Strain gauge

A sensor whose electrical resistance changes when it is stretched or compressed. Its resistance change is used to measure mechanical strain.

Gauge factor: A dimensionless measure of a strain gauge’s fractional resistance change per unit mechanical strain. It quantifies how strongly the gauge’s resistance responds to deformation.
Mechanical strain: A measure of deformation expressed as change in length relative to original length. The gauge’s intended measurement is the strain of the surface beneath it.
Load cell: A transducer that converts force or weight into an electrical signal, commonly using bonded strain gauges. Strain gauges measure the deformation of the load cell’s elastic element.
Optical fiber sensor: A sensor that uses changes in light traveling through an optical fiber to measure physical quantities. It can measure strain without relying on an electrical resistance change.
Wheatstone bridge: An electrical circuit that measures an unknown resistance by balancing two branches of a bridge. A bridge circuit detects the small resistance changes produced by the gauge.
Elasticity: The ability of a material to return to its original shape after a deforming load is removed. Elastic deformation lets a gauge track reversible loading without permanent distortion.
Structural health monitoring: The assessment of a structure’s condition over time using measurements and inspections. Installed gauges can track strain changes in bridges, buildings, and other structures.
Capacitive sensor: A sensor that detects changes in capacitance caused by changes in geometry, position, or material properties. It measures deformation through capacitance rather than conductor resistance.
Poisson's ratio: The negative ratio of transverse strain to axial strain in a material under uniaxial loading. Lateral contraction or expansion also strains the gauge grid and affects its response.
Young's modulus: The ratio of tensile stress to tensile strain in the linear elastic range of a material. It relates measured strain to stress when the tested material behaves elastically.

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