Force, pressure and flow
1.5.1 Strain gauge
A strain gauge is a metal or semiconductor whose resistance changes markedly when it is deformed. The deformation is usually taken to be a measurement of strain, and hence force, applied to a structure.
The resistance of a specimen of material of length 1 and cross-sectional area A is given by:
A change in length or area with strain produces a change in resistance of a particular element.
If the resistance of a particular element is Ro with no strain, then the strain gauge factor G is given by:
Strain gauges typically carry only a small current (15 – 100 mA) to avoid self-heating changes in ...