Assessment of Fatigue Strength of Welded Connections in Thick Plates

Fatigue is a governing limit state for design of wind turbine structures. This implies use of thicker plates in these structures than that used as basis for derivation of standard design S-N curves. Due to a significant number of wind turbine support structures designed in a similar way it is important to use a reliable design procedure that does not require use of unnecessary steel costs or fabrication costs. There are also questions related to calculation of structural stresses to be entered the different S-N curves for calculation of fatigue lives. Therefore an alternative assessment method based on notch stress and very fine element meshes has been used to assess target hot spot stress values for calculation of best estimates of fatigue lives.