Wide Range Strain Indicator Units

[sean882]

In lab for our final project, we used a Wide Range Strain Indicator connected to strain gages on a part we machined to function as a scale. The Indicator device was much like this one: http://www.datasheetcatalog.org/datasheet/vishay/3800.pdf

What units would the numbers be that we're getting? They ranged from 12 for a light weight, to 1070 for a relatively heavier weight.

I understand because it's strain that the numbers may be unitless... but, where are these numbers coming from? Do they mean anything besides just being arbitrary numbers?

Thanks,
-Sean

 

[AlephZero]

On page 2 it says "Range and display +/- 19,999 units" and "Resolution 1 microstrain at any gauge factor..."

So I would take it that if you have set the gauge factor correctly, "15" means "15 microstrain", or a strain of 15 x 10^-6.

I understand because it's strain that the numbers may be unitless... but, where are these numbers coming from? Do they mean anything besides just being arbitrary numbers?

Strain doesn't have "units" like mass or length measurements do, but the numbers are not "arbitrary". Strain = change in length / original length. In practice, strains are often small numbers, and writing them as microstrains is easier than keeping track of all the zeros after the decimal point.

Of course your meter is really measuring and comparing electrical resistances, not strains, so you have to tell it the "gauge factor" which converts the change of resistance into the strain measurements.