questions about reference control input

This forum if for discussing controls. Questions about how to implement controls in FAST are more appropriate to the CAE Tools forum.

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Re: questions about reference control input

Postby Cheng.Zhang » Thu Jul 12, 2018 3:24 am

Dear Jason,

I want to use mlife to calculate the Damage Equivalent Load (DEL) as a performance index for my controller, and I read the topic concerning the Mlife and the Mlife_user, but I still don't understand how to calculate it.

For example.
If I want to calculate the DEL of blade flap-wise bending (RootMxb1) and tower fore-aft bending (TwrBsMyt).
How can I choose the parameters of NSlopes, SNslopeLst, BinFlag, BinWidth/Number, TypeLMF, LUlt.

I read a paper that you are a co-author In this paper, you also use DEL as a performance index (e.g. 'Flap DEQL', 'Tower FA DEQL', 'Tower SS DEQL', 'LSS DEQL'). Could you tell me how to calculate the DEL of those item?

Thank you!

Best regards,

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Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO

Re: questions about reference control input

Postby Jason.Jonkman » Fri Jul 13, 2018 12:11 am

Dear Cheng,

SNslopeLst is the slope of the SN curve. If not known for the specific components you are analyzing, it is often appropriate to assume the slope is 3, 4, or 5 for steel structures or 8, 10, or 12 for composite structures (you can choose one or use all three to assess the sensitivity). You can check the sensitivity of the binning based on your own results. TypeLMF and LUlt are discussed in our FAQ (, but are unused if you are not using the Goodman correction to account for the influence of the load means on the DELs.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901

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