Questions on subdyn TP about iea-15-240-rwt HOT 4 OPEN

Great catch. Definitely a bug in the interface joint label.

The reason for the joints very close to one another is to achieve a piecewise-constant thickness distribution, instead of linearly varying thickness, as it better captures monopile manufacturing realities from rolling steel plates.
https://github.com/IEAWindTask37/IEA-15-240-RWT/blob/master/OpenFAST/IEA-15-240-RWT-Monopile/IEA-15-240-RWT-Monopile_SubDyn.dat#L79-L91

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Hi @gbarter

In the monopile subdyn file, the joints very close to one another adopted the same cross-section property. For example, both joint1 and joint2 of member1 adopted PropSet1. And both joint2 and joint3 of member2 adopted PropSet1. In my understanding, that is equivalent to a member staring from joint1 and ending at joint3 which adopts a constat PropSet1. Therefore, joint2 is not necessary.

Similarly, member 3 and member4 have the same cross-section property PropSet2, meaning joint4, which is in between member 3 and member4, is unnecessary.

I am confused why those joints, e.g. joint2, joint4, joint6 are remained. They will lead to members with a short length of 0.001m. I think it may do harm to the convergency performance. However, if removing those unnecessary joints, e.g. joint2, joint4, joint6 and so on, the monopile is still distributed as a piecewise-constant thickness. But we can avoid short-length members.

The reason for the joints very close to one another is to achieve a piecewise-constant thickness distribution, instead of linearly varying thickness, as it better captures monopile manufacturing realities from rolling steel plates.

Kind regards,
Ran

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Yup, I should have been more thorough in my review. You are correct that the current element-property assignment did not achieve the desired distribution. This has now been fixed. I also caught that the transition piece point mass needed to be moved to the correct node as well. See #185

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Thanks for the fix.

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