It's now possible to get into the nuts and bolts of torque, in a flexible way
Torque loads cause shear strains 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-tension and compression. Strain gages easily sense these. That’s why it takes two strain gage sensing grids to resolve one shear strain value. For mathematical convenience, these grids are normally oriented 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 angle relative to one another and the shear strain can still be calculated.
