Axial Strain in Slender Beams

Two strain gages are mounted on two opposite sides of the bar, along the longitudinal direction and connected on opposite branches of the bridge in order to double the strain of the bar due to a normal load. The two additional gages are mounted on the same opposite sides of the bar but on transversal directions, Fig. 2.17 and connected on the remaining branches of the bridge. Through this scheme the following results are obtained and the Equation is the following, Eq.2.60:

• The strains due to a bending moment My are not recorded.

• All the apparent strains are eliminated.

• The strains due to a bending moment Mx are also not recorded.

Axial Strain in Slender Beams

Fig. 2.17 Full bridge applications. a Measurement of axial stress in a bar; b measurement of torsion in a shaft

• The circuit sensitivity is improved due to the concurrent contributions of the four gages.

• The output signal is linearly related the axial load only.

Axial Strain in Slender Beams(2.60)