Extensometer Types TYPICAL USES
Axial Static and dynamic applications including testing of: tension/compression, low and high-cycle fatigue, creep/stress relaxation, and strain rate.
Averaging axial Simultaneously measures axial deflection of opposite sides of the specimen, usually on solid, tubular composite, or metal specimens.
Axial/torsional Simultaneously measures the axial deflection and torsional strain on solid or tubular composite or metal specimens.
Biaxial Provides axial and transverse outputs when performing Poisson's ratio, composite, or metal formability tests.
Circumferential Measures circumferential strain on round specimens.
Diametric Diametric strain in tensile, compressive, and fatigue testing.
Axial Extensometer
This type is used to measure changes along the length of the specimen. Typical methods of mounting them to the specimen are:
Quick-attachment springs
Metal extension springs
Elastic bands
This has two knife edges, mounted on the extensometer arms, to contact the specimen. Elongation or compression of the specimen causes movement of the arms. This movement is transmitted to the metallic element, causing it to bend, straining the bonded gages and changing their resistance. This change in resistance unbalances the Wheatstone bridge circuit, causing a change in electrical output that is proportional to the strain experienced by the specimen.