Upload
vuongthuan
View
228
Download
3
Embed Size (px)
Citation preview
GUDLAVALLERU ENGINEERING COLLEGE GUDLAVALLERU
MMMEEECCCHHHAAANNNIIICCCSSS OOOFFF
SSSOOOLLLIIIDDDSSS LLLAAABBB MMMAAANNNUUUAAALLL
DEPARTMENT OF MECHANICAL ENGINEERING
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
INDEX
S.NO. NAME OF THE EXPERIMENT PAGE NO
1 SPRING TEST 1 – 4
2 TENSION TEST 5 – 11
3 TORSION TEST 12 – 15
4 IMPACT TEST( CHARPY) 16 – 22
5 IMPACT TEST(IZOD) 23 – 28
6 DEFLECTION TEST 29 – 35
7 COMPRESSION TEST 36 – 40
8 HARDNESS TEST(ROCKWELL) 41 – 43
9 HARDNESS TEST(BRINELL’S) 44 - 48
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Spring Test
SPRING TESTING
MACHINE
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Spring Test
SPRING TESTING MACHINE
AIM:
To find the stiffness of the given spring using tensile testing machine
APPARATUS:
KMI testing machine model 1.3-D ,,set of weight discs and springs.
PROCEDURE:
1. Select the measuring range by attaching weights on the pendulum rod. (Use
‘B’ for 0- 5000N range).
2. To control sudden fall of the pendulum the valve opening of the dash point is
increased for lower range and decreased for higher range.
3. Set the zero in the measuring dial by moving the collar as on the pendulum
bracket arm
4. Fix the griper for tensile testing.
5. Fix the spring between these two grippers.
6. After fixing spring, note the reading of the knife-edge pointing on scale
provided on upper gripping device
7. Turn the power on and press down button to apply gradual tensile force on
the spring.
8. Note the tensile force from the measuring dial for every 10mm elongation of
spring
9. Draw the graph by taking elongation (δ) on X-axis and force (F) on Y- axis.
10. Calculate the slope of the line joining all the measured points by a straight
line, which gives the stiffness of the given spring.
11. Repeated procedure for different springs of same material.
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Spring Test
OBSERVATIONS:
S.No.
Deflection ( ) mm Tensile Force (F) N
Stiffness
(
fk )
mmN
Loading Un-Loading
Initial mm
Final mm
Net mm
Initial mm
Final mm
Net mm
Initial Final Net
1
2
3
4
CALCULATION:
Net Deflection in loading = Final – Initial = mm
Net deflection in unloading = Final – Initial = mm
Net Tensile force = Final – Initial = N
Stiffness
fk = =
mmN
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Spring Test
Forc
e in
N
GRAPH:
A graph is drawn taking elongation on x- axis and tensile force on y- axis.
Y
F2
F1
1 2 Deflection in mm .
RESULT:
Stiffness of the given spring =
From graph =
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Tension Test
TENSION TEST
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Tension Test
TENSION TEST
AIM:
To conduct tension test on the given steel specimen for determining the
1. Stress at yield point.
2. Ultimate stress.
3. Nominal breaking stress.
4. Actual breaking stress.
5. Percentage elongation.
6. Percentage reduction in area.
7. Young’s modulus.
APPARATUS:
1. Universal testing machine with accessories
2. Vernier calipers.
3. Scale.
4. Dot punch.
5. Hammer.
6. Specimens as ISI
THEORY:
The Tension test which is conducted on a universal testing machine at room
temperature is a common method to evaluate strength and ductility under static load
conditions. The tension test is carried out by loading a standard specimen gripped
at both ends and measuring the resultant elongation of the specimens at various
increments of loads.
PROCEDURE:
1. Measure the diameter of the given mild steel specimen at three different
places with the help of vernier calipers and determine the average diameter of
the specimen and gauge length.
2. Mount the specimen in the grip of the movable and fixed cross head
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Tension Test
3. Adjust the load stabilizer, start the machine and open the inlet valve slightly.
When the load pointer just kicks it, indicates that the load is held caught
between the grips, and then adjusts the pointer to read zero.
4. Apply the load at a steady uniform rate and until specimen breaks.
5. After some time the actual point returns slowly. At this stage, a neck is formed
in the specimen, which breaks. Note the position of actual pointer during
breaking. Record the maximum load as “Breaking load”.
6. Press the freeze button and then print to get the graph between load verses
elongation.
7. Repeat the procedure for other specimen.
OBSERVATIONS:
Diameter of rod --- Trial 1 = mm
Trial 2 = mm
Trial 3 = mm
Average diameter of rod od = mm
Original length (Gauge length) of rod 0L = mm
Yield point load yP = KN
Ultimate load uP = KN
Breaking load bP = KN
Diameter of the rod at neck fd = mm
Gauge length ol = mm
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Tension Test
TABULAR FORM
S.no
Original
diameter
od mm
Neck
diameter
fd mm
Original
Length
oL mm
Final
Length
fL
mm
Original
Area
oA 2mm
Neck
area
fA
2mm
Yield
stress
2mmN
Ultimate
stress
2mmN
Breaking
stress
2mmN
Young’s
Modulus
2mmN
%
Elongation
%
Reduction
in area
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Tension Test
GRAPH:
Print the graph between load [y-axis] and deflection [x-axis] from the graph
calculate stresses.
CALCULATION:
Original area of cross section oA = 2
0d4
Area of cross section at neck fA = 2
fd4
Stress at yield point = 2/ mmNeaOriginalar
Yieldload
Ultimate stress = 2mm/NeaOriginalar
adUltimatelo
Actual breaking stress = 2mm/NeaOriginalar
adBreakinglo
Percentage reduction in area = 100A
AA
0
f0
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Tension Test
Percentage elongation = 100L
LL
0
f0
Young’s modulus =
Original Length 0L = mm
Final Length fL = mm
RESULT:
Stresses from graph =
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Torsion Test 1
TORSION TEST
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Torsion Test 2
TORSION TEST
AIM:
To find out the shear stress and rigidity modulus of the given material using
the torsion testing machine
APPARATUS:
Torsion testing machine – Model TT-6. Vernier calipers, scale, specimens
SPECIFICATIONS:
Max torque capacity : 60 mN
Torque ranges : 0- 60 mN
No of divisions on dial : 600
Torsion speed : 1.5 RPM
Clearance between grips : 0- 420 mm
Grips for round bars : 4- 8 mm
Grips for flat bars (t) : 1- 5 mm , 25 mm
Motor power : 0.5 HP
Accuracy of torque indication: +1% of true torque above 20% its range
PROCEDURE:
1. Measure the diameter of the specimen and select the suitable grips for the
specimen and insert into the driving and driven chucks
2. Insert the specimen into the two chucks by holding driven chuck firmly.
3. Adjust torque range depending on the type of specimen (hard or soft) by
turning a knob on the right hand side of measuring panel.
4. Then adjust the zero of the angle-measuring disc.
5. Switch on the motor by pressing green button.
6. Switch off the motor after the specimen breaks.
7. Note down the torque shown by the red pointer in the dial and that is the
maximum capacity of specimen.
8. The angle of twist can be directly read on the angle-measuring disc.
9. Repeat the Same Procedure for different specimens of the same material.
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Torsion Test 3
T T
OBSERVATIONS:
S.NO Material Gauge length (L)mm
Diameter (d) mm
Torque (T) N-m
Twist “ ” Rad
Shear stress
( )
2mmN
Rigidity modulus
(G)
2mmN
CALCULATIONS:
Polar moment of inertia of rod (J) = 32
4d
L
G
rJ
T
Slope = Tan θ =
Rigidity of modulus= J
LTG
2mmN
Shear stress (τ) =J
rT 2mmN
RESULT:
The maximum shear stress on the given material is ___________ 2mmN
Rigidity modulus ________ 2mmN
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Charpy Test 1
IMPACT TEST
(CHRPY TEST)
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Charpy Test 2
IMPACT TEST (CHARPY)
AIM:
To determine the impact strength of the given specimen by conducting
Charpy test.
APPARATUS:
Charpy testing machine with accessories, specimen, Vernier Calipers.
THEORY:
The loads that are suddenly applied to a structure are known as impact loads.
The performance on engineering materials like strength, toughness etc. vary with
rate of loading. Materials exhibits poor performance under dynamic or shock loads.
Hence it is required to know how the strength and toughness varies with impact or
instant shock loads. In the impact test, the impact strength (i.e. the resistance to
shock loads) and the toughness of material under dynamic load is determined.
The principle employed in all impact testing procedures is that a material
absorbs a certain amount of energy before it breaks or fractures. The quantity of
energy thus absorbed is characteristic of the physical nature of the materials. If it is
brittle it breaks more readily, i.e., absorbs a lesser quantity of energy and if it is
tough, it needs more energy for fracture.
The two important standard impact tests are (1) Izod Impact test and (2)
Charpy impact test.
DESCRIPTION:
The machine consists of a swinging pendulum that has an arm and head. For
this test the dimensions of standard specimen are 55 mm x 10 mm x 10 mm . It is a
simple supported beam. Swinging Head strikes other side of the specimen notch.
Pendulum falls from 1.457 m height or from an angle of 1400. The weight swinging
hammer is 20.932 kg or 250 N. The specimen struck exactly at its centre i.e. 27.5
mm . The machine also has a pedal operated brake, to stop the hammer after the
specimen is struck.
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Charpy Test 3
SPECIFICATIONS:
Maximum impact energy of pendulum 300 Joules
Minimum value of scale graduation 2 Joules
Distance between supports 40 mm ± 0.2 mm
Angle of test piece supports 780 to 800
Angle of inclination of supports 00
Radius of supports 1 mm to 1.5 mm
Maximum width of striker 10 – 18 mm
Angle of striking edge 300± 10
Radius of curvature of striking edge 2 mm to 2.5 mm
Weight of the machine 415 kg (approx.)
PROCEDURE: 1. Measure the dimensions of specimen by using Vernier Calipers.
2. Raise the pendulum and keep it in position, fix the correct striking edges to
the head of the swinging pendulum.
3. Set the pointer of the scale to maximum energy value.
4. Calibrate the tester by releasing the clutch so that the pointer coincides with
zero on the scale with no specimen at the anvil
5. Re-clutch the hammer after calibration.
6. Place the specimen centrally over the supports such that the notch is
opposite to striking end.
7. Reset the pointer on the scale at its maximum value
8. Release the pendulum by operating the two levers simultaneously. The
striking edge strike against the specimen and ruptures it. The specimen
absorbs a part of the energy due to fall of the pendulum.
9. Stop the free swinging or oscillations of pendulum by a pedestal brake.
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Charpy Test 4
10. Collect the broken pieces of specimen to observe the nature of fracture.
11. Read the scale reading as shown by the pointer as the toughness of material
in Joules.
OBSERVATIONS:
BREADTH
S.No Main Scale Reading
MSR , mm
Vernier Coincidence
VC , mm
LCVCMSR mm
1
2
3
Avg. Breadth = mm
THICKNESS
S.No
Main Scale Reading MSR mm
Vernier Coincidence
VC , mm
LCVCMSR mm
1
2
3
Avg. Thickness = mm
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Charpy Test 5
TABULAR FORM
S.No.
Material of the Specimen
Area of the specimen
at the Notch mmmm
Energy absorbed,
J
Energy absorbed to break the
specimen, J
Specific Impact Power
2mmJ
Initial Final
1
2
3
CALCULATIONS:
Specific impact power = Energy absorbed / area of cross section at the notch
PRECAUTIONS:
1. Ensure no one is at the path of swinging hammer, before its every return case
2. The pointer should be at the bottom i.e. it should at maximum value of scale,
prior to the release of the hammer.
3. Ensure the right striking edge, and correct weight of the swinging head.
4. Swinging hammer should be clutched at the standard height depending upon
the type of testing.
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Charpy Test 6
RESULT:
Specific impact power of the given material =
ASSESSMENT QUESTIONS:
1. Differentiate between Impact loads, gradually applied load and suddenly
applied load?
2. Define strength, toughness, Brittleness?
3. Which type of material absorbs more energy i.e. either Brittle or ductile
material?
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Izod Test 1
IZOD TEST
AIM : To determine the suitability of a material, which is expected to resist repeated
shocks, by determining the energy required to break the material by conducting Izod
test.
APPARATUS:
1. Izod testing machine with Accessories
2. Specimen
3. Vernier calipers
THEORY:
The loads that are suddenly applied to a structure are known as impact loads.
The performance on engineering materials like strength, toughness etc. vary with
rate of loading. Materials exhibits poor performance under dynamic or shock loads.
Hence it is required to know how the strength and toughness varies with impact or
instant shock loads. In the impact test, the impact strength (i.e. the resistance to
shock loads) and the toughness of material under dynamic load is determined.
The principle employed in all impact testing procedures is that a material
absorbs a certain amount of energy before it breaks or fractures. The quantity of
energy thus absorbed is characteristic of the physical nature of the materials. If it is
brittle it breaks more readily, i.e., absorbs a lesser quantity of energy and if it is
tough, it needs more energy for fracture.
The two important standard impact tests are (1) Izod Impact test and (2)
Charpy impact test.
DESCRIPTION:
The machine consists of a swinging pendulum that has an arm and head. For
this test the dimensions of standard specimen are 75 mm x 10 mm x 10 mm . It is a
cantilever beam. Swinging Head strikes face of the specimen notch. Pendulum falls
from 0.758 m height or from an angle of 840. The weight swinging hammer is 21.79
kg or 214 N. The specimen struck exactly at its centre i.e. 27.5 mm . The machine
also has a pedal operated brake, to stop the hammer after the specimen is struck.
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Izod Test 2
PROCEDURE:
1. The specimen is of square cross section of 10 mm side of and its length is 75
mm . It is notched at a distance of 28 mm from one side, the notch being 2
mm deep and with an inclined angle of 45o.
2. Rise the pendulum and keep it in position, Fix the correct striking edges to the
head of the swinging pendulum.
3. See the pointer of the scale is positioned at the maximum energy value.
4. Calibrate the tester by releasing the clutch so that the pointer coincides with
zero on the scale with no specimen at the anvil
5. Re-clutch the hammer after calibration.
6. The specimen is firmly held in the vice and fastened to base of the machine.
7. Place the specimen centrally over the supports such that the notch is
opposite to striking end.
8. Reset the pointer on the scale at its maximum value
9. Release the pendulum by operating the two levers simultaneously. The
striking edge strike against the specimen and ruptures it.The specimen
absorbs a part of the energy due to fall of the pendulum.
10. Stop the free swinging or oscillations of pendulum by a pedestal brake.
11. Collect the broken pieces of specimen to observe the nature of fracture.
12. Read the scale reading as shown by the pointer as the toughness of material
in Joules.
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Izod Test 3
OBSERVATIONS:
BREADTH
S.No
Main Scale Reading MSR mm
Vernier Coincidance
VC mm
LCVCMSR mm
1
2
3
Avg. Breadth = mm
THICKNESS
S.No
Main Scale Reading MSR mm
Vernier Coincidance
VC mm
LCVCMSR mm
1
2
3
Avg. Thickness = mm
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Izod Test 4
TABULAR FORM
S.No.
Material of the Specimen
Area of the specimen
at the Notch mmmm
Energy absorbed,
J
Energy absorbed to break the
specimen, J
Specific Impact Power
2mmJ
Initial Final
1
2
3
CALCULATIONS:
Specific impact power = Energy absorbed / area of cross section at the notch
PRECAUTIONS:
1. Ensure no one is at the path of swinging hammer, before its every return case
2. The pointer should be at the bottom i.e. it should at maximum value of scale,
prior to the release of the hammer.
3. Ensure the right stricking edge, and correct weight of the swinging head.
4. Swinging hammer should be clutched at the standard height depending upon
the type of testing.
RESULT: Specific impact power of the given material =
ASSESSMENT QUESTIONS:
1. Differentiate between Impact loads, gradually applied load and suddenly
applied load?
2. Define strength, toughness, Brittleness?
3. Which type of material absorbs more energy i.e. either Brittle or ductile
material?
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Deflection Test 1
DEFLECTION TEST
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Deflection Test 2
DEFLECTION TEST
AIM:
To determine the young’s modulus and bending stress for the given steel
beam by conducting deflection test.
APPARATUS:
Two knife edge supports, Deflectometer, Calipers, Scale, load hanger, set of
weights.
THEORY:
A beam extremely supported at both ends and load applied normal to axis of
beam is called simply supported beam. The maximum deflection occurs at middle of
span, where the load is applied at the Mid Point of the beam. The loads are placed
in pan. The pan is adjusted to exactly middle of the beam. Weights are slowly
placed on the pan. The beam under goes deflection. The deflection of the beam is
measured with the help of dial gauge and with the help of relation between deflection
of beam and load system. The Modulus of elasticity of material of the beam is
obtained. For this purpose consider two cases loading & unloading.
Load
Simply supported beam
2L
Beam cross section
b
t
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Deflection Test 3
DESCRIPTION:
The apparatus consists of beam testing on two simply supported knife
edges. The load ‘W’ is applied at centre and the maximum deflection is
measured at centre. For this load condition the deflection at centre is given by
=
E
W
I48
L3
f = I
My
E =
W
I48
L3
Where
W = concentrated load at centre in N E=Young’sModulus in 2mmN
L = Length of the beam in mm f = bending stress 2mmN
= Deflection of the beam in mm y = Distance of top fiber from
I = Moment of Inertia about Neutral axis Neutral axis
b = breadth of the beam in mm M = Bending moment 4
WL
t = Thickness of the beam in mm
PROCEDURE:
1. Adjust the knife-edge supports for the required span.
2. Measure the dimensions of the given beam.
3. Place test beam over the center of supports.
4. Place the deflectometer under the beam where the deflection is to be
measured.
5. Suspend the hanger at the point where the deflection of the beam is to be
noted.
6. Note the initial reading of the deflectometer.
7. Add the loads to the hanger art the rate of 500N, the load should be carefully
applied with out causing any shock.
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Deflection Test 4
8. Note the corresponding deflectometer reading for each increasing load.
9. Observe five set of readings.
10. Remove the loads at the rate of 500 N
11. Note the corresponding deflectometer reading for each decreasing load.
12. Draw the graph load Vs deflection mm taking deflection on X-axis and load
on Y-axis.
OBSERVATIONS:
Span of the beam (L) = mm
Width of the beam (b) = mm
Thickness of the beam (t) = mm
Least count of Deflectometer =
BREADTH
S.No
Main Scale Reading MSR mm
Vernier Coincidence
VC mm
LCVCMSR mm
1
2
3
Avg. Breadth = mm
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Deflection Test 5
THICKNESS
S.No
Main Scale Reading MSR mm
Vernier Coincidence
VC mm
LCVCMSR mm
1
2
3
Avg. Thickness = mm
TABULAR FORM
S.No. Load W (N)
Deflectometer Reading Deflection in, mm
(Initial – Final) Young’s modulus
2mmN
Loading Un-Loading Loading
Un-Loading
Aveg Initial Final Initial Final
1
2
3
4
5
6
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Deflection Test 6
SAMPLE CALCULATIONS:
For a simply supported beam of span l with central load W and deflection is
measured at mid span
Deflection at center, = EI
WL
48
3
Moment of inertia, I =12
3bt
E=
W
I48
L3
From the bending equation, Y
F
I
M
YI
MF
GRAPH:
Plot a graph between load and deflection from the graph corresponding to
any convenient points. Find the value of W/ ratio and calculate E from expression
E =
W
I48
L3
RESULT:
Young’s modulus of beam materials is = _________ 2mmN
Young’s modulus from Graph = __________ 2mmN
Bending stress at the applied maximum load is = __________ 2mmN
ASSESSMENT QUESTION:
1. Define Young’s modulus, what are its units?
2. What is moment of inertia?
3. Define Hooks Law?
4. Define Bending moment?
5. Area under stress – Strain curve is?
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Compression Test
COMPRESSION TEST
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Compression Test
COMPRESSION TEST
AIM: -
To determine the ultimate crushing strength of concrete and wood
EQUIPMENT & MATERIALS USED:
Compression Testing Machine M/C (CTM).
Wooden block or Concrete block
Scale.
THEORY:
Concrete and Wood are generally used in engineering constructions and it
may be subjected to compressive loads. To with stand the structural loads, it is
necessary to determine the compressive strength of concrete and wood.
Compressive test is conducted at room temperature to determine the ultimate
compressive strength of the given concrete and wooden block under static loading
conditions. The external faces of wooden block are made perfectly plane. The block
is held between the lower and upper cross head of C. T. M. Inter mutual loads are
applied gradually on the specimen. The concrete or wood undergoes compression.
At a particular load the needle of the control unit starts to rotate anti clock wise,
which can be noted as ultimate crushing load.
DESCRIPTION OF THE EQUIPMENT:
Compression Testing Machine is operated hydraulically. Driving is performed
with the help of electric motor. Depending upon the size of the specimen the C. T. M.
can be set into two ranges C. T. M. consists of two units
(a) Loading & (b) Control Unit.
The specimen is tested upon the loading unit and the corresponding readings are
taken from the dial fitted to the control unit. Hydraulic cylinder is fitted in the center of
the base and the piston slides in the cylinder when the machine is in operated. A
lower table is rigidly connected to an upper crosshead by two straight columns. This
assembly moves up and down. Compression test is conducted by putting the
specimen in between lower table and upper crosshead.
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Compression Test
The control panel consists the two valves one is at right side and the another
one at left side. These valves control the flow of oil in the hydraulic system. The right
side valve is a pressure flow control valve and left side valve is return valve to allow
the oil from cylinder to go back in to the tank. Control panel consists of
dynamometer, which measures and indicates the load on the specimen.
PROCEDURE:
1) Prepare the concrete or wood specimen as per required dimensions.
a) In case of compression test of wood perpendicular to the grain, tests
are made on normal 50 x 50 x 150 mm .
b) In case of compression test of wood parallel to the grains the
dimensions of the specimen are 50 x 50 x 200 mm .
c) Incase of concrete block 150 x 150 x 150 mm
2) Measure the dimensions of the specimen with the help of scale.
3) Place the specimen in between the lower table and upper crosshead of C. T.
M. in such a way that the grains of the specimen are perpendicular to the
direction of application of the load.
4) Apply the compressive load on the specimen. The needle of the control unit
rotates in clockwise direction.
5) By applying the load the specimen crushes. At particular load the needle
starts to rotate in anti clockwise direction. The corresponding load is called
ultimate crushing load.
6) Repeat the same procedure by keeping the specimen in such away that the
grains are along the axis of loading and take the ultimate crushing load.
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Compression Test
OBSERVATIONS:
When the load is applied perpendicular to the grains of the specimen.
S.No
Area of cross section
in 2mm A
Ultimate crushing
load in N cP
Ultimate Crushing Stress
A
Pcc 2mm
N
When the load is applied along the grains of the specimen.
S.No
Area of cross section
in 2mm A
Ultimate crushing
load in N cP
Ultimate Crushing Stress
A
Pcc 2mm
N
RESULT:
Ultimate crushing strength of given concrete or wood specimen =
When the load is applied perpendicular to the grains of the specimen =
When load acts along the grains =
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Rockwell Hardness Test 1
ROCKWELL HARDNESS
TEST
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Rockwell Hardness Test 2
ROCKWELL HARDNESS TEST
AIM: To measure the Rockwell hardness number for the given material.
APPARATUS: Rockwell hardness testing machine with accessories, emery paper,
Specimen.
THEORY:
Hardness is the property exhibited by a material. It can be defined as the
property of a material by virtue of which it resists scratch, wear, abrasion or
indentation.
DESCRIPTION:
Rockwell Hardness Testing consists of an anvil which can be changed
depending up on the shape of the specimen under test. Different anvils are
available for different specimen. The anvil can moved up or down. But turning the
hand wheel, which is situated, at bottom of the spindle a loading leaver is situated at
the right hand side bottom position of the machine. The loading mass also be
applied by simple operating a handle leaver which is just below the handle wheel.
The machine reading type. These are two scales B and C. B for soft
material, C for Hard materials.
PROCEDURE:
1. Remove all mill scales from the surface of the specimen by rubbing it with
emery paper
2. Based on the type of materials, select the proportional load on the indenting
tool for very hard materials, measure in Rockwell ‘C’ scale, 1500N
proportional load and diamond penetrator. For medium hard and soft
materials measure in Rockwell ‘E’ scale, 1000N proportional load and 1.58
mm dia. ball penetrater.
3. Insert indenter and fasten with a screw.
4. Keep the load required for the scale which we are using.
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Rockwell Hardness Test 3
5. Place the specimen on the anvil and turn the wheel to raise the elevating
screw till the small pointer on the dial reaches the set position. Now the
specimen is subjected to the preliminary load of 100N and also set the big
pointer to zero.
6. Push forward the Loading handle to transmit the major load to the specimen.
7. When the penetration is complete (Give 5 to 6 seconds for hard material and
6 to 8 seconds for soft material) release the major load by pushing backward
the loading handle. Keep the initial 100N load still on the specimen.
8. Then directly read the Rockwell ‘C’ or Rockwell ‘B’ hardness number on the
dial where the needle stopped and record it.
9. Then release the minor load of 100N by rotating the hand wheel and lowering
the screw.
10. Repeat the Experiments to obtain at least four different sets of observation for
the same material.
OBSERVATIONS:
S.No Material Trail No.
Minor
load in
‘N’
Major
load in
‘N’
Indenter
used
Scale
used R. H. No.
1
2
3
4
Average R.H.No. =
RESULT: Rockwell hardness No. for the given material = _________ Rc or RB
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Brinnel’s Hardnes Test 1
BRINNELL HARDNESS
TEST
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Brinnel’s Hardnes Test 2
BRINNEL’S HARDNESS TEST
AIM: To measure the Brinnel hardness number for the given material.
APPARATUS: Brinnel’s hardness testing machine with accessories, emery paper,
microscope, specimen.
THEORY:
Hardness is the property exhibited by a material. It can be defined as the
property of a material by virtue of which it resists scratch, wear, abrasion or
indentation.
DESCRIPTION:
For a number of engineering materials which are subjected to friction such as
steel, cast iron etc. it is necessary to find out their resistance to wear and tear
(hardness). Hardness of a surface can be increased by heat treatment or by
chemical treatment and finding out the hardness can check the efficiency of the
process. The Brinnel’s hardness test is carried out by forcing a hardened steel ball
of diameter D under a load of P into a test specimen and measuring the mean
diameter d of the indentation left on the surface after removal of the load. Normally
for hard materials a ball of 10 mm diameter should be used. For soft material 5mm,
2.5mm, 2mm and 1mm are to be used depending upon the softness of the surface.
The British Standard Institution has recommended the following four different 2D
P
ratios for different materials.
The hydraulic pump applies the load required for specified time. A Brinnel
Microscope is used to measure the Indentation.
BHN = ][
2
22 dDDD
P
Where P is the load adjusted in the machine in N
D is the diameter of indenter and
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Brinnel’s Hardnes Test 3
d is the diameter of impression
In Brinnel’s Machine the surface area of the Indentation is calculated and is
used as an index of hardness of the metal.
The surface area of Indentation is dependent upon the depth of penetration.
The load applied (in kgf) divided by the spherical area of Indentation in square mm is
taken as the Brinnel’s Hardness number.
PROCEDURE:
1. Polish the surface with emery paper.
2. Place the specimen on the work table and raise it by turning the elevating
screw till the small pointer on the dial reaches the set position. Now the
specimen is subjected to the preliminary the load 10 kgf
3. Adjust the diaphragm the required weight, that is, if the penetrate diameter is
25mm, and P/D2 ratio is 30, then the load to be adjusted to 187.5 Kg. If the
diameter of penetrater is 10 mm, then the load is 30 Kg (300N). Apply the
load by operating the lever arm.
4. Wait for 30 Sec for soft materials and 15 sec for hard material so as to make
the load reach the specimen fully. Wait till the pointer stops moving.
5. Remove the specimen and measure the diameter of the indentation correct to
0.1mm with Brinnel microscope. To do this, keep the specimen at
microscope adjusted indentation to the scale of the microscope and measure
the diameter of the indentation.
6. Repeated the process to obtain at least 4 different sets of observation for the
same material.
7. Brinnel Hardness number B.H.N = ][
2
22 dDDD
P
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Brinnel’s Hardnes Test 4
OBSERVATIONS:
Diameter of the indenter = mm
Load = kgf
TABULAR FORM
S.No
Material
Diameter
of indentor
mm
Diameter of impression Load P
kgf
B.H.N
Trail I Trail II Average
1
2
3
4
5
CALCULATION:
B.H.N = ][
2
22 dDDD
P
=
RESULT:
Brinnel Hardness Number for the given material = _________ BHN
GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB
Brinnel’s Hardnes Test 5
ASSESSMENT QUESTION:
1. Define Hardness? What is meant by Indentation?
2. How the ball Indenter diameter varies with load?
3. What is the load, ball Indenter ratios for different materials?
4. What is the least count for Brinnel Microscope?
5. What are the different grades of ball Indenters?