A second way to determine the shear modulus is to use the Isopescu shear test.
The sample is placed in a jig and loaded as shown. Under load, a region of pure shear exists at the centre of the sample. Strain gauges are bonded at +/-45° to the axis of the sample. The shear stress is calculated from the force, P, and the cross-sectional area, A, using: The shear strain is calculated from the strain gauges using: The shear stress is again plotted against shear strain to determine the shear modulus.