Experiment No. 4
Uniaxial Tensile test
Shiva Yadav
(Dated: February 19, 2023)
In this experiment, a mild steel sample is subjected to tensile load using Universal Testing
Machine and the stress-strain curve is plotted in order to determine properties such as Yield
strength, Young’s Modulus, etc. These properties are used to judge the usefulness of the material
for applications which require the material to withstand tensile loads
I. INTRODUCTION
A tensile test, also known as tension test, is one of
the most fundamental and common types of mechan-
ical testing. A tensile test applies tensile (pulling)
force to a material and measures the response of the
specimen to the stress. By doing this, tensile test
determine how is stronger material is and how much
it can elongate before fracture.
Tensile tests are typically conducted on
universal testing instruments, are simple to perform,
and are fully standardized. By measuring the change
in length of the material while it is being subjected
to load at fixed loads, we can obtain a complete pro-
file of its tensile properties via a Stress-Strain Curve.
When the applied load exceeds the ultimate
strength point, the sample breaks and the ends of the
resulting two pieces will form cup and cone structure
if a cylindrical sample is used. The data collected
from the experiment can be used for simulation of
components in service.
II. THEORY
The tensile test is most applied one of all the me-
chanical tests. In this test ends of test piece are fixed
into grips connected to a straining device and to a
load measuring device. If the applied load is small
enough, the deformation of any solid is entirely elas-
tic. An elastically deformed solid will return to its
original form as soon as load is removed. However,
if the load is too large , the material can be de-
formed permanently . The initial part of the tension
curve which is recoverable immediately after unload-
ing is termed as elastic and rest of the curve which
represents the way in which solid undergoes plastic
deformation is termed as plastic.
When plotted, this data will provide a
stress/strain curve which shows how the mate-
rial reacted to the force being applied. The point of
break or failure is of much interest, but another im-
portant property include the modulus of elasticity,
yield strength and strain. Ultimate tensile strength
is one of the most important properties we can
determine about a material. This is the maximum
stress that a specimen sustains during the test .The
ultimate tensile strength may or may not equate to
the strength of the specimen at break, depending on
whether the material is brittle, ductile, or exhibits
properties of both. Sometimes a material may be
ductile when tested in a lab, but when placed in
service and exposed to extreme cold temperatures,
it may transition to brittle behaviour. Hooke’s
law for most materials, the initial position of the
test will exhibit a linear relationship between the
applied force or load and the elongation exhibited
by the specimen.[1]
In this linear region, the line obeys hooke’s law
where the ratio of stress to strain is constant.Let E
be the slope of the line in the region where the stress
is proportional to strain and is called the modulus of
elasticity or young’s modulus. Modulus of elasticity
measures the stiffness of the materials which only ap-
plies in the initial linear region of the curve. Within
this linear region the tensile load can be removed
from the specimen and the material will return to
the exact same condition it had been in prior to the
load being applied. At the point when the curve
is no longer linear and deviates from the straight -
line relationship( this point is called the proportional
limit), Hooke’s law no longer applies and some per-
manent deformation occurs in the specimen. This
point is called the elastic or proportional limit. From
this point on in the tensile test, the material reacts
plastically to any further increase in load or stress.
It will not return to its original, and unstressed con-
dition if the load is removed.
The following properties are obtained through the
experiment[2]:-
•Elastic Limit - Elastic limit is the maxi-
mum stress that a material can sustain with-
out permanent deformation after removal of
the stress.
•Modulus of Elasticity - The modulus of
elasticity is the ratio of stress (below the pro-
