SOM Write Up1

S. E. (MECHANICAL) PVG’S COET

P.V.G.’s

College of Engineering and Technology, Pune-09.

Name of Student:

Roll No:

Exam Seat No:

Class:

Batch:

Division:


Exam Seat No:

Pune VidyarthiGriha’s

College of Engineering and Technology, Pune. Contents

List of Experiments

Sr.

No.

Title of Experiment Page Date Remark Date

of Submission

Signature of

Staff

1 Tension Test

2 Compression Test

3 Shear Test

4 Verification of flexural formula for cantilever

5 Verification of flexural formula for simply supported beam

Assignments

1 Shear Force Diagram and Bending Moment Diagram (Diff. End Cond.)

2 Slope and deflection

3 Principal Stresses ( Analytical Method and Mohr’s Circle Method)

Certified that Shri/Miss of Class S. E. (Mechanical)

Division Semester IV Roll No. has completed the term work satisfactorily in the subject

Strength of Material (202051) ofMechanical Engineering Departmentof PVG’s College of

Engineering and Technology, Pune during the academic year 2013-14.

Staff In charge Head of Department


Description of Universal Testing Machine 200 KN Capacity

The evaluation of the mechanical behaviour of a sample under conditions of tension can be

performed to provide basic material property data that is critical for component design and

service performance assessment. The requirements for tensile strength values and the methods

for testing these properties are specified in various standards for a wide variety of materials.

Testing can be performed on machined material samples or on full-size or scale models of

actual components. These tests are typically performed using a universal mechanical testing

machine (shown in Fig. 1).

Fig. 1 Universal Testing Machine

The Universal Testing Machine consists of two units.

1) 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. Thereis a connection between lower table and upper head assembly that moves upand

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 pump is

mounted on four studs which is fitted on the right side of the tank. There is an arrangement for

loosening or tightening of the valve. The 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. 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.


Experiment No. 1

Date of Performance:

Title of Experiment:Tension test for ductile and brittle material using

Extensometer

Aim

To conduct Tension test for ductile and brittle material using extensometer

Apparatus

Hydraulic Universal Testing Machine 200 KN, Electronic Extensometer, Test Specimens

Theory

A tensile test is a method for determining behaviour of materials under axial tensile

loading. The tests are conducted by fixturing the specimen into the test apparatus and then

applying a force to the specimen by separating the testing machine crossheads. The crosshead

speed can be varied to control the rate of strain in the test specimen. Data from the test are used

to determine tensile strength, yield strength, and modulus of elasticity. Measurement of the

specimen dimensions after testing also provides reduction of area and elongation values to

characterize the ductility of the material. Tensile tests can be performed on many materials,

including metals, plastics, fibres, adhesives, and rubbers. Testing can be performed at sub

ambient and elevated temperatures.For smaller applied loads, the deformation of any solid

componentis within elastic limit. An elastically deformed solid component will return to its

original position as soon as load is removed. However, if the magnitude of load is very large,

the material shows permanent deformation. This behaviour of material can be observed from

stress-strain diagram. Referring Fig. 1.1 (a) for ductile materials, the initial part of the diagram

which is recoverable immediately after unloading is termed as elastic and rest of the curve

representing the manner in which the material undergoes plastic deformation is termed as

plastic. At a certain value of load the strain continues at slow rate without any further stress.

This phenomenon of slow extension increasing with time, at constant stress is termed creep. At

this point a neck begins to develop along the length of the specimen and further plastic


deformation is localized within the neck.After necking the nominal stress decreases until the

material fractures at the point of minimum cross-sectional area.

Brittle material is one which is having very low percentage of elongation.Brittle

materials break suddenly under stress at a point just beyond its elastic limit.A Brittle material

exhibits little or no yielding before failure. Brittle material will have a much lower elongation

and area reduction than ductile ones. The tensile strength of Brittle material is usually much

less than the compressive strength.Grey cast iron is a best example for brittle material.If the

percentage of elongation is at or below 5%, assume brittle behavior.For the determination of

yield strength in such materials, one has to draw a straight line parallel to the elastic portion of

the stress strain curve at a predetermined strain ordinate value (say 0.1%). The point at which

this line intersects the stress-strain curve is called the yield strength. Fig. 1.1 (b) shows stress

strain curve for brittle material.

(a)


(b)

Fig. 1.1 Stress-Strain diagram for (a) Ductile material (b) Brittle Material

That value of stress below which the deformation is essentially entirely elastic is known as the

yield strength of material. In some materials like Mild Steel, the onset of plastic deformation is

denoted by a sudden drop in load indicating both an upper and 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 decreases. This stage is referred as the Ultimate Strength

which is defined as the ration of Maximum load applied to the cross sectional area. Beyond this

stage, loading will eventually cause ‘neck’ formation and rupture.

In a tension test, the load is applied gradually. For this test, either round or flat

specimens may be used. The round specimens may have smooth, shouldered or threaded ends.

The load on the specimen is applied mechanically or hydraulically depending on the type of

machine.


Experimental Setup and Test Specimen

Fig. 1.2 Universal Testing Machine for Tension Test

Fig. 1.3 Mild Steel Test Specimen for Tension Test


Procedure

1. Measure following dimensions of a specimen (Fig. 1.3)

Diameter = d = mm.

Total length of specimen = mm.

Cross sectional area = A0 = mm2.

Gauge Length = L0 = 5Xd= mm.

Mark gauge length at three different positions on the specimen, covering effective

length of the specimen. This is required so that necked portion will remain between any

two points of gage length on the specimen.

2. Adjust the position of lower cross head according to the length of specimen.

3. Grip the test specimen in the jaws of upper and lower cross heads of a machine as shown

in Fig. 1.2.

4. Fix the extensometer (Fig. 1.4) within the gage length marked on the specimen and

adjust the dial of the extensometer to zero.

5. Switch on the UTM

6. Operate the button for driving the motor to drive the pump

7. Start applying the load on the specimen gradually.

8. Observe the Stress-Strain diagram on the screen and note down the value of proof stress

and remove the extensometer.

9. Continue applying load on the specimen and observe various phases of Stress-Strain

diagram. Note down the yield point, maximum load point and point of breaking the

specimen.

10. Remove the test specimen from the jaws and observe the type of failure.

11. Measure the reduced diameter and final gauge length by fitting the broken pieces

together (Fig. 1.5).


Fig. 1.4 Electronic Extensometer

Fig. 1.5 Specimen after breakage

Observations

Test specimen prepared from MS/CI/AL

1. Diameter = d0 = mm.

2. Gauge length = L0= mm.

3. Original cross sectional area of the specimen = A0 = mm2.

4. Final gauge length = Lf = mm.

5. Final diameter = df = mm.

6. Final cross sectional area of the specimen = Af = mm2.

Calculations

1. Modulus of Elasticity (E)

= = N/mm

2 = Gpa.


2. Yield Stress (σy)

σy=

= = N/mm

2

3. Ultimate Strength(σu)

σu =

= = N/mm

2

4. % Elongation =

X 100 = %.

Results

Yield Stress = N/mm2

Ultimate Stress = N/mm2

% Elongation = %

Ductile Material


Fig. 1.6 Load-Displacement Diagram from tension test of MS bar

Brittle Material


Fig. 1.7 Stress-Strain Diagram from tension test of Brittle Material

Conclusion


Experiment No. 2


Title of Experiment: Compression test for ductile and brittle material

Aim

To conduct Compression test for ductile and brittle material

Apparatus

Hydraulic Universal Testing Machine 200 KN, Test Specimens

Theory

A compression test is a method for determining the behaviour of materials under a compressive

load. Compression tests are conducted by loading the test specimen between two plates, and

then applying a force to the specimen by moving the crossheads together. During the test, the

specimen is compressed, and deformation versus the applied load is recorded. The compression

test is used to determine elastic limit, proportional limit, yield point, yield strength, and (for

some materials) compressive strength. 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 increased height of members, there is tendency towards bending at

constant cross sectional area and load. The compressive strength is the maximum compressive

stress a material is capable of withstanding without fracture. Brittle materials fracture during

testing and have a definite compressive strength value.

A member under compression usually bends along minor axis i.e. along least lateral

dimension. With increase in slenderness ratio, axial compressive stress decreases and the

member buckles more and more. End conditions at the time of test affect the compressive

strength of material. Effective length must be taken according to end conditions assumed, at the

time of test. The following materials are typically subjected to a compression test.

Concrete

Metals


Plastics

Ceramics

Composites

Corrugated Cardboard

Brittle material has high compressive strength and this is attributed to their fracture properties.

Under a tensile stress fracture occurs too fast. If there is a micro crack in a brittle material, like a

ceramic when a tensile load is applied, the crack propagates immediately because the crack- tip

plastic zone in such a material is too small. However, if a compressive load is exerted the crack

is closed and the plastic zone in front of the crack does not play a role in fracture behaviour of

the material (in fact there is no crack- tip plastic zone under compressive loading) and the

material can tolerate a high level of pressure without occurrence of fracture. In the case of

compressive loading, the strong bonds between atoms are responsible for high compressive

strength of the brittle materials; especially it is true for ceramics.Brittle materials, such as cast

iron and concrete, are often weak in tension because of the presence of submicroscopic cracks

and faults. However, these materials can prove to be quite strong in compression, due to the fact

that the compression test tends to increase the cross sectional areas of specimens, preventing

necking to occur. In general, the average compressive strength to tensile strength ratio of brittle

materials is around 8/1.In some materials such as brittleand fibrous ones, the tensile strength is

considerably different from compressive strength as seen in Fig 2.1. Therefore it is necessary to

test them under tension and compression separately.

Fig. 2.1 Compression and Tension stress strain curves for GCI and Concrete



Fig. 2.2 Universal Testing Machine for Compression Test

Procedure

1. Place the test specimen in position between the compression pads

2. Adjust the position of lower cross head according to the length of specimen.



5. Gradually increase the load till the specimen fails.

6. Note down the load at which the specimen fails

7. Stop the machine and remove the specimen.

Observations

Specimen prepared from MS bar/CI/AL

1. Length of test specimen = 70 mm.

2. Lateral dimension (diameter) of test specimen = mm.

3. Cross sectional area of test specimen = mm2.

4. Load at the time of failure = N.


Calculations

Compressive strength of specimen (σc) =

=

= N/mm2.

Fig. 2.3 Load Displacement Diagram for Concrete Block


Results

Compressive strength of given specimen is N/mm2.

Conclusion


Experiment No. 3


Title of Experiment: Shear test of ductile material on Universal Testing M/c

Aim

To conduct Shear test ofductilematerial on Universal Testing Machine

Apparatus

Hydraulic Universal Testing Machine 200 KN, Shear test attachment, Test Specimen

Theory

A type of force which causes or tends to cause two contiguous parts of the body to slide relative

to each other in a direction parallel to their plane of contact is called the shear force. The stress

required to produce fracture in the plane of cross-section, acted on by the shearforce is called

shear strength. Shear test is meant for knowing the shear strength of material subjected to

transverse loading. If shear occurs along one plane only, it is termed as single shear. If shearing

occurs along two planes, it is termed as double shear failure. For carrying out shear test on

Universal Testing machine, shear test attachment is placed on the lower table. This attachment

has a provision to hold the test specimen and consists of a cutter. Fig. 3.1 shows the attachment.

Fig. 3.1 Shear Test Attachment



Fig. 3.2 Universal Testing machine for Shear Test

Procedure

1. Insert the test specimen in position in the shear test attachment and insert one end of the

attachment in the upper portion and other in the lower position.

2. Adjust the position of lower cross head accordingly.



5. Gradually increase the load till the specimen shears.

6. Note down the load at which the specimen shears.

7. Stop the machine and remove the specimen.


Observations

Specimen prepared from MS bar/CI/AL

1. Diameter of test specimen = mm.

2. Cross sectional area of test specimen (in double shear) = mm2.

3. Load at the time of failure = N.

Calculations

Shear Strength of the rod = τ =

τ =

τ = N/mm2.

Results

Shear strength of the specimen = N/mm2.


Fig. 3.3 Load Displacement Diagram for M.S. Bar

Conclusion


Experiment No. 4


Title of Experiment: Experimental verification of flexural formula in bending

for cantilever beam

Aim

To verify flexural formula in bending for cantilever beam

Apparatus

Hydraulic Universal Testing Machine 200 KN, Dial Indicator,Flexure attachment for cantilever

beam, Test Specimen

Theory

The primary focus in engineering design is to prevent material failure. Failure is often described

as the loss of the load carrying capacity of material resulting in local to widespread destruction

of the object. In most of the cases, objects are designed to withstand predicted forces and

operate well within the elastic limit. The purpose of this experiment is to theoretically predict

and experimentally measure the deflection of a cantilever beam and then to verify the flexure

formula for a cantilever beam.

For any case of pure bending, the extent of deflection will depend on

The magnitude and type of loading

Length of the member

Material properties of the beam

Geometric properties of the beam

Boundary conditions

Point at which deflection is to be found

The equation that describes the extent of deflection in a cantilever beam is given by


ymax =

(4.1)

Where

W = Point load at free end of cantilever beam in N

L = Length of beam in mm

E = Modulus of Elasticity of beam material in N/mm2

I = Moment of Inertia of cross section @ N. A. in mm4

The deflection of the beam can be theoretically determined using Equation 4.1. The goal of this

experiment is to both predict and experimentally verify the deflection of a cantilever beam and

thus to verify the flexure formula. Deflection below the point of application of load will be

experimentally measured through the use of dial indicator. The dial measures deflection by

mechanically measuring the distance that a vertical plunger displaces. As the plunger extends or

retracts, the dial will rotate and display a measured amount of deflection. Fig. 4.1 shows the dial

indicator for measuring the deflection of beam.

Fig. 4.1 Dial Indicator


Fig. 4.2 shows the deflection curve of a cantilever beam.

Fig. 4.2 Deflection Curve of a cantilever beam


Fig. 4.3 shows the Universal Testing Machine with attachment for cantilever beam. Dial

indicator is placed just below the beam at which load is applied. The test specimen used in this

test is MS member of rectangular cross section as shown in Fig. 4.4.

Fig. 4.3 Universal Testing machine for Bending of a Cantilever beam


Fig. 4.4 Test Specimen for Bending

Procedure

1. Measure the cross-section of the beam so that the moment of inertia, I, can be calculated.

2. Clamp the beam in the cantilever attachment and position the dial indicator as per the

requirement i.e. just below the point of application of load.

3. Adjust the dial indicator to zero corresponding to zero loading.

4. Apply load gradually. With each load step, record the deflection at dial indicator.

5. End the experiment when the maximum load is reached.

6. Draw a graph between load W and deflection y. On the graph choose any two

convenient points and between these points find the corresponding values of W and y.

Putting these values in equation 4.2,

calculate the value of E.

E =

(4.2)

Observations

Test specimen prepared from MS

1. Width of beam = b = mm.

2. Depth of beam = d = mm.

3. Length of Member = L = 200 mm.


Observation Table

Sr.

No.

Load (W)

N

Deflection (y)

mm

1

2

3

4

5

6

7

8

Calculations

Moment of Inertia of rectangular section, I =

= = mm

4.

For 5 mm deflection, theoretical load is 1250 N.


Result Table

Sr.

No.

Load (W)

N

Deflection (y)

mm

Theoretical Modulus

of Elasticity

(Gpa)

Experimental Modulus

of Elasticity

(Gpa)

1

2

3

4

5

6

7

8

Results

Modulus of Elasticity = Gpa.

For 5 mm deflection, theoretical load = 1250 N.

For same deflection, actual load =

Conclusion


Experiment No. 5


Title of Experiment: Experimental verification of flexural formula in bending

for simply supported beam

Aim

Experimental verification of flexural formula in bending for simply supported beam

Apparatus

Hydraulic Universal Testing Machine 200 KN, Dial Indicator, Flexure attachment for simply

supported beam

Theory

The primary focus in engineering design is to prevent material failure. Failure is often described

as the loss of the load carrying capacity of material resulting in local to widespread destruction

of the object. In most of the cases, objects are designed to withstand predicted forces and

operate well within the elastic limit. The purpose of this experiment is to theoretically predict

and experimentally measure the deflection of a simply supported beam at the centre and then to

verify the flexure formula.

For any case of pure bending, the extent of deflection will depend on

The magnitude and type of loading

Length of the member

Material properties of the beam

Geometric properties of the beam

Boundary conditions

Point at which deflection is to be found

The equation that describes the extent of deflection in a simply supported beam is given by


ymax =

(5.1)

Where

W = Central Point load N

L = Length of beam in mm

E = Modulus of Elasticity of beam material in N/mm2

I = Moment of Inertia of cross section @ N. A. in mm4

The deflection of the beam can be theoretically determined using Equation 5.1. The goal of this

experiment is to both predict and experimentally verify the deflection of a simply supported

beam and thus to verify the flexure formula. Deflection below the point of application of load

will be experimentally measured through the use of dial indicator. The dial measures deflection

by mechanically measuring the distance that a vertical plunger displaces. As the plunger extends

or retracts, the dial will rotate and display a measured amount of deflection. Fig. 5.1 shows the

dial indicator for measuring the deflection of beam.

Fig. 5.1 Dial Indicator

Fig. 5.2 shows the deflection curve of a simply supported beam.


Fig. 5.2 Deflection Curve of a simply supported beam


Fig. 5.3 shows the Universal Testing Machine with attachment for simply supported beam. Dial

indicator is placed just below the beam at which load is applied. The test specimen used in this

test is MS member of rectangular cross section as shown in Fig. 5.4.

Fig. 5.3 Universal Testing machine for Bending of a Simply Supported beam


Fig. 5.4 Test Specimen for Bending

Procedure

1. Measure the cross-section of the beam so that the moment of inertia, I, can be

calculated.

2. Place the beam on the supports and position the dial indicator as per the requirement

i.e. just below the point of application of load.

3. Adjust the dial indicator to zero corresponding to zero loading.

4. Apply load gradually. With each load step, record the deflection at dial indicator.

5. End the experiment when the maximum load is reached.

6. Draw a graph between load W and deflection y. On the graph choose any two

convenient points and between these points find the corresponding values of W and

y. Putting these values in equation 5.2,calculate the value of E.

E =

(5.2)

Observations

Test specimen prepared from MS

7. Width of beam = b = mm.

8. Depth of beam = d = mm.

9. Length of Member = L = mm.


Observation Table

Sr.

No.

Load (W)

N

Deflection (y)

mm

1

2

3

4

5

6

7

8

Calculations

For known deflection, Modulus of Elasticity is calculated by Equation (5.2) as

Moment of Inertia of rectangular section, I =

= = mm

4.

E =

= = N/mm

2 = Gpa.

Result Table

Sr.

No.

Load (W)

N

Deflection (y)

mm

Theoretical Modulus

of Elasticity

(Gpa)

Experimental Modulus

of Elasticity

(Gpa)

1

2

3

4

5

6

7

8


Results

Modulus of Elasticity = Gpa.

Conclusion

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