IMC CANSAS - Page 184

184 Measurement Technique
imc CANSAS Users Manual - Doc. Version 1.9 - 05.12.2014© 2014 imc Meßsysteme GmbH
5.1.2.1.3 Poisson half bridge
N
4
K
U
U
B
IN
1N
R
2
R
3
U
IN
U
B
1
4
1
4
14
In this circuit, 2 active WSGs are used. The WSG is positioned transverse to the main direction of strain.
The transversal contraction is exploited. For this reason, the Poisson's ratio for the material, which is its
transversal expansion coefficient, must be supplied along with the gauge factor. This circuit offers good
temperature compensation. The strain is computed as:
5.1.2.1.4 Half bridge with two active strain gauges in uniaxial direction
N
4
K
U
U
B
IN
2N
R
2
R
3
U
IN
U
B
1
4
1
1
4
4
Two active strain gauges are placed under stress in opposite directions but equal magnitude, i.e. one
strain gauge is under compression and another under equal tension. (bending beam circuit). This
arrangement doubles the measurement's sensitivity to a bending moment. On the other hand,
longitudinal force, torque and temperature are all compensated for. The strain is computed as: