Prediction of Wind Turbine Blade Fatigue and Life Using the National Renewable Energy Laboratory Open-Source Software

With the growing importance of renewable energy, there is a critical need for software and tools that accurately predict wind turbine blade strain and fatigue. OpenFAST, TurbSim, and MLife are open-source wind turbine simulation tools that couples aerodynamics, structural dynamics, wind simulation, and control systems to accurately predict the performance and behavior of wind turbines. This study centers on utilizing the aforementioned software to model turbulent wind conditions with a predefined set of basic starting parameters, and subsequently determining the service life. Collaboration between the NREL and university team, helped establish a foundational baseline, and implement realistic input parameters to ascertain the ultimate load, determine damage equivalent loads (DEL), and project the service life. A 1.5 factor of safety (FOS) was used throughout all simulations. From a TurbSim-generated turbulent wind file at 12.5 m/s, the maximum root blade load is 444kN, reaching 666kN with the FOS. Including the blade weight, the total load on the root is 840kN. Under default, zero initial conditions for the control, the blade life calculated was 34 years using a Woehler exponent of 10. After adjusting initial conditions to match real-time values, such as attack angle, the loading on the root was calculated to be 806kN with a design life of 20 years. This does not consider failures of the M45 grade 10 steel threaded inserts that hold the root to the hub, due to corrosion or vibrations.