Quarter-bridge System (1-gage System)
See the figure below. If a strain gage is bonded on a surface of a pillar which receives uniform load from one direction and the gage axis is aligned to the direction, stress σ is calculated by the following equation :
Stress (σ) = ε0 ・E
where, E : Young's modulus (See table "Mechanical Properties of Industrial Materials" at the left.)
ε0 : Indicated strain
And, the load W applied to the pillar is obtained by the following equation:
Load W = A・σ
where, A: Cross-sectional area of the pillar
Half-bridge System (2-gage System)
If another strain gage is bonded to the pillar at a right angle to the loading direction and 2 gages are connected to adjacent legs of the bridge, the surface stress σ on the pillar is expressed by the following equation:
If 2 more strain gages are bonded to the opposite sides of the pillar to eliminate bending strain and full-bridge system is adopted, the surface stress σ is calculated by the following equation:
