I was trying to show one of my colleagues by experimentation how we can use both this methods to generate the same modal parameters. As I was looking at the data of Imaginary FRF'S obtained by this two methods (at different points) and overlaying them on each other, I observed a variation in the...
I am trying to understand cepstrum analysis techniques employed in reciprocating/rotating machinery equipment. I will appreciate if someone can point me to a source where I can find good information about it or provide me with a web-link.
Thanks.
Dr. Platten, Assuming the Sound energy is exciting resonances at many frequencies in a particular structure, how many resonant modes can we expect it to excite?, since a structure will almost have infinite modes the Sound power level should be able to excite only first couple of modes. Since...
ME'Scope VES is a popular software by Vibrant Technologies and extensively used in automotive industry and gaining more popularity. You can get lot of other post-processing modules like SDM where you can add mass/dampers/stiffness and see how the new modified structure would behave. I have...
In my defense
"Octave
An octave is a frequency interval having a ratio of two. It is called an octave from the music tradition where an octave spans eight notes of the scale. The second harmonic of a spectral component is one octave above the fundamental. In acoustical measurements, sound...
well sir, with all due respect to you, octaves is not a term extensively used in vibrations, its very rarely used and no wonder I didnt pay much attention to it. but still i said i am ashamed bcos its no reason not to know for my background.
So I guess octave is an acoustic equivalent of an harmonic in vibrations so they are even multiples of 2 so the octaves between 10 to 2000 hz would be
20,40,80,160,320,640,1280 so they are 7+x Octaves right?
x should be less than 1 since octave of 1280 would be 2560 which is greater than 2000 so...
Never mind I got it, n=(log(2000)-log(10))/log(2)=7.64385
So if they are 7.64 octaves between 10 to 2000 and I need it to sweep from 10 to 2000Hz in 10minutes, it needs to sweep at the rate of 7.64/10 octaves/minute=0.764octaves/minute and thats how I got the sweep rate
Got it. Thanks a lot for...
Thanks for the reply Greg,but still it doesnot explain how I would end up with a .764 number (I got this number from a report on the same test done previously at a different test lab -test was outsourced). Using your formula
n=(log(200)-log(10))/log(2)=4.321
considering it is 4.321 octave/sec...
I am trying to figure out how to calculate octaves/minute for one of the shaker tests I am running. The original test request said that I needed to run a shaker test with a logarithmic Sine sweep from 10 to 2000 Hz and back to 10 Hz in a period of 20Minutes (10minutes/sweep). Now I want to...
