[NRVR-Members] Strain Gauge Reccomendations

[Pat Artis]

Bob and I the MIT at NASA SLI, I can chase details

On Tue, Aug 11, 2015 at 10:52 PM, Thomas Weeks <tweeksjunk2 at theweeks.org>
wrote:

> Just going through old email.. sorry I missed this guys!  I think I'm the
> guy
> who recommended doing so (if you were worried about fin flutter.
>
> I haven't worked with strain gauges in like 30yrs.. but if I recall.. you
> can
> get different patterns for different applications, and also get them to
> measure
> different axis (X vs X+Y deformations, for example).  I would just keep it
> simple though and start off measuring in just one axis (or mount it
> diagonally)
> to see if it's even an issue. Also, if you use hardware attached fins you
> can
> also play with fin thickness more easily (if that's a goal of yours).
>
> Here's a study the MIT did on fin flutter on HP rockets. They also used
> high
> speed cameras (as regular video speeds are fooled and often LOOK like
> there's
> fin flutter when really it's the camera CCD vibrations that just cause
> optical
> illusions like this:
> https://www.youtube.com/watch?v=u-b_VDFWFDg
>
> vs REAL fin flutter like this:
> https://www.youtube.com/watch?v=M_FCQ550770
> or this:
> https://www.youtube.com/watch?v=qpJBvQXQC2M
>
> Here's their study:
> http://web.mit.edu/rocketteam/www/payload/flutteroverview.html
>
> As for which strain gauges to use... I dunnknow. They used "1-Axis
> Precision
> Strain Gauges"... probably something  wide enough to catch a couple of
> different vibration modes of deflection and at a couple of kHz of sample
> rate,
> in an active circuit like this:
> http://www.linear.com/solutions/1565
>
> Or (if down and dirty is all you need) even in a simple voltage divider
> config
> using an arduino to sample it.
>
> Tell us what you all end up doing! Fun!
>
> Tweeks
>
>
>
> On Monday 27 April 2015 17:10:48 Matthew Barnes wrote:
> > NRVR,
> >
> > I am emailing on behalf of the INVENTS HP Rocketry Team at Virginia Tech.
> >
> > With the launch delayed to this Saturday, we would like to put strain
> > gauges on our 3D printed fin can to measure the fin flutter of the 3D
> > printed material.
> >
> > We are not very knowledgeable on the subject and are looking for
> > recommendations for strain gauges. We are currently looking at the many
> > options available through the Omega website:
> > http://www.omega.com/guides/straingages.html
> >
> > Any help/recommendations would be greatly appreciated!
> >
> > Respectfully,
> >
> > Matthew Barnes
> > INVENTS HP Rocketry Team
> >
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