I’m currently working on a project where I analyze acceleration data measured in edge- and flapwise direction of a rotor blade. As validation of measurement data, I wanted to see how the acceleration data generated in a FAST simulation looks like. Therefore I did several runs on the NREL 5MW onshore turbine and extracted some SpnALxb and SpnALyb values and did a FFT on the signals.
This is when I realized that FAST only uses one edgewise and two flapwise blade modes to generate the acceleration signals. Also when looking into the FASTKinetics formulas, only these three eigenmodes are taken into account. Since I am more interested in higher order eigenmodes of the blades, which I can see in real measurement data, is it possible to add more blade eigenmodes to the simulation? I’m especially interested in changes in higher order frequencies due to damages or atmospheric icing.