Fall 2012 ME 395 - GSI Josh Lacey

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 Strain Gauge Resolution and Accuracy

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acbash



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Join date : 2012-09-12

PostSubject: Strain Gauge Resolution and Accuracy   Mon Sep 24, 2012 5:14 pm

The spec sheets for the strain gauge don't appear to list any specific accuracy and resolution, unless it is called by another name or derived from another value... It appears that the data sheets only give a range for strain, ohms, and resistance but no uncertainties. Should we assume the strain gauge is completely accurate? And where would the resolution of the measurements come from?
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GSI Overlord
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PostSubject: Re: Strain Gauge Resolution and Accuracy   Mon Sep 24, 2012 8:14 pm

The resolution uncertainty is again, as in lab 1, a product of the data acquisition system you are using so you'll calculate that in a similar fashion. Remember as a simplification, because the DAQ is 24 bits, it's more likely that your resolution error will just be tied to the last significant digit that the LabVIEW interface outputs.

It's a little bit tricky to come up with the accuracy error associated with the strain gage, but there's actually a formula in the Lab 2 lecture that talks about the internal workings of the quarter-bridge strain gage everyone was using. You'll find that the accuracy of the strain gage is related to the accuracy of the gage factor, which you do have quoted on the spec sheet.
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acbash



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Join date : 2012-09-12

PostSubject: Re: Strain Gauge Resolution and Accuracy   Mon Sep 24, 2012 10:13 pm

Thanks Mr. Overload. Where do we find input and excitation voltage for the relation, then?
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PostSubject: Re: Strain Gauge Resolution and Accuracy   Tue Sep 25, 2012 12:16 am

I think that might be a bit outside the scope of the lab...the only thing they really gave you was the accuracy on the gage factor and that equation so I would use that.
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