Department of Sciences & Technologies, FEST,
Indus University Karachi
INDUSTRIAL MATERIALS LAB (MT-223A)
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Department of Sciences and Technologies, FEST, Indus University, Karachi
S.No
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List of Experiments
Rockwell hardness test
Brinell hardness test
Vicker’s Hardness Test
Charpy’s Impact Test
Iozod’s Impact Test
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6
7
8
9
10
11
Bending test
Shear test
Torsion test
Torsion test of ductile steel
Torsion test of cast iron
Torsion test of brass
Date
Remarks
Department of Sciences and Technologies, FEST, Indus University, Karachi
INSTRUCTIONS & PRECAUTIONS
FOR LABORATORY SAFETY
Laboratory safety
All students must read and understand the information in this document with regard to
laboratory safety and emergency procedures prior to the first laboratory session. Your personal
laboratory safety depends mostly on YOU. Effort has been made to address situations that may pose
a hazard in the lab but the information and instructions provided cannot be considered all- inclusive.
Students must adhere to written and verbal safety instructions throughout the academic term.
Since additional instructions may be given at the beginning of laboratory sessions, it is important
that all students arrive at each session on time.
With good judgment, the chance of an accident in this course is very small. Nevertheless,
research and teaching workplaces (labs, shops, etc.) are full of potential hazards that can cause
serious injury and or damage to the equipment. Working alone and unsupervised in laboratories is
forbidden if you are working with hazardous substances or equipment. With prior approval, at least
two people should be present so that one can shut down equipment and call for help in the event of
an emergency.
Safety training and/or information should be provided by a faculty member, teaching
assistant, lab safety contact, or staff member at the beginning of a new assignment or when a new
hazard is introduced into the workplace.
Emergency Response
1. It is your responsibility to read safety and fire alarm posters and follow the instructions
during an emergency
2. Know the location of the fire extinguisher, eye wash, and safety shower in your lab and
know how to use them.
3. Notify your instructor immediately after any injury, fire or explosion, or spill.
4. Know the building evacuation procedures.
Common Sense
Good common sense is needed for safety in a laboratory. It is expected that each student will work
in a responsible manner and exercise good judgment and common sense. If at any time you are not
sure how to handle a particular situation, ask your Teaching Assistant or Instructor for advice.
DO NOT TOUCH ANYTHING WITH WHICH YOU ARE NOT COMPLETELY FAMILIAR!!!
It is always better to ask questions than to risk harm to yourself or damage to the equipment.
(Lab) Personal and General laboratory safety
1. Never eat, drink, or smoke while working in the laboratory.
2. Read labels carefully.
3. Do not use any equipment unless you are trained and approved as a user by your
supervisor.
4. Wear safety glasses or face shields when working with hazardous materials and/or
equipment.
5. Wear gloves when using any hazardous or toxic agent.
Department of Sciences and Technologies, FEST, Indus University, Karachi
6. Clothing: When handling dangerous substances, wear gloves, laboratory coats, and safety
shield or glasses. Shorts and sandals should not be worn in the lab at any time. Shoes are
required when working in the machine shops.
7. If you have long hair or loose clothes, make sure it is tied back or confined.
8. Keep the work area clear of all materials except those needed for your work. Coats should be
hung in the hall or placed in a locker. Extra books, purses, etc. should be kept away from
equipment that requires air flow or ventilation to prevent overheating.
9. Disposal - Students are responsible for the proper disposal of used material if any in
appropriate containers.
10. Equipment Failure - If a piece of equipment fails while being used, report it immediately to
your lab assistant or tutor. Never try to fix the problem yourself because you could harm
yourself and others.
11. If leaving a lab unattended, turn off all ignition sources and lock the doors.
12. Never pipette anything by mouth.
13. Clean up your work area before leaving.
14. Wash hands before leaving the lab and before eating.
Electrical safety
1. Obtain permission before operating any high voltage equipment.
2. Maintain an unobstructed access to all electrical panels.
3. Wiring or other electrical modifications must be referred to the Electronics Shop or the
Building Coordinator.
4. Avoid using extension cords whenever possible. If you must use one, obtain a heavy- duty
one that is electrically grounded, with its own fuse, and install it safely. Extension cords
should not go under doors, across aisles, be hung from the ceiling, or plugged into other
extension cords.
5. Never, ever modify, attach or otherwise change any high voltage equipment.
6. Always make sure all capacitors are discharged (using a grounded cable with an insulating
handle) before touching high voltage leads or the "inside" of any equipment even after it
has been turned off. Capacitors can hold charge for many hours after the equipment has
been turned off.
7. When you are adjusting any high voltage equipment or a laser which is powered with a high
voltage supply, USE ONLY ONE HAND. Your other hand is best placed in a pocket or behind
your back. This procedure eliminates the possibility of an accident where high voltage current
flows up one arm, through your chest, and down the other arm.
Mechanical safety
1. When using compressed air, use only approved nozzles and never directs the air towards
any person.
2. Guards on machinery must be in place during operation.
3. Exercise care when working with or near hydraulically- or pneumatically-driven
equipment. Sudden or unexpected motion can inflict serious injury.
Chemical safety
1. Treat every chemical as if it were hazardous.
Department of Sciences and Technologies, FEST, Indus University, Karachi
2. Make sure all chemicals are clearly and currently labeled with the substance name,
concentration, date, and name of the individual responsible.
3. Never return chemicals to reagent bottles. (Try for the correct amount and share any
excess.)
4. Comply with fire regulations concerning storage quantities, types of approved containers
and cabinets, proper labeling, etc. If uncertain about regulations, contact the building
coordinator.
5. Use volatile and flammable compounds only in a fume hood. Procedures that produce aerosols
should be performed in a hood to prevent inhalation of hazardous material.
6. Never allow a solvent to come in contact with your skin. Always use gloves.
7. Never "smell" a solvent!! Read the label on the solvent bottle to identify its contents.
8. Dispose of waste and broken glassware in proper containers.
9. Clean up spills immediately.
10. Do not store food in laboratories.
Lasers safety
1. NEVER, EVER LOOK INTO ANY LASER BEAM, no matter how low power or "eye
safe" you may think it is.
2. Always wear safety goggles if instructed by your Instructor or Teaching Assistant.
3. The most common injury using lasers is an eye injury resulting from scattered laser light reflected
off of mountings, sides of mirrors or from the "shiny" surface of an optical table. The best way to
avoid these injuries is to always wear your goggles and NEVER LOWER
YOUR HEAD TO THE LEVEL OF THE LASER BEAM! The laser beam should
always be at or below chest level.
4. Always use "beam stops" to intercept laser beams. Never allow them to propagate into the
laboratory. Never walk through a laser beam. Some laser beams of only a few watts can
burn a hole through a shirt in only a few seconds.
5. If you suspect that you have suffered an eye injury, notify your instructor or teaching
assistant IMMEDIATELY! Your ability to recover from an eye injury decreases the longer
you wait for treatment.
Additional Safety Guidelines
·
·
·
·
·
·
·
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·
·
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Never do unauthorized experiments.
Never work alone in laboratory.
Keep your lab space clean and organized.
Do not leave an on-going experiment unattended.
Always inform your instructor if you break a thermometer. Do not clean mercury yourself!!
Never taste anything. Never pipette by mouth; use a bulb.
Never use open flames in laboratory unless instructed by TA.
Check your glassware for cracks and chips each time you use it. Cracks could cause the
glassware to fail during use and cause serious injury to you or lab mates.
Maintain unobstructed access to all exits, fire extinguishers, electrical panels, emergency
showers, and eye washes.
Do not use corridors for storage or work areas.
Do not store heavy items above table height. Any overhead storage of supplies on top of
cabinets should be limited to lightweight items only. Also, remember that a 36" diameter
area around all fire sprinkler heads must be kept clear at all times.
Department of Sciences and Technologies, FEST, Indus University, Karachi
·
·
·
Areas containing lasers, biohazards, radioisotopes, and carcinogens should be posted
accordingly. However, do not post areas unnecessarily and be sure that the labels are
removed when the hazards are no longer present.
Be careful when lifting heavy objects. Only shop staff may operate forklifts or cranes.
Clean your lab bench and equipment, and lock the door before you leave the laboratory.
Declaration By Student
It is here by declared that I have read all instructions and precautions carefully and I will follow
them to ensure safety.
Name of Student:
Name of Lab Instructor:
Signature of Student:
_ Signature of Lab Instructor:
Department of Sciences and Technologies, FEST, Indus University, Karachi
Experiment 1
Aim: To determine the Rockwell hardness number of the given specimen.
Apparatus: Rockwell hardness testing machine, penetrator and test specimen.
Theory: The hardness of a material is resistance to penetration under a localized pressure or resistance to
abrasion. The general method of judging the hardness is measuring the resistance of a material to indentation.
Hardened steel, sintered tungsten carbide or diamond indenters are generally used for indentation. In this tests,
a load is applied by pressing the indenter at right angles to the surface being tested. The hardness of the
material depends on the resistance which it exerts during a small amount of yielding or deformation. The
resistance depends on friction, elasticity, viscosity and the intensity and distribution of plastic strain produced
by a given tool during indentation. Various scales in Rockwell hardness test are given belowTable 4(b)-1.
Type of
Initial Major Pointer
Scale
indenter
Color
load
load position
Kind of material.
(Dimensions)
(Kgf) (Kgf). on dial.
Much harder such as
Cone, 1200
A
Black
10
50
0
carburized steels, cemented
carbides.
B
Ball, 1.588
mm
Red
10
90
30
Soft steels, copper, brass,
grey cast iron.
C
Cone, 1200
Black
10
140
0
Hard steels, Ti, W, Va, etc.
Fig.4(b)-1 Rockwell Hardness Testing Machine
Procedure
1.
2.
3.
Select the proper size of ball and insert ball of diameter “D” in the ball holder of the m/c
Make the test specimen surface clean by removing dust, dirt, oil and grease etc.
Mount the test specimen surface at right angles to the axis of the ball indenter plunger.
4.
Place the specimen on platform of a machine. Using the elevating screw raise the platform and bring the
specimen just in contact with the ball. Apply an initial load until the small pointer shows red mark.
5.
Release the operating valve to apply additional load. Immediately after the additional load applied, bring
back operating valve to its position.
6.
Read the position of the pointer on the relevant scale of graduation, which gives the Rockwell hardness
number.
7.
Repeat the procedure three times on the specimen selecting different points for indentation.
Observations
1.
2.
3.
4.
Material of test piece
Hardness of scale used
Minor load
Major load
Result: Rockwell Hardness number of the specimen was found for the given material as follows
1
. Copper
2
. Brass
3
. Alumium
= ……………………….. HRC
=…………………………HRC
= ……………………….. HRC
Department of Sciences and Technologies, FEST, Indus University, Karachi
Experiment 2
Aim: To find the Brinell Hardness number for the given metal specimen.
Apparatus: Brinell hardness machine, test specimen and Brinell microscope.
Theory: Hardness represents the resistance of material surface to abrasion, scratching and indentation. In all
hardness tests, a definite force is mechanically applied on the test piece for about 15 seconds. The indenter, which
transmits the load to the test piece, varies in size and shape for different tests. Common indenters are made of
hardened steel or diamond.
In Brinell hardness testing, steel balls are used as indenter. Diameter of the indenter and the applied force depend
upon the thickness of the test specimen. For accurate results, depth of indentation should be less than 1/8 th of the
thickness of the test pieces.
System description
The machine consists of a lever of a dial indicator an elevating screw, a hand wheel, load changing lever, load lever,
hanging weights, etc. there are two scales on the dial B scale marked 0in red color and C scale marked in black color.
Each scale is graduated with hundred divisions. Zero reading in C scale is opposite to 30 numbers in B scale, so that
there is a difference between C and B scales at any point. There are flat and V shape anvils available and they can be
used for plane and cylindrical surface respectively. Anvil is placed on the elevating screw so that the specimen can
be placed. Indenter can be hold in the indenter holder which is just above the elevating screw.
Formulae
The depth of indentation, t =
The surface area of indentation =
Brinell hardness number = Test load / Surface area of indentation
Department of Sciences and Technologies, FEST, Indus University, Karachi
Where
D – Diameter of indenter in millimeters
d – Diameter of indentation in millimeters
P – Applied test load
Observations and calculations
1. Test piece material
2. Diameter of Ball
3. Load application time
4. Least count of Brinell Microscope
Procedure
Select the proper size of ball and insert ball of dia “D” in the ball holder of the m/c
Make the test specimen surface clean by removing dust, dirt, oil and grease etc.
Mount the test specimen surface at right angles to the axis of the ball indenter plunger.
Make contact between the specimen surface and the ball by rotating the jack adjusting wheel.
Apply the load by shifting the “load-lever” and wait for minimum 15 seconds. The load will be applied
gradually.
6. Release the load by shifting the “load-lever”.
7. Remove the specimen from support table and mark the indentation so made.
8. View the indentation through microscope and measure the diameter‘d’ by micrometer fitted on
microscope.
9. Repeat the entire operation, three times at other positions of test piece.
10. Calculate the value of BHN.
1.
2.
3.
4.
5.
Result The given materials were tested and their Brinell hardness numbers are
1. Mild steel =……………………………BHN
2. High carbon steel =……………………BHN
3. Brass =…………………………………BHN
4. Copper =……………………………….BHN
5. Aluminum =……………………………BHN
Department of Sciences and Technologies, FEST, Indus University, Karachi
Experiment 3
Aim: To find the Vickers Hardness number for the given metal specimen.
Apparatus: Brinell hardness machine, test specimen and Brinell microscope.
Theory: Hardness represents the resistance of material surface to abrasion, scratching and indentation. In all
hardness tests, a definite force is mechanically applied on the test piece for about 15 seconds. The indenter, which
transmits the load to the test piece, varies in size and shape for different tests. Common indenters are made of
hardened steel or diamond.
In Brinell hardness testing, steel balls are used as indenter. Diameter of the indenter and the applied force depend
upon the thickness of the test specimen. For accurate results, depth of indentation should be less than 1/8 th of the
thickness of the test pieces.
System description
The machine consists of a lever of a dial indicator an elevating screw, a hand wheel, load changing lever, load lever,
hanging weights, etc. there are two scales on the dial B scale marked 0in red color and C scale marked in black color.
Each scale is graduated with hundred divisions. Zero reading in C scale is opposite to 30 numbers in B scale, so that
there is a difference between C and B scales at any point. There are flat and V shape anvils available and they can be
used for plane and cylindrical surface respectively. Anvil is placed on the elevating screw so that the specimen can
be placed. Indenter can be hold in the indenter holder which is just above the elevating screw.
Formulae
The depth of indentation, t =
The surface area of indentation =
Brinell hardness number = Test load / Surface area of indentation
Department of Sciences and Technologies, FEST, Indus University, Karachi
Where
D – Diameter of indenter in millimeters
d – Diameter of indentation in millimeters
P – Applied test load
Observations and calculations
5. Test piece material
6. Diameter of Ball
7. Load application time
8. Least count of Brinell Microscope
Procedure
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Select the proper size of ball and insert ball of dia “D” in the ball holder of the m/c
Make the test specimen surface clean by removing dust, dirt, oil and grease etc.
Mount the test specimen surface at right angles to the axis of the ball indenter plunger.
Make contact between the specimen surface and the ball by rotating the jack adjusting wheel.
Apply the load by shifting the “load-lever” and wait for minimum 15 seconds. The load will be applied
gradually.
Release the load by shifting the “load-lever”.
Remove the specimen from support table and mark the indentation so made.
View the indentation through microscope and measure the diameter‘d’ by micrometer fitted on
microscope.
Repeat the entire operation, three times at other positions of test piece.
Calculate the value of BHN.
Result The given materials were tested and their Brinell hardness numbers are
6. Mild steel =……………………………HV
7. High carbon steel =…………………… HV
8. Brass =………………………………… HV
9. Copper =………………………………. HV
10. Aluminum =…………………………… HV
Department of Sciences and Technologies, FEST, Indus University, Karachi
Experiment 4
Aim: To study the Impact testing M/c, and perform the charpy impact test.
Apparatus Impact testing M/c, charpy test specimens of mild steel, Aluminum, Vernier calipers, specimen
setting fixture.
Mounting of specimen
Specimen is tested as a beam supported at each end (Fig.7b). Hammer is allowed to hit then specimen at the
opposite face behind the notch.
Procedure
1. Lift the hammer to an appropriate knife edge position and note the energy stored in the hammer. For
the standard charpy test the energy stored should be 300J
2. Place the test specimen on the m/c supports. The notch is on the tension face.
3. Release the hammer. The hammer will break the piece and shoot up the other side of the specimen.
4. Note the energy indicated on the scale by the hammer.
5. Impact strength of the test specimen is the difference of the initial energy stored in hammer and the
residual energy.
Department of Sciences and Technologies, FEST, Indus University, Karachi
Calculations
1. Modulus of rupture = Rupture/Effective volume of specimen
2. Notch impact strength = Absorbed energy/ Effective cross section area.
Result
S.No.
Material
Energy Absorbed J/mm2
Department of Sciences and Technologies, FEST, Indus University, Karachi
Experiment 5
Aim: To determine the Impact toughness (strain energy) of a given specimen through Izod Impact test.
Apparatus
Izod impact testing machine, test specimen of mild steel, Aluminum, Vernier calipers, steel rule and specimen
setting fixture.
Theory
In manufacturing locomotive wheels, connecting rods etc. the components are subjected to impact (shock)
loads. These loads are applied suddenly. The stress induced in these components is more than stress produced
due to gradually applied loads. Therefore, impact tests are performed to assess shock absorbing capacity of
materials subjected to suddenly applied loads. These capabilities are expressed as (i) rupture energy (ii)
Modulus of rupture (iii) Notch impact strength.
Two types of notch impact tests are used
1. Charpy test
2. Izod test
In Charpy test, the specimen is placed as ‘cantilever beam’. The specimens have V-shaped notch of 450 or a
U-shaped notch. The notch is located on tension side of specimen during impact loading. Depth of notch is
generally taken as t/5 to t/3, where ‘t’ is thickness of the specimen.
Impact Strength The resistance of material to fracture under suddenly applied loads is known as Impact
Strength.
Specification of M/c and Specimen details
•
•
•
•
Impact capacity 300joule
Least count of capacity (dial) scale = 2 joule
Weight of striking hammer = 18.7 kg
Swing diameter of hammer = 1600mm
•
•
•
•
•
•
•
Angle of hammer before striking = 900/1350
Distance between supports = 40mm.
Striking velocity of hammer = 5.6m/sec.
Specimen size = 75 X10 X 10 mm
Type of notch = V-notch
Angle of notch = 450
Depth of notch = 2mm.
Department of Sciences and Technologies, FEST, Indus University, Karachi
Department of Sciences and Technologies, FEST, Indus University, Karachi
Procedure
1. With the striking hammer (pendulum) in safe test position, place the test specimen in impact testing
machine’s anvil in such a way that the notch face the hammer and is half inside and half above the top
surface of the anvil. The notch is on the tension face. For a standard test, the energy is set to 168 J.
2. Bring the striking hammer to position of Initial energy, and lock it at this position.
3. Note down the initial energy.
4. Release the hammer by trigger, it will fall due to gravity and break the specimen through its momentum,
the total energy is not absorbed by the specimen. Then it continues to swing. At its topmost height after
breaking the specimen, the indicator stops moving, while the pendulum falls back. Note the indicator
reading at the top most final position.
5. Again, bring back the hammer to its initial position and lock it.
6. Remove the broken specimen by loosening the clamping screw.
Calculations
1. Modulus of rupture = Rupture/Effective volume of specimen
2. Notch impact strength = Absorbed energy/ Effective cross section area.
Result
S.No.
Material
Energy Absorbed J/mm2
Department of Sciences and Technologies, FEST, Indus University, Karachi
Experiment 6
Aim: To perform bend test on universal testing machine
Apparatus: UTM machine, wooden specimen of rectangular section, bending dogs, scale.
Theory:
When a beam is subjected to a bending moment M. Bending theory relates the moment to
the beam’s curvature, deflection and stress.
Assumptions:
1) Small deflections
2) Linear-elastic behavior
3) Plane sections remain plane - line ab straight before and after bending
4) Pure bending - no shear or axial forces - in practice stress and deflections due
to shear and axial forces can be calculated separately and added on using
superposition.
Overall simple bending equation
Procedure:
(i)
(ii)
(iii)
(iv)
(v)
(vi)
(vii)
(viii)
(ix)
(x)
(xi)
(xii)
M/I= E/R= σ/y
Measure the dimensions of the specimen of wood.
Note the zero error on UTM if any.
Place the wooden specimen in the lower zone (compression zone) of UTM
Fix the bending dogs in UTM.
Lower the moveable arm of the UTM so that bending dog touches the
specimen firmly.
Read the load on the machine if any.
Now apply load on the specimen with the help of loading wheel
slowly till the wooden beam breaks.
Note the load on the UTM.
Calculate moment of inertia ‘ I ‘ of the specimen.
Measure y of the beam.
Calculate the stress at rupture by using the simple
bending equation.
Find the standard value of rupture stress from the handbook.
Department of Sciences and Technologies, FEST, Indus University, Karachi
Experiment 7
Aim: To perform the shear test on UTM.
Apparatus Used: A UTM, Specimen, shearing attachment, vernire caliper etc.
Theory:
A type of force which causes or tends to cause two contiguous parts of the body to
slide relative to each other in a direction parallel to their plane of contact is called the
shear force. The stress required to produce fracture in the plane of cross-section, acted
on by the shear force is called shear strength.
Procedure:
The method for determining the shear strength consists of subjecting a suitable length
of steel specimen in full cross-section to double shear, using a suitable test rig, in a
testing m/c under a compressive load or tensile pull and recording the maximum load
‘F’ to fracture.
Observation:
Applied compressive force (F) = --------- kgf.
Diameter of specimen = --------- mm.
Calculations:
The shear strength shall be calculated from the following formulae :
τs = (F/2) / (πd2/4) = 2F / πd2
where ‘d’ is the actual diameter of the specimen
Conclusion: Shear strength of specimen = --------
Department of Sciences and Technologies, FEST, Indus University, Karachi
Experiment 8
Aim:
To study the Torsion Testing Machine & perform torsion test.
Requirements:
1. Torsion Testing Machine
2. Specimen
3. Micrometer
4. Steel Scale
Theory:
A circular cylindrical shaft is said to be subjected to pure torsion when the torsion is
caused by a couple, so that the axis of the applied couple coincides with the axis of
the shaft. In such a case the state of stress at any point in the cross-section of the shaft
is pure shear.
Torsional formula is given by:
T/J = t/r = Gθ/L
Where,
T= Twisting Moment
J= Polar M.O.I. of original cross-section
t= Shear Stress induced in specimen
r= Radius of original cross-section
G= Modulus of Rigidity
θ= Angle of Twist
L= Parallel length of initial specimen
Procedure:
1. Measure the diameter of the test piece of four different planes on its parallel
length by using a Micrometer. At each plane measure the diameter at right angle
to each other.
2. Measure the parallel length of the test piece.
3. Insert the test piece in the grips of the machine.
Department of Sciences and Technologies, FEST, Indus University, Karachi
4. Select a suitable scale on the digital indicator and adjust the initial torque and
angle of twist reading to zero position.
5. Apply the torque on specimen with the driving chuck. To activate the driving
chuck, switch on the. Electrical lever control, with this, the test specimen start
twisting and with the increased load, the digital display on the digital indicator
unit progressed.
6. Torque is applied until specimen breaks and maximum torque that sample has taken is
read out from Digital Indicator unit by pressing the PEAK push button.
7. Angle of twist is noted from Angle of twist measuring wheel after the specimen has
failed.
8. Initially a line may be marked parallel to the length of the test piece to visually see the
helix formation.
Observations:1. Material of test specimen=
2. Least count of micrometer=
3. Parallel length of test specimen=
4. Diameter:
5. Maximum torque (N-m) =
6. Breaking torque (N-m) =
7. Angle of twist Ø =
Department of Sciences and Technologies, FEST, Indus University, Karachi
Department of Sciences and Technologies, FEST, Indus University, Karachi
Calculations:Modulus of rupture ts = Tr/J
Modulus of rigidity G = Tl/Jθ
Where:
T= Maximum twisting moment.
r= Original outer radius of specimen
J= Polar moment of inertia of the original cross-section
θ= Angle of twist
l= Parallel length of specimen.
Results:1.Maximum torque=
2.Breaking torque=
3. Total angle of twist to fracture
4.Modulus of rupture=
5.Modulus of rigidity=
Department of Sciences and Technologies, FEST, Indus University, Karachi
Experiment 9
Aim:To study the Torsion Testing Machine & perform torsion test for ductile steel
Requirements:
5. Torsion Testing Machine
6. Specimen
7. Micrometer
8. Steel Scale
Theory:
A circular cylindrical shaft is said to be subjected to pure torsion when the torsion is
caused by a couple, so that the axis of the applied couple coincides with the axis of
the shaft. In such a case the state of stress at any point in the cross-section of the shaft
is pure shear.
Torsional formula is given by:
T/J = t/r = Gθ/L
Where,
T= Twisting Moment
J= Polar M.O.I. of original cross-section
t= Shear Stress induced in specimen
r= Radius of original cross-section
G= Modulus of Rigidity
θ= Angle of Twist
L= Parallel length of initial specimen
Procedure:
6. Measure the diameter of the test piece of four different planes on its parallel
length by using a Micrometer. At each plane measure the diameter at right angle
to each other.
7. Measure the parallel length of the test piece.
8. Insert the test piece in the grips of the machine.
Department of Sciences and Technologies, FEST, Indus University, Karachi
9. Select a suitable scale on the digital indicator and adjust the initial torque and
angle of twist reading to zero position.
10. Apply the torque on specimen with the driving chuck. To activate the driving
chuck, switch on the. Electrical lever control, with this, the test specimen start
twisting and with the increased load, the digital display on the digital indicator
unit progressed.
9. Torque is applied until specimen breaks and maximum torque that sample has taken is
read out from Digital Indicator unit by pressing the PEAK push button.
10. Angle of twist is noted from Angle of twist measuring wheel after the specimen has
failed.
11. Initially a line may be marked parallel to the length of the test piece to visually see the
helix formation.
Observations:7. Material of test specimen=
8. Least count of micrometer=
9. Parallel length of test specimen=
10. Diameter:
11. Maximum torque (N-m) =
12. Breaking torque (N-m) =
7. Angle of twist Ø =
Department of Sciences and Technologies, FEST, Indus University, Karachi
Calculations:Modulus of rupture ts = Tr/J
Modulus of rigidity G = Tl/Jθ
Where:
T= Maximum twisting moment.
r= Original outer radius of specimen
J= Polar moment of inertia of the original cross-section
θ= Angle of twist
l= Parallel length of specimen.
Results:1.Maximum torque=
2.Breaking torque=
3. Total angle of twist to fracture
4.Modulus of rupture=
5.Modulus of rigidity=
Department of Sciences and Technologies, FEST, Indus University, Karachi
Experiment 10
Aim:To study the Torsion Testing Machine & perform torsion test for cast iron
Requirements:
9. Torsion Testing Machine
10. Specimen
11. Micrometer
12. Steel Scale
Theory:
A circular cylindrical shaft is said to be subjected to pure torsion when the torsion is
caused by a couple, so that the axis of the applied couple coincides with the axis of
the shaft. In such a case the state of stress at any point in the cross-section of the shaft
is pure shear.
Torsional formula is given by:
T/J = t/r = Gθ/L
Where,
T= Twisting Moment
J= Polar M.O.I. of original cross-section
t= Shear Stress induced in specimen
r= Radius of original cross-section
G= Modulus of Rigidity
θ= Angle of Twist
L= Parallel length of initial specimen
Procedure:
11. Measure the diameter of the test piece of four different planes on its parallel
length by using a Micrometer. At each plane measure the diameter at right angle
to each other.
12. Measure the parallel length of the test piece.
13. Insert the test piece in the grips of the machine.
Department of Sciences and Technologies, FEST, Indus University, Karachi
14. Select a suitable scale on the digital indicator and adjust the initial torque and
angle of twist reading to zero position.
15. Apply the torque on specimen with the driving chuck. To activate the driving
chuck, switch on the. Electrical lever control, with this, the test specimen start
twisting and with the increased load, the digital display on the digital indicator
unit progressed.
12. Torque is applied until specimen breaks and maximum torque that sample has taken is
read out from Digital Indicator unit by pressing the PEAK push button.
13. Angle of twist is noted from Angle of twist measuring wheel after the specimen has
failed.
14. Initially a line may be marked parallel to the length of the test piece to visually see the
helix formation.
Observations:13. Material of test specimen=
14. Least count of micrometer=
15. Parallel length of test specimen=
16. Diameter:
17. Maximum torque (N-m) =
18. Breaking torque (N-m) =
7. Angle of twist Ø =
Department of Sciences and Technologies, FEST, Indus University, Karachi
Calculations:Modulus of rupture ts = Tr/J
Modulus of rigidity G = Tl/Jθ
Where:
T= Maximum twisting moment.
r= Original outer radius of specimen
J= Polar moment of inertia of the original cross-section
θ= Angle of twist
l= Parallel length of specimen.
Results:-
Maximum torque=
Breaking torque=
Total angle of twist to fracture
Modulus of rupture=
Modulus of rigidity=
Department of Sciences and Technologies, FEST, Indus University, Karachi
Experiment 11
Aim:To study the Torsion Testing Machine & perform torsion test for brass
Requirements:
13. Torsion Testing Machine
14. Specimen
15. Micrometer
16. Steel Scale
Theory:
A circular cylindrical shaft is said to be subjected to pure torsion when the torsion is
caused by a couple, so that the axis of the applied couple coincides with the axis of
the shaft. In such a case the state of stress at any point in the cross-section of the shaft
is pure shear.
Torsional formula is given by:
T/J = t/r = Gθ/L
Where,
T= Twisting Moment
J= Polar M.O.I. of original cross-section
t= Shear Stress induced in specimen
r= Radius of original cross-section
G= Modulus of Rigidity
θ= Angle of Twist
L= Parallel length of initial specimen
Procedure:
16. Measure the diameter of the test piece of four different planes on its parallel
length by using a Micrometer. At each plane measure the diameter at right angle
to each other.
Department of Sciences and Technologies, FEST, Indus University, Karachi
17. Measure the parallel length of the test piece.
18. Insert the test piece in the grips of the machine.
19. Select a suitable scale on the digital indicator and adjust the initial torque and
angle of twist reading to zero position.
20. Apply the torque on specimen with the driving chuck. To activate the driving
chuck, switch on the. Electrical lever control, with this, the test specimen start
twisting and with the increased load, the digital display on the digital indicator
unit progressed.
15. Torque is applied until specimen breaks and maximum torque that sample has taken is
read out from Digital Indicator unit by pressing the PEAK push button.
16. Angle of twist is noted from Angle of twist measuring wheel after the specimen has
failed.
17. Initially a line may be marked parallel to the length of the test piece to visually see the
helix formation.
Observations:19. Material of test specimen=
20. Least count of micrometer=
21. Parallel length of test specimen=
22. Diameter:
23. Maximum torque (N-m) =
24. Breaking torque (N-m) =
7. Angle of twist Ø =
Calculations:Modulus of rupture ts = Tr/J
Modulus of rigidity G = Tl/Jθ
Where:
T= Maximum twisting moment.
r= Original outer radius of specimen
J= Polar moment of inertia of the original cross-section
θ= Angle of twist
l= Parallel length of specimen.
Results:-
Maximum torque=
Breaking torque=
Total angle of twist to fracture
Modulus of rupture=
Modulus of rigidity=