Accelerometer mounting methods

[floattuber]

Can somebody point me to literature showing the accuracy of using various mounting methods such as beeswax, dental cement, stud, cyanoacrolate, etc. I found one from endevco but there must be more out there. I'm probably not using the right search terms in google.

 

[MikeyP]

I just typed your thread title "accelerometer mounting methods" into Google and the first two hits at least should tell you what you need to know.

M

--
Dr Michael F Platten

 

[floattuber]

Unfortunately, they do not.

I found the dytran one already and it does not give numbers. The second one from MMF does not give specifics on the types of adhesives used. It only says "adhesives" but that can be any number of things.

I'd like to find actual % deviation for specific methods.

 

[hydtools]

Here's one from Honeywell/Sensotec:

http://content.honeywell.com/sensing/sensotec/accelerometer_faq.asp?category=22

Ted

 

[hydtools]

Is this the Endevco information you referenced in your first post?

http://www.endevco.com/resources/tp_pdf/TP312.pdf

Ted

 

[GregLocock]

If it is that important to you then you need to do the work yourself, on your structure, with your accelerometers.

Results form a welded steel frae will not read across to an aluminium casting, for example.





Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[dgallagher]

http://www.wilcoxon.com/knowdesk/mounting.pdf

Slide #4

Dave G.

http://www.ReliabilityDirectStore.com

 

[floattuber]

Thanks all, everything that's been posted so far is close but no cigar. And yes, the Endevco one is the one I found earlier and is the most complete.

I did do the work myself. That's the reason I'm looking for some numbers out there... for a sanity check of my work. I have the % difference between a stud mounted reference accelerometer and the test accelerometer for CA, CA with mesh, CA with kapton, CA with mesh and block, Dental cement, and beeswax.

This must be one of the simplest and most tested processes in the world of vibrations so I can't believe there's nothing else out there. I guess I'll start contacting the accelerometer companies directly to see if they have any more technical papers not on the web.

 

[Tmoose]

Are you interested in frequencies much over 2000 Hz?

At some point the thickness of the adhesive often gets real important. I'd kind of expect that adding "stuff" like kapton or mesh would be springy compared to CA with minimal bond line and pull down the frequency limit.

Back when B and K was here in Marlboro(ugh) Massachusett they did not hesitate to plonk general purpose (for machine diagnostics) accelerometers to the test shaker with beeswax. I guess I know why.

 

[floattuber]

No, not too much over 2000Hz. 99% of our tests are 10-2000Hz but my testing did go up to 3000Hz just for completeness.

Up to 2000 Hz, the added "stuff" to the CA only increased the error by tenths of a percent. Dental Cement was the most accurate and the surprising thing for me was that beeswax was almost as good.

 

[Tmoose]

"beeswax was almost as good."

Seems like another instance when damping is really only necessary or even desireable when resonance is close enough to get involved and make trouble.

 

[MarkUMSU]

Sorry I don't know a reference off hand, but the deviations depend largely on frequency. Studs and cyanoacrelates are probably your best bet depending on the environment.

Higher frequencies are lost in a poor mounting.

If you use an adhesive, be sure to have a thin film.

 

[Rob45]

Sometimes beeswax is used with a stud.

See the B&K tutorial on accelerometers.

 

[jimkinney]

Here is another reference from IES Proceedings Apr. 1967.

Jim Kinney
Kennedy Space Center, FL

 

[floattuber]

That's awesome, thanks Jim.