RANDOM VIBRATION DATA CONVERSION

[cdc02254]

Hello,

I have with little knowledge of Rnadom Vibration but working on a project that requires some. I have been given a sample of random vibration data from a road car (z axis). This data has been logged at 5000Hz and in G.

Is there a way of taking this data and converting it into somthing I can test on a vibration table with?.

I beleive this can be done by means of the "Fourier transform" method but will need some guidance.

Any help would be greatly appreciated.

 

[GregLocock]

5000 Hz? wow.

What are you trying to do with it? Test a component's durability? Or simulate the road for noise work?

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[IRstuff]

Depends on what the intent is. If you simply want to exercise the UUT to a real profile, you should be able to simply jam the time series directly into the shaker control software.

Alternately, you can Fourier Transform the time series, clean up the frequency profile and feed that to the shaker.

Thirdly, you can do the above, add a guardband in the frequency domain and feed that profile to the shaker.

TTFN

 

[cdc02254]

Thanks for your replys.

Basically the data is from a car and taken at 5000HZ time intervals with a series of G readings. I have some kit that I have tested on a shaker table and am quite sure we have used the right profile, 15g 30-1000Hz. I want to see if I can use fourier transform but have very little knowledge of how to extrapolate the required data.

 

[tomirvine]

Random vibration may be converted to a Power Spectral Density (PSD). A vibration test on a shaker table can then be performed using the PSD.

Note that a PSD can be calculated from a Fourier transform.

Published examples of PSD for automobiles are difficult to find due to the highly competitive nature of the auto industry.

A good a example of a PSD for "truck vibration" is given in MIL-STD-810F, Meethod 514.5, Figure 514.5C-1.

Also, refer to:

http://www.vibrationdata.com/Newsletters/August2004_NL.pdf

Tom Irvine

http://www.vibrationdata.com