I am currently working on a university project where a 120 MW offshore wind farm, composed of 15 8MW is to be proposed.
For context, a university software has been provided to produce the blade, and a proper FEA analysis has been conducted. However, a fatigue analysis is being asked for, but no composite software analysis are available like nCode/FE Safe - in turn, making me turn to NREL for guidance.
Would it be possible to know to what extent the fatigue analysis within OPENFast and MLife is possible? How would the blade be set up? Apart from the blade geometry (r/R, c/R, Pre-Twist and others) what other parameters would it be necessary to potentially produce a fatigue analysis?
I understand that composites are extremely hard to produce fatigue analysis due to the lack of S-N curves, which is why I am wanting to ask on the FORUMS before, in order to understand the limitations that the open source software may have.
To do fatigue analysis of blade–which has many aerodynamic, structural, and control nonlinearities–in a wind farm properly, requires running a loads analysis across the full range of operational conditions, as well as a detailed structural analysis of the blade. The loads analysis requires a a full aero-servo-elastic model (or aero-hydro-servo-elastic for offshore), like OpenFAST. To capture farm-level wake effects requires a dynamic wake meandering model, like FAST.Farm (which wraps around the OpenFAST models of each turbine), or a simpler effective turbulence model. The structural analysis requires an FE model of the blade, but if the fatigue analysis is limited to damage equivalent loads (DELs), rather than stress/strain, the FEA model is not needed other than to estimate a couple of the MLife (or equivalent) post-processsor inputs.