The full-bridge type I configuration only measures the bending strain.



The following figure shows how to position strain gage resistors in a bending configuration for the full-bridge type I.



Full-bridge type I strain gage configurations have the following characteristics:
  • Four active strain gage elements, two mounted in the direction of bending strain on the top side of the strain specimen and the other two mounted in the direction of bending strain on the bottom side.
  • High sensitivity to bending strain.
  • Rejection of axial strain.
  • Compensation for temperature.
  • Compensation for lead resistance.
  • Sensitivity at 1000 µε is ~ 2.0 mVout / VEX input.

Full-Bridge Type I Circuit Diagram

Figure 5. Full-Bridge Type I Circuit Diagram

Full-Bridge Type I Circuit Diagram
The following symbols apply to the circuit diagram:
  • R1—Active strain gage element measuring compressive Poisson effect (–ε).
  • R2—Active strain gage element measuring tensile strain (+ε).
  • R3—Active strain gage element measuring compressive Poisson effect (–ε).
  • R4—Active strain gage element measuring the tensile strain (+ε).
  • VEX—Excitation voltage.
  • RL—Lead resistance.
  • VCH—Measured voltage.

    • The following equation converts voltage ratios to strain units for full-bridge type I configurations:

    Strain ( ε ) = - V r GF
    where
    • Vr is the voltage ratio that virtual channels use in the voltage-to-strain conversion equation.
    • GF is the gage factor.