Feature request-- Calculate natural frequency and modal shape of a single blade through beamdyn

[winder365]

Dear all,

I have known that through the MBC toolbox can calculate the natural frequency of the rotor (for example progressive and regressive modes), however I want to know how to calculate the natural frequency (especially the tortional frequency) and modal shape of a single blade through beamdyn. I will appreciate it if someone can give me some direction.

Thanks

[jjonkman]

Dear @winder365,

A similar question was recently asked on our forum, although I don't understand and not as expected: https://forums.nrel.gov/t/beamdyn-the-blade-modal-are-calculated-using-the-beamdyn-sum-file/6258.

Best regards,

[winder365]

Dear @jjonkman ,

As you direction, I browse the url "https://forums.nrel.gov/t/beamdyn-the-blade-modal-are-calculated-using-the-beamdyn-sum-file/6258."

However, the results I got maybe wrong.

by solve the eigenvalue and eigenvector of the matrix K_BD*inv(M_BD), the eigenvalue matrix (30x30) was obtained as below:

The eigenvalue ω^2 ( (rad/s)^2) above are too large, which are not consistent with that of NREL-5MW blade. The case I use is from "https://github.com/OpenFAST/r-test/tree/main/modules/beamdyn/bd_5MW_dynamic", and the order_elem is equal to 5. So the full system matrix from the ".sum" file is 36x36, and I have eliminated the first six rows and columns .

Thank for your attention.

[jjonkman]

Dear @winder365,

Derek Slaughter has now responded on the forum with the solution.

Best regards,