Author Topic: Strain gauge info  (Read 1278 times)

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Offline Rachie5272Topic starter

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Strain gauge info
« on: November 18, 2016, 06:49:26 am »
I have an old strain gauge I'm trying to use for a project.  I got it mostly working, but there are two problems.  First, I'm having trouble deciphering the data on the label.  Whoever wrote it doesn't seem to understand proper units and SI notation.  I'm trying to find the gauge factor, and the scaling factor to read out force in Newtons.

Second, can anyone identify the connector so I can find a proper mate?  My makeshift pins won't hold up for long.  It has a metal shell, is about 20 mm in diameter, 11 mm high from the top of the square base, and I can't find a manufacturer or part number anywhere on it.
 

Offline bagnoz

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Re: Strain gauge info
« Reply #1 on: November 18, 2016, 02:53:44 pm »
I have found a few heuristics when dealing with funny units:
  • Almost every time someone writes Kg [Kelvin·gram] they mean kg [kilogram]
  • likewise MM [~megameter?] probably means mm [millimeter]
  • sometimes MV [megavolt] means mV [millivolt]
  • and so on...

"cps" is cycles per second, aka Hz.
The reading of Kgm [Kelvin·gram·meter] really confused me at first, but then I found that WP:EN says:
"kg·m, sometimes run together as kgm (kilogram-metre, actually kilogram-force so kgf·m) is a unit of torque"
"kgm is sometimes an abbreviation for kilogram (proper symbol kg)"
I think the latter makes more sense, but my straing-gauge-fu is not good enough to be sure.

I'm assuming the kg are meant as a unit of force, so I will substitute daN [decanewton].

I guess what is meant is the following:

maximum working range daN [decanewton]
  500 mN

displacement ratio mm/daN [millimeter per decanewton]
  2 mm/N

minimum reliable force mg [milligram] ? 10 µN [micronewton]
  20 µN

self-resonant frequency Hz [Hertz]
  85 Hz

output (mV/daN)/V ? this would be a ratio which could be written as (mV/V)/daN, 0.1 (V/V)/kN or just as 0.1 kN^-1
  3 (V/V)/kN

output (mV/mm)/V ? this would be a ratio which could be written as (mV/V)/mm, (V/V)/m or just as m^-1
  1.5 (V/V)/m

maximum displacement mm [millimeter]
  ±1.1 mm

maximum force daN [decanewton]
  10 daN = 1 hN

maximum applied tension V [volt]
  8 V


But this all might be wrong, because I don't understand what is be meant by "FORCE RATE Kg/mm".
 


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