1. MECHANICAL BEHAVIOR OF
MATERIALS
TENSILE TEST
Lectures 2 and 3

2. Deformation of Material Components under
load during service - static and dynamic loads
P, weight of Fan
A A
A A
P
P
A A

3. A
P


σ = lim0A
A
dA P 
2
4P P
A d
σ =
The stress, σ, at any point O on the section AA within the
cylindrical body is defined by considering a small area, ΔA,
around the point O on plane AA and finding the resultant of
the distributed force, ΔP, acting in that area ΔA. The stress, σ,
at point O on plane AA is given by,

4. http://www.directindustry.com/prod/in
stron/tensile-compression-testing-
machine-18463-41713.html

5. Load- Extension Behaviour
Ideal Brittle Material Ductile Material
Standard Specimen
Necking
Gage length and cross section
of the specimen is specified
in the standards like IS, ASTM,
DIN, BS etc.
The Test is often carried out by moving the cross head with a certain
velocity or imposing a certain strain rate

6. Deformation of a metal
Stress-strain curve for brass
I II III

7. Elastic deformation
Change in modulus of
elasticity with temperature
Elastic and shear moduli, and Poisson’s
ratio at room temperature

8. NPCIL, 26/9/2008
Tensile Stress-Strain curve

9. Engineering Vs. True Stress-Strain Curves
Stress
Strain
True Stress - Strain
Curve
Engineering
Stress - Strain
Curve
Ultimate Tensile Strength
Fracture
Fracture

10. Toughness and Resilience
Area under engineering stress- strain curves corresponding to
resilience ur and tensile toughness uf.