Frequency response analysis

[DavideITA]

If a frequency response analysis on a modal basis is done in a certain range (eg. 0-5000 Hz) how many vibration modes to be calculated so that the analysis is valid?
You can use a number of ways to recruit the 90% of the total mass, although this does not cover the entire frequency range?

 

[Mustaine3]

I usually recommend to use >90% of the mass moving in the direction of the primary loading.

 

[DavideITA]

If I understand it correctly, then the minimum frequency range to use is what allows to engage 90% or more of the mass in the direction of primary loading?

 

[Mustaine3]

yes

 

[DavideITA]

Thanks

 

[IRstuff]

Seems to me that would depend on the specific application. On stabilized systems our requirement is that no more than 10% of the mass is allowed to decouple at the minimum specified frequency, which is usually about 5x the control system bandwidth.

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529


Of course I can. I can do anything. I can do absolutely anything. I'm an expert!
There is a homework forum hosted by engineering.com:

http://www.engineering.com/AskForum/aff/32.aspx