one third octave alaysis

[henriquegpo]

Hello everybody.

First, I'm sorry for my bad english. Hope everybody understands! 🙂

I'm studying vibration analysis, and I need to use an already measured data (acceleration in g/ time in seconds) to compare with the vibration criteria curves (picture below).

Note that the VC curves axis are Vrms (um/s) X 1/3 octave band Frequency (Hz). Well, I am able to do some integration of my raw data and get the values in velocity X time.

If I use a FFT, I can go to frequency domain. But I don´t know how to express my data using this 1/3 octave band.

I would appreciate a lot if someone could help me!

Thanks in advance!

Henrique

[Abel_Souza]

Hello Henrique,

To have a function to do 1/3 Octave analisys direct you need have installed LabVIEW Sound and Vibration Toolkit or Sound and Vibration Measurement Suite.

https://www.ni.com/docs/en-US/bundle/labview-sound-and-vibration-toolkit/page/svmain/svmain.html

https://www.ni.com/en-us/shop/product/labview-sound-and-vibration-toolkit.html

The following link have an example using Sound and Vibration Toolkit functions, but only open if you have this toolkit installed.

https://forums.ni.com/t5/Archive-TKB/Sound-and-Vibration-Third-Octave-Spectrum-Analysis/ta-p/3502736

Best regards,

[henriquegpo]

Hello Abel. 

Thank you for the help!

Well, I do have the Sound and Vibration Toolkit, so I'm able to use those functions you've mentioned.

As I could see from the example, the correct is to wire the raw time data to the octave band analyser, right? But in that way, the octave analyser returns a power[dB] x frequency[Hz] graph, which is different from the VC curves I mentioned above.

How could I get a velocity x 1/3 octave band graph, just like the VC curves?

Thanks in advance,

Henrique

PS: should we talk in portuguese, since we are both from Brazil?

[Abel_Souza]

Olá Henrique,

Além deste exemplo que eu te passei da internet no LabVIEW tem diversos exemplos que podem ser encontrados pelo find examples. Para você encontrar estes exemplos voce pode ir em:

Find Examples>>Modules and Toolkits>>Sound and Vibration Toolkit

Eu não sou especialista nesta parte de análise de som e vibração, mas pelo que eu pude ver do exemplo tem um controle chamado channel info onde você configura as escalas de resposta da função.

Atenciosamente,