Elastic Constants – Young’s Modulus, Modulus of Rigidity and Bulk Modulus
In this article you will learn about the Elastic Constant – Young’s modulus, Modulus of rigidity and Bulk modulus. We will also
discuss about the difference between Young’s modulus, Modulus of rigidity and
Bulk modulus.
discuss about the difference between Young’s modulus, Modulus of rigidity and
Bulk modulus.
The various elastic constants in strength of materials are
 Young’s modulus or modulus of elasticity
 Modulus of rigidity or Shear Modulus
 Bulk Modulus
Let’s discuss about them one by one
Young’s Modulus
Definition: It is defined as the ratio of tensile
stress or compressive stress to the corresponding strain within elastic limit. It
is denoted by symbol E. It is also known as modulus of elasticity or elastic modulus.
stress or compressive stress to the corresponding strain within elastic limit. It
is denoted by symbol E. It is also known as modulus of elasticity or elastic modulus.
Where
E = Young’s Modulus
σ = Tensile or compressive stress
e = Tensile or compressive strain
 The SI unit of Youngs modulus is N/mm2.
Modulus of Rigidity
Definition: It is defined as the ratio of shear stress to
corresponding shear strain within elastic limit. It is also known as shear modulus. It
is represented by C or G or N.
corresponding shear strain within elastic limit. It is also known as shear modulus. It
is represented by C or G or N.
Where
τ = Shear stress
ɸ = Shear strain
 The SI unit of C is N/mm2
Bulk Modulus
Definition: It is defined as the ratio of direct stress to the
corresponding volumetric strain within elastic limit. It is denoted by K.
corresponding volumetric strain within elastic limit. It is denoted by K.
σ = Direct stress
(dV/V) = Volumetric strain
 The SI unit of C is N/mm2
Difference Between Young’s Modulus, Modulus of Rigidity and Bulk
Modulus.
S.no

Young’s Modulus

Modulus of Rigidity

Bulk Modulus

1.

It is the ratio of tensile or compressive stress to the corresponding
strain within elastic limit. 
It is the ratio of shear stress to the corresponding shear strain within
elastic limit. 
It is the ratio of direct
stress to the corresponding volumetric strain within elastic limit. 
2.

It is denoted by E.

It is denoted by C or G or N.

It is denoted by K.

3.

E = stress/ strain

C = shear stress/shear strain

K = direct stress/ volumetric strain.

This is all about the Elastic constant – Young’s modulus, modulus
of Rigidity and Bulk modulus. If you find anything missing or incorrect than
comment us. And if you find this article informative and useful than don’t forget
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of Rigidity and Bulk modulus. If you find anything missing or incorrect than
comment us. And if you find this article informative and useful than don’t forget
to like and share us.
What is the relation b/w these three.