extensometer

An extensometer is an instrument used to measure very small deformations in test specimens. These deformations can be caused by tension, compression, bending, or twisting. Essentially, it quantifies how much a material stretches or compresses under stress.

Strain gauges are a type of extensometer. They operate on the principle that the electrical resistance of a wire changes when it is stretched or compressed. Modern strain gauges often use fine wire or foil arranged in a grid pattern, bonded to the surface of the material being tested. When the material deforms, the strain gauge deforms with it, and its electrical resistance changes. This change is then measured and converted into a strain value. These devices are crucial for calculating stresses in materials and for building instruments that measure force, pressure, and acceleration.12