Strain Gauges Calibration Video

You will calibrate the strain gauges to relate measured voltage to an equivalent strain.

"Zero" the bridge circuit by adjusting the ZERO and GAIN potentiometers until the output voltage (read from the Digital Multimeter) is zero. This should remove any bridge voltage due to unbalanced conditions. You may need to route the output from the bridge amplifier to an additional amplifier if you are unable to remove the DC signal using only the bridge amplifier.

Apply a simulated load by introducing a shunt resistor between 5 k and 100 k in parallel with one leg of the bridge circuit to introduce the equivalent resistance. Adjust the GAIN potentiometer, until the measured output voltage is a convenient multiple of the strain.

The equivalent strain, is given by:

(1)     

equivalent is the equivalent strain,

F is the gauge factor,

R is the resistance of one leg, and

Rs is the shunt resistance (see Equation 3 of the Calibration Principes)

Example:

if:

R=120 W

Rs=56 W

F=2.06

then:

[[epsilon]]equivalent=0.0011

Thus if the voltage is set to read 2.2 V, the calibration factor is 0.0005 strain/V.