What is a Foil Strain Gauge?

The Measuring Principles of Foil Strain Gauges

Foil strain gauges are used to determine the value and direction of strain. This is achieved by a measuring grid that is usually installed on a material surface to acquire applied strain as a factor of changes in electrical resistance against the foil strain gauge’s nominal resistance and its sensitivity factor. It registers compression as a decrease in electrical resistance and elongation as an increase. To calculate material stresses (Experimental stress analysis) the strain values are coupled with a material’s physical properties such as its Young’s modulus (Hooke’s law). Alternate applications for strain gauges are transducers such as load cells, force-, torque- and pressure transducers. There are thousands of distinct foil strain gauges available from HBM including linear, rosette, torsion/shear, full bridge, and chain formats.

• Linear strain gauges are preferable for measuring strain across a single plane of direction
• Rosette foil strain gauges feature dual measuring grids to offset strain measurements at a 90° angle to measure biaxial stress
• Torsion/shear strain gauges feature uniquely arranged measuring grids for determining the shear stress of torsion bars
• Double linear foil strain gauges feature parallel measuring grids for acquiring perpendicular stress in bending beams
• Full bridge strain gauges feature 4 integrated measuring grids for robust strain measurements of shear stresses in tension and compression bars
• Chain foil strain gauges are equipped with a number of smaller measuring grids to acquire shear force gradients across the measuring bridge