Why do a bare fixture eval?
Why do a bare fixture eval?
(OP)
We run aerospace parts ranging in size from baseball size up to 1000 pound engines on our shakers. Some customers want to do a bare fixture evaluation and some don't. I've heard some reasons to do it and some reasons for why it's a waste of time but I haven't been able to really delve into it and decide for myself.
So if you do a bare fixture eval you find all the natural frequencies of the fixture. I got that. But as soon as you put the test unit on there, you've changed the natural frequencies, so what did you gain by doing the bare fixture eval?
So if you do a bare fixture eval you find all the natural frequencies of the fixture. I got that. But as soon as you put the test unit on there, you've changed the natural frequencies, so what did you gain by doing the bare fixture eval?





RE: Why do a bare fixture eval?
Cheers
Greg Locock
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RE: Why do a bare fixture eval?
TTFN

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RE: Why do a bare fixture eval?
Greg, the best response that I've heard so far is that bare fixture response is close enough to real test conditions and fixing any resonances in the region of interest is better than doing nothing.
RE: Why do a bare fixture eval?
Could it be a QA check to ensure the fixture was designed properly?
If the mount fixture has a mode within your test range, it has to be re-designed.
--
JHG
RE: Why do a bare fixture eval?
Have Fun!
James A. Pike
www.xl4sim.com
www.erieztechnologies.com
RE: Why do a bare fixture eval?
RE: Why do a bare fixture eval?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?