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CHENNAI INSTITUTE OF TECHNOLOGY

Sarathy Nagar, Kundrathur, Pudupedu, Chennai– 600 069.


Department of Civil Engineering

Subject Name: Strength of Materials Lab Subject Code: CE 2252

1. BRINELL’S HARDNESS TEST

AIM

To determine the hardness number of various specimens like steel, cast iron aluminium brass.

APPARATUS REQUIRED

1. Berinell’s hardness test2. Ball indicator

3. Traveling microscope

FORMULAThe surface area of indentation

A = πD/2 * (D-√(D²-d²))

Where,D = Diameter of BallD = the mean diameter of indentation

The Brinells hardness number= test load/surface area of indentation

= P/A

PROCEDURE:1. Based on the following table, the proper load and ball was selected to suit material in test. The

surface of the specimen is brushed and well cleaned.2. The selected ball is inserted in the machine and specimen load is determined.3. Now the load is released.4. The diameter of indentation is measured.

RESULT:

BHN FOR “A1” SAMPLE=

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S.NO MATERIAL LOAD DIA OFINTENTATIONIN mm

SURFACEAREA OFINTENTATIONIN mm

BHN

ALUMINIUM

BRASS

STEEL

CAST IRON

OBSERVATION

Material of test piece:

Type of penetrator:

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2. TORSION TEST

AIM:

To determine the modulus of rigidity of the sample of given rod.

APPARATUS REQUIRED1. Torsion testing machine2. Test specimen3. Steel rule4. Caliper

FORMULATorsional equation T/J = Cθ /L

Modulus of rigidity C = TL/Jθ

WhereT= Torsional moment in N-mmL= Length of test pullJ= Polar moment of inertiaθ= Angle of twist in radian

PROCEDURE:1. Using the micrometer the diameter ‘L’ of specimen is measured in four places.2. The length of ‘l’ of the specimen is measured accurately of seeing into the

machine.3. After selecting the suitable scale on the machine the initial and angle of twistwhere adjusted zero.

4. Up to angle of twist the torque was applied zero.5. There are the machine was separated electrically and readings at 10 intervals

where the reading is noted continuously unit specimen failed.

GRAPHThe angle of twist ,in degree values. Torque in N-m graph was drawn. Angle of twist in

x-axis and torque in y-axis.

RESULT1. The modulus of rigidity of sample (from tabulation) =2. The modulus of rigidity of sample (from graph) =

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S.NO APPLIEDTORQUE

ANGLE OF TWIST θ INRADIANS

MODULUSOF RIGIDITYIN N- MM²KG-

CMN-MM

DEGREE OF FREEDOM

θ1 θ 2 θ AVERAGE

OBSERVATION:

Material of test piece =Length of the specimen =

Diameter of the specimen =

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3.TEMPERING

AIM:

To perform the heat treatment tempering on the given material C-40 steel.

APPARATUS REQUIRED:1. Muffle furnace: tongs2. Given material: C-40 steel3. Quenching medium: water

PROCEDURE:

1. The given specimen is subjected to Rockwell hardness test and Rockwellhardness number is measured before hardening that the specimen issubjected to rough grinding.

2. The specimen is placed inside the combustion chamber of muffle furnaceand is heated up to 630˚ C.

3. Then the specimen is soaked for 10 minutes at the same temperature630˚C.4. After soaking it is taken out from the furnace and it is cooled in air.5. The specimen is cooled, now the tempering is completed.6. Again the specimen is subjected to Rockwell hardness test and Rockwell

hardness number is measured.

RESULT:

The heat treatment tempering on the given material C-40 steel and its Rockwell hardness numberis measured

Rockwell hardness number before tempering =Rockwell hardness number after tempering =

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S.NO SPECIMENMATERIAL

LOAD

N

PENETRATOR SCALE RHN MEANRHN

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4. HARDENING

AIM:

To perform the heat treatment on the given material C-40 steel.

APPARATUS REQUIRED:1. Muffle furnace: tongs2. Given material: C-403. Quenching material: water

PROCEDURE:

1.The given specimen is subjected to Rockwell hardness test andRockwell hardness number is measured before hardening.

2.The specimen is placed inside the combustion chamber of mufflefurnace and is heated up to 830˚ C.

3.Then the specimen is socked for 10 minutes at the same temperature

830˚C.4.After socking it is taken out from the furnace and it is quenched in thewater.

5.The specimen is cooled, now the hardening is completed.6.Again the specimen is subjected to Rockwell hardness test and Rockwell

hardness number is measured.

RESULT:

The heat treatment hardening on the given material C-40 steel and its Rockwell hardness numberis measured

Rockwell hardness number before tempering =Rockwell hardness number after tempering =

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S.NO SPECIMEN

MATERIAL

LOAD

N

PENETRATOR SCALE RHN MEAN

RHN

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5. ROCKWELL HARDNESS TEST

AIM:

To determine Rockwell hardness number for steel aluminium, copper, brass, and alloy.

APPARATUS REQUIRED:

1.Rockwell hardness tester.2.120˚ diamond cone penetrator3.1/16 diamond steel4.specimen

PROCEDURE:

1.The test piece was cleaned and placed on the special anvil of the machine.2.The capstan wheel was turned to elevate the test specimen to contact the indenter point.

3.The wheel was further turned to face the test specimen against the indenter. This will ensurethat a minor load has been applied on the specimen.4.The pointer was set on to appropriate scale; the dial gauge was set in appropriate position

based on the scale used.5.The lever was pushed forward and the major load was applied.6.As soon as the pointer in the dial goes to rest, release the lever which will release the major

load. The pointer will rotate in the reverse direction.7.The Rockwell hardness is used on the appropriate scale dial.

RESULT:

The Rockwell hardness number forAluminium sample =Copper sample =Steel sample =

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S.NO SPECIMENMATERIAL

LOAD

N

PENETRATOR SCALE RHN MEANRHN

OBSERVATION:Material of test piece =

Type of penetrator =

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6.IMPACT TEST (CHARPY)

AIM:

To determine the impact of the material using Charpy’s glove.

APPARATUS REQUIRED:

1.impact testing machine.2.test specimen.3.scale.4.caliper.

FORMULA: Impact strength = Energy required to break the specimen

Area of cross section of notch point

PROCEDURE:1.The striker was screwed firmly to the center of the hammer.2.The hammer was screwed freely to note down the energy loss due to friction.3.The test specimen was fixed on support with the notch.4.The pointer scale was read.5.The striker was released by operating a lever and the specimen was broken.6.The pendulum was brought to rest by applying brake.7.The pointer and the scale value were read. This is the energy required to break the specimen.8.The broken specimen and the striker are removed.

RESULT:Impact strength of the given material was found to be =……..J/mm².

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S.NO LOSS OFENERGY DUE

TO FRICTION

Jm

ENERGYREQUIRED

BREAK THESPECIMEN

Jm

ACTUALENERGY

REQUIRED

Jm

IMPACTSTRENGTH

Jm

OBSERVATION:

Dimension of test piece =Type of notch =Angle of notch =Depth of notch =

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7. IMPACT TEST (IZOD’S)

AIM: To determine the impact of the material using Izod’s glove.

APPARATUS REQUIRED:1. Impact testing machine.2. Test specimen.3. Izod’s machine.4. Izod’s accessories.5. Caliper.

FORMULA:

Impact strength = Energy required to break the specimen

Area of cross section of notch point

PROCEDURE:

1.The striker was screwed firmly to the center of the percussion of the hammer with screws.2.The hammer was swing freely to note down the energy loss due to friction.3.The test specimen was fixed on support with the notch facing the striking direction and the

clamp screw are tightened.4.The pointer scale was read.5.The striker is released by operating a lever and the specimen was broken.6.The pendulum was brought to rest by applying brake.7.The pointer and the scale value were read. This is the energy required to break the specimen.8.The broken specimen and the striker are removed.

RESULT:Impact strength of the given material was found to be =……..J/mm².

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S.NO LOSS OF

ENERGY DUETO FRICTION

Jm

ENERGY

REQUIREDBREAK THESPECIMEN

Jm

ACTUAL

ENERGYREQUIRED

Jm

IMPACT

STRENGTH

Jm

OBSERVATION:Dimension of test piece =Type of notch =Angle of notch =Depth of notch =Distance of notch from one end =

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8. VERIFICATION OF MAXWELL’S RECIPROCAL THEOREM

AIM:

To verify the Maxwell’s reciprocal theorem.

APPARATUS:1. Beam to be tested2. Roller supports3. Set of weight of hanger4. Deflectometer5. Vernier caliper6. Scale

PROCEDURE:

1. Place the given beam over the supports of measure the span of the beam.2. Place the hanger ¼ span from right hand side.3. Note the deflectometer reading at no load position.4. Load the beam at uniform rate of note down the corresponding

deflectometer reading.5. Decrement the load at the same uniform rate and down the corresponding

deflectometer reading.6. Now place the deflectometer at ¼ of span from left hand side and place

hanger at ¼ of span from right hand side and repeat the steps 4 and 6.

RESULT:Deflection of beam from load at A and deflection for at B E =Deflection of beam from load at B and deflection for at A E =Therefore Maxwell’s reciprocal theorem is verified.

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DEFLECTION AT “A” AND LOAD AT “B”

S.NO LOAD DEFLECTOMETER READING IN mm DEFLECTIONAT “A” INmm * L.C

YOUNG’SMODULUSIN N/mm²LOADING UNLOADING MEAN

DEFLECTION

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DEFLECTION AT “B” AND LOAD AT “A”

S.NO LOAD DEFLECTOMETER READING IN mm DEFLECTIONAT “B” INmm * L.C

YOUNG’SMODULUSIN N/mm²

LOADING UNLOADING MEANDEFLECTION

OBSERVATION:1. Length of simply supported beam =2. Breadth of simply supported beam =3. Depth of simply supported beam =4. Position of load from left support =5. Position of load from right support =6. Position of deflectometer =

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9. DEFLECTION TEST ON BEAMS (simply supported)

Aim: To determine the young’s modulus of the given beam material.

APPARATUS:1. Beam to be rested2. Roller supports3. Weight with hangs4. Deflectometer5. Calipers6. Measuring scale

FORMULA:The general expression for deflection of any point ‘x’ is given by

∆ = wbx(l²-b²-x²) for x<a where l = a+b

6EIl

I = moment of Inertia = Bd³/12 (mm^4)∆ = deflection (mm)B = breadth of simply supported beam (mm)

l = length of simply supported beam (mm)x = position of deflectometerb = position of loadw = load

PROCEDURE:

1. The breadth ‘B’ and depth ‘d’ of beam where measured accurately.2. The supports are arranged to the required span and the beam is placed over the supports.3. The loading point was marked and the distance ‘y’ from left support.4. The deflectometer reading was noted down at no reading condition.5. The beam was loading at uniform rate and corresponding deflectometer readings were

noted.6. Deflection vs. load graph was drawn and young’s modulus of beam material was found

out.

Graph:

A graph draw by taking load in the y-axis and deflection in the ‘x’ axis.

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Result:The young’s modulus of the beam material is found to be for steel from tabulations E =

From graph E =

S.NO LOAD DEFLECTOMETER READING IN mm DEFLECTIONAT “b” IN mm* L.C

YOUNG’SMODULUSIN N/mm²

LOADING UNLOADING MEANDEFLECTION

OBSERVATION:1. Span of simply supported beam =2. Distance of load system from left support =3. Breadth of beam =4. Depth of beam =5. Distance of deflection from left support =6. Least count of deflectometer =

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10.COMPRESSION TEST ON HELICAL SPRING (Open coiled)

AIM:

1. To determine the rigidity modulus of the spring.

2. To find the stiffness of the spring.3. To determine the energy absorbed by the spring for a particular load.

APPARATUS REQUIRED:1.Open coiled helical spring2. Spring testing machining.3. Caliper etc.

FORMULA USED:

1. The mean radius of the spring is touch using the inner and outer diameter of spring.

R = (Do+Di )/4WhereDo = outer diameter of springDi = inner diameter of spring.

2.The angle of helix

α = tan-1 (pitch/2 π R)Average pitch = [total height spring/No. of turns]

3.The rigidity modulus of the material is found from the mean deflection using the following

∆ = 64WR3N secα Cos²α + 2sin²α d^4 C E

4. The stiffness of the spring is given byS = W/D * N/mm

5. The energy is started for particular load is given by

U = ½ WD N-mm

PROCEDURE:1.The inner and outer diameter of the spring was measured.2. The diameter of the coil was measured.3. The number of turns and the angle of helix counted.

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4. The spring was loaded at uniform rate and the corresponding scalereading was noted at every step

5.The scale was placed between the places at reading unit.

6. The load was released at the same step and the scale readings are noted.

GRAPH:The graph was drawn taking mean deflection in x-axis level in y-axis.

RESULT:

1.Thestiffnes of the given spring is =2. The rigidity modulus of the spring =3. The energy started in the spring for a load of …..N =

From graph

The load of …..N from graph=

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MEAN=

OBSERVATIONOuter dia of the spring =Inner dia of the spring =Young’s modulus =

Dia of the coil wire =Length of the spring =No. of turns =

S.NO LOAD VERTICAL SCALE READING DEFLECTIONIN mm

STIFFNESSIN N/mm²

RIGIDITYMODULUSIN N/mm²

INITIAL FINAL DEFLECTION

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11. TENSION TEST ON HELICAL SPRING (Closed coil)

AIM:

1. To determine the rigidity modulus of the spring material.2. To find the stiffness of the spring.3. To determine the energy started in the spring at particular load.

APPARATUS REQUIRD:1. Closed coiled helical spring2. Spring testing machine3. Caliper’s etc.

FORMULA:Rigidity modulus P = 64WR³N∆ d^4

W = load in NN = No. of turns∆ = deflection in mmD = diameter of coil wire in mm

Stiffness of the spring = W/ ∆ N /mm²Strain energy rated = W*∆ /2 N/mm²

PROCEDURE:1. The inner and outer diameters of the spring were measured.2. The diameter of coil was measured.3. The number of turns of before curve was counted.4. The spring was placed between the plates of the loading unit.5. The initial scale reading was noted.6. The load was applied at an uniform7. The scale readings were noted for regular interval of increased a load.8. Then the released at same point steps and scale readings were noted.

GRAPH:The mean value of deflection was plotted on x- axis and load was plotted on y- axis.

RESULT:1.Strain energy stored in the spring =2.Rigidity modulus of the spring =3.Stiffness of the spring =4.By graph =

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MEAN=

OBSERVATION

Outer dia of the spring =Inner dia of the spring =

Young’s modulus =Dia of the coil wire =Length of the spring =No. of turns =

S.NO LOAD VERTICAL SCALE READING DEFLECTIONIN mm

STIFFNESSIN N/mm²

RIGIDITYMODULUSIN N/mm²INITIAL FINAL DEFLECTION

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12.TENSION TEST ON MILD STEEL ROD

AIM

1. To determine the yield stress of steel.

2. To determine the ultimate stress of steel.3. To determine the breaking stress of steel.4. To determine the reduction in area in steel.5. To determine the percentage of elongation of steel.6. To determine the elasticity modulus of steel.

APPARATUS REQUIRED

1. Universal testing machine.2. Extensometer.3. Scale.4. Vernier caliper etc..,

PROCEDURE1. Accurately measure the diameter of given rod.2. Mark the gauge length to determine the elongation.3. Assuming the ultimate stress of the material, choose the load range in UTM for

the given steel bar the ultimate Stress may be assumed as 500N/mm² and therequired Ultimate load can be calculated.

4. Fix the test specimen between the steel grips of the UTM taking care to see thatthe load will be applied axially and fix the extensometer.

5. Apply the load gradually and in uniform steps and note down the correspondingextensometer reading.

6. Remove the extensometer after 70% of the yield load is applied .Yield load may

be calculated by product of projected yield stress (250N/mm² in case of steel)and the area of cross section.7. Note down the load at yield i.e., the short deviation of time when the pointer

remains stationary.8. Increase the load and note down the ultimate load. At the ultimate load the red

pointer will be left in position and the black point which indicate theinstantaneous applied load will move in to reverse direction.

9. Note down the break point load at which the specimen fails.10. Remove the specimen and note down the diameter of the neck and the elongation.

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RESULT

1. The yield stress of material = N/mm²

2. The ultimate stress of material = N/mm²

3. The breaking stress of material = N/mm²

4. Percentage of elongation of material = %

5. Percentage of reduction of cross section area = %

OBSERVATION:

Specimen load =

Diameter of specimen = mm

Area of specimen =

Gauge length =

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13. DOUBLE SHEAR TEST

AIM

To determine the ultimate shear strength of the material by conducting a double shear test.

APPARATUS USED1. Universal testing machine2. Shear test attachment.3. Calipers etc.,

FORMULA

Cross sectional area of the specimen = π /4 * d²Ultimate shear strength = Failure load/ 2π /4 *d²

PROCEDURE1. By using calipers, measure the diameter of specimen.2. The specimens were inserted in shearing apparatus and tightly screwed3. This assembly is kept between the plates of the compression zone of the UTM4. The load was applied gradually and the failure load was noted.5. This experiment was repeated for more specimens.

RESULT

The Ultimate shear strength of the given material = N/mm²

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S.NO TYPE OF

MATERIAL

LOAD OF FAILURE (N) ULTIMATE SHEAR

STRENGTH N/mm²

OBSERVATION

Material of test piece =Length of specimen =Diameter of specimen =

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