How can I test the frequency of a vibration

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Discussion Overview

The discussion revolves around methods for testing the frequency of vibrations, specifically in the context of evaluating vibration dampeners for a tennis racket equipped with a shock absorber. Participants explore various measurement techniques and setups for accurately assessing the vibrations experienced by the user.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant inquires about alternatives to accelerometers for testing vibration dampeners.
  • Another participant suggests that the choice of method may depend on the frequency range and size of the object being tested.
  • A list of potential measurement techniques is provided, including accelerometers, strain gauges, laser measurement, Doppler radar, and others, emphasizing that the choice depends on various factors such as size, material, and surrounding medium.
  • A participant describes a classic modal testing approach involving accelerometers and a striking hammer to assess modal characteristics.
  • There is a suggestion to use a shaker to simulate vibrations while measuring responses at the isolator.
  • One participant proposes using a sensitive microphone embedded in a solid material to capture sound waves and analyze the frequency spectrum, noting that this method sacrifices amplitude information but can still identify modes.
  • Another participant confirms the viability of using microphones for capturing natural frequencies during modal tests, suggesting that proximity to the vibrating part is crucial.

Areas of Agreement / Disagreement

Participants express various methods and ideas for testing vibrations, but there is no consensus on a single approach. Multiple competing views on measurement techniques remain present throughout the discussion.

Contextual Notes

Participants mention the importance of factors such as frequency range, size, and material of the vibrating object, but do not resolve how these factors influence the choice of measurement method.

DarkTiger
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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?
 
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That might depend upon what frequency range you're dealing with, and how large the thing to be tested is.
 
It's not uncommon to use:
accelerometer
strain gauge
laser or non-laser reflective angle measurement
laset or non-laser reflective interferometry
doppler radar
doppler acoustics
sonar
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.
 
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?
 
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):
http://www.ata-engineering.com/solutions/modal_page.htm

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.
 
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But where do get the stuff to make that test?
 
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?
 
Guna82m said:
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?
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.
 
Ok thanks i will try that :)
Thank you all for your suggestions :)
 

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