How to Find Resonance Frequency
Resonance frequency is confirmed by a 180-degree phase shift or changes in real and imaginary parts of the frequency response function (FRF).
How to find resonance frequency?
Knowing which peak in vibration response is resonance is a challenge and need other confirmation. Most common confirmation is 180o shift in phase. Sometime tracking phase shift is not easy, specially for system with higher damping, so the best confirmation can get from change in real and imaginary parts of frequency response function (FRF). Based on measurement of response (displacement / velocity / acceleration), three different of FRF are available and below graphs shows how they change at resonance frequency:
Receptance FRF= (displacement response / force excitation)
Mobility FRF= (velocity response / force excitation)
Accelerance FRF= (acceleration response / force excitation)
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