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reduce vibration levels

reduce vibration levels

reduce vibration levels

(OP)
what are the typical techniques to reduce the levels of random vibration (g_rms) passed to a DUT-device under testing?

RE: reduce vibration levels

Vibration isolators. Normally some compliant mounting with an energy absorber. Wire-rope is often used as it is both springy and therefore compliant, but also the strands have friction with each other to dump some energy as heat. Wire-rope isolators also aren't so sensitive to temperature like elastomer/rubber isolators can be, but which is best depends on the mass of the item and the temperature range and the amount of energy to be dumped.

Makers of vibration isolators have extensive experience and can give more guidance when provided with sufficient details.

RE: reduce vibration levels

why the "DUT" ? are you saying that in a test the device is seeing unexpectedly high vibrations ... not expected in the design installation ?

Is the test fixture too flexible/rigid ??

another day in paradise, or is paradise one day closer ?

RE: reduce vibration levels

(OP)
Thanks for the observation IRstuff

Maybe I didnt ask with enough details:
I will have an interface structure in-between
was wondering if there is any typical method followed, like putting some rubbers or anything similar

so I want to design this interface structure to limit (and then verify by test) the vibration passed from the shaker to the DUT:

DUT
|
interface mounting
|
plate
|
Shaker

RE: reduce vibration levels

why "DUT" ?

is this "interface" part of the design/installation ? or just part of the test set-up ?

if the latter, then I thin you've wrong to do this. The shaker should excite the unit as required.

Now if you're "kludging" your test and using a shaker that would over-test the unit, and want to reduce the power/frequency of the shaker to match what you want to apply in the test ... well, that's different. I might use something like an oil bath ... some way to siphon off some of the shaker energy.

another day in paradise, or is paradise one day closer ?

RE: reduce vibration levels

Quote:

was wondering if there is any typical method followed, like putting some rubbers or anything similar

so I want to design this interface structure to limit (and then verify by test) the vibration passed from the shaker to the DUT:

I think you have that backwards; you want 100% transmissibility in the fixture, that means it needs to be, practically speaking, infinitely stiff, i.e., there will be ZERO, or close to zero, resonances within the test band, and there will be no attenuation, either. That means, no rubber baby buggy bumpers.

TTFN (ta ta for now)
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RE: reduce vibration levels

Well, if you make the rubber bumpers part of your design, then yeah you can do that.

It's also possible that the vibration levels you have been given to perform testing to represent a worst-case of a worst case scenario, i.e. the rocket guys took some spectrum data and boosted the levels by 1.5x or 3x "to be conservative", and the next person did the same, and so on. Ask if you can "notch" the spectrum in a frequency band centered around your resonance.

RE: reduce vibration levels

check out McMaster-Carr website, they have some rubber products - I have used it as a rubber bumper long time ago for antenna installation on a chopper and it did reduce vibrations quite a bit
https://www.mcmaster.com

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