The goal is to develop fast and reliable prognostic tools for fatigue (re)assessment of the welded joints in substructures of offshore wind turbines to serve both lifetime assessment of existing infrastructure and aid future designs. Following innovation targets are foreseen:

• To transition from the simplified/conservative representation of weld details in current practice to high-fidelity finite element models of critical joints. To calculate fatigue damage parameters at hotspots, to obtain a more accurate representation of fatigue accumulation and to directly incorporate the exact geometry, e.g. including fabrication tolerances.
• To include as-built information into the digital twin, an integrated foundation/substructure/tower model that correctly represents the structural dynamics of realworld
  assets. Full-field stresses and load-histories will be obtained on the different levels and headings by combining in-situ measurements with the digital twin. Allowing a more accurate representation of the load histories of an asset as well to account for advanced fatigue models, e.g. crack retardation.

Combining the high-fidelity local fatigue strength degradation of as-built details with accurate historic loads will open a new route for optimized O&M and lifetime extension of the existing infrastructure. Simultaneously a higher fidelity in modelling fatigue details will allow to reduce conservatism in the design of new assets.