Muhammed Fuad Rashid
Petroleum Engineering Department at Koya University
Mechanics of material Laboratory
2020
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0 exp no.3 torsion
1. Faculty of Engineering Petroleum
Engineering Department
Mechanics of material Laboratory, 2nd stage
Experiment Name. Torsion Test
Prepared by: Muhammed Fuad Rashid
Ahmad Jalal Hasan
Muhammad Hasan Aziz
Safwan Tofiq Ameen
Group: A
Supervised by: Dr. Diyar
2. 2
Table of Contents
Introduction................................................................................................................................3
TORSION TEST .........................................................................................................................3
WHY WE PERFORM A TORSION TEST? .....................................................................................4
Aim of the experiment ................................................................................................................5
Results and discussion.................................................................................................................6
References:...............................................................................................................................11
3. 3
Introduction
TORSION TEST
Torsion testing is a type of mechanical testing that evaluates the
properties of materials or devices while under stress from angular
displacement. Torsion testing can be split into two distinct
categories: testing raw materials like metal wires or plastic tubing
to determine properties such as shear strength and modulus, or
functional testing of finished products subjected to torsion, such as
screws, pharmaceutical bottles, and sheathed cables. The most
common mechanical properties measured by torsion testing are:
Modulus of elasticity in shear
Yield shear strength
Ultimate shear strength
Modulus of rigidity in shear
Ductility
4. 4
WHY WE PERFORM A TORSION TEST?
Many products and components are subjected to torsional forces
during their operation. Torsion testing is necessary when engineers
wish to change or update the materials used in these products. For
example, the metal used in vehicle drive trains experiences a
complex combined loading when in use, with torsion being the
main component. An engineer trying to design a more fuel-
efficient vehicle may need to change the material of the driveshaft
in order to reduce vehicle weight. Torsional testing can help the
engineer identify an appropriate material that will possess the
required torsional strength while also contributing to the goal of
light weighting.
Many finished products are also subjected to torsional forces
during their operation. Products such as biomedical tubing,
switches, and fasteners are just a few devices subjected to torsional
stresses in their everyday use. By testing their products in torsion,
manufacturers are able to simulate real life service conditions,
check product quality, verify designs, and ensure proper
manufacturing techniques.
5. 5
Aim of the experiment
The purpose of a torsion test is to determine the behavior a
material or test sample exhibits when twisted or under torsional
forces as a result of applied moments that cause shear stress about
the axis. Also finding measurable values like Modulus of elasticity
in shear and Yield shear strength and so on. Used to find The
modulus of rigidity. And The general characteristics of the torque,
angle of twist relationship.
6. 6
Results and discussion
The general formula of torsion is 𝝉 =
𝚻𝝆
𝓙
T = torque or twisting moment, [N×m, lb×in]
J = polar moment of inertia or polar second moment of area about
shaft axis, [m4
, in4
]
τ = shear stress at outer fibre, [Pa, psi]
r = radius of the shaft, [m, in]
in the proceeded test the values of the specimens properties was
obtained and calculated such as its radius in different dimeters and
its polar moment of inertia also was calculated using the dimeters
of the specimen. all this variables were uses to calculate the shear
stress a round or by other mean the surface of the shaft, and the
data which obtained was plotted and finally we obtained a two
curves which;
7. 7
1-fisrt plot represents the shear stress acts on the round the
shafts versus the different radius of the specimens.
Dimeter=𝟏𝟎𝒎𝒎
Radius = 𝟓𝒎𝒎
polar moment of inertia= 𝟗𝟖𝟏. 𝟐𝟓𝒎4
According to this plot which as we mentioned its between different
radius which may be obtained from different specimens as are
result we calculated the shear stress will act on the shaft, here as
we observe here with increase the radius will also the shear stress
acts on the shaft will increase and logically we can prove that for
example when a tire made of wood rotates on ground first the
surface the tire damages then after that its core due to friction of
the ground which also makes a shear stress on the tire and this is
due to the formula of shear stress on a shaft which equals;
𝝉 =
𝚻𝝆
𝓙
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
0 5 10 15 20 25 30 35 40
shearstress
Torque
shear stress and torque
8. 8
So due to this equation the relation between the shear stress and
the radius is proportional relation which means as increasing one
values the other values increases to in the same ratio or different.
9. 9
2-the second plot represents the shear stress acts on
surface of the shaft versus the polar moment of inertia.
D (Dimeter)=𝟏𝟎𝒎𝒎
T (Torque or twisting moment)= 𝟏𝟎𝟎 𝓝 ∗ 𝒎
J (polar moment of inertia)= 𝟗𝟖𝟏. 𝟐𝟓𝒎4
In this plot we can say that the relation between the torque and
the shear stress is also a proportional relation which means as the
torque of the shaft increases also the shear stress acts on the
surface of the shat increase that is because the torque
And this relation is due to the equation of shear stress which
conclude torque which equals;
𝝉 =
𝚻𝝆
𝓙
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
-2 -1.5 -1 -0.5 0 0.5 1 1.5 2
raduis
shear stress
raduis and shear stress
10. 10
Conclusion:
Many mechanical structures are subjected to torsion during their
operations. By testing these materials used in these structures on
torsion test, the manufacturers are able to simulate real life
service conditions, check products quality, verify designs, and
ensure proper manufacturing techniques as the shear stress,
shear stress proportional limit, ultimate shear stress and the
modulus of rigidity of these materials are known.
Figure 1 Instron machine testing torsion experiment
11. 11
References:
- co, i. (2019). What is Torsion Testing? - Instron. [online] Instron.in.
Available at: https://www.instron.in/en-in/our-company/library/test-
types/torsion-test [Accessed 25 Nov. 2019].
- Types, T. (2019). Torsion Test. [online] Testresources.net. Available
at: https://www.testresources.net/applications/test-types/torsion-test/
[Accessed 25 Nov. 2019].
- Hibbeler, R. C. "Mechanics of Materials", Prentice-Hall, 7th Edition.