Strain Measurement Equations; Strain Gage Multiplexer Block Diagrams - Agilent Technologies HP E1355A User Manual

Strain
Measurement
Equations
⁄
Bridge
1
4
Bending
1
Poisson 1
Bending Full Bridge
Bending Poisson Full Bridge
Poisson Full Bridge
ε = strain. For results in microstrain, multiply the calculated (measured)
NOTE: tensile strain is (+), compressive strain is (-)
Vr = [(Vout/VS)strained - (Vout/VS) unstrained]
Vout = bridge output voltage
Vs = bridge excitation voltage
GF = Gage Factor
ν = Poisson Ratio

Strain Gage Multiplexer Block Diagrams

52 Understanding the Strain Gage Multiplexers
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The equations in the instrument firmware which calculate the measured
strain are given in Table 4-1.
Table 4-1. Strain Measurement Equations
Arrangement
ε = -4Vr/GF(1 + 2Vr)
⁄ ε = -2Vr/GF
Bridge
2
ε = -4Vr/GF[(1 + ν)-2Vr(ν −1)]
⁄
Bridge
2
ε = -Vr/GF
ε = -2Vr/GF(ν + 1)
ε = -2Vr/GF[(ν + 1) -Vr(ν −1)]
strain by 1E-6.
The manner in which strain-related signals are routed from the specimen to
the multimeter is illustrated with the block diagrams in Figure 4-1.
Figure 4-1. Strain Gage Multiplexer Block Diagrams
Equation Parameter
QUARter
HBENding
HPOisson
FBENding
FBPoisson
FPOisson
Chapter 4