Eng-Tips is the largest engineering community on the Internet
Intelligent Work Forums for Engineering Professionals
-
Congratulations waross on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!
reduce vibration levels 1
- Thread starter FSB1
- Start date
-
1
- #2
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.
Makers of vibration isolators have extensive experience and can give more guidance when provided with sufficient details.
Presumably, the test level are intended to be passed to the DUT, so if it's having issues, that's a design problem, not a test problem.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
- Thread starter
- #5
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
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
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 ?
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 ?
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)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
btrueblood
Mechanical
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.
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.
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
- Status
Similar threads
- Locked
- Question