Hello friends,
Today we are going to learn about elastic constant or
more appropriate young modulus of elasticity. In our previous articles we have
learnt about strain, stress and their types and relationship. In stress strain
curve article, we have learnt about proportional limit and I have discussed
about a constant there. This constant is known as young modulus of elasticity.
Don’t worry if you have missed that article. In this
article we will to learn it from basic and also describe its value for some
basic materials.
Let’s start the article.
Young modulus of elasticity:
Before learn about
young modulus you should know about strain and strain. I am giving a brief
introduction about them. If you want to learn them completely, kindly follow
the link given below their definitions.
Stress:
Resistant Force applied per unit area of any cross
section is known as stress. For ideal conditions, the applied force is equal to
the resisting force so the ratio of the applied force to cross section area of
any object is known as stress. It is the resistant force which resists the
deformation in any body. For more detail click Stress and its Types
Strain:
The ratio of change in dimension to original dimension is
known as stain. This dimension is taken only in one direction. In common words
the change in length to original length under loading condition is known as
strain. For more detail click Strain and its Types
Young Modulus of Elasticity:
For understanding this elastic constant, first read the
diagram given below.
It is stain strain curve for a ductile material. This
diagram is obtain by applying an increasing load on a specified dimension
specimen and observe its behavior and change in dimension. The region AB is
known as proportional limit and AC is known as elastic limit. Under the elastic
limit the stress is directly proportional to the strain. This law is known as
Hooke’s law. The proportionality constant of Hook’s law is known as young
modulus of elasticity.
According to the definition,
The ratio of direct stress to longitudinal stain under
elastic limit is known as young modulus of elasticity. Its unit is same as that
of stress which is newton per meter square (N/m2). This constant is independent
on any constrain like dimension of object, applied load etc. and unique for
every material. It is only depended upon material type and varied
for material to material.
For practical observation
let us now consider an object of length L having area of cross-section equal to
A. If the force F acting on the wire, and the change in length due to loading
is ∆L
Signification or practical observation by Young modulus:
We have discussed that every unique material have unique
value of young modulus. If a material has high value of this constant, it means
that this material specimen or object required high value of force to little
change in its original dimension. It is less elastic or that material got a
little variation in its dimension for a high value of stress. It can say that
the high value of modulus shows high rigidity of the material. The value of
this modulus for steal is 210 GN/m2.
If a material has low value of this constant means the material
is high elastic or it shows a very high deformation for small value of loading.
The value of young modulus of aluminum is 70 GN/m2.
Table of Modulus of Elasticity for some common material:
S.No.
|
NAME OF MATERIAL
|
VALUE OF YOUNG MODULUS
( GN/m2 )
|
1.
|
Plastics
|
1 - 3
|
2.
|
Aluminum
|
70
|
3.
|
Brass
|
100 – 125
|
4.
|
Carbon Fiber
|
150
|
5.
|
Copper
|
120
|
6.
|
Glass
|
50 – 90
|
7.
|
Diamond
|
1200
|
8.
|
Gold
|
75
|
9.
|
Gray Cast Iron
|
120 – 130
|
10.
|
Iron
|
210
|
11.
|
Stainless Steel
|
180 – 190
|
12.
|
Tungsten Carbide
|
450 – 650
|
13.
|
Nylon
|
0 – 5
|
This is complete information about young modulus of
elasticity at beginner level. If you have any query regarding this article, ask
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