Strain Gage Shear Patterns

Advanced Sensors Technology Shear and Torque Strain Gages

Torque loads cause shear strain in the structure to which the torsional loads are being applied. This is a good thing, because strain gages can measure these shear strains. That's actually not a precisely true statement. Bonded electrical resistance strain gages do not respond to pure shear strains. Fortunately, associated with all shear strains are two normal components of strain, tension and compresion, which strain gages easily sense. This is why it takes two strain gage sensing grids to resolve one shear strain value. For mathematical convenience, these grids are normallyoriented at ±45° to the measurement direction (90° between the two grids), allowing the gage, when properly connected to a strain indicator instrument, to directly display strain magnitude. But, the grids could be oriented at any relative to one another and the shear strain casn be calculated.

Torque transducers provide a convenient way of measuring torque-loads being applied to a structure, shaft, bolt, door knob, and so on. The sensor used in many high quality torque transducers is a Micro-Measurements Transducer Class shear-strain gage. These precision measuring devices allow designers to optimize structures for anticipated loads.