NI WSN-3214 User Guide and Specifications
20
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Half-Bridge Type II
This section provides information for the half-bridge strain-gage configuration type II. The half-bridge
type II only measures bending strain. Figure 17 shows how to position strain-gage resistors in a bending
configuration. Figure 18 shows the half-bridge type II circuit wiring diagram.
Figure 17.
Half-Bridge Type II Rejecting Axial and Measuring Bending Strain
A half-bridge type II configuration has the following characteristics:
•
Two active strain-gage elements. One strain-gage element is mounted in the direction of bending
strain on one side of the strain specimen (top) while the other is mounted in the direction of bending
strain on the opposite side (bottom).
•
Half-bridge completion resistors (R
1
and R
2
) are provided by the NI WSN-3214.
•
Sensitive to bending strain.
•
Rejects axial strain.
•
Sensitivity ~ 1.0
μ
V/V per
με
, for GF = 2.0.
Figure 18.
Half-Bridge Type II Circuit Diagram
R
4
(– )
(+ )
R
3
R
3
R
4
Reject
s
Axi
a
l
Me
asu
re
s
Bending
V
CH
V
EX
R
1
R
2
R
3
(
–
ε
)
R
4
(+
ε
)
+
–
NI W
S
N-
3
214
R
COMP
/EX–
AI+
EX+
R
S
+
R
S
–
+
–
