Fatigue spectra
Fatigue spectra
(OP)
Hi guys,
I was wondering if there is anyone familiar with wind turbine design?
My question is how could I find the peak tensile stress in the bars in the pile under the maximum overturning moment form the fatigue spectra.
Any help is really appreciated.
Many Thanks,
Leo
I was wondering if there is anyone familiar with wind turbine design?
My question is how could I find the peak tensile stress in the bars in the pile under the maximum overturning moment form the fatigue spectra.
Any help is really appreciated.
Many Thanks,
Leo






RE: Fatigue spectra
is your fatigue spectrum in terms of windspeed ?
is it reasonable to scale your design loads ?? (hint, it may not be, depending on your assumptions)
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RE: Fatigue spectra
RE: Fatigue spectra
ie if you know that, what is the problem scaling for the different fatigue cases ?
another day in paradise, or is paradise one day closer ?
RE: Fatigue spectra
RE: Fatigue spectra
another day in paradise, or is paradise one day closer ?
RE: Fatigue spectra
RE: Fatigue spectra
another day in paradise, or is paradise one day closer ?
RE: Fatigue spectra
RE: Fatigue spectra
what's your fty ? your ftu is > 200MPa (30ksi ... should be ! ... sorry 200MPa sounded like a lot !)
how frequent is the peak fatigue load ? how peaky is the spectrum ??
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RE: Fatigue spectra
Yield stress 500 MPa
Please find my attached excelsheet calcs
RE: Fatigue spectra
Is your design life (20years) meant to be a safe life ? If so, I think your design is marginal (typical safe life factor = 5, so miner's rule damage sum is 0.2, and I think you're a little over that ... maybe safe life factor =4 ?).
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RE: Fatigue spectra
RE: Fatigue spectra
the previous table looked like a simple cumulative damage table, so I can sum the few numbers to get something like 0.3 by observation. Safe life factor divides into the allowable (sum damage < 1/n) so I figured a safe life factor of 5 wouldn't work, maybe a factor of 3 would.
I don't understand your table "fatigue loads LM and NR", or your term "deltasigmaRsk".
The S/N curve looks reasonable. Your Miners rule calc is good-ish (I don't see why you'd do a fatigue calc for ultimate load), but don't you apply a safe life factor?
this is re-bar, right ? is it installed with preload ??
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RE: Fatigue spectra
deltasigmaRsk is allowable stress for rebar, I am not sure if it is installed with preload, I have to check that.