Dear Lingling Yin,
Here’s how I interepret your linearization output:
Mode → Description
1 → 1st Tower Side-to-Side
2 → 1st Tower Fore-Aft
3 → 1st Blade Flap Asymmetric
4 → 1st Blade Flap Asymmetric
5 → 1st Blade Flap Collective
6 → 1st Blade Edgewise Collective
7 → 1st Blade Edgewise Asymmetric
8 → 1st Blade Edgewise Asymmetric
9 → 2nd Blade Flap Asymmetric
10 → 2nd Blade Flap Asymmetric
11 → 2nd Blade Flap Collective
12 → 2nd Tower Fore-Aft
13 → 2nd Tower Side-to-Side
Is that what you got?
The mode shapes of an individual tower or blade as a function of distance along the beam – as shown in NREL/CP-500-43045 – are inputs to FAST, not outputs from FAST. What the FAST linearization output provides is the full-system modes; that is, how the various DOFs get coupled together in the FAST representation of the full wind turbine system (blades, drivetrain, nacelle, tower, platform).
In NREL/CP-500-43045, we’ve compared the results from the FAST linearization analysis with the results from a linearization analysis from ADAMS, where the ADAMS model was built through the FAST-to-ADAMS preprocessor.
I hope that helps.
Best regards,