Specifications

Poisson 1/2 Bridge
(HPOisson)
In applications where there is no equal strain of opposite sign as there is for
the beam in Figure 4-10, an increase in measurement sensitivity and
temperature compensation is achieved by mounting the strain gages at right
angles on the specimen. Mounting the gages in this manner is known as a
Poisson arrangement and is represented in Figure 4-11. With a Poisson
arrangement, the sensitivity is not as great as with the bending
1
⁄
2
bridge;
however, it is approximately 25% greater than a
1
⁄
4
bridge arrangement.
Again, since the gages are adjacent legs of the Wheatstone Bridge circuit,
complete temperature compensation is achieved.
Dummy Gage
In a dummy gage configuration, one of the strain gages in the
1
⁄
2
bridge
arrangement is mounted to an unstrained portion of the specimen (Figure
4-12). This gage arrangement provides complete temperature
compensation; however, measurement sensitivity is not increased since a
1
⁄
4
bridge measurement is made with the one active gage.
Figure 4-12. Dummy Gage Arrangement
Figure 4-11. Strain Gages in Poisson Arrangement
60 Understanding the Strain Gage Multiplexers Chapter 4
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