equivalent) of accelerated fatigue loading without catastrophic failure. FastBlade identifies possible improvements to the testing procedures, i.e., control strategies, load introduction, instrumentation layout, instrument calibration, and test design.