Shear Modulus
Index
A linear elastic material loaded in shear by an applied shear stress t = F/A0, responds by exhibiting a deformation characterized by the shear strain g = tanq. These two quantities are linked through a Hooke's law type of expression for shear: t = G g, where G is an elastic constant known as the Shear modulus. G is related to Young's modulus, E, and Poison's ratio, n, for the material by: G = E/2(1 + n).
 
From: Callister, 
"Materials Science and Engineering," 
Wiley (1994)