Shear Modulus from Elastic Constants
For an isotropic material the elastic constants are linked, so the shear modulus follows from the more commonly quoted Young’s modulus.
The relation is G = E/(2·(1 + ν)). where E is Young’s modulus and ν Poisson’s ratio.
Apply the isotropic elastic-constant relation.
Results
For steel this gives about 77 GPa. The relation means only two elastic constants are independent for an isotropic material.