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Frequency response analysis

Frequency response analysis

Frequency response analysis

(OP)
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?

RE: Frequency response analysis

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

RE: Frequency response analysis

(OP)
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?

RE: Frequency response analysis

yes

RE: Frequency response analysis

(OP)
Thanks

RE: Frequency response analysis

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.

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