Tutorial 7
Keysight 34970A/34972A User’s Guide 311
Using the Mx+B scaling function with the equations shown below will allow you to
display results directly in strain on the 34970A/34972A front-panel display. You
can use a custom measurement label to display readings in “με” (micro-strain)
directly. The instrument will automatically add the micro (“μ”) prefix based upon
actual calculated values. For more information on scaling, see page 148.
M = B = -
Temperature Effects
The resistive element of a strain gage will produce a resistance change ΔR due to
measured strain as well as changes in gage temperature. This will create an
“apparent” strain change which is undesirable. A second gage of similar type can
be used to detect temperature changes and thus remove this error source. You
should mount the second gage in close proximity and at 90° to the first gage, thus
responding to local temperature changes but rejecting strain changes.
Subtracting measurements from the second gage will remove any undesirable
strain errors.
Strain GF
R
0
ΔR DMM Sensitivity
1 με 2.0 120Ω 0.24 mΩ 0.1 mΩ (0.4 με)
1 με 2.0 350Ω 0.70 mΩ 1.0 mΩ (1.4 με)
1 με 2.0 1000Ω 2.0 mΩ 1.0 mΩ (0.5 με)
1
GF R
0
×
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