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.
Dear @Jason.Jonkman,
Excuse me. For the sectional outputs of BeamDyn, is it possible for user to obtain the number of nodal outputs that more than “station_total” (Number of blade input stations)?
For example, in my BEAMDYN INPUT FILE, “member_total”=1; “kp_total”=“station_total”=50; “order_elem”=5; and I want to get more than 100 sectional outputs. Is there a way to achieve this?
Thank you for your patience.
Best regards,
Dear @Baoxuan.Wang.
In addition to the named outputs from the BeamDyn OutList, you can use the nodal output option to output results from all analysis nodes of the BeamDyn model. See the nodal output documentation here for more information: 4.2.4.3. Input Files — OpenFAST v3.5.0 documentation.
Best regards,
Thank you for your reply. I would like to clarify my question. Actually, I find if “station_total”=50, then I can output results for at most 50 sectional outputs.
So, if I need more section outputs, it seems that I must add more sectional input stations used to define the blade mass and stiffness distribution (analysis nodes of the BeamDyn model).Can I obtain more sectional results without adding more refined stations?
Best regards,
Dear @Baoxuan.Wang,
You can set Refine in BeamDyn greater than 1 to add refinement to trapezoidal quadrature (Quadrature = 2), without increasing the number of input stations.
Best regards,
Thank you very much for your guidance.
