Resolution of any stress system into uniform tension and shearing stress (contd...)
A cylinder or prism of any form, subjected to tension which is uniform over its plane ends and free from traction at the lateral surfaces. Then we can write,
Then from equation 3.15, state of strain can be written as,
where, we put,
The quantity obtained by dividing the simple longitudinal tension by the measure of the extension produced by it, is known as the Young's modulus . The number is the ratio of lateral contraction to longitudinal extension is called Poisson's ratio . is called shear modulus.
Furthermore, note the relations:
Material |
Specific garvity,
|
Young’s modulus,
|
Bulk modulus,
|
Shear modulus,
|
Poisson’s ratio,
|
|
|
N/m 2 |
N/m 2 |
N/m 2 |
|
Steel |
7.849 |
2.1x10 12 |
1.84x10 12 |
8.2x10 11 |
0.31 |
Brass |
8.471 |
1.085x10 12 |
1.05x10 12 |
3.66x10 11 |
0.327 |
Copper |
8.843 |
1.234x10 12 |
1.684x10 12 |
|
0.378 |
Glass |
2.942 |
6.03x10 11 |
4.15x10 11 |
2.4x10 11 |
0.258 |
|