Constant Displacement v. Grms
Constant Displacement v. Grms
(OP)
Is it possible to calculate a relationship between constant displacement within a specific frequency range and Grms. If so how.
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Constant Displacement v. Grms
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RE: Constant Displacement v. Grms
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Cheers, DG at www.reliabilitydirect.com
RE: Constant Displacement v. Grms
The GRMS value at a given sine frequency f is:
GRMS = [ 0.072 ][ f^2 ][ X ]
where X is the zero-to-peak displacement in inches.
On the other hand, GRMS is more commonly used to represent random vibration. If you are trying to compare sine vibration to random vibration, then that brings up a different set of concerns.
Sincerely, Tom Irvine
http://www.vibrationdata.com
RE: Constant Displacement v. Grms
You can derive the acceleration in G as a function of the frequency in Hz giving the displacement either in mils or mm.
Are you referring to Grms or G's RMS?
In the first it is as stated be Tom is for random vibration (PSD) while the other is the RMS of the acceleration in G's/
Take Care
RE: Constant Displacement v. Grms
Cheers
RE: Constant Displacement v. Grms
G = Acceleration in g-units
D=inches peak to peak (Double-Amplitude)
F=Frequency in Hz
G=0.0511 F^2 D
Note: Convert this to Grms by
Grms = 0.7071 G
Grms=(0.0511 / 0.7071) F^2 D = 0.072 F^2 D
Converserly,
d0 = Peak Displacement = 9.8 G / F^2 (Zero to Peak Magnitude)
Also, in rms quantities....
drms = 9.8 Grms / Fc^2, where Fc = center frequency of response
Note: Pay particular attention to when using d0 - Peak Amplitude and D - Double Amplitude it obviously makes a big difference.