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Comparative Study on the Fatigue Assessment Concepts for Horizontal Butt Welds of Wind Turbine Towers

This paper presents a comparative study on the fatigue life prediction of different fatigue assessment methods. The nominal stress concept, the local stress concept and a two‐stage‐model, which consists of the strain‐life approach and the crack propagation method are applied to compute the fatigue life of horizontal butt welds and to assess the methods capability to provide adequate prognosis of fatigue life of wind turbine towers. The comparative study shows the impact of weld imperfections on the fatigue life according to the local stress concept and the strain‐life approach. The later approach even considers the influence of actual geometry and imperfection on the total damage sum. The approach has a great potential to accurately predict the fatigue life of butt welds and notch details of wind turbine structures with precise manufacturing, sophisticated processes and high‐quality control.