K = Bulk Modulus
K is a bulk Modulus and it can be defined as the ratio between hydrostatic pressure to the Volumetric strain. And thus it can be represented as
K = Hydrostatic pressure / Volumetric strain
= σ / ϵv = σx + ϵy +ϵz
E = 3k (1-2µ)
Here, σ taken as hydrostatic pressure
And ϵv = Volumetric Strain
µ = Poisson’s ratio
G = modulus of rigidity
E = modulus of elasticity.
All the above factors must be known to understand the relation in a proper way. The relationship is important to understand the various mechanical concepts related to metallic material.