# Calculate the Young's modulus

• ErnieChicken

#### ErnieChicken

Hey Guys, I am new to the forums but have seen you guys help a lot with pointing people in the right direction.

Here is my problem:
A Cylinder with a Volume of 8000m3 has a pressure of 80MPa, Bulk Modulus of 74 MPa. I need to calculate the Young s modulus and determine the material type.

So Far here is what i have:

Using Bulk Modulus, Volumetric Strain can be found:
Bulk Modulus K = Pressure / Volumetric Strain
Volumetric Strain = Pressure / Bulk Modulus K = 80 x 106 Pa / 74 x 106 Pa = 1.081
Volumetric Strain Can also be determined using this formula:
Volumetric Strain = Change in Volume / Volume
Then the Change in Volume can be found using the Volumetric Strain:
Change in Volume = Volumetric Strain x Volume = 1.081 x 8000m3 = 8648m3

My train of thought with calculating the youngs modulus is to use

E = Stress (Volume x Pressure) / Volumetric strain
So E = 592.05 GPa

Or by Using K
E = 3K(1-2v) --> 3x74MPa x (1-0.6) = 88.8MPa

But neither answer looks right. Have i overlooked something here?

Your input will be greatly appreciated.

## Answers and Replies

well. i think bulk modulus =direct stress/ vol strain .here pr stress

Thanks for the reply Praveen. I have looked at going back and getting the area of the cylinder and working through stress and strain but I am getting x10^6 numbers which is low for the elastic modulus.