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IEAWindTask37 / IEA-22-280-RWT

Repository for 22MW offshore reference wind turbine developed by the IEA Wind Task 37
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Questions on Material Properties [Tower Design] #80

Open Joao97ribeiro opened 3 weeks ago

Joao97ribeiro commented 3 weeks ago

I've been reviewing the "Definition of the IEA Wind 22-Megawatt Offshore Reference Wind Turbine" and have some questions about the material properties mentioned:

  1. The Poisson's ratio for the tower's structural steel is listed as 0.265. Could you provide insight into why this value is used, as it appears somewhat low compared to typical values for structural steel?
  2. Is it possible to access the fatigue curves for this material?

Thank you all for the great work on this project!

ptrbortolotti commented 2 weeks ago

Hello,

this is a good catch, thanks for posting this issue.

I can see that the previous reference wind turbines from IEA Wind Task 37 use Poisson's ratio of 0.3. The new value of 0.265 comes from an initial design performed by DTU. image

@fzahle @tkbadtu, any reference for those values?

This said, if we use the simple formula $[ \nu = \frac{{E}}{{2G}} - 1 ] $

for the steel used in the tower and monopile of the IEA-22, we get 0.261.

I will add that the in our design approach E, G, and $\rho$ matter greatly, but $\nu$ doesn't

As for fatigue, we have not designed the tower against fatigue and the windIO yaml simply lists a slope of 3 https://github.com/IEAWindTask37/IEA-22-280-RWT/blob/aacbcd7d1ce7ed1f360a3e8d41b66f9d6c6af4d0/windIO/IEA-22-280-RWT.yaml#L1223

If you are looking at fatigue on tower and monopile, please keep us informed on what you find!

kenloen commented 5 days ago

Hi,

It was indeed us at DTU doing the initial tower and monopile design and hence also adding the material properties.

As @ptrbortolotti points out, the Poisson ratio is currently not used in the design phase, and following back our toolchain, I can confirm that the current value of 0.265 was computed from the equation that @ptrbortolotti is showing above. I was not able to figure out the source of the number being 0.265 and not 0.261, as one should expect.

I would suggest that the value should be updated and that we preferably add a source that is consistent with the values for E, G, and $\rho$. Any suggestions for a source?