[scilab-Users] vibration test analysis
paul.carrico at free.fr
paul.carrico at free.fr
Mon Oct 11 14:11:54 CEST 2010
Hi,
Thanks everybody for the answers ...
I'll have a look on all the information's ...
Regards
Paul
----- Mail Original -----
De: "Michael J. McCann" <mjmccann at iee.org>
À: users at lists.scilab.org
Envoyé: Lundi 11 Octobre 2010 12h38:20 GMT +01:00 Amsterdam / Berlin / Berne / Rome / Stockholm / Vienne
Objet: Re: [scilab-Users] vibration test analysis
It it's raw vibration data, and very noisy, make a Fast Fourier
transform of the raw data. The reciprocal of the record length will
define the frequency resolution you get.
Go through the magnitude of the data looking for values that are
local peaks relative to their neighbours on either side.
As a refinement you can use, as the measure, the value of a
locally weighted magnitude (e.g mostly the a centre frequency with a
20% or so of the adjacent values) so that if your real peak falls
between two of the sample frequencies it will get picked up because
the FFT will give some of the energy to adjacent samples.
You will need to select the peaks relative to the noise
level. So generate the magnitude data (or it's locally weighted
values) and then read off the peaks that come high enough to be
recognizable. You can calculate a local noise level for the signal
frequency band for comparison.
I've used it for raw data from moving vehicle vibration. In
a laboratory situation the search in frequency can be applied to the
sweep frequency test data
Mike.
www.mccannscience.com
At 20:02 10/10/2010, you wrote:
>All,
>
>Does somebody has ever wrote/coded (under Scilab but not necessary)
>a program that analyses the vibration tests results (i.e.
>automatically find the natural frequencies) ?
>
>I do it manually but studying the transmissibility's and the phase
>changes but I would like to code it under Scilab and of course there
>won't be any human appreciation/analysis
>
>The purpose of this email is not to have this code but to have
>advices/information's on the method / algorithm and so on !
>
>In any way It's a good challenge for me
>
>
>Thanks for any help
>
>Paul
>
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