DEL/Fatigue Loads with MCrunch

Wind & Water Computer-Aided Engineering Software Tools
1

Dear Jason,

I have a few questions regarding DELs calculated with MCrunch:

  • Are the DEL results in the Html window displayed as load ranges or as one-sided amplitudes? Because in MLife you can choose between those two types.
  • Furthermore in MLife you can choose the equivalent frequency for the DELs. But at which cycle frequency do the DELs in MCrunch oscillate?
  • If I understand this correctly, the DELs oscillate about the manually defined LMF value. So e.g. if TypeLMF is 100 and my DEL is 50, and assuming the DEL is a one-sided amplitude (question #1), the DEL oscillates between 50 and 150 units. Is my understanding of DELs correct?

Thank you very much in advance!

Best Regards,
Randi

2

Dear Randi,

Here are my answers:

  • The DELs computed by MCrunch are ranges (peak-to-peak), not amplitudes (peak-to-mean).
  • In MCrunch, input parameter RF_Per determines the equivalent frequency. However, RF_Per is entered as the equivalent period (with units of seconds/cycle) instead of the equivalent frequency (with units of cycle/second), based on the relation RF_Per = 1/f_eq.
  • Because the DELs are ranges, not amplitudes, if TypeLMF = 100 and DEL = 50, the actual oscillation is between 75 and 125.

I hope that helps.

Best regards,

3

Dear Jason,

Thank you for your answers, they helped me a lot!

Best Regards,
Randi