BeamDyn Sectional Motions

Dear all,

I have been trying to get Sectional Motions (e.g. N2TDxr) from BeamDyn, FAST runs without a problem but, as outputs TDxrs are “INVALID” and are all equal to zero. I dont understand if I am providing fast with Invalid inputs or BeamDyn is not successfully calculating those motions.
I came across some similar problems in the forum and saw dr. Jonkman recommend Openfast on github, I also gave that a try and got the same results.
I appreciate your guidance.

Best regards,
farhad

ps: In the attached photo I put any changes that I did to the default FAST files in a red circle.

Dear Farhad,

BeamDyn is not outputting the nodal motions because you’ve set NNodeOuts = 0. From your BeamDyn input file, I see that your BeamDyn model has 6 nodes, so, you can set NNodeOuts as high as 6. Also, if you want the tip motions output, change “N9” to “N6” in the output names in your OutList.

I hope that helps.

Best regards,

Thank you dr. Jonkman for quick response, It is working now.
I understand that section 1-9 and tip are available as outputs. Is there a way to get results for rest of the sections? for example NREL 5WM-Baseline has 49 sections, can BeamDyn calculate behavior of 10-48 sections?

Dear Farhad,

The nodal outputs are available for the finite-element nodes, not for the sectional input stations used to define the blade mass and stiffness distribution. If you wish to have more than 6 output nodes, you’ll have to increase the order of the finite element.

Best regards,

Thank you dr. I think I understand now.