Strength of Materials LAB Manual

TENSION TEST ON A MILD STEEL ROD USING

UNIVERSEL TESTING MACHINEEXPT. NO. : DATE :

AIM:

To conduct the tension test on the given specimen (M.S.rod) and to determine the following

Young’s modulus

Yield stress

Ultimate stress

Normal breaking stress

Actual breaking stress

Percentage elongation

Percentage reduction in area

APPARATUS REQUIRED:

Universal Testing Machine

Extensometer

Mild steel specimen

Screw gauge and scale

PROCEDURE:

1. The diameter of the given specimen is measured using screw gauge.

2. The gauge length is marked on the specimen using dot punch.

3. Suitable load range is selected in U.T.M and dial pointer is adjusted to zero.

4. The specimen fixed with extensometer is fixed between the tension grips and extensometer

dial is adjusted to zero.

5. The specimen is loaded and extensometer readings are noted at regular interval.

6. The extensometer is removed and the specimen is loaded further and the load at yield point,

ultimate load and breaking load are noted.

7. After the breaking load, the specimen is removed from the grips and final gauge length and

diameter of the specimen at the breaking point are measured.

8. A graph is drawn by taking load (stress) along the Y-axis and elongation (strain) along the

X-axis.

1Strength of Materials

FORMULAE USED:

1. Young’s modulus (E)¿ [Load∗Length ]/[ Area∗Elongationof the rod ]...N/mm2

2. Yield Stress ¿¿Load at the yield point ¿ Cross sectional area]… ……….N/ mm2

3. Ultimate stress¿ [Ultimate load ¿ Cross sectional area]………..………..N/ mm2

4. Normal breaking stress¿[Breaking load¿ Cross sectional area]………….N/ mm2

5. Actual breaking stress¿[Breaking load¿ C.S Area at the failure]…………N/ mm2

6. Percentage elongation ¿[L1-L2¿ L2]*100

Where

L1 =Original length in mm

L2=Final length in mm

7. Percentage reduction in area ¿[A1-A2¿ A1]*100

Where

A1 =Original C.S Area in mm2

A2=Final C.S Area in mm2

RESULT:

1. Young’s modulus =

2. Yield stress =

3. Ultimate stress =

4. Normal breaking stress =

5. Actual breaking stress =

6. Percentage elongation =

7. Percentage reduction in area =


DOUBLE SHEAR TEST ON A MILD STEEL ROD

EXPT. NO.: DATE :

AIM:

To determine the ultimate shear strength of given specimen (M.S rod) by conducting

Double shear test.

APPARATUS REQUIRED:

Compression testing machine.

Double shear arrangement

Vernier Calipers

PROCEDURE:

1. Diameter of the specimen is measured and fixed in the double shear arrangement.

2. The specimen is loaded in the compression testing machine and ultimate load is noted. (i.e.

load at which the specimen fails).

3. The procedure is repeated for different specimens and ultimate shear stress is calculated.

FORMULAE USED:

Ultimate shear strength of the specimen= P/ (2*A)……… N/ mm2

Where

P= Ultimate load in N

A=C.S Area of the rod in mm2

OBSERVATION:

Least count of the Vernier = 0.02mm

TABULATION:

Sl.No Diameter of the rod(mm)

Ultimate LoadP(N)

Ultimate shear stress(N/ mm2)

RESULT:

Ultimate shear strength of the given specimen= …………


IMPACT STRENGTH OF MATERIALS

(CHARPY’S METHOD)EXPT. NO. : DATE :

AIM:

To determine the impact strength of the given specimen using Charpy’s method.

APPARATUS REQUIRED:

Impact testing machine

Test specimen calipers etc.,

MACHINE CAPACITY:

The testing machine available in the lab can expand up to 300 Joules of energy on the

sample.

PROCEDURE:

1. Adjust the pointer reading with the pointer carrier when the pendulum swings freely.

2. Fix the pendulum hammer at the collar of the testing machine. Now the pointer should read

300 Joules.

3. Without the specimen, drop the hammer so that its swings freely. Note down the energy loss

due to friction.

4. If there is no energy loss, the pointer should read zero.

5. Refit the hammer in the collar and place the Charpy test specimen in the anvil.

6. Drop the hammer to break the specimen and obtain the energy absorbed in fracturing the

specimen.

OBSERVATION:

Material of the test specimen :

Size of the specimen : mm

Type of notch : U-Shaped

Total depth of notch : mm

Width of notch : mm

Radius of semi-circle : mm

Distance of the notch from one end : mm


TABULATION:

Sl.NoLoss of energy due to friction

(N-m)

Energy to break friction

(N-m)

Actual energy required (N-m)

Area of Specimen

(mm2)

Impact Strength(N-m/ mm2)

RESULT:

The Impact strength of given specimen by Charpy’s method is ……………


IMPACT STRENGTH OF MATERIALS

(IZOD’S METHOD)EXPT. NO. DATE:

AIM:

To determine the impact strength of the given specimen using Izod’s groove.

APPARATUS REQUIRED:

Impact testing machine. Izod’s accessories. Test specimen calipers etc.,

MACHINE CAPACITY:

The testing machine available in the lab can expand up to 164 N-m of energy on the sample.

PROCEDURE:

1. Fix the striker firmly at the center of percussion of the hammer with the screws.

2. Swing the hammer freely to note down the energy loss due to friction.

3. Fix the test specimen in the specimen support, with the notch facing the striking

direction and tighten the clamp screws.

4. Read the pointer scale (164 N-m).

5. Release the striker by operating a lever and break the sample.

6. Bring the pendulum to rest by applying brakes.

7. Read the pointer and read the scale value. This is the energy required to break the

specimen.

8. Remove the broken specimen and the striker.

OBSERVATIONS:

Dimension of the test piece : mm

Type of notch : V-Notch

Angle of notch : 450

Depth of notch : mm

Distance of notch from one end : mm


FORMULAE USED:

Impact strength of the material =Energy required to break the specimen/C.S. Area atnotch point

TABULATION:

Sl.NoLoss of energy due to friction

(N-m)

Energy to break friction

(N-m)

Actual energy required (N-m)

Area of Specimen

(mm2)

Impact Strength (N-m/ mm2)

RESULT:

The Impact strength of given specimen by Izod’s method is…………….


BRINELL HARDNESS TEST

EXPT. NO. : DATE :

AIM:

To find the Brinell Hardness number for the given metal specimen.

APPARATUS REQUIRED:

Brinell Hardness Testing Machine

Metal Specimens

Brinell Microscope.

FORMULAE USED:

Brinell Hardness Number (BHN) = 2P / { D* [ D - ( D 2 – d 2 ) ] }

Where,

P = Load applied in Kgf.

D = Diameter of the indenter in mm.

d = Diameter of the indentation in mm.

DESCRIPTION:

It consists of pressing a hardened steel ball into a test specimen. In this usually a steel ball

of Diameter D under a load ‘P’ is forced in to the test piece and the mean diameter‘d ’ of the

indentation left in the surface after removal of load is measured. According to ASTM (American

Society for Testing Materials) specifications a 10 mm diameter ball is used for the purpose. Lower

loads are used for measuring hardness of soft materials and vice versa. The Brinell hardness is

obtained by dividing the test load ‘P’ by curved surface area of indentation. This curved surface is

assumed to be portion of the sphere of diameter ‘D’.

Where

D = Ball diameter

d = Impression (indentation) diameter

P = Load

TEST REQUIREMENTS:8

Strength of Materials

1. Usual ball size is 10 mm + 0.0045 mm. Some times 5 mm steel ball is also used. It shall be

hardened and tempered with a hardness of at least 850 VPN. (Vickers Pyramid Number).

It should be polished and free from surface defects.

2. Specimen should be smooth and free from oxide film. Thickness of the piece to be tested

shall not be less than 8 times from the depth of indentation.

3. Diameter of the indentation will be measured in two directions normal to each other with an

accuracy of + 0.25% of diameters of ball under microscope provided with cross tables and

calibrated measuring screws.

PROCEDURE:

1. Specimen is placed on the anvil. The hand wheel is rotated so that the specimen along with

the anvil moves up and contact with the ball.

2. The desired load is applied mechanically (by gear driven screw) and the ball presses into the

specimen.

3. The diameter of the indentation made in the specimen by the pressed ball is measured by the

use of a micrometer microscope, having transparent engraved scale in the field of view.

4. The indentation diameter is measured at two places at right angles to each other, and the

average of two readings is taken.

5. The Brinell Hardness Number (BHN) which is the pressure per unit surface area of the

indentation is noted down.

TABULATION:

Sl.No. MaterialLoad

(Kg-f)

Diameter

of the Indenter

(mm)

Diameter of the

indentation

(mm)

Brinell Hardness

Number

(BHN)

RESULT:

Thus the Brinell hardness number of the given Specimen is…………………


ROCKWELL HARDNESS TESTEXPT. NO. : DATE :

AIM:

To determine the Rockwell hardness number for the given metal specimen.

APPARATUS REQUIRED:

Rockwell Hardness Testing Machine.

Indenter

Metal Specimen.

PROCEDURE:

1. Test piece is placed on the machine.

2. Hand wheel is rotated; thereby raising the test piece up against the steel ball indenter till the

needle of the small dial is against the red mark. This applies minor load.

3. Major load is applied by pressing the crank provided on the right hand side of the machine.

Time is given as 30 seconds so as to make the load reach the specimen fully.

4. When the penetration is completed, the crank is turned in the reverse direction thereby with

drawing the minor load but the leaving the major load applied.

5. The pointer moves further and becomes stand still. This reading is taken as Rockwell

Hardness Number – C scale.( HRC)

6. Hand wheel is rotated and the test piece is lowered.

TABULATION:

Sl.No. MaterialLoad (Kg-f)

IndenterScale

Trial NumberRockwell Hardness

Number(HRC)

1 2 3

RESULT:

Rockwell Hardness number of the given specimen is as follows:

1. Copper = ----------- HRC2. Brass = ----------- HRC3. Aluminium = ------------ HRC.


TEST ON SPRINGS

EXPT. NO. : DATE :

AIM:

To conduct test on spring to determine the following:

Stiffness

Modulus of rigidity

Strain energy stored per unit volume.

APPARATUS REQUIRED:

Spring testing machine

Tension spring (close coiled) & Compression spring (open coiled)

Vernier caliper

FORMULAE USED:

1. Stiffness of spring (K)=w /

Where,

=Deflection of spring in mm

W=Load applied in N

2. Modulus of Rigidity= 64 WR3n/ d4 *……….N/mm2

Where,

W=Load applied in Newton

R=Mean radius of spring coil = (D+d) / 2

n= Number of turns in the coil

E=Young’s modulus of the spring material

3. Maximum energy stored per unit volume = 0.5 x Wmax x max….N-mm

Where,

Wmax=Maximum load applied...N

max=Maximum deflection……mm

PROCEDURE:1. By using vernier caliper measure the diameter of the wire of the spring and also the

diameter of spring coil and count the number of turns in the coil.

2. The spring is fixed between the grips and load is applied (tension in the case of close

coiled spring & compression in the case of open coiled spring).

3. A graph is drawn by taking load along the Y-axis and deflection along the X-axis and

modulus of rigidity is calculated.


OBSERVATION:

To determine the wire diameter, and coil diameter of spring (each 3 readings)

Diameter of spring coil (D) =

Diameter of spring wire (d) =

Number of turns in spring=

Least count of Vernier =0.02mm

TABULATION:

Sl.NoMain Scale Reading

MSR(mm)

Vernier scale reading (VSR)

VSR x LC (mm)

Total reading = MSR=(VSRxLC)

(mm)


TABULATION:

To determine the load versus deflection (min 12 readings)

Sl.No Load (Kg-f)

Scale readings(mm)

Deflection (mm)

Modulus of rigidity

(N/mm2)

Stiffness (N/mm)

RESULT:

Under compression test on open coil helical spring

Modulus of rigidity(N) =

Stiffness of spring (K)=

Maximum strain energy stored per unit volume =

Under tension test on close coil helical spring

Modulus of rigidity (N) =

Stiffness of spring (K)=

Maximum strain energy stored per unit volume =


TORSION TEST

EXPT. NO. : DATE :

AIM:

To conduct a torsion test on the given specimen to determine the following

Modulus of rigidity

Yield strength

Modulus of rupture in tension

APPARATUS REQUIRED:

Torsion testing machine

Scale

Micrometer

FORMULAE USED:

1. Modulus of rigidity of sample, T/J=CӨ/L=FS/R

For J=IXX+IYY

For J= (bd3/12) + (db3/12)

Where,

T=Twist moment or torque

J= Polar moment of inertia

Fs=Shear stress

R=Outer radius of the specimen

C=Modulus of rigidity

2. Modulus of rupture, Fs=T*R

Where

T=Tmax

PROCEDURE:

1. Using the micrometer, measure the diameter (d) of the specimen in four places.

2. Accurately measure the length (l) of the specimen after securing the specimen into the

machine.

3. After selecting the suitable scale on the machine adjust the initial torque and angle of

twist reading to zero.


4. Up to 10 degree angle of twist applied the torque by hand and note down the torque and

angle of twist.

5. From 10 degree to 20 degree angle of twist, apply the torque by hand and note down the

torque for every increment of 2 degree twist.

6. The machine may be operated electrically and note down the readings at 10 degree

intervals.

7. Repeat the same procedure until the specimen fails.

TABULATION:

Sl.No Torque (N-mm)

Angle of twist Modulus of Rigidity(N/mm2)Degrees Radians

RESULT:

The Modulus of rigidity of the given specimen is =

The Modulus of rupture of the given specimen is =


DEFLECTION TEST ON BEAMS

EXPT. NO. : DATE :

AIM:

To determine the Young’s modulus of the given material of the beam by observing the

deflection on a simply supported beam with central point load.

APPARATUS REQUIRED:

Beam deflection apparatus

Rectangular section of beams

Scale to measure deflection

Screw gauge/Vernier caliper or a Scale

FORMULAE USED:

Y=WL3/48EI

Where,

W is the load

Y is the deflection

E is the young’s modulus

I is the moment of inertia of the given section.

PROCEDURE:

1. The selected span length is measured with the steel rule and marked on the beam

section.

2. The breadth and depth of the section are measured by using steel rule accurately with

the Screw gauge/Vernier caliper.

3. The beam is supported over the marked span length.

4. The beam is subjected to gradual loading at the center and deflection for every known

load is noted.

RESULT:

The young’s modulus of the given beam section is =


STRAIN MEASUREMENT USING ROSETTE STRAIN GAUGE

EXPT. NO. : DATE :

AIM:

To determine the value of young’s modulus of given aluminium using Rosette strain gauge

APPARATUS REQUIRED:

Cantilever aluminium beam

Strain measuring system

Weight

Strain indicator

Vernier caliper

FORMULAE USED:

σ=6P Lbt2

ε0

Where,

P – Load is Newton

b – Breadth of beam

t – Thickness of beam

ε - strain

PROCEDURE:

1. Connect the cantilever beam with the train indicator using cables (with respect to colour of

specimen)

2. Plus the main closed to the 230V , 50Hz supply switch on the instrument then switch on the

function to at position

3. Two the function switch to road position

4. Adjust zero in potentiometer and is the display bits 000

5. Then the function switch to road position to energe 0000

6. Applied the load, display additionally shows for the w respond strain for the corresponding

load


Model calculation:

Strain ε 0 = micro strain x 10-6 x 4

= ……. 10-6 x 4

Tabluation:

Sl.No Load

(kg)

Load

(N)

Micro Strian

10-6

Strian 10-6 x 4

ε 0

Young’s modulus

N/mm2

1.

2.

Mean =

RESULT:

Thus the modulus of given aluminium specimen using

Rosette strain gauge = ……N/mm2


Strength of Materials LAB Manual

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