Side-to-side tower top deflection

Wind & Water Computer-Aided Engineering Software Tools
14

Dear @Huajian.Xiao,

Here are my responses:

  1. I agree with your interpretation of the state matrix A. Regarding the distinct mass, stiffness, and damping matrices, these can be found for 6x6 rigid-body mass, stiffness and damping matrices as outlined in the following forum post: OpenFast 2nd order Linearization. But this process would not work for structurally flexible models. I’m not aware of a simple way to separate out the mass, stiffness, and damping matrices for structurally flexible models derived through an OpenFAST linearization analysis.

  2. Interpretation of the eigensolution to identify the specific modes has been discussed in many other forum posts. Our new ACDC tool under development is targeted at automating and simplifying the process: GitHub - OpenFAST/acdc: ACDC: Automated Campbell Diagram Code.

  3. The natural frequencies of the NREL 5-MW baseline wind turbine atop the OC3-Hywind spar are documented in the OC3 Phase IV results paper: https://www.nrel.gov/docs/fy10osti/47534.pdf.

Best regards,