There are many methods for measuring strain, most of which are based on displacement measurements. The electrical-type strain gauges provide local one- or two-dimensional strain information, while the optical methods can provide whole-field information.
The rest of this section will discuss resistance strain gauges.
Strain measurement devices should:
Resistance strain gauges, the type you will use in this experiment, measure the small displacement that occurs on an object experiencing a mechanical load, and produces a resistance that is proportional to the displacement. These gauges meet all of the above criteria, plus are inexpensive. Hence, they are the most commonly used type of strain gauge.