Multi-Level FEM Modelling of Offshore Wind Turbines accounting for the Environment Uncertainty

Offshore wind turbines are complex structural and mechanical systems located in a demanding environment. In this paper, a multi-level system approach is proposed for studying the structural behaviour of the support structure of an offshore wind turbine. In accordance with this approach, a proper numerical modelling requires the adoption of a suitable technique in order to organize the qualitative and quantitative assessment in various sub-problems, which can be solved by means of sub-models at different level of detail, both for the structural behaviour and for the simulation of loads. Consequently, in a first place, the effects on the structural response induced by the uncertainty of the parameters used to describe the environmental actions and the finite element model of the structure are inquired. In addition, a meso-level FEM model of the blade is adopted in order to obtain the detailed load pattern acting on the blade/hub connection.