Bulk Modulus Elasticity

The Bulk Modulus Elasticity is a material property characterizing the compressibility of a fluid - how easy a unit volume of a fluid can be changed when changing the pressure working upon it.

The Bulk Modulus Elasticity can be expressed as

E = - dp / (dV / V)     .....................(1)

where

E = bulk modulus elasticity

dp = differential change in pressure on the object

dV = differential change in volume of the object

V = initial volume of the object

The Bulk Modulus Elasticity can alternatively be expressed as

E = dp / (dρ / ρ)  ..........................(2)

where

dρ = differential change in density of the object

ρ = initial density of the object

An increase in the pressure will decrease the volume ...............(1).

 A decrease in the volume will increase the density.................. (2).

• The SI unit of the bulk modulus elasticity is N/m² (Pa)
• The imperial (BG) unit is lb_f/in² (psi)
• 1 lb_f/in² (psi) = 6.894 10³ N/m² (Pa)

****A large Bulk Modulus indicates a relative in compressible fluid.