How do we choose a frequency range of interest for flutter prediction? I'm trying to perform some flutter and dynamical (gust etc.) calculations with Nastran. It has been told to use a range up to 30 Hz for an aircraft I'm working with, but why the upper limit is so choosen 30 Hz? Why for some aircraft the range is up 60 Hz and for another one even up to 100 Hz? I suppose it depends on matirials used in a particular structure and/or a frequency range of presumed loads. I would be grateful if someone can explain how the frequency range of interest is exactly chosen. Thanks!
You might want to try reviewing MIL-A-8870C  AIRPLANE STRENGTH AND RIGIDITY
VIBRATION, FLUTTER, AND DIVERGENCE.  The CRJs were certified to this standard.  Available here: http://everyspec.com/MIL-SPECS/MIL-SPECS-MIL-A/MIL-A-8870C_6746/  Just click the Download File button.