In
materials science, 'shear modulus', ''G'', or sometimes ''S'' or ''μ'', sometimes referred to as the 'modulus of rigidity', is defined as the ratio of
shear stress to the
shear strain:
[1]
:
where
:
= shear stress;
:force
acts on area
;
:
= shear strain;
:with initial length
and transverse displacement
.
Shear modulus is usually measured in GPa (
gigapascals) or ksi (thousands of pounds per square inch).
Explanation
The shear modulus is one of several quantities for measuring the strength of materials. All of them arise in the generalized
Hooke's law.
Young's modulus describes the material's response to linear strain (like pulling on the ends of a wire), the
bulk modulus describes the material's response to uniform
pressure, and the shear modulus describes the material's response to shearing strains.
Anisotropic materials such as
wood and
paper exhibit differing material response to stress or strain when tested in different directions.
The shear modulus concerns 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.
In solids, there are two kinds of
sound waves, pressure waves and shear waves. The
speed of sound for shear waves is controlled by the shear modulus.
See also
★
Hooke's law
References
1.