

Measured in (SI unit):  pascal 
Commonly used symbols:  G 
Expressed in other quantities:  G = τ / γ 
In materials science, shear modulus or modulus of rigidity, denoted by G, or sometimes S or μ, is defined as the ratio of shear stress to the shear strain:^{[1]}
where
Shear modulus is usually measured in GPa (gigapascals) or ksi (thousands of pounds (kips) per square inch).
Material  Typical values for shear modulus (GPa) (at room temperature) 

Diamond^{[2]}  478. 
Steel^{[3]}  79.3 
Copper^{[4]}  44.7 
Titanium^{[3]}  41.4 
Glass^{[3]}  26.2 
Aluminium^{[3]}  25.5 
Polyethylene^{[3]}  0.117 
Rubber^{[5]}  0.0006 
Contents 
The shear modulus is one of several quantities for measuring the stiffness of materials. All of them arise in the generalized Hooke's law:
The shear modulus is concerned with the deformation of a solid when it experiences a force parallel to one of its surfaces while its opposite face experiences an opposing force (such as friction). In the case of an object that's shaped like a rectangular prism, it will deform into a parallelepiped. Anisotropic materials such as wood and paper exhibit differing material response to stress or strain when tested in different directions. In this case, when the deformation is small enough so that the deformation is linear, the elastic moduli, including the shear modulus, will then be a tensor, rather than a single scalar value.
In homogeneous and isotropic solids, there are two kinds of waves, pressure waves and shear waves. The velocity of a shear wave, (v_{s}) is controlled by the shear modulus,
where

Conversion formulas  

Homogeneous isotropic linear elastic materials have their elastic properties uniquely determined by any two moduli among these, thus given any two, any other of the elastic moduli can be calculated according to these formulas.  
