A Quality‐Driven Framework for Local Fatigue‐Strength Assessment of Wind–Energy Structures Considering Size Effects

ABSTRACT Reliability, safety, and the lifetime of wind energy systems are mainly driven by the quality of each single component. Especially, large structures made of cast material or welded structures, such as the nacelle, the machine carrier, or the tower, are subjected to cyclic loading. In these cases, various factors determine the fatigue strength and thus the reliability. For castings, local material defects and the local microstructure are the relevant properties; for welded joints, the weld geometry and weld imperfections. While new and practical methods to assess the influence of defects resp. imperfections on fatigue strength are needed, wind energy components can profit from new cast materials and welding procedures with improved properties to enable a lightweight and more reliable component design. The paper discusses reliability aspects and the lifetime assessment of cast and welded wind energy components based on production quality and connected size effects. Therefore, new methods based on the quality assurance process are presented coupling digital nondestructive test results with local fatigue strength of cast and welded components. Moreover, newer achievements in improved materials and production quality and their benefit for lifetime and lightweight are discussed based on modern cast iron materials like high‐silicon nodular cast iron.