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vibration conversion

vibration conversion

vibration conversion

(OP)
how do i convert a vibration reading in dB and G's to Hz? This is reading of the floor slab on grade.  

RE: vibration conversion

You don't.  dB and g's relate to amplitude and acceleration, while Hz relates to frequency

TTFN

RE: vibration conversion

(OP)
thank you for clarifying that.  however i have a client who would like to convert the vibration reading in G's to dB.  is there an equation to convert such G number to dB.

RE: vibration conversion

Not without some reference level.  dB is a ratio relative to some reference value.  g is a reference to 9.8 m/s2.

TTFN

RE: vibration conversion

For acceleration levels I have always used 10^-6 ms^-2 ie 20*log_10(accel_in_SI_units/10^-6). I don't think it is a standard though.

M

--
Dr Michael F Platten

RE: vibration conversion

There was a draft ISO standard for a reference level, but can't remember what they came up with. I typically use 1g RMS or 1 m s-2 RMS, since that gives sensible numbers for engine vibration.

Cheers

Greg Locock

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RE: vibration conversion

Floor vibration standards are typical defined in terms of velocity.

Furthermore, some ISO standards require the floor velocity in terms of a one-third octave spectrum.  The amplitude in each band is represented in terms of RMS velocity.

This format is called "Generic Vibration Criteria (VC) for Vibration-Sensitive Equipment."

Tom Irvine
www.vibrationdata.com

RE: vibration conversion

Manny:
Try using 1 G for your reference level; in the eqn L = 20 log G's
That is, G's = 10^(dBg/20)

RE: vibration conversion

I look at this that you want the difference (dB) between the acceleration levels from one reading (before a fix) compared to another (after fix) at a certain frequency (Hz).  Thus a phrase would be “ the fix is good the difference between the G levels dropped 6 dBs at 500 Hz”.  Is this what you are asking?

Good Luck!

Go Mechanical Engineering
Tobalcane

RE: vibration conversion

wilcoxon has a vibration calculator/converter to download.


AdB is re: 1 micro g

then there's pk vs RMS, ISO vs ??

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