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Updated on 27th March, 2023 , 2 min read
Bulk modulus is the change in relative volume of an object caused by uniformly applying a unit compressive or tensile stress to its surface.
There are three types of bulk modulus of elasticity based on the type of stress applied and the resulting strain:
Type of Bulk Modulus |
Description |
Bulk Modulus |
It is defined as the volumetric stress to strain ratio and is denoted by B. |
Young's Modulus |
It is denoted by Y as the ratio of longitudinal stress to longitudinal strain. |
Shear Modulus |
It is significant as the shear stress to shear strain ratio, as noted by G, S. |
Given below formula is known as the Bulk Modulus formula
K = ΔP × V / ΔV
Where,
K = Bulk modulus (Pascal)
V = Actual volume of object (m3)
ΔP = Change in pressure (Pascal)
ΔV = Change in volume (m3)
Note: Dimension of Bulk modulus is, L-1M1T-2
According to Hooke's Law,
Strain is directly proportional to stress.
Volume strain Hydraulic stress
Hydraulic stress = B × Volume strain
The proportionality constant is B, and B is the bulk modulus of elasticity.
p = B × ΔV / V
∴ B = ΔP × V / ΔV
Bulk modulus is a measurement of a material's incompressibility. For example, the value of K for steel is 1.61011 N/m2, while the value of K for glass is 41010 N/m2. In this case, k for steel is more than three times that of K for glass. As a result, glass is more compressible than steel.
If we try to calculate the value of a diamond and compare it to the values of glass and steel, we will find that
The dimensional formula for bulk modulus is [ML-1 T-2].
The bulk is a constant that indicates how compressible a substance is. Because a compressed material returns to its true volume once the stress is removed, the bulk modulus has been used as a descriptor of elastic properties.
The bulk modulus of elasticity is defined as the ratio of normal stress to volume stain.
The bulk modulus formula is as follows: B = pV/ΔV