INDIAN INSTITUTE OF TECHNOLOGY (INDIAN SCHOOL OF MINES)
DHANBAD
MECHANICAL ENGINEERIG DEPARTMENT
LAB MANUAL ON
Strength of Material Lab
INDEX
S.NO.
Name of Experiment
01.
Tensile Strength Testing of a given mild steel
specimen on Universal Testing Machine (UTM)
Study of Universal Testing Machine (U.T.M.)
02.
03.
Page no.
1/A
06 - 09
03
10-14
02 - 05
02
15 – 16
04, 04/A
17 - 22
05, 05/A
23 - 32
07.
Bending and Shear test of a Material on
Universal Testing Machine (UTM)
Compressive Strength testing of a given
specimen on UTM
Impact testing on Impact testing machine: Charpy and Izod.
Hardness testing of given specimen using
Rockwell and Vickers / Brinell testing machine
Torsional rigidity test of shaft
08
33 - 34
08.
Stiffness test of closed coiled helical spring
09
35
04.
05.
06.
09.
1
Experiment
no.
01
- To find Young’s Modulus (E) of M.S and
Timber beam by flexure of beam method.
36 - 37
AIM: -Tensile test of a standard sample on a ductile material (Mild Steel)
OBJECT: - To Perform the tensile test upon given specimen to determine yield strength,
ultimate strength, breaking strength, percentage elongation.
APPARATUS: (i)
(ii)
(iii)
(iv)
(v)
DIAGRAM:-
2
Universal Testing Machine (UTM)
Mild steel specimens
Graph paper
Scale
Vernier Caliper
THEORY:-The tensile test is most applied one, of all mechanical 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 body is
entirely elastic. 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 deformed permanently. The
initial part of the tension curve which is recoverable immediately after unloading is termed. As
elastic and the rest of the curve which represents the manner in which solid undergoes plastic
deformation is termed plastic. The stress below which the deformations essentially entirely
elastic is known as the yield strength of material. In some material the onset of plastic
deformation is denoted by a sudden drop in load indicating both an upper and a lower yield
point. However, some materials do not exhibit a sharp yield point. During plastic deformation,
at larger extensions strain hardening cannot compensate for the decrease in section and thus the
load passes through a maximum and then begins to decrease. This stage the “ultimate strength”’
which is defined as the ratio of the load on the specimen to original cross-sectional area, reaches
a maximum value. Further loading will eventually Cause ‘neck’
formation and rupture.
Hooks law:-When material is loaded within proportional limit, stress is directly proportional to strain
produced by the stress. It is observed that there is a limit up to which the applied stress is directly
proportional to the induced strain. The limit is called limit of proportionally.
Yield strength:-This is the stress of the material where it changes its elastic behavior to Plastic
behavior. At this particular stress the material starts deforming permanently, it can be measured as the
load at which material.
Ultimate Strength:- this is measured by the maximum load that a material can take Divided by the
original area of the section.
Elastic limit:-It is maximum stress that the metal can withstand without experiencing a permanent
Strain that is when it is unloaded; it comes to its original position.
Proof stress:-It is the stress required to produce a strain of 0.2% of mild steel sample.
% Elongation= (l1-l0)/l0x100
Stress strain
3
diagram
Technical data of the Machine/Instruments used.
Name
of
Machine
Model
Make
Maximum Load
UNIVERSAL
MACHINE
AMT-100
ASI
1000KN
Specification
Max Capacity
Range
Motor
Max. slide
Grips
Sample
TESTING
1000KN
,120KN,300KN,600KN,1000KN
3HP,3.5HP
10mm-40mm
Standard as per is specification
or for rod(non standard)
Diameter of Sample
PROCEDURE:1.
Measure the original length and diameter of the specimen. The length may either be length
of gauge section which is marked on the specimen with a preset punch or the total length
of the specimen.
2. Insert the specimen into grips of the test machine and attach strain-measuring device to it.
3. Begin the load application and record load versus elongation data.
4. Take readings more frequently as yield point is approached.
5. Measure elongation values with the help of dividers and a ruler & vernier calipers
6. Continue the test till Fracture occurs.
7. By joining the two broken halves of the specimen together, measure the final length and
diameter of specimen.
OBESERVATION:- A) Material: --------------------------------------------Original dimensions _____ _____ Length = ------------ Diameter = --------- Area = --------Sl.no
4
Diameter
Nominal Yield
cross
load(KN)
sectional
area in
mm2
Ultimate
load(KN)
Breaking
load(KN)
Yield
Ultimate
Breaking
%
Stress(MPa) Stress(MPa) Stress(MPa) Elongation
RESULT:- -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------------------------------------------------------------------------------------------CONCLUSION:- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Sample Calculation:-
(i) Yield strength
Yield load
= Original area of cross-section =….N/mm2
(ii) Ultimate strength
Maximum tensile load
=Original area of cross-section =N/mm2
(iii) Breaking Strength
Breaking load
= Original area of cross-section =….N/mm2
(vi) Percentage elongation
Final length (at fracture) – original length
Original length
Machine Diagram
5
EXPERIMENT NO :-01/A
AIM: -
Study of Universal Testing Machine (U.T.M.)
OBJECT: - To Study the various component parts of the Universal Testing Machine
(U.T.M.) & test procedures of various practical’s to be performed.
APPARATUS: - Universal Testing Machine with all attachment i.e. shears test
attachment, bending attachment, tension grips, compression test attachment etc.
DIAGRAM:-
6
THEORY : - The Universal Testing Machine consists of two units.
2) Loading unit,
2) Control panel.
LOADING UNIT:It consists of main hydraulic cylinder with robust base inside. The piston which moves
up and down. The chain driven by electric motor which is fitted on left hand side. The
screw column maintained in the base can be rotated using above arrangement of chain.
Each column passes through the main nut which is fitted in the lower cross head.
The lower table connected to main piston through a ball & the ball seat is joined to
ensure axial loading. There is a connection between lower table and upper head
assembly that moves up and down with main piston. The measurement of this
assembly is carried out by number of bearings which slides over the columns.
The test specimen each fixed in the job is known as ‘Jack Job’. To fix up the specimen
tightly, the movement of jack job is achieved helically by handle.
CONTROL PANEL:It consists of oil tank having a hydraulic oil level sight glass for checking the oil level.
The pump is displacement type piston pump having free plungers those ensure for
continuation of high pressure. The pump is fixed to the tank from bottom. The suction
& delivery valve are fitted to the pump near tank Electric motor driven the pump is
mounted on four studs which is fitted on the right side of the tank. There is an
arrangement for loosing or tightening of the valve. The four valves on control panel
control the oil stroke in the hydraulic system. The loading system works as described
below.
The return valve is close, oil delivered by the pump through the flow control valves to
the cylinder & the piston goes up. Pressure starts developing
& Either the specimen breaks or the load having maximum value is controlled with
the base dynameters consisting in a cylinder in which the piston reciprocates. The
switches have upper and lower push at the control panel for the downward & upward
movement of the movable head. The on & off switch provided on the control panel &
the pilot lamp shows the transmission of main supply.
METHOD OF TESTING:Initial Adjustment: - before testing adjust the pendulum with respect to capacity of
the test i.e. 60KN; 120 KN; 300 KN; 600 KN etc.
For ex: - A specimen of 6 tones capacity gives more accurate result of 10 Tones
capacity range instead of 20 Tones capacity range. These ranges of capacity are
adjusted on the dial with the help of range selector knob. The Control weights of the
pendulum are adjusted correctly. The ink should be inserted in pen holder of recording
7
paper around the drum & the testing process is started depending upon the types of test
as mentioned below.
TENSION TEST:Select the proper job and complete upper and lower check adjustment. Apply some
Greece to the tapered surface of specimen or groove. Then operate the upper cross head
grip operation handle & grip the upper end of test specimen fully in to the groove. Keep
the lower left valve in fully close position. Open the right valve & close it after lower
table is slightly lifted. Adjust the lower points to zero with the help of adjusting knob.
This is necessary to remove the dead weight of the lower table. Then lock the jobs in
this position by operating job working handle. Then open the left control valve. The
printer on dial gauge at which the specimen breaks slightly return back & corresponding
load is known as breaking load & maximum load is known as the ultimate load.
COMPRESSION TEST:Fix upper and lower pressure plates to the upper stationary head & lower table
respectively. Place the specimen on the lower plate in order to grip. Then adjust zero
by lifting the lower table. Then perform the test in the same manner as described in
tension test.
FLEXURAL OR BENDING TEST:Keep the bending table on the lower table in such a way that the central position of
the bending table is fixed in the central location value of the lower table. The bending
supports are adjusted to required distance.
Stuffers at the back of the bending table at different positions. Then place the
specimen on bending table & apply the load by bending attachment at the upper
stationary head. Then perform the test in the same manner as described in tension test.
BRINELL HARDNESS TEST:Place the specimen on the lower table & lift it up slightly. Adjust the zero fixed value
at the bottom side of the lower cross head. Increase the load slowly ultimate load
value is obtained. Then release the load slowly with Left control valve. Get the
impression of a suitable value of five to ten millimeter on the specimen & measure the
diameter of the impression correctly by microscope & calculate Brinell hardness.
8
SHEAR TEST:Place the shear test attachment on the lower table, this attachment consists of cutter.
The specimen is inserted in roles of shear test attachment & lift the Lower table so
that the zero is adjusted, then apply the load such that the specimen breaks in two or
three pieces. If the specimen breaks in two pieces then it will be in angle shear, & if it
breaks in three pieces then it will be in double shear.
STUDY OF EXTENSOMETER:This instrument is an attachment to Universal / Tensile Testing Machines. This
measures the elongation of a test place on load for the set gauge length. The least
count of measurement being 0.01 mm, and maximum elongation measurement
up to 3 mm. This elongation measurement helps in finding out the proof stress at
the required percentage elongation.
WORKING OF THE INSTRUMENT:-The required gauge length (between 30to 120) is set
by adjusting the upper knife edges (3) A scale (2) is provided for this purpose. Hold
the specimen in the upper and lower jaws of Tensile / Universal Testing Machine.
Position the extensometer on the specimen. Position upper clamp (4) To press upper
knife edges on the specimen. The extensometer will be now fixed to the specimen by
spring pressure. Set zero on both the dial gauges by zero adjust screws (7 ). Start
loading the specimen and take the reading of load on the machine at required
elongation or the elongation at required load. Force setter accuracies mean of both
the dial gauge ( 8) readings should be taken as elongation. It is very important to note
& follow the practice of removing the extensometer from the specimen before the
specimen breaks otherwise the instrument will be totally damaged. As a safety, while
testing the instrument may be kept hanging from a fixed support by a slightly loose
thread.
9
EXPERIMENT NO:- 03
AIM:-Bend and Rebend test of TMT/TOR Steel Bars
OBJECTIVE:- The bend and Rebend test is done to find out any rupture or cracks visible to any
person of normal vision on the Bend and Reband portion.
APPARATUS:-Universal Testing Machine (UTM), TMT Bar/Mild Steel Sample, Scale, Hacksaw.
Theory:- These tests are performed in accordance with the requirements of IS1599.This
standard specific the ability of metallic material to undergo plastic deformation in bending.
The Deformation by bending is observed under the unidirectional load until a specific angle is
reached.
Bend Test:-The test piece, when cold, shall be double over the mandrel by continuous
pressure until the sides are parallel ie.1800
A bend test is used to determine whether a specific piece of metal in question will break or fracture under
pressure. This is important in the construction of any project using metal, otherwise the building or the item
being made could collapse from the immense pressure exerted on it. Every piece of metal made cannot be
tested, therefore certain pieces are tested and if they pass, the other pieces are made using the same
process. The results of a bend test are reported differently depending on the type of material tested. There
is no standard method for reporting the durability that applies to all materials, rather each group has its
own set by which it is judged and compared to other metals in that group
10
The Diameter of the mandrel as per standard is specific by the formula D=Constant x Ø,
Where Ø is diameter of the sample. The mandrels constant are to be selected as the chart
given below.
Diameter of the Bar Ø Grade
Up
to
and
and FE415
including 20mm
FE415D
FE500
FE500D
Constant
3
2
4
3
The Distance between the support (I)=D(Diameter of Mandrel)+3x Ø.
Rebend Test:- The test piece is bent to an included angle of 1350 using the mandrel of
appropriate diameter. The bend piece shall be aged by keeping in boiling water for 30 minute
and allowed to cool. Then the piece shall be bent to have included angle of 157½ 0. Then the
sample is considered to be passed if No Cracks are visible on the rebent part.
The purpose of re-bend test is to measure the effect of strain ageing on steel. Strain
ageing has embrittlement effect which takes place after cold deformation by diffusion of
nitrogen in steel. Hence, there is limitation stated in some design codes to restrict the
nitrogen content of steel to 0.012%.
11
The Diameter of the mandrel as per standard is specified by the formula D=Constant x Ø,
Where Ø is diameter of the sample. The Mandrel constants are to be selected as the chart
given below.
Diameter of the bar( Ø) Grade
Up to and and including FE415
20mm
FE415D
FE500
FE500D
Over 10mm-20mm
FE415
FE415D
FE500
FE500D
Constant
5
4
5
4
7
6
7
6
Technical data of the Machine/Instruments used.
Name
of
Machine
Model
Make
Maximum
Load
Mandrel Size
Specification
UNIVERSAL
MACHINE
UTN-60
ASI
1000KN
TESTING
R20,R22,R25,R32,R40,R62.5,R70
Max Capacity
Range
Motor
Max. slide
Grips
Sample
1000KN
60KN,120KN,300KN,600KN
3HP,3.5HP
10mm-40mm
Standard as per is specification
or for rod(non standard)
Diameter of Sample
Procedure:Bend:1. Selection the diameter of TMT bar.
2. Cut the sample in required length.
3. Selection of suitable mandrel diameter for bending.
12
4. The TMT bar is kept on the support and bends with the help of continuous
pressure with mandrel.(Universal Testing Machine)
5. The TMT bar is bent till the time until the two sides become parallel to each other
i.e,1800.
6. Load is removed for the machine slowly.
7. The bar is checked in normally to see if there is any crack.
Reband:1. Selection the diameter of TMT bar.
2. Cut the sample in required length.
3. Selection of suitable mandrel diameter for Re- bending.
2. The TMT bar is kept on the support and bends with the help of continuous
pressure with mandrel.(Universal Testing Machine).
3. The TMT bar is bent till the time until the two sides become parallel to each other
i.e,1350.
4. The Bent sample is aged by keeping it in boiling water for 30 minuite and then left
it cooled.
5. The TMT bar is rebent till the time until the two sides become parallel to each
other i.e,1570.
6. Load is removed for the machine slowly.
7. The bar is checked in normally to see if there is any crack.
OBESERVATION:- A) Material: --------------------------------------------Sl.no
Diameter
Of Rod
Diameter of Mandrel
Remark
Safe/Unsafe
1
2
OBESERVATION TABLE FOR COMPARE OF BENDING STRESS:Sl.n
o
1
2
3
4
5
13
Load(kg Deflection(m
)
m)
Ascending
Deflection(m
m)
descending
Average(
h)
mm
Theoretic
al stress
Practic
al
stress
%
Erro
r
Result:Conclusion:Bending Stress Calculation By Beam Deflection method
A Simply Supported beam with equel overhang both ends is carrying loads (w) ends as shown
in figure.
Find and compare.
Theoretical bending stress σT = 6Wa/(bd2)
Practical bending stress
σ P = E.d.h/(h2+l2)
Figure of setup/sample
14
EXPERIMENT NO:- 02
AIM OF EXPERIMENT:- TO find the Compressive strength of a cast iron specimen.
APPARATUS REQUIRED: -1. Universal Testing Machine (UTM)
2. Specimen to be tested
3. Vernier caliper
4. Steel ruler
Theory
This is the test to know strength of a material under compression. Generally
Compression test is carried out to know either simple compression characteristics of
material or column action of structural members.
It has been observed that for varying height of member, keeping cross-sectional
and the load applied constant, there is an increased tendency towards bending of a
member .Member under compression usually bends along minor axis, i.e., along least
lateral dimension. According to column theory slenderness ratio has more functional
value. If this ratio goes on increasing, axial compressive stress goes on decreasing
and member buckles more and more. End conditions at the time of test have a
pronounced effect on compressive strength of materials. Effective length must be
taken according to end conditions assumed, at the time of the test.
As the ends of the member is made plain and fit between two jaws of the machine,
fixed end is assumed for calculation of effective length. Effective length is taken as
0.5 L where L is actual length of a specimen
15
PROCEDURE:
1. Measure the length and diameter of the test pieces.
2. Place the test piece at the centre on lower block
3. Lower the middle block up to the top face of the test piece
4. Set the proper scale and load as per test piece size.
5. Set the deformation measuring scale.
6. Set the graph plotter.
7. Start the Hydraulic pump and allow the piston slowly to load test piece
8. Take the reading of load at the internal of 1 mm of deformation scale.
9. After rupture stop the motor.
READING AND CALCULATION:a. Initial length of specimen in cm.
b. Initial diameter of specimen in cm.
c. Area of specimen in cm2
d. Length after fracture in cm
e. Diameter after facture in cm
f. Area of section after facture in cm2
g. Total load at breaking point in tones. Stress is in tones/ cm2 at breaking point.
Contraction is the length (a – d)
Percentage contraction in length = [ ( a – d) / (a)] X 100
Percentage Increase in area = [(f – c) / (c)] X 100
Plot the bar graph for Load Vs Contraction
REMARKS:-
16
EXPERIMENT NO:-04
OBJECT: -To Determine the impact strength of steel by Izod impact test
APPARATUS: - 1.Impact testing machine A steel specimen 75 mm X 10mm X
10mm
DIAGRAM:-
\
THEORY:An impact test signifies toughness of material that is ability of material to absorb
energy during plastic deformation. Static tension tests of unnotched specimens do not
always reveal the susceptibility of a metal to brittle fracture. This important factor is
determined by impact test. Toughness takes into account both the strength and ductility
of the material. Several engineering materials have to withstand impact or suddenly
applied loads while in service. Impact strengths are generally lower as compared to
strengths achieved under slowly applied loads. Of all types of impact tests, the notch
bar tests are most extensively used. Therefore, the impact test measures the energy
necessary to fracture a standard notch bar by applying an impulse load. The test
measures the notch toughness of material under shock loading. Values obtained from
these tests are not of much utility to design problems directly and are highly arbitrary.
17
Still it is important to note that it provides a good way of comparing toughness of
various materials or toughness of the same material under different condition. This test
can also be used to assess the ductile brittle transition temperature of the material
occurring due to lowering of temperature.
Technical data of the Machine/Instruments used.
Name of Machine
IMPACT TESTING MACHINE
Model
Make
Maximum Impact Energy
Angle of Impact
Hammer Weight
RI-300
Ratnakar
168/300 Joule
90/141
21.79kg/20.54kg
PROCEDURE:(a) lzod test
1. with the striking hammer (pendulum) in safe test position, firmly hold the steel
specimen in impact testing machine’s vice in such a Way that the notches face the
hammer and are half inside and half above the top surface of the vice.
2. Bring the striking hammer to its top most striking position unless it is already
there, and lock it at that position.
3. Bring indicator of the machine to zero, or follow the instructions of the operating
manual supplied with the machine.
4. Release the hammer. 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 at that topmost final position.
5. Again bring back the hammer to its idle position and back
18
OBESERVATION TABLE
Sl.no
Specimens
Absorbed Energy
1
2
Result:-
Sample Calculation:-
Conclusion:-
Figure of setup/sample
PRECAUTION:1 Measure the dimensions of the specimen carefully.
2. Hold the specimen ( lzod test) firmly.
3. Note down readings carefully.
19
Striking Velocity
EXPERIMENT NO:-04/A
AIM: -To determined impact strength of steel.
OBJECT: -To Determine the impact strength of steel by (Charpy test)
APPARATUS: -1. Impact testing machine
2. A steel specimen 10 mm x 10 mm X 55mm
DIAGRAM:-
THEORY:- An impact test signifies toughness of material that is ability of material to
absorb energy during plastic deformation. Static tension tests of unmatched specimens
do not always reveal the susceptibility of a metal to brittle fracture. This important
factor is determined by impact test. Toughness takes into account both the strength and
ductility of the material. Several engineering materials have to withstand impact or
suddenly applied loads while in service. Impact strengths are generally lower as
compared to strengths achieved under slowly applied loads. Of all types of impact tests,
the notch bar tests are most extensively used. Therefore, the impact test measures the
energy necessary to fracture a standard notch bar by applying an impulse load. The test
measures the notch toughness of material under shock loading. Values obtained from
these tests are not of much utility to design problems directly and are highly arbitrary.
Still it is important to note that it provides a good way of comparing toughness of
various materials or toughness of the same material under different condition. This test
can also be used to assess the ductile brittle transition temperature of the material
occurring due to lowering of temperature.
20
Technical data of the Machine/Instruments used.
Name of Machine
IMPACT TESTING MACHINE
Model
Make
Maximum Impact Energy
Angle of Impact
Hammer Weight
RI-300
Ratnakar
168/300 Joule
90/141
21.79kg/20.54kg
PROCEDURE :-( a) Charpy Test
1.With the striking hammer (pendulum) in safe test position, firmly hold
the steel specimen in impact testing machines vice in such a way that the notch
faces s the hammer and is half inside and half above the top surface of the vice.
2. Bring the striking hammer to its top most striking position unless it is
Already there, and lock it at that position.
3. Bring indicator of the machine to zero, or follow the instructions of the
Operating manual supplied with the machine.
4. Release the hammer. 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 at
that topmost final position.
5. The specimen is placed on supports or anvil so that the blow of hammer is
opposite to the notch.
21
OBESERVATION TABLE
Sl.no
Specimens
Absorbed Energy
Striking Velocity
1
2
Result:-
Sample Calculation:-
Conclusion:Figure
of
setup/sample
PRECAUTION:1 Measure the dimensions of the specimen carefully.
2. Locate the specimen (Charpy test) in such a way that the hammer, strikes it at the
middle.
3. Note down readings carefully.
22
EXPERMENT NO ;- 05
TITLE:- To study the Brinell Hardness testing machine and the Brinell hardness test.
OBJECTIVE:- To determine the Brinell Hardness number(BHN) of given sample as per IS by Brinell
Hardness Tester. This test is carried out to evaluate the effect of Hot and Cold Working upon the basic
properties of the metal
APPARATUS: - Brinell hardness testing machine, specimen of mild steel / cast iron/ non Ferrous
metals and Brinell microscope.
THEORY: - Hardness represents the resistance of material surface to abrasion, scratching
and cutting, hardness after gives clear identification of strength. In all hardness testes, a define 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 testes. Common indenters are made of hardened
steel or diamond.
In Brinell hardness testing, steel balls are used as indenter. Diameter of the inventor and the applied
force depend upon the thickness of the test specimen, because for accurate results, depth of
indentation should be less than 1/8th of the thickness of the test pieces. According to the thickness of
the test piece increase, the diameter of the indenter and force are changed.
The Brinell Hardness Number (BHN)=
Load in kgf(p)
Indentation Area in mm
A= Area of contact between the ball and indentation.
The load on the ball will be suitably selected depending on the ball diameter and the material property
.the standard constant values (p/d2) are provided to find the laod as listed below metal wise.
Metal
Constant(c)=p/d2
Steel hardened
Zn alloys
Al alloy
30
15
10
Area of contact=
23
Diameter of indenter
in mm
10,5,2.5
10
10,5
Load in kgf
3000,750,187.5
1500
1000,250
Technical data of the Machine/Instruments used.
Name of Machine
Model
Make
Maximum Load
Diameter of Ball
Brinell Microscope
Ability to determine
hardness
Method of load
application
Brinell Hardness Tester
upto 500BHN
Lever type
PROCEDURE OF EXPERIMENT
1. Insert ball of dia ‘D’ in ball holder of the m/c.
2. Make the specimen surface clean by removing dust, dirt, oil and grease etc.
3. Make contact between the specimen surface and the ball by rotating the jack
Adjusting wheel.
4. Push the required button for loading.
5. Pull the load release level and wait for minimum 15 second. The load will
Automatically apply gradually.
6. Remove the specimen from support table and locate the indentation so made.
7. View the indentation through microscope and measure the diameter‘d’ by
Micrometer fitted on microscope.
8. Repeat the entire operation, 3-times.
24
OBSERVATION /DATA TABLE
Sl.No
Diameter of
indentor
SAMPLE:-MILD STEEL
Diameter of the impression
Ød1
Ød2
Ød3
BHN1
BHN2
BHN3
PRECAUTIONS:-
1. The specimen should be clean properly.
2. Take reading more carefully and correct.
3. Place the specimen properly.
4. Jack adjusting wheel move slowly
5. After applying load remove the load.
Result:-
Conclusion:-
Sample Calculation:-
25
Load IN Kgf
3000
BHN(Average)
26
EXPERIMENT NO:-05/A
AIM : To study the Rockwell Hardness testing machine and perform the
Rockwell hardness test.
APPARUTS :- Rockwell Hardness testing machine, specimen of mild steel or other
Material.
THEORY: - Hardness represents the resistance of material surface to abrasion,
scratching and cutting, hardness after gives clear indication of strength. In all hardness
tests, a define force is mechanically applied on the piece, varies in size and shape for
different tests. Common indentors are made of hardened steel or diamond.
Rockwell hardness tester presents direct reading of hardness number on a dial provided
with the m/c. principally this testing is similar to Brinell hardness testing. It differs
only in diameter and material of the indentor and the applied force. Although there are
many scales having different combinations of load and size of indentor but commonly
‘C’ scale is used and hardness is presented as HRC. Here the indentor has a diamond
cone at the tip and applied force is of 150 kgf. Soft materials are often tested in ‘B’
scale with a 1.6mm dia. Steel indentor at 60kgf.
27
Technical data of the Machine/Instruments used.
Name
of
Machine
Model
Make
Maximum Load
Load range
Indenter
scales
Method of load
application
Rockwell Hardness Tester
60kgf,100kgf,150kgf,187.5kgf,250kgf
1/16”steel ball, Diamond cone of 120.
A,B,C,D,E,F,G,H AND K
Lever type
PROCEDURE:8. Insert ball of dia. ‘D’ in ball holder of the m/c.
9. Make the specimen surface clean by removing dust, dirt, oil and grease
etc.
10. Make contact between the specimen surface and the ball by rotating the
jack
adjusting wheel.
4. Push the required button for loading.
5. Pull the load release lever wait for minimum 15 second. The load will
Automatically apply gradually.
6. Remove the specimen from support table and locate the indentation so
made.
7. Repeat the entire operation, 3-times.
28
OBSERVATION
/DATA
STEEL(Unhardened/hardened)
TABLE
SAMPLE:-MILD
Sl.no
Indenter
scale
RHB1
RHB2
RHB3
RHB4
RHB5
Average
RHB
1 Mild
steel
1/16”
steel ball
B
Load in
kgf
100
120.
Tipped
Diamond
cone
C
150
RHC1
RHC2
RHC3
RHC4
RHC5
Average
RHC
PRECAUTIONS:-
1.
The specimen should be clean properly.
2. Take reading more carefully and correct.
3. Place the specimen properly.
4. Jack adjusting wheel move slowly
5. After applying load remove the load.
Result:-
Conclusion:-
Sample Calculation:-
29
EXPERIMENT NO :-05/B
AIM:- Vickers Hardness Test of a given sample.
OBJECTIVE:- To Determine Vickers hardness number of a given steel sample.
THEORY:- It is the standard method for measuring the hardness of metals, particularly
for the very hard surfaces. The surface is subjected to a standard pressure for standard
length of time by means of standard diamond pyramid indinter.The apex angle of the
the pyramid is 136.The indenter is pressed against the specimen at a fixed load ranging
from 5kgf to 120kgf and the VHN is calculated like BHN as the ratio of load and surface
area of indentation in mm2.
VHN=
Load applied in kgf
Area of indentation in mm2
The Area is calculated by measuring the diagonals of the impression left by the
indenter. Thus Vickers Hardness value is.
VHN= 2P sin(θ/2)
D2
Where P=Load applied=length of the diagonal, θ=Angle between the opposite faces of
pyramid (1360)
30
Technical data of the Machine/Instruments used.
Name of Machine
Model
Make
Maximum Load
Load range
Indenter
Magnification
Least count scale
VICKERS HARDNESS TESTER.
VM-50
FIE
30kgf
10kgf,20kgf,30kgf
Diamond pyramid 1360
70x
0.001mm
Procedure:-
OBSERVATION /DATA TABLE
SAMPLE:-BRASS OR ALUMINIUM
Sl.no
Indenter
Load in kgf
1 Brass
1360Diamond
pyramid
30kgf
2.Aliminium
31
Diagonal
(D1)
Diagonal
(D2)
Diagonal
(Average)
VHN
Figure of setup/sample
32
EXPERIMENT NO: - 08
TORSIONAL RIGIDITY TEST OF SHAFT ON TORSION TESTING MACHINE
AIM: - TO DETERMINE THE TORSION PROPERTIES OF A MILD STEEL BAR.
APPARATUS REQUIRED: -
TORSION TESTING MACHINE
VERNIER CALIPER
SPECIMEN TO BE TESTED
THEORY:Shear Stress at Yield point =
Shear Stress at breaking =
Modulus of Rigidity =
2𝑇
𝜋𝑅 3
3𝑇
2𝜋𝑅 3
𝟐𝑻𝑳
𝝅 𝑹𝟒 𝜽
Kg/cm2
Kg/cm2
Kg/cm2
Before starting the experiment, the value of torque at yield point and at breaking point
should be determined assuming the value of shear stresses at these two points.
The shear stress at yield point and at breaking point is calculated as following:Shear stress at Y.P = 0.6 X the elastic limit of M.S
Subjected to tensile load = 0.6 X 2835 = 1700 Kg/cm2
Shear stress at Breaking point =
Subjected to tensile load = =
5
6
5
6
X breaking stress of M.S.
X 4725 = 4000 Kg/cm2
Therefore, The theoretical torque at Y.P =
1700 𝑋 𝜋 𝑅 3
2
And, the theoretical torque at breaking point =
33
4000 𝑋 2 𝑋 𝜋 𝑅 3
3
PROCEDURE: The mean diameter, Length of the test specimen is noted and then the
specimen is fixed on the machine.
 The torque is applied by giving a twist of 10 and the corresponding torque
reading is noted. Like this 5 to 6 reading are taken up to the yeild point.
Again the test is continued further, till the specimen breaks.
 The shear stress at Y.P and at breaking point should be calculated from the
observed final reading of torque at Y.P and at breaking point respectively.
 A graph of torque against twist up to yield point and a similar graph for the
entire test are drawn in the same graph sheet.
 From the graph by taking any point of the graph. Torque and corresponding
twist are noted. Then substituting these values in the formula,
Modulus of Rigidity (C) =
𝟐𝑻𝑳
𝝅 𝑹𝟒 𝜽
Thus, Module of Rigidity of M.S specimen is calculated.
OBSERVATION TABLE
s.no.
𝜃 (In Degree. )
RESULT:PRECAUTION:34
Load
EXPERIMENT NO:-09
AIM OF EXPERIMENT: - To find out Stiffness of a Helical spring experimentally and to
compare it with theoretical one.
APPARATUS REQUIRED: - Spring stiffness apparatus,
vernier caliper, Standard weights
THEORY: - The Stiffness of a helical spring is the ratio of the load and deflection, which
is given by –
K=
𝑮𝑿𝒅
𝟖 𝑪𝟑 𝒏
Where, G = modulus of rigidity (8.4 X 105 Kg/cm2 in this case)
d = wire diameter
C=
𝐷
𝑑
(where, D means diameter of the coil)
n = number of turns.
PROCEDURE:1. Measure the coil. And wire dia. and find out mean dia. of the coil.
2. Put some standard weight on hanger and record the deflection ( 𝛿 )
3. Find out K =
𝑊
𝛿
4. Compare it with theoretical value
5. Repeat this procedure for each spring ( i.e, tensile and compression) and find
out the average.
OBSERVATION:s.no.
W
𝛿
Average
Theoretical
Difference
𝑊
𝑊
Value of K
In K
K=
𝛿
𝛿
Precautions to be taken: (write your own)
35
EXPERIMENT NO:- 10
OBJECT: - To find Young’s Modulus (E) of M.S and Timber beam by flexure of beam
method.
APPARATUS REQUIRED:1. Requisite beam of M.S, Timber
2. Two supports
3. Dial gauge
4. Weight pan
5. Weights
6. Measuring tape and Vernier caliper.
THEORY:- The deflection for simple supported beam with central load is given by
𝛿=
𝑊𝐿3
48𝐸𝐼
Where, L = Length (cm) of the beam
E = Young’s modulus Kg/cm2
I = Moment of inertia of cross section of the beam (cm 4)
I=
𝐵𝐷3
12
Where, B = Width of beam transverse to line of action of force
D = Depth of beam
𝛿 = Deflection (cm)
W = Weight (Kg f)
PROCEDURE:1. Measure the cross section of the beam
2. Put the beam on supports
3. Measure the length of the beam between two knife edges of the
support
4. Find centre of the beam
5. Fix the point and weight pan at centre
6. Keep the dial gauge considering zero to pointer
7. Put the weight on pan
8. Note the deflection due to weight at centre
9. Obtain deflection due to weights at centre
10. Repeat the experiment with timber beam as above
36
OBSERVATIONS:Sl.no.
Weight (Kg)
Deflection (cm)
Young’s Modulus (E)
Precaution:- Weights should be kept on the pan within elastic limit of the
material.
37