mos edited 30july - copy

MECHANICS OF SOLIDS

LABORATORY MANUAL

II – I SEMESTER

Prepared By

L.Sushma, Assistant Professor

DEPARTMENT OF AERONAUTICAL ENGINEERING

MALLA REDDY COLLEGE OF ENGINEERING AND TECHNOLOGY(Sponsored by CMR Educational

Society) (Affiliated to JNTU, Hyderabad) Secunderabad-100.

Dept of ANE, MRCET MOS LAB MANUAL

CONTENTS

S.NO EXPERIMENT NAME PAGE NO

1 IMPACT TEST

2

3

4

5

6

7

8

9

10


PROGRAMME EDUCATIONAL OBJECTIVES

PEO1: PROFESSIONALISM & CITIZENSHIPTo create and sustain a community of learning in which students acquire knowledge and learn to apply it professionally with due consideration for ethical, ecological and economic issues.PEO2: TECHNICAL ACCOMPLISHMENTSTo provide knowledge based services to satisfy the needs of society and the industry by providing hands on experience in various technologies in core field.PEO3: INVENTION, INNOVATION AND CREATIVITYTo make the students to design, experiment, analyze, interpret in the core field with the help of other multi disciplinary concepts wherever applicable.PEO4: PROFESSIONAL DEVELOPMENTTo educate the students to disseminate research findings with good soft skills and become a successful entrepreneur.PEO5: HUMAN RESOURCE DEVELOPMENTTo graduate the students in building national capabilities in technology, education and research.


CODE OF CONDUCT FOR THE LABORATORIES

All students must observe the Dress Code while in the laboratory.

Sandals or open-toed shoes are NOT allowed.

Foods, drinks and smoking are NOT allowed.

All bags must be left at the indicated place.

The lab timetable must be strictly followed.

Be PUNCTUAL for your laboratory session.

Program must be executed within the given time.

Maintain silence.

Workspace must be kept clean and tidy at all time.

Handle the systems and interfacing kits with care.

All students are liable for any damage to the accessories due to their own negligence.

Students are strictly PROHIBITED from taking out any items from the laboratory.

Students are NOT allowed to work alone in the laboratory without the Lab Supervisor

Report immediately to the Lab Supervisor if any malfunction of the accessories, is there.


Before leaving the lab

Place the chairs properly.

Turn off the system properly

Turn off the monitor.

Please check the laboratory notice board regularly for updates.


EXPERIMENT NO: 1

TENSILE TESTAIM:

To conduct tensile test on a mild steel specimen and determine the following

1. Limit of proportionality 2. Elastic Limit

3. Upper yield point 4. Lower yield point

5. Ultimate strength 6. Fracture strength

7. Young`s Modulus 8. Percentage elongation

9. Percentage reduction in area 10. Ductility

11. Toughness 12. True stress & true strain

13. Malleability

APPARATUS: tensile testing machine, specimen, steel rule, vernier caliper, micrometer

THEORY:

The tensile test is most applied one of all mechanical tests. In this test, a test specimen is fixed

into grips connected to a straining device and to a load-measuring device. (One end in

stationary grips and the other in movable grips). If the applied load is small enough, the

deformation of any solid body is entirely elastic. An elastically deformed solid will return to its

original form as soon as load is removed. However if the load is too large, the material can be

deformed permanently. The initial part of the tension curve, which represents the manner in

which solid undergoes plastic deformation is termed as plastic. The stress below which the

deformation is essentially entirely elastic is known as the elastic limit of the material. In some

materials like mild steel a sudden drop in load indicating both an upper and lower yield point

denotes the onset of plastic deformation. However some materials do not exhibit a sharp yield

point. During plastic deformation at lager extensions, strain hardening cannot compensate for

the decrease in section and thus the load passes through a maximum and then begins to

decrease. At this stage the ultimate strength, which is defined as the ration of the load on the

specimen to the original cross-section area, reaches a maximum value. Until this point the

deformation is uniform at all the sections of the specimen. Further loading will eventually


cause neck formation and rupture follows.

Usually a tension test is conducted at room temperature; the tensile load is applied slowly. During this test either round or flat specimens may be used. The load on the specimen is applied mechanically or hydraulically depending on the type of testing machine.

1. Nominal stress and Nominal strain:

Original C/S area = A0 (mm2)Original gauge length = L0 (mm)Increase in gauge length = δL0Nominal stress = P/A0 (N/ mm2)Nominal strain = δL0/L0

2. Limit of Proportionality:Stress is proportional to strain up to this point.Normal Stress = PA/ PONormal Strain = (δ LO) A/LO

3. Elastic limit:When the load is removed at “B” , the specimen will go back to originalDimensions i.e LO and δ AO Nominal stress = PB/AONormal Strain = (δ LO) B/LO

If the specimen is loaded beyond elastic limit it will undergo permanent strain ie. Plastic deformation.

4. Upper yield point:Nominal stress = PC/AONominal strain = (δ LO) D/LO

5. Lower yield point:Nominal stress = PD/AONominal strain = (δ LO) D/LO

6. Ultimate load or maximum load point:Nominal ultimate stress = PE/AONominal strain = (δ LO) E/LO

7. Fracture Load point F:Nominal fracture stress = PF/AONominal strain at fracture = (δ LO) F/LO

8. Young`s modulus (E):Young`s modulus (E) = Stress/Strain(In the elastic region limit of proportionality = Nominal stress at A/Nominal strain at A

9. Modulus of resilience = (Nominal stress at elastic limit)2 /2EArea under Engg. Stress - Strain diagram up to elastic limit

10. Resilience = Modulus of Resilience x Volume of specimen undergoing Tensile stress.


11. Yield point Elongation:Elongation taking place in the specimen from C to D. this is taking place without increase in stress.

12. Modulus of toughness:Area under engineering stress – strain diagram up to fracture 13. Toughness = Modulus of toughness x Volume of specimen.

This indicates the amount of energy absorbed by the specimen before fracture take place. 14. Ductility= (Final length at fracture – original length 10) x 100

15. Malleability:It is the ability of the material to undergo plastic deformation prior fracture under compressive loading conditions. In a tensile test it is approximated as percentage reduction in cross sectional area of the specimen. Malleability ={(AO - Af)/AO) x 100

True stress – true strain diagramEngineering stress is calculated based on original cross sectional area (AO)

But not on the actual cross sectional area at load „P‟True stress = P/A = P/AO x AO/ ASince volume remains constant during plastic deformation we have AO LO = AL

True stress = P/AO x L/ LO

= P/AO x ((LO + δLO) /LO) = P (1+e) = Nominal stress (1+ nominal strain)

True strain = Є = 1n (1+e)These relations are valid up to ultimate load i.e., up to which the strain is

uniform all along the gauge length.

1. True Stress at upper yield point = Nominal stress at upper yield point ( 1+eO) True strain at C = 1n (1+eo)

2. True stress at ultimate load (E1)= Nominal ultimate stress ( 1+eE) True strain at ultimate load = 1n (1+eE)

3. True stress at fracture (E1) = Pf / Af Where Af is the area of cross section at fracture can be measured. True strain at fracture = 1n(Ao/Af)

Area relation is taken instead of lengths because the strains are localized in the region between ultimate load point and fracture point.

4. Strain Hardening :

From lower yield point onwards increase in load is required for increase in strain. Thus the stress required for further deformation is more. This phenomenon is called strain hardening.

5. True – stress – true strain curve in log – log co – ordinates.

When the true – stress and true – strain are plotted on log – log co – ordinates the curve is a straight line.


6. Ductile and Brittle Materials

If a material fails without much plastic deformation it can be called brittle. If the percentage elongation at fracture is less than 2.5 the material is classified as brittle.

Usually the metals with F.C.C and CPH structures are highly ductile.

DESCRIPTION OF APPARATUS :

The machine serves the purpose of conducting tension, compression and bending test. The testing machine is operated hydraulically. Driving is performed by help of electric motor. The machine is equipped with pendulum dynamometer. It is a recording device for

registering load deformation diagram.

DESCRIPTION OF PARTS :

CONTROL PANNEL :

The control panel consists of a power pack complete with drive motor and oil tank, control valves a pendulum dynamometer a load indicator system and an autographic recorder.

POWER PACK:

The power pack generates the maximum pressure of 200 kgf/cm2 the hydraulic pump provides continuously non-pulsating oil flow. Hence the load application is very

smooth.

Load indicator system:

This system consists of a large dial and a pointer. A dummy pointer is provided to register the maximum load reached during the test. Different measuring ranges can be selected by operating the range selecting knob. An overload trip switch is in corporate, which automatically cuts out the pump motor when the load range in use is exceeded.The load ranges will be 4 positions. i.e., 0 to 40 KN

0 to 100 KN

0 to 200 KN

0 to 400 KN


Pendulum dynamometer:

This unit permits selection of favorable hydraulic ratios producing relatively small

directional forces. Pressurized oil in the loading cylinder pushes up the measuring

piston proportionately and actuates the special dynamometer system. The piston is

constantly rotated to eliminate friction. The dynamometer system is also provided

with an integral damper and ensures high reliability of operation. The load transmitted

to the dynamometer is transferred through a pendulum to the load indicator.

Autographic continuous roll load –Elongation recorder:This unit is of the pen and

drums type and is supplied as standard

Graph paper:

The graph paper which is to be there in the UTM machine is used to draw the stress. Strain

dig for the given material.

Graph Drum:

On which the graph paper is rolled. By which we can draw the stress Vs strain diagram for the given material.


ELONGATION SCALE :

On this scale we measure the elongation (or) compression of the specimen. This is marked from 0 to 20 cm.

PEN HOLDER:

This is placed above the graph drum, which is to be used for holding of the pen. While the

needle of the pendulum dynamometer is rotating this is to be moved, by using this pen

holder we can draw the stress-strain diagram.

LOADING PLATFORM : On which we put the specimen for doing the compression. This loading platform is to be

moved in to upward direction by put on the upward switch of the driving motor. And it is

moved downwards my pressing the down switch of the driving motor.

3 PHASE ELECTRIC MOTOR :

This type of electric motor is used to give the power supply to the system by which we can

operate the driving motor properly. This power supply is given to the threading device of

the UTM.

PROCEDURE:

1. Measure the original gauge length and diameter of the specimen. 2. Insert the specimen into grips of the test machine. 3. Begin the load application and record load vs elongation data. 4. Take the readings more frequently as yield point is approached. 5. Measure elongation values. 6. Continue the test till fracture occurs.

7. By joining the two broken halves of the specimen together measure the final length and diameter of specimen at fracture.

RESULTS AND DISCUSSIONS:

1. Plot the Stress strain curve and determine the following

Limit of proportionality = (N/mm2)

Yield strength = (N/mm2)

Ultimate strength = (N/mm2)

Young`s modulus = (N/mm2) Percentage elongation = %


Percentage reduction in area = %

Fracture strength = (Nominal /Engg)

Toughness = Area under stress – strain curve up tofracture

Malleability

2. Plot True Stress, True strain curve after calculating true – stress and true strain values at various points.

Estimate1) Strength coefficient 2) Strain hardening coefficient 3) Determine whether the material is ductile or brittle 4) Comment on the results.

S.No Load Deformation Stress Strain E

TABLE:


CALCULATION PART:


Viva Questions:

1. Loading accuracy of the machine is?A. + 1%

2. Which type of motor used in the UTM?

A. 3φ3. Define stress?A. Force / area

4. Define strain?A. e = change is dimensions/ original dimensions

5. What is the unit for stress?

A. N/m2

6. What is the unit of strain?

A. Dimension Less

7. Why we are using only rectangular threading in the UTM?

A. Power supply is more in rectangular threading to lift the loading platform.

8. Define young’s modulus of elasticity.

A. It is the ratio of shear stress to the shear strain

9. What is the unit for young’s modulus of elasticity?

A. KN/mm2

10. What is the purpose of UTM?

A. The machine serves the purpose of conducting tension compression and bending.


11. What is the purpose of dynamometer?

A. The dynamometer which measures and indicates the load on the specimen.

12. Load indicator system having how many types of positions.

A. The loading system will be 4 positions

i.e., 0 to 40 KN

0 to 100 KN

0 to 200 KN

0 to 400 KN

13. What is the purpose of graph paper

A. The graph paper is used to draw the stress strain dig.

14. Define tensile stress.A. when a section is subjected to two equal and opposite pulls and the body tends to increase its length, the stress induced is called tensile stress.

15. Define Compressive stress.A. When a section is subjected to two equals and opposite pushes and the body tends to decrease its length, the stress induced is called tensile stress.

16. What is the maximum pressure which generates in the power pack?

A. 2000 kgf/cm2

17. What is elastic limit?A. Within this limit stress is directly proportional to strain.

18. Define unit stress.A. Unit stress represents the resistance developed by a unit area of cross section


19. Define volumetric strain.A. It is a ratio between the change in volume and original volume of the body

20. Define elastic limit.A. There is always limiting value of a load up to which the strain totally on the removal of the load, the stress

corresponding to this load is called elastic limit

21. Define modulus of elasticity.A. the ratio between tensile stress and tensile strain or compressive stress to compressive strain is termed as modulus elasticity

22. What is the relation between the modulus of elasticity (E) and modulus of rigidity? A. E = 2C (1+1/m)

23. What is Poisson’s ratio? A. The ratio of lateral strain to linear strain is known as poisons ratio

24. What is the relation between E,K & C?A. E = 9KC/3K+C

25. What is linear strain?A. Linear strain is the deformation of the bar per unit length in the direction of the force.


EXPERIMENT NO 2

BENDING TEST ON SIMPLY SUPPORTED BEAMAim:

To conduct bending test on simply supported beam and verify the Maxwell’s reciprocal theorem

Apparatus:

Simply supported beam, dial gauge to measure the deflection of the beam, Dial gauge

Specification:

Type of beam used : MS flat

Width of beam : 4.64 cm

Depth of beam : 0.27 cm

Type of measuring of instrument: Dial test indicator

Materials and equipment:

a. Deflection of beam apparatus

b. Weights

c. Beam of different cross-sections and materials

The specimen is to be tested in a rectangular steel beam. A weight holder with a sliding hook and weights of 1 kg, 4

kg, 10 kg and 25 kg is given.

Description of apparatus:

Beam:

The beam which is to be used here is of simply supported beam having width of the beam is 4.64 cm and the depth is

0.27 cm

Weights: The weights are of 1kg, 4kg, 10kg and 25kg

Supports: This supports or supporting device is used to place beam and weights.


Theory:

The bending test apparatus consists of a long rectangular steel bar resting on stands at both the ends. On this

horizontal steel bar, two sliding supports rest vertically. A dial guage with a pointer on its head is provided, which

can be adjusted with the nut provided.

Maxwell reciprocal theorem:

The Maxwell reciprocal theorem states that the deflection of a beam at any intermediate point D due to the load at

the point ‘C’ will be same as the deflection at point C due to the load at point D.

Procedure:

a. Arrange the beam on the two supports having equal distance from both ends.

b. Maintain a good gap between the two supports

c. Place the dial guage under the beam touching the flexible pin to the beam

d. Set the weight holder on the beam by hanging to its hook.

e. Set the dial guage pointer to initial point (i.e., zero)

f. Now apply load and note down corresponding deflection

g. Gradually increase the load and note down the deflection for each load.

h. Now, gradually remove the load and again take the deflection

i. Make the average of the gradual loading 4 unloading.

j. Having done this change the arrangement set up to the other end of beam

k. After changing the position repeat the same procedure as you have done to the previous end.

l. It the average of the one end matches to the average deflection of the other end then the experiments

successful and is satisfying the Maxwell reciprocal theorem.


Tabular Column

Precautions:

1. Be sure that the distance marked on the beam is equal.

2. Before applying load do not forgot to set the dial guage pointer to the initial point end.

3. Make sure there is nothing placed on the table except the apparatus a smallest pressure on the table can soil the

experiment.

4. Make sure that the beam and load are placed in the proper position

Result:

From the above experiment we observe that the deflection at ‘C’ end is equal to the deflection at end ‘D’ so that

the Maxwell’s reciprocal theorem is proved.

S

no.

Load Applied

(kg)

Deflection at C in mm Deflection at D in mm

Loading Unloading Avg. Loading Unloading Avg.

1.

2.

3.

4.

5.


Viva questions:

Define beam?

A. Beam is structural member, which is acted upon by a system of external loads at right angles to the axis.

What is meant by bending?

A. Bending is defined as the deformation of a bar produced by loads acting perpendicular to its axis.

How many types of bending are there?

A. A) plane bending,

b) Oblique bending.

Define plane bending?

A. If the plane of loading passes through one of the principle centroidal axis of the cross section of the beam; the

bending is said to be plane or direct bending.

Define oblique bending?

A. If the plane of loading does not pass through one of the principle centroidal axis of the cross section of the

beam, the bending is said to be oblique.

Explain the types of loads?

A. The loads will be divided into i) point load ii) distributed load

Define point load?

A. A point load is one, which is considered to act at a point.

Define distributed load?

A. A distributed load is one which distributed or spread in some manner over the length of the beam

9. Define UDL?

A. If load distribution is said to be uniform through out the length then that load is called uniformly distributed load

10. Explain the types of beams?

A. a) Cantilever beam b) Simply (or) freely supported beam c) Over hanging beam

d) Fixed beam e) Continuous beam

11. Define Maxwell’s reciprocal theorem?

A. The Maxwell reciprocal theorem states that the deflection of a beam at any intermediate point ‘D’ due to the load at

the point ‘C’ will be same as the deflection at point ‘C’ due to load at point ‘D’


12. What is bending equation?

A. M/I = σb / Y

13. What are the units of bending moment?

A. Nmm

14. What are the units of moment of Inertia?

A. mm4

15. Units of bending stress is

A. N/mm2

16. What is the Deflection of beam or specimen?

A. δ = wl3/48EI

17) Define load?

A. The combine effect of external forces acting on a body is called load.

18) Define cantilever beam?

A. A cantilever is a beam whose one end is fixed and the other end is free.

19) Define over hanging beam?

A. A over hanging beam is one in which the supports are not situated at the ends i.e., both the ends project beyond the

support.

20) Define simply supported beam?

A. A simply supported beam is one whose ends freely rest on walls or columns or knife edges.

21) Define fixed beam?

A. A fixed beam is one whose both ends are rigidly fixed or built is into its supporting walls or columns

22) Define continuous beam?

A. a continuous beam is one which has more than two supports


EXPERIMENT NO-3

BENDING TEST ON CANTILEVER BEAMAim:

To conduct bending test on simply Cantilever beam and verify the Maxwell’s reciprocal theorem

Apparatus:

Simply supported beam, dial gauge to measure the deflection of the beam

Specification:

Type of beam used : MS flat

Width of beam : 4.64 cm

Depth of beam : 0.27 cm

Type of measuring of instrument: Dial test indicator

Materials and equipment:

a. Deflection of beam apparatus

b. Weights

c. Beam of different cross-sections and materials

The specimen is to be tested in a rectangular steel beam. A weight holder with a sliding hook and weights of 1 kg, 4 kg,

10 kg and 25 kg is given.


Beam: The beam, which is to be used, is of simply supported beam having width of the beam is 4.64 cm and the depth is

0.27 cm

Weights:

The weights are of 1Kg, 4kg, 10kg, 25kg

Supports: This supports or supporting device is used to place beam and weights.


Theory:

The bending test apparatus consists of a long rectangular steel bar resting on stands at both the ends. On this

horizontal steel bar, two sliding supports rest vertically. A dial guage with a pointer on its head is provided, which can be

adjusted with the nut provided.

MAXWELL RECIPROCAL THEOREM:

The Maxwell reciprocal theorem states that the deflection of a beam at any intermediate point D due to the load

at the point ‘C’ will be same as the deflection at point c due to the load at point D.

PROCEDURE:

1. Fix one end of the beam and other end is to be free.

2. Fix dial gauge at one point of the beam.

3. Fix loads at the other end of the beam

4. Note down the deflections of the beam by using dial gauge

5. Repeat the experiment for different loads

6. Repeat the same procedure for the unloading also

Tabular Column

S no. Load Applied

(kg)

Deflection at C in mm

Loading Unloading Avg.


Precautions:

1. Be sure that the distance marked on the beam is equal.

2. Before applying load do not forgot to set the dial guage pointer to the initial point end.

3. Make sure there is nothing placed on the table except the apparatus a smallest pressure on the table can soil the

experiment.

4. Make sure that the beam and load are placed in the proper position

Result:

From the above experiment the deflection of the beam at L/2nd and L/4th is increasing.

That is deflection for cantilever increases from fixed end to free end.


CALCULATION PART:


Viva questions:

1. Define beam?

A. Beam is structural member, which is acted upon by a system of external loads at right angles to the axis.

2. What is meant by bending?

A.Bending is defined as the deformation of a bar produced by loads acting perpendicular to its axis.

3. How may types of bending?

A. a) plane bending,

b) Oblique bending.

4. Define plane bending?

A. If the plane of loading passes through one of the principle centroidal axis of the cross section of the beam; the

bending is said to be plane or direct bending.

5. Define oblique bending?

A. If the plane of loading does not pass through one of the principle centroidal axis of the cross section of the beam, the

bending is said to be oblique.

6. Explain the types of loads?

A. The loads will be divided into i) point load ii) distributed load

7. Define point load?

A. A point load is one, which is considered to act at a point.

Define distributed load?

A. A distributed load is one which distributed or spread in some manner over the length of the beam.

Define UDL?

A. If load distribution is said to be uniform through out the length then that load is called uniformly distributed load.


Explain the types of beams?

A. a) Cantilever beam

b) Simply (or) freely supported beam

c) Over hanging beam

d) Fixed beam

e) Continuous beam

Define Maxwell’s reciprocal theorem

A. The Maxwell reciprocal theorem states that the deflection of a beam at any intermediate point ‘D’ due to the load at

the point ‘C’ will be same as the deflection at point ‘C’ due to load at point ‘D’

13. What is bending equation?

A. M/I = σb / Y

14. What are the units of bending moment?

A. Nmm

15. What are the units of moment of Inertia?

A. mm4

16. Units of bending stress is?

A. N/mm2

17. What is the Deflection of beam or specimen?

A. δ = wl3/48EI

18. Define load.

A. The combine effect of external forces acting on a body is called load.

19. Define cantilever beam.

A. A cantilever is a beam whose one end is fixed and the other end is free.

20. Define over hanging beam.


A. A over hanging beam is one in which the supports are not situated at the ends i.e., both the ends project beyond the

support.

21. Define simply supported beam.

A. A simply supported beam is one whose ends freely rest on walls or columns or knife edges.

22. Define fixed beam.

A. A fixed beam is one whose both ends are rigidly fixed or built is into its supporting walls or columns

23. Define continuous beam.

A. a continuous beam is one which has more than two supports


EXPERIMENT NO:4

IMPACT TEST

Aim:

To determine the impact strength of the given specimen of material by performing the pendulum test.

Apparatus:

Izod testing machine, specimen, Vernier calipers, steels rule.

Impact strength: the high resistance of material to fracture under suddenly applied loads.

MATERIALS: Two types of test pieces are used for this test as given.1) Square cross-section 2) Round cross-section.

THEORY:

The pendulum is mounted on antifriction bearings. It has two starting positions, the upper one for Charpy and the lower one for Izod testing. On release the pendulum swings down to break the specimen and the energy absorbed in doing so is measured as the difference between the height of drop before rupture and the height of rise after rupture of the test specimen and is read from the maximum pointer position on the dial scale.

There are two strikers and one combined support available for lifting into the pendulum and on to the base of the machine for Izod, Charpy test changing from one striker to another is achieved simply by fixed the new striker into its position.

Related formulae I = K / A

Where I = impact strength

K = impact energy

A = area of cross section of the specimen.

The type of test specimen used for this test is a Square Cross-section

The specimen may have single, two or three notches. The testing machine should have the following specifications.

The angle between top face of grips and face holding the specimen vertical = 900

The angle of tip of hammer = 750±10


The angle between normal to the specimen and underside face of the hammer at striking point =

100±10

Speed of hammer at impact = 3.99m/sec

Striking energy = 168 N-m

Angle of drop of pendulum = 900

Effective weight of pendulum= 21.79kg

Minimum value of scale graduation=2 Joules.

Permissible total friction loss of corresponding energy=0.50%

Distance from the axis of rotation of distance between the base of specimen notch and the point of specimen hit by the hammer= 22mm±0.5mm

The longitudinal axes of the test piece shall lie in the plane of swing of the center of gravity of the hammer. The notch shall be positioned so that its in the plane of the hammer .the notch shall be positioned its plane of symmetry coincides with the top face of the grips .for setting the specimen the notch impact strength I is calculated according to the following relation.Sketch:


The machine consists of


i. Pendulum type hammer:

A pendulum with an arm and head can swing to and fro is used for the test. This is used to strike the specimen. This pendulum gives the required impact to the specimen. The hammer is used along with the striker. The striker is of 2 types.

i) for Charpyii) for Izod

Hammer holder:

This is a spring-loaded and hand operated by means of a lever. It is having 2 positions one is at 140 0 for Charpy and other is at 900 for Izod. It is removed with the help of align key by removing the bolts.

Hand break:

It is used to stop the swinging hammer care must be taken while stopping the swinging hammer to avoid hand injury.

Vice:

It is used to grip the Izod specimen and support the charpy specimen.

Dial guage:

The pointer of the dial guage moves along with the swinging hammer till the speed of the hammer is restricted by any obstruction i.e., specimen.

It is having 2 types of graduations

For Izod test 0 to 164 other

For Charpy test 0 to 300

The striking hammer is fixed to rod, which is positioned according to the test i.e., 1400 for charpy test and 900 horizontal for Izod test.

Procedure:

1. For conducting the Izod test, a proper striker is to be fitted firmly to the bottom of the hammer with the help of the clamping piece.

2. The latching take for Izod test is to be firmly fitted to the bearing housing at side of the columns.


3. Adjust the reading pointer along with pointer carries on 168 J reading on the dial when the pendulum is hanging free vertically

4. The frictional test can be determined from the free fall test. Raise the hammer by hands and latch in. Release the hammer by operating liver, the pointer will then indicate the energy loss due to friction. From this reading confirm that the friction loss is not exceeding 0.5 % of the initial potential energy. Other wise friction loss has to be added to the final reading.

5. Now raise the pendulum by hands and latch in with latch.6. The specimen for Izod tests is firmly fitted in the specimen support with the help of clamping screw

and align key care is to be taken that the notch on the specimen should face the pendulum striker.7. After ascertaining that there is no person in the range of swing pendulum release the pendulum to

smash the specimen.8. Carefully operate the pendulum break when returning after one swing to stop the oscillations.9. Read off position of reading pointer on dial and note indicated value.

The notch impact strength depends on largely on the shape of the specimen and the notch. The value determined with other specimens therefore may not be compare with each other.

Observations:

K = impact energy KJ

A= Area of cross-section of the specimen mm2

Calculate value of I = K/A

Tabular column:

S NO. Area of cross-section A, m2

Impact energy factor (k) joules

Impact strength (I=K/A)kJ /m2

Precautions:

1. Do not stand before the striker when the pendulum is released you may get injured2. Do not forget to change the specimen and the position of the release position3. The screws and bolts must be fixed tightly so that the pendulum does not fall off.4. While applying hand break to the swinging hammer apply break smoothly or it will injure the elbow.5. Load the hammer only after placing the specimen in the vice.

Result:

The impact strength of the given specimen found by


CALCULATION PART:


Viva Questions:

1. Define load?A. The combined effect of external forces acting on a body is called load

.

2) Define impact strength?

A. The high resistance of material to fracture under suddenly applied loads.

3) Define impact load ?

A. The load which falls from a height or strike the body with certain momentum is called impact load.

4) Define suddenly applied load?

A. When the load is applied all of sudden and not step wise is called as suddenly applied load.

5) Define gradually applied load?A. A body is said to be acted upon by a gradually applied load if the load increases from zero and it reaches

its final value stepwise is called gradually applied load.

6) How many types of hardness machines we have ?A. Charpy & Izod

7). Hammer holder is kept for charpy test at what angle?

A.1400

8) Hammer holder is kept for Izod test at what angle?

A.900

9) What is the purpose of hand break?


A. Hand break is used to stop the swinging hammer

10) What is the range of dial guage for the Izod test?

A. 0 to 164

11) What is the range of dial guage for the charpy test?

A.0 to 300

12) Write down the formula for impact strength?

A. I = K/A Where I = impact strength

K = impact energy

A = area of cross section of spring

13) What is the purpose for conducting impact test?A. An impact test signifies turning of the material i.e., ability of material to absorb energy during plastic deformation.

14) What is the unit of impact energyA. kJ

15) What is the purpose of vice?A. It is used to grip the Izod support for charpy

mos edited 30july - copy

Documents

test specimen

tensile test aim

impact test

lab timetable

applied load

laboratory session

lab supervisor report

laboratory notice board