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How can I test the frequency of a vibration

  1. Jul 25, 2007 #1
    For a project i want to see which viration dampeners would work most effiecently is there any way i could use some sort of invention other then an accelerometer to test this?
  2. jcsd
  3. Jul 25, 2007 #2


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    Gold Member

    That might depend upon what frequency range you're dealing with, and how large the thing to be tested is.
  4. Jul 25, 2007 #3


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    It's not uncommon to use:
    strain gauge
    laser or non-laser reflective angle measurement
    laset or non-laser reflective interferometry
    doppler radar
    doppler acoustics
    eddy current position sensor
    capacitive position sensor
    hall effect magnetic pickup
    listen for acoustic waves

    just depends on the size and material and frequency
    of vibration, the surrounding medium, and the
    measurement apparatus available.
  5. Jul 26, 2007 #4
    Ok what i want to test is the vibrations set of by a tennis racket while i have a shock absorber on.
    I want to use three diffrent types in three diffrent tests.
    in order to be accurate i want to determine the "shock" that is given to the user holding the racket
    So how can i set up this test?
  6. Jul 27, 2007 #5


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    You're pretty much describing a classic rap test for modal characteristics. Basically you outfit the test samples with an array of accelerometers and you strike the sample with a special hammer. You can see this here (about half way down):

    You could also put it on a shaker and mount the racket so it represents how it would be held. You would then run the shaker through a spectrum of vibrations and measure the output responses at the isolator.
  7. Jul 29, 2007 #6
    But where do get the stuff to make that test?
  8. Aug 1, 2007 #7
    I've a idea..but not sure about it... I think the simplest way is by using sound wave... get a high sensitive mircrophone... embled it in a solid material...I mean cover the microphone with material like clay...then stick the clay on top of the virbrating part...play the recorded sound on a pc... U should be able to see frequency spectrum..

    TIPS : there are a lot of freeware to view frequency spectrum of sound data..

    Let me know if this works???
  9. Aug 1, 2007 #8


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    You are not too far off. We use microphones to pick up turbine and compressor blade natural frequencies during modal tests. You do sacrifice amplitude information by doing it this way, but really, we are just concerned with finding modes. It is a viable option. You don't have to put anything around the microphone. It does have to be in very close approximation though.
  10. Aug 4, 2007 #9
    Ok thanks i will try that :)
    Thank you all for your suggestions :)
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