strength of materials laboratory -...

GUDLAVALLERU ENGINEERING COLLEGE MECHANICS OF SOLIDS LAB

Department of Civil Engineering Tension Test

STRENGTH OF MATERIALS LABORATORY

GUDLAVALLERU ENGINEERING COLLEGE SESHADRI RAO KNOWLEDGE VILLAGE: GUDLAVALLERU

DEPARTMENT OF CIVIL ENGINEERING

Name : ………………………………………………………

Regd. No : ……………………………………………………….

Year & Semester : ……………………………………………………..

Academic Year : ……………………………………………………….



GUDLAVALLERU ENGINEERING COLLEGE SESHADRI RAO KNOWLEDGE VILLAGE::GUDLAVALLERU

DEPARTMENT

OF

CIVIL ENGINEERING

Strength of Materials - Lab Manual



GUDLAVALLERU ENGINEERING COLLEGE SESHADRI RAO KNOWLEDGE VILLAGE:: GUDLAVALLERU

DEPARTMENT OF CIVIL ENGINEERING

INDEX S.n

o Date

Name of the Experiment Signature

of the

faculty

1

2

3

4

5

6

7

8

9

10

11

12



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

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



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



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?



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.



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



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.



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



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 =



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.



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.



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



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.



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?



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.



PROCEDURE:

12. 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.

13. Rise the pendulum and keep it in position, Fix the correct striking edges to the

head of the swinging pendulum.

14. See the pointer of the scale is positioned at the maximum energy value.

15. Calibrate the tester by releasing the clutch so that the pointer coincides with

zero on the scale with no specimen at the anvil

16. Re-clutch the hammer after calibration.

17. The specimen is firmly held in the vice and fastened to base of the machine.

18. Place the specimen centrally over the supports such that the notch is

opposite to striking end.

19. Reset the pointer on the scale at its maximum value

20. 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.

21. Stop the free swinging or oscillations of pendulum by a pedestal brake.

22. Collect the broken pieces of specimen to observe the nature of fracture.

23. 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

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



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:

5. Ensure no one is at the path of swinging hammer, before its every return case

6. The pointer should be at the bottom i.e. it should at maximum value of scale,

prior to the release of the hammer.

7. Ensure the right stricking edge, and correct weight of the swinging head.

8. 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:

4. Differentiate between Impact loads, gradually applied load and suddenly

applied load?

5. Define strength, toughness, Brittleness?

6. Which type of material absorbs more energy i.e. either Brittle or ductile

material?



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



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 2mm

N

L = Length of the beam in mm f = bending stress2mm

N

= 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.



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



THICKNESS

S.No

Main Scale Reading

MSR mm

Vernier

Coincidence

VC mm

LCVCMSR

mm

1

2

3

Avg. Thickness = mm

TABULAR FORM

.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



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 = _________ 2mm

N

Young’s modulus from Graph = __________ 2mm

N

Bending stress at the applied maximum load is = __________ 2mm

N


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?



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.



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

2mm

N

Shear stress (τ) = J

rT

2mm

N

RESULT: he maximum shear stress on the given material is ___________

2mmN

Rigidity modulus ________ 2mm

N



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.



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.



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 =



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



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



TABULAR FORM

S.no

Original

diamet

er

od mm

Neck

diamete

r

fd mm

Original

Length

oL mm

Final

Lengt

h

fL

mm

Original

Area

oA 2mm

Neck

area

fA

2mm

Yield

stress

2mmN

Ultimat

e

stress

2mmN

Breaki

ng

stress

2mmN

Young’

s

Modul

us

2mmN

%

Elongat

ion

%

Reductio

n in area


Department of Civil Engineering Shear 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



Percentage elongation =

100L

LL

0

f0

Young’s modulus =

Original Length 0L

= mm

Final Length

fL = mm

RESULT:

Stresses from graph =



DEFLECTION TEST ON CANTILIVER BEAM

AIM:

To determine the young’s modulus and bending stress for the given steel beam

by conducting deflection test.on cantilever

APPARATUS:

Cantilever set up, Deflectometer, Calipers, Scale, load hanger, set of weights.

THEORY:

A beam is fixed at the one end and freely hanging other end and load applied

normal to axis of beam is called cantilever beam. The maximum deflection

occurs at the free end of the span, where the load is applied at the free end of the

beam. The loads are applied through hanger. Weights are slowly applied on the

beam. 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

Cantilever beam

L

Beam cross section

b

t



DESCRIPTION:

The apparatus consists of beam testing on fixed support at one and freely

hanging on other side. The load ‘W’ is applied at free end and the maximum

deflection is measured at free end. For this load condition the deflection at

centre is given by

=

EI

WL

3

3

f = I

My

E =

W

I

L

3

3

Where

W = concentrated load in N E=Young’sModulus in

2mmN

L = Length of the beam in mm f = bending stress2mm

N

= 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

WL

t = Thickness of the beam in mm

PROCEDURE:

13. Measure the dimensions of the given beam.

14. Place the deflectometer under the beam where the deflection is to be

measured.

15. Suspend the hanger at the point where the deflection of the beam is to be

noted.



16. Note the initial reading of the deflectometer.

17. Add the loads to the hanger art the rate of 500N, the load should be

carefully applied with out causing any shock.

18. Note the corresponding deflectometer reading for each increasing load.

19. Observe five set of readings.

20. Remove the loads at the rate of 500 N

21. Note the corresponding deflectometer reading for each decreasing load.

22. 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



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

SAMPLE CALCULATIONS:

For a cantilever beam of span l with end load W and deflection is measured at

the end span

Deflection at center, =

EI

WL

3

3

Moment of inertia, I = 12

3bt



E =

W

I

L

3

3

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

I

L

3

3

RESULT:

Young’s modulus of beam materials is = _________ 2mm

N

Young’s modulus from Graph = __________ 2mm

N

Bending stress at the applied maximum load is = __________ 2mm

N


6. Define Young’s modulus, what are its units?

7. What is moment of inertia?

8. Define Hooks Law?

9. Define Bending moment?

10. Area under stress – Strain curve is?



SHEAR TEST

AIM:

To determined the ultimate shear test after given steel spacimen by

conducting a shear test

APPARATUS:

7. Universal testing machine with accessories

8. Vernier calipers.

9. Scale.

10. Shear attachments

THEORY:

For rivets in trusses, plate girders etc., mild steel and high tensile steel are used.

Rivets are subjected to bearing and shearing stresses. We will now investigate

experimentally the behavior of a steel rod under shear. The intensity of internal

resistance when the applied force is parallel to the section being sheared is

called shear stress OR, if the applied load consists of two equal and opposite

parallel Forces which do not share the same line of action, then there will be a

tendency for one part of the body to slide over or shear from the other part.

PROCEDURE:

8. 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.

9. Fix the lower jig and upper jig in the machine.

10. 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.Insert the steel specimen to pass through

the holes in the shear attachments, provided for the purpose,

centrally with equal over handing.



11. Apply the load at a steady uniform rate and until specimen

breaks.

12. Takeout the shear attachment and remove the broken pieces

of the specimen.

13. 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

Ultimate load uP

= KN

TABULAR FORM

S.no diameter

od mm

Area

oA 2mm

Ultimate

shear load

N

Ultimate shear

stress

2mmN


Department of Civil Engineering Brinnel’s Hardnes Test 47

CALCULATION:

Area of cross section oA

=

2

0d4

Ultimate shear stress =

2mm/NeaOriginalar

adUltimatelo

RESULT:

Average Ultimate Shear Stresses =



STRAIN MEASUREMENT USING STRAIN GUAGE

AIM:

Measurement of strain using strain gauge.

APPARATUS:

Digital panel meter, cantilever beam, weights.

THEORY:

Strain gauges are devices used to measure the dimensional change of components

under test. These are used in many applications like force measuring devices,

measurement of vibration, measurement of pressure etc., In this experiment bonded

strain gauges are used . These gauges are directly bonded (that is pasted) on the

surface of the structure under study. In this fine wire strain gauges are used. A fine

resistance wire of diameter of 0.025mm, which is bent again and again as shown in

figure. This is due to increase the length of the wire so that it permits a uniform

distribution of stress. This resistance wire is placed between the two carrier bases

(paper, bakelite or Teflon), which are cemented to each other. The carrier base

protects the gauge from damages. Loads are provided for electrically connecting

the strain gauge to a measuring instrument (wheat stone bridge).

PROCEDURE:

1. Ensure that the instrument is switched off.

2. Connect the flexible wires provided with the strain gauge cantilever beam

between the terminals 1-1,2-2,3-3 &4-4.

3. Keep switch S1 to right position marked.

4. Turn ‘ON’ the main supply by gently moving the balance. Put p1 and p2 obtain

initial balance on the meter and wait for 5 minutes to allow the strain gauge

temperature to stabilize.



5. Now apply a gentle pressure with hand on the end of the cantilever beam, the

Digital Panel Meter (DPM) should indicate some change in reading. This

indicates the strain gauge setup is ready for experiment dial.

6. Now keep p3 pot in minimum clock-wise position corresponding to position of

gain =100. Check for null balance again.

7. Now apply weight of 1kg, 2kg etc., and note down the DPM reading, neglecting

the decimal point.

CALCULATIONS: E0= Ei*R/R (Ei =5V)

Guage Factor = (R/R)/( l/l) (G=2)

E=Stress/Strain= 6Wl/bt2 (E= 2*106)

W= Applied Load, l= Length of Cantilever Beam, b= Breadth of Cantilever Beam

t= Thickness of Cantilever Beam.

OBSERVATION TABLE:

Stress = WL/ ((1/6) bt²)

W-Applied load

L-length of cantilever beam

b-breadth of cantilever beam

t-thickness of cantilever beam

Theoretical value of strain = stress\ E (E=2x 10)

Strain = change in length / original length

SL.NO. LOAD DPM

INDICATION STRAIN



GAUGE FACTOR (Strain sensitivity factor)

The fractional change in resistance due to a unit change in length (unit strain) is

called as gauge factor.

Gauge factor = (R/R)/( L/L)

Where Robotics= Resistance L=Length

Practical strain = (L/L) = ( R/R)/(G) [G=2]

R/R= Eout / Eexcitation [Eexcitation= 5V]

PRECAUTIONS:

1. Make the connection to the binding posts and terminals very care fully.

2. Provide a warm up time of about 10 to 15 minutes before taking readings.

3. Ensure that the cantilever beam arrangement is fixed to the table .

GRAPHS: Load vs DPM reading

Load vs practical strain

Theritical strain vs practical strain

RESULT:

strength of materials laboratory -...

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