Shear Modulus - ISO 537
Shear modulus is the ratio of shear stress to shear strain. Testing is performed using a torsional pendulum. A test specimen of uniform cross-section is clamped at both ends, one end fixed and the other to a weighted disc that acts as an inertial member. The system is put into motion and the oscillation period and amplitude is measured and plotted as a function of time. The shear modulus is derived from the amplitude vs. time plot.
For isotropic materials the shear modulus can be related to the tensile modulus with the formula:
G = E / [2(1+ν)]
where G is the shear modulus,
E is the tensile modulus,
and ν is the Poisson's ratio of the material.
ISO 537 has been discontinued and was replaced by ISO 6721-2.