Bmodes for tower (with rna_on and rna_off)

Wind & Water Computer-Aided Engineering Software Tools
21

Dear @Roger.Bergua , I think i am having a problem with the version because despite of having the discussed parameters correct, I am having an error as it can be seen as follows:
image

What version of BModes do you run? I am saying this because I am using v3.00 and in this version, supposedly only a cantilever connection can be employed. According to the link provided by @Pietro.Bortolotti (IEA15_BModes/RNAon/BModes_tower.bmi at master · ptrbortolotti/IEA15_BModes · GitHub), in the BModes (version 3.00) file .bmi we can only add a cantilever connection , and not free-free one.

I believe my problem is that i have added this line in my BModes v3.00

image
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and it is not compatible with BModes v3.00 since BModes v3.00 can only deal with cantilever beams.

I suppose i have to download another version of BModes, right? I do not know if it is v1.03.01 or another…

Thank u . Alberto

22

Hi @Roger.Bergua , Does the cm_pform value have to be the same as ref_msl?? Plus, regarding the platform mass, i suppose i have to put 0, no?

I have read a forum by @Jason.Jonkman in which it is said that the platform mass inertia matrix has to be this way:
image
However, i have seen one more post forum, in which it is said that the platoform mass inertia matrix should be this one:
image
What shall i put?
thanks

23

You should use BModes v1.03.01. Actually, the eigensolver between BModes v.1.03.01 and BModes v3.00.00 is different. Even for a cantilever system, you will get different results. I can only recommend using BModes v.1.03.01.

image

Regarding the “platform”, you should only include a platform and corresponding mass and inertia if you were not including that in SubDyn. Otherwise, you are already accounting for the monopile in the mass matrix expressed at the tower base. So, does your OpenFAST model (i.e., ElastoDyn definition) include a platform mass and/or inertia?

The platform doesn’t have to be located at the mean sea level.

24

Dear @Roger.Bergua, I am afraid BModes v.1.03.01 cannot longer be installed since the only one available in the NREL webpage is BModes v3.00.00. I have been searching, but there is not anything about BModes v.1.03.01.

25

Dear @Alberto.Utrera,

BModes v1.03.01 is often called “BModes_JJ” on this forum and is available through my Google drive: BModes_JJ.exe - Google Drive.

Best regards,

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