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ST. ALOYSIUS INSTITUTE OF TECHNOLOGY

PRACTICAL FILEON

STRENGTH OF MATERIALSLAB. MANUAL (CE -303)

SUBMITTED TO - SUBMITTED BY-

LIST OF EXPERIMENT

The experimental work to cover tension, compression, bending and impact test etc. on steel,cast iron, RCC and timber, Fire Resistant Test of Structures and Combustibility of BuildingMaterials Test as per I.S.I. and other experiments based on the syllabus. (RGPV)

1. Rockwell Hardness test

2. Brinell hardness test.

3. Impact test

4. Tension test

5. Torsion test

6. Bending test

7. Shear test

8. Compression test

Experiment Page No.

Date of Experiment

Date of Submission

Remark/Sign

1. Rockwell Hardness test

2. Brinell hardness test.

3. Impact test

4. Tension test

5. Torsion test

6. Bending test

7. Shear test

8. Compression test

INDEX

EXPERIMENT NO.-1

OBJECTIVE: - To determine the hardness of the given specimen using Rockwell hardness test.

MATERIALS AND EQUIPMENTS REQUIRED

Rockwell hardness testing machine.

Black diamond cone indenter,

Hard steel specimen.

THEORY: -

Rockwell test is developed by the Wilson instrument co U.S.A in 1920.This test is an indentation test used

for smaller specimens and harder materials. The test is subject of IS: 1586.In this test indenter is forced

into the surface of attest piece in two operations, measuring the permanent increase in depth of an

indentation from the depth increased from the depth reached under a datum load due to an additional load.

Measurement of indentation is made after removing the additional load. Indenter used is the cone having

an angle of 120 degrees made of black diamond.

PRECAUTIONS:-

1. Thickness of the specimen should not be less than 8 times the depth of indentation to avoid the

deformation to be extended to the opposite surface of a specimen.

2. Indentation should not be made nearer to the edge of a specimen to avoid unnecessary concentration of

stresses. In such case distance from the edge to the center of indentation should be greater than 2.5 times

diameter of indentation.

3. Rapid rate of applying load should be avoided. Load applied on the ball may rise a little because of its

sudden action. Also rapidly applied load will restrict plastic flow of a material, which produces effect on

size of indentation.

PROCEDURE:-

1. Examine hardness testing machine (fig.1).

2. Place the specimen on platform of a machine. Using the elevating screw raise the platform and bring the

specimen just in contact with the ball. Apply an initial load until the small pointer shows red mark.

3. Release the operating valve to apply additional load. Immediately after the additional load applied, bring

back operating valve to its position.

4. Read the position of the pointer on the C scale, which gives the hardness number.

5. Repeat the procedure five times on the specimen selecting different points for indentation.

OBSERVATION:-

1. Take average of five values of indentation of each specimen. Obtain the hardness number from the dial

of a machine.

2. Compare Brinell and Rockwell hardness tests obtained.

Rockwell hardness machine

RESULT:-

Rockwell hardness of given specimen is…………..

Viva Voice:-

1. Define Stress. Ans- When an external force acts on a body, it undergoes deformation. At the same time the body resists deformation. The magnitude of the resisting force is numerically equal to the applied force. This internal resisting force per unit area is called stress. 2. Define strain. Ans -When an external force acts on a body, there is some change of dimension in the body. Numerically the strain is equal to the ratio of change in length to the original length of the body.

3. Define Modulus of Elasticity. Ans- The ratio of tensile stress to the corresponding tensile strain is constant within its elastic limit. The ratio is known as Young’s Modulus or Modulus of Elasticity.

4. State Bulk Modulus. Ans -The ratio of direct stress to the corresponding volumetric strain is constant within elastic limit. The ratio is known as Bulk Modulus.

5. Define poison’s ratio. Ans -When a body is stressed, within its elastic limit, the ratio of lateral strain to the longitudinal strain is constant for a given material. 6. On which steel you have performed tension test.

What is its carbon content?Ans. On mild steel (0.3 to 0.6% carbon).

7. What kind of fracture has occurred in tensile specimen.Ans. Ductile fracture.

8. Define temperature stress.Ans. Stress introduced by uniform or nonuniform temperature change in a structure or material which is constrained against expansion or contraction.

9. What is hardness?Ans. Hardness is the resistance of a material to localized deformation. OrHardness is the mechanical resistance which a material asserts against the mechanical penetration of a harder test body.

10. What is toughness?Ans. Toughness is the amount of energy per volume that a material can absorb before rupturing. It is also defined as the resistance to fracture of a material when stressed.

EXPERIMENT NO.-2

AIM: - To determine the hardness of the given specimen using Brinell hardness test.

SPECIMEN AND SPECIMEN

Brinell hardness tester (fig.2)

Aluminum specimen

Ball indenter.

PRECAUTIONS:-

1. Thickness of the specimen should not be less than 8 times the depth of indentation to avoid the

deformation to be extended to the opposite surface of a specimen.

2. Indentation should not be made nearer to the edge of a specimen to avoid unnecessary concentration of

stresses. In such case distance from the edge to the center of indentation should be greater than 2.5 times

diameter of indentation.

3. Rapid rate of applying load should be avoided. Load applied on the ball may rise a little because of its

sudden action. Also rapidly applied load will restrict plastic flow of a material, which produces effect on

size of indentation.

4. Surface of the specimen is well polished, free from oxide scale and any foreign material.

THEORY:-

Hardness of a material is generally defined as Resistance to the permanent indentation under static and

dynamic load. When a material is required to use under direct static or dynamic loads, only indentation

hardness test will be useful to find out resistance to indentation.

In Brinell hardness test, a steel ball of diameter (D) is forced under a load (F) on to a surface of test

specimen. Mean diameter (d) of indentation is measured after the removal of the load (F).

OBSERVATION:-

1. Take average of five values of indentation of each specimen. Obtain the hardness number from equation.

2. Compare Brinell and Rockwell hardness tests obtained.

PROCEDURE:-

1. Load to be applied for hardness test should be selected according to the expected hardness of the

material. However test load shall be kept equal to 30 times the square of the diameter of the ball

(diameter in mm)

F=30.D 2

Where ball diameter, generally taken as 10 mm.For guidelines hardness range for standard loads given

below

Ball diameter Load (kg) Range of Brinell hardness

10

3000 96 to 600

1500 48 to 300

500 16 to 100

2. Apply the load for a minimum of 15 seconds to 30 seconds. [if ferrous metals are to be tested time

applied will be 15 seconds and for softer metal 30 seconds]

3. Remove the load and measure the diameter of indentation nearest to 0.02 mm using microscope

(projected image)

4. Calculate Brinell hardness number (HB). As per IS: 1500.

5. Brinell hardness number

where D is the diameter of ball indenter and d is the diameter of indentation. Hardness numbers normally

obtained for different materials are given below (under 3000 kg and 10 mm diameter ball used)

Ordinary steels mediumcarbonStructural steelVery hard steel

100 to 500130 to 160800 to 900

NOTE:- Brinell test is not recommended for then materials having HB over 630. It is necessary to mention

ball size and load with the hardness test when standard size of ball and load are not used. Because

indentation done by different size of ball and load on different materials are not geometrically similar. Ball

also undergoes deformation when load is applied. Material response to the load is not same all the time.

6. Brinell hardness numbers can be obtained from tables 1 to 5 given in IS: 1500, knowing diameter of

indentation, diameter of the ball and load applied.

BRINELL HARDNESS TESTER

RESULT:

The Brinell hardness number of the specimen is……….

Viva Voice:-

1. Define buckling facto r and buckling load.

Buckling factor: It is the ratio between the equivalent length of the column to the

minimum radius of gyration.

Buckling load : The maximum limiting load at which the column tends to have

lateral displacement or tends to buckle is called buckling or crippling load. The

buckling takes place about the axis having minimum radius of gyration, or least moment

of inertia

2. Define safe load.

It is the load to which a column is actually subjected to and is well below the

buckling load. It is obtained b y dividing the buckling load by a suitable factor o f safety

(F.O.S).

Safe load = Buckling load /Factor of safety

3. State Hooke’s law.

It states that when the material is loaded, within its elastic limit, the stress is

directly proportional to the strain.

Stress α Strain

4. Define Factor of Safety.

It is defined as the ratio of ultimate tensile stress to the permissible stress(working

stress).

5. State the tensile stress & tensile strain.

When a member is subjected to equal & opposite axial pulls the length of the

member is increased. The stress is included at any cross section of the member is called

Tensile stress & the corresponding strain is known as Tensile strain.

EXPERIMENT NO.-3

TITLE: - Impact test

AIM: - To determine the Impact toughness (strain energy) through Izod test and Charpy test

THEORY: - In a impact test a specially prepared notched specimen is fractured by a single blow from a

heavy hammer and energy required being a measure of resistance to impact.

Impact load is produced by a swinging of an impact weight W (hammer) from a height h. Release of the

weight from the height h swings the weight through the arc of a circle, which strikes the specimen to

fracture at the notch (fig..

Kinetic energy of the hammer at the time of impact is mv2 /2, which is equal to the relative potential energy

of the hammer before its release. (M gh), where m is the mass of the hammer and is its

tangential velocity at impact, g is gravitational acceleration (9.806 m/s 2 ) and h is the height through which

hammer falls. Impact velocity will be 5.126 m/s or slightly less.

Here it is interesting to note that height through which hammer drops determines the velocity and height

and mass of a hammer combined determine the energy.

Energy used can be measured from the scale given. The difference between potential energies is the

fracture energy. In test machine this value indicated by the pointer on the scale. If the scale is calibrated in

energy units, marks on the scale should be drawn keeping in view angle of fall () and angle of rise (.

Height h1and h2 equals,

h1= R (1cosθ) and h2= (1cosθ).

With the increase or decrease in values, gap between marks on scale showing energy also increase or

decrease. This can be seen from the attached scale with any impact machine.

Energy used in fracturing the specimen can be obtained approximately as

Wh1-Wh2

This energy value called impact toughness or impact value, which will be measured, per unit area at the

notch.

Izod introduced Izod test in 1903. Test is as per the IS: 1598

Charpy introduced Charpy test in 1909. Test is as per the IS: 1499.

A. IZOD TEST

SPECIMEN AND EQUIPMENT:-

1. Impact testing machine

2. Specimen and v notch is shown in the fig.4. Size of the specimen is 10mm

X 10mm X 75mm

MOUNTING OF THE SPECIMEN:-

Specimen is clamped to act as vertical cantilever with the notch on tension side. Direction of blow of

hammer is shown in fig. (). Direction of blow is shown in fig

IZOD IMPACT TESTING EQUIPMENT

SCHEMATIC IMPACT TESTING

POSITION OF SPECIMEN FOR IZOD TEST

PROCEDURE:-

1. Measure the dimensions of a specimen. Also, measure the dimensions of The notch.

2. Raise the hammer and note down initial reading from the dial, which will be energy to be used to

fracture the specimen.

3. Place the specimen for test and see that it is placed center with respect to hammer. Check the position of

notch.

4. Release the hammer and note the final reading. Difference between the initial and final reading will give

the actual energy required to fracture the Specimen.

5. Repeat the test for specimens of other materials.

6. Compute the energy of rupture of each specimen.

OBSERVATION:-

Initial and final reading of the dial.

RESULT:-

Strain energy of given specimen is………..

B. CHARPY TEST

SPECIMEN AND EQUIPMENT:

1. Impact testing machine. (Fig.6)

2. U notch is cut across the middle of one face as shown in (fig.5).

FIGURE 5

SPECIMEN FOR CHARPY TEST

CHARPY IMPACT TESTING EQUIPMENT

MOUNTING OF SPECIMEN:-

Specimen is tested as a beam supported at each end (fig.7). Hammer is allowed to hit then specimen at the

opposite face behind the notch. PROCEDURE:-

1. Measure the dimensions of a specimen. Also, measure the dimensions of The notch.

2. Raise the hammer and note down initial reading from the dial, which will be energy to be used to

fracture the specimen.

3. Place the specimen for test and see that it is placed center with respect to hammer. Check the position of

notch.

4. Release the hammer and note the final reading. Difference between the initial and final reading will give

the actual energy required to fracture the Specimen.

5. Repeat the test for specimens of other materials.

6. Compute the energy of rupture of each specimen.

OBSERVATION:-

Initial and final reading of the dial.

RESULT: - Strain energy of given specimen is……..

Viva Voice:-

1. Who postulated the theory of curved beam? ANS- Winkler-Bach postulated the theory of curved beam.

2. What is the shape of distribution of bending stress in a curved beam? ANS- The distribution of bending stress is hyperbolic in a curved beam.

2. Where does the neutral axis lie in a curved beam?

ANS- The neutral axis does not coincide with the geometric axis.

4. What is the nature of stress in the inside section of a crane hook? ANS - Tensile stress

5. Where does the maximum stress in a ring under tension occur? ANS- The maximum stress in a ring under tension occurs along the line of action of load.

6. Differentiate Shear Strain and Shear stress. Ans. Stress is a measure of how much force is taken by an object of particular size. shear stressis therefore shear force divided by area under shear. Clearly, increasing the force and/or decreasing the size or cross sectional area will result in larger stresses.Shear strain is a measure of the deflection caused by a shear stress, and is related via the shear modulus (or modulus of rigidity) G, where G= shear stress/shear strain.

7. What is factor of safety?Ans. The ratio of the breaking stress of a structure to the estimated maximum stress.

8. What is Ultimate strength?Ans. Absolute maximum compressive, shear, or tensile stress a material can bear without failure is called ultimate strength.

9. Define elastic constants E,K & G.Ans. Young’s modulus of elasticity(E) is the ratio of normal stress to normal strain.Bulk modulus of elasticity(K) is the ratio of normal stress to volumetric strain.Shear modulus of elasticity or modulus of rigidity(C or G) is the ratio of shear stress to shear strain.

10. What is Yield Strength?Ans. The ability of a metal to tolerate gradual progressive force without permanent deformation. Yield strength is the stress at which a specified amount of permanent deformation of a material occurs.

EXPERIMENT NO.-4

AIM: - To determine the tensile strength of specimen

SPECIMEN AND EQUIPMENTS - Universal testing machine , Specimen as shown in the Of different

ferrous and non ferrous materials

Universal testing machine

THEORY:- The tensile test is most applied one, of all mechanical tests. In this test ends of a test piece are

fixed into grips connected to a straining device and to a load measuring device. 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 position 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 (fig.8), which is recoverable immediately after unloading, is

termed as elastic and rest of the curve, which represents the manner in which solid undergoes plastic

deformation is termed plastic. The 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 begins to

decrease. As this stage the’ Ultimate strength ‘, which is defined as the ratio of the specimen to original cross

–sectional area, reaches a maximum value. Further loading will eventually cause ‘neck’ formation and

rupture.

Usually a tension test is conducted at room temperature and the tensile load is applied slowly. During this

test either round or flat specimens (fig.7) 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 testing machine.

STRESS STRAIN DIAGRAM

PROCEDURE:-

1. Measure the dimensions of a specimen

Diameter=d=,

Total length of a specimen,

Cross sectional area = Ao=,

Mark gage length (Lo) at three different portions on the specimen, covering effective length of a specimen.

(this is required so that necked portion will remain between any two points of gage length on the

specimen.)

3. Grip the specimen in the fixed head of a machine. (Portion of the specimen has to be gripped as shown

in the fig.7.

3. Fix the extensometer within the gauge length marked on the specimen. Adjust the dial of extensometer

at zero.

4. Adjust the dial of a machine to zero, to read load applied.

5. Select suitable increments of loads to be applied so that corresponding elongation can be measured from

dial gauge.

6. Keep speed of machine uniform. Record yield point, maximum load point, point of breaking of

specimen.

7. Remove the specimen from machine and study the fracture observes type of fracture.

8. Measure dimensions of tested specimen. Fit the broken parts together and measure reduced diameter and

final gage length.

OBSERVATIONS:- Specimen prepared from M.S bar/CI/Al

1. Diameter = d = mm

2. Gage length (lo) = 5Xd= mm

3. Original crosses sectional area of the specimen

= Ao = mm2

4. Final gage length obtained= Lo’=

5. Final diameter obtained = mm

OBSERVATION TABLE 1

Sr.

No

Load applied

(N)

(p)

Area of a

specimen

(Ao)

Stress

N/mm 2

Modulus of

elasticity (E)

N/mm 2

OBSERVATION TABLE 2.

Sr.

No

Contraction in

diameter (dd)

(mm)

Deformation

in length

(mm)

Lateral

strain

Linear

strainPoisson

ratio

NOTE -

1. Use venire caliper to measure diameter, gage length etc. for the specimen.

2. If C.I. specimen is to be tested only one observation will be taken at failure.

RESULTS

1. Calculate stress and strain for every interval of applied load. Draw stress strain curve as shown in the

Fig. ()

2. Compute the following;

a. Modulus of elasticity

Hook’s law states that stress is always proportional to strain within elastic limit. The ratio of stress and

strain is constant, called modulus of elasticity or young’s modulus (E)

E= Stress/strain =Constant=E=,

b. Yield stress (fy) ;

The point, at which strain increases without increase in stress, is known as Yield point. Stress measured at

yield point is called yield stress.

c. Tensile strength:

Maximum carrying capacity of a material in tension is called tensile strength

Tensile strength= maximum tensile load/ original cross sectional Area.

d. Percentage elongation:

The extension produced in a gage length, expressed as a percentage

of its original value(LO)

% Elongation= [(LO’ – Lo)/Lo] X 100

Where Lo’ is final gage length after fracture.

e. Percentage reduction in area:

= [(AoAo’)/Ao ] X100

Where Ao’ is final reduced cross sectional area after fracture.

Viva Voice:-

1.What is uniformly distributed load?

If a load which is spread over a beam in such a manner that rate of loading ‘w’ is uniform

through out the length, then it is called as UDL. 2. Define shear force

Shear force SF at any cross section of is defined as the algebraic sum of all the forces acting either

side of a beam.

3.Define Bending Moment at a section.

BM at any cross section if the algebraic sum of the moments of all forces which are

placed either side from the support.

4. What is meant by positive or sagging BM?

BM is said to be positive or sagging if the moment of the forces in the left side of the

beam is clockwise or right side of the beam is counter clock wise. Otherwise the beam to

bend like concave manner.

5. What is meant by negative or hogging BM?

BM is said to be positive or sagging if the moment of the forces in the left side of the

beam is counter clockwise or right side of the beam is clock wise. Otherwise the beam to

bend like concave manner.

6. Who postulated the theory of curved beam?

Winkler-Bach postulated the theory of curved beam.

6. What is the shape of distribution of bending stress in a curved beam?

The distribution of bending stress is hyperbolic in a curved beam.

7. Where does the neutral axis lie in a curved beam?

The neutral axis does not coincide with the geometric axis.

9. What is the nature of stress in the inside section of a crane hook?

Tensile stress

10. Where does the maximum stress in a ring under tension occur?

The maximum stress in a ring under tension occurs along the line of action of load.

EXPERIMENT NO.-5

AIM: - To find the modulus of rigidity.

Specimen and equipments

1. A torsion testing apparatus,

2. Standard specimen of mild steel or cast iron.

3. Twist meter for measuring angles of twist

4. A steel rule and calipers and micrometer.

TORSION EQUIPMENT

THEORY:-

A torsion test is quite instrumental in determining the value of rigidity (ratio of shear

Stress to shear strain) of a metallic specimen. The value of modulus of rigidity can

Be found out through observations made during the experiment by using the torsion

Equation:

Where T=torque applied,

Ip= polar moment of inertia,

C=modulus of rigidity,

= Angle of twist (radians), and

l= gauge length.

In the torque equipment refer fig. One end of the specimen is held by a fixed support and the other end to a

pulley. The pulley provides the necessary torque to twist the rod by addition of weights (w). The twist

meter attached to the rod gives the

Angle of twist.

PROCEDURE:-

1. Prepare the testing machine by fixing the two twist meters at some constant lengths from fixed support.

2. Measure the diameter of the pulley and the diameter of the rod.

3. Add weights in the hanger stepwise to get a notable angle of twist for T1 and T2

4. using the above formula calculate C

Conclusion:-

RESULT

Modulus of rigidity of the shaft

Viva Voice:- Define Hooke’s Law.Ans. It states that when the material is loaded within the elastic limit the stress is directly proportional to strain.

i.e. Stress α strain. or Stress = constant x Strain

2. Define Strength of materials.Ans. The strength of a material is its ability to withstand an applied stress without failure.

3. What is stress?Ans. When load is applied on any object then a resisting force is induced, that resisting or reacting per unit area of cross-section is called stress.

4. What is strain?Ans. Stress is change in dimensions upon original dimentions.5. What is deformation?Ans. Deformation is change in dimensions of any object due to applied load.6. On which steel you have performed tension test. What is its carbon content?Ans. On mild steel (0.3 to 0.6% carbon).

7. What kind of fracture has occurred in tensile specimen.Ans. Ductile fracture

8. What are the factors affect the strength column? 1.Slenderness ratio: Strength of the column depends upon the slenderness ratio, it is increased the compressive strength of the column decrease as the tendency to buckle is increased. 2.End conditions: Strength of the column depends upon the end conditions also

9 What is pure bending of a beam? When the loads pass through the bending axis of a beam, then there shall be pure bending of the beam.

10.What is shear centre or angle of twist? The shear centre for any transverse section of the beam is the point of intersection of the bending ax is and the plane of the transverse section

EXPERIMENT NO.6

AIM:- To find the values of bending stresses and young’s modulus of the material of a beam (say a

wooden or steel) simply supported at the ends and carrying a concentrated load at the center.

Material and equipment

1. Universal testing machine

2. Beam of different cross sections and materials (say wood or steel)

THEORY:-

If a beam is simply supported at the ends and carries a concentrated load at the center, the beam bends

concave upwards. The distance between the original position of the beam and its position after bending is

different at different points (fig) along the length if the beam, being maximum at the center in this case.

This difference is called ‘deflection’.

In this type of loading the maximum amount of deflection () is given by the relation,

Or

Where W= load acting at the center, N

L =length of the beam between the supports, mm

E =young’s modulus of material of the beam, N/mm2

I =second moment of area of the cross section (moment of inertia) of the beam,

About the neutral axis, mm4

Bending stress:

As per bending equation,

Where M= bending moment, Nmm

I= moment of inertia, mm 4

=Bending stress, N/mm 2

y=distance of the fiber of the beam from the neutral axis.

OBSERVATION:-

Refer Fig.

Width of the beam=………mm (for rectangular cross section)

Depth of the beam D=…mm (for circular cross section)

Moment of inertia of rectangular section= bd 3 /12=………mm 4

Moment of inertia of circular section =………mm4

Initial reading of the venire= ….mm

(It should be subtracted from the reading taken after putting the load)

S.

No

Load

W(N

)

Bending

Moment

)

Bending stress Deflectio

n

Young’s modulus

of elasticity

PRECAUTIONS:-

1. Make sure that the beam and load is placed at the proper position.

2. Cross section of the beam should be large

3. Note down the readings of the venire scale carefully.

PROCEDURE:-

1. Adjust the supports alone the UTM bed so that they are symmetrically with respect to the length of the

bed

2. Place the beam on the knife-edges on the blocks so as to project equally beyond each knife-edge. See

that the load is applied at the center of the beam.

3. Note the initial reading of venire scale.

4. Apply a load and again note the reading of the venire scale.

5. Go on taking reading applying load in steps each time till you have minimum 6 readings.

6. Find the deflection (d) in each time by subtracting the initial reading of venire scale.

7. Draw a graph between load (W) and deflection (δ). On the graph choose any two convenient points and

between these points find the corresponding

Values of W and d. putting these values in the relation

Calculate the value of E.

8. Calculate the bending stresses for different loads using relation as given in the observation

table.

9. Repeat the experiment for different beams.

RESULT:-

a. Bending stress………..units

b. Young’s modulus………units

Viva Voice:-1. Define elastic constants E,K & G.

Ans. Young’s modulus of elasticity(E) is the ratio of normal stress to normal strain.Bulk modulus of elasticity(K) is the ratio of normal stress to volumetric strain.Shear modulus of elasticity or modulus of rigidity(C or G) is the ratio of shear stress to shear strain.

2. What is Yield Strength?Ans. The ability of a metal to tolerate gradual progressive force without permanent deformation. Yield strength is the stress at which a specified amount of permanent deformation of a material occurs.

3. Define impact strength.Ans. The ability of a material to withstand shock loading.

4. What is beam.Ans. A beam is a horizontal structural element in which longitudinal dimensions are very large in comparison of lateral dimensions and that is capable of withstanding load primarily by resisting bending.

5. What is difference between force and load.Ans. Force is a push or pull applied on a body to change its state.Load is the combined effect of external applied forces at any point.

6. Types of Loads.Point load, uniformly distributed load, uniformly varying load.

7. What is torque?Ans. Torque is the tendency of a force to cause or change rotational motion of a body. A force applied at a right angle to a lever multiplied by its distance from the lever's fulcrum (the length of the lever arm) is its torque.

8. What is Torsional force?Ans. A force acting on a body that tends to twist the body.

9. What is torsional rigidity?Ans. The applied torque needed to produce a unit angle of twist in a circular elastic material, it isa measure of a body's resistance to torsion.10. Types of beams.Ans. Simply supported beam, over hanging beam, Cantelever beam, continuous beam, fixed beam.

EXPERIMENT NO. - 7

AIM: - To find the shear strength of given specimen

Material and Equipment

1. Universal testing machine

2. Shear test attachment

3. Given specimen

FIGURE

SHEARING FIXTURE

OBSERVATION:-

Diameter of the pin d= ….mm

Cross sectional area of the pin (in double shear)

= 2 X π/4 Xd2 =…. mm2

Load taken by the specimen at the time of failure, W =. …… (N)

Strength of the pin against shearing ( )

PROCEDURE:-

1. Insert the specimen in position and grip one end of the attachment in the upper portion and one end in

the lower position

2. Switch on the UTM

3. Bring the drag indicator in contact with the main indicator.

4. Select the suitable range of loads and space the corresponding weight in the pendulum and balance it if

necessary with the help of small balancing weights

5. Operate (push) the button for driving the motor to drive the pump.

6. Gradually move the head control ever in left hand direction till the specimen shears.

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

8. Stop the machine and remove the specimen. Repeat the experiment with other specimens.

PRECAUTIONS:-

1. The measuring range should not be changed at any stage during the test.

2. The inner diameter of the hole in the shear stress attachment should be slightly grater than the specimen.

3. Measure the diameter of the specimen accurately.

RESULT:-

Shear strength of the specimen ………N/mm2

Viva Voice:-1. Explain about Principal stresses.

Ans. The stresses normal to principal planes are known as principal stresses2. Units of force, deflection, stress, strain, E, K, G.

Ans. SI Unit of force is Newton, SI unit of deflection is meter,SI unit of stress,E,K&G is N/m Strain is unitless quantity.

3. Purpose of UTM.Ans. UTM is used to test the tensile stress and compressive strength of materials.

4. What are lifting machines?Ans. Lifting machines are devices which are used to lift heavy load by applying less effort.

5. What is torsion equation?Ans. T/J = τ/R = Gθ/L

6. What is flexural rigidity?Ans. The product EI is called flexural rigidity.

7. Define Mechanical Advantage,velocity ratio & efficiency.Ans. M.A. is the ratio of load lifted to effort applied.V.R. is the ratio of distance moved by effort to distance moved by load.Efficiency is the ratio of mechanical advantage to velocity ratio.

8. Define Section modulus.Ans. The elastic section modulus is defined as S = I / y, where I is the second moment of area (or moment of inertia) and y is the distance from the neutral axis to any given fibre.

9. What is a composite beam?Ans. A structural member composed of two or more dissimilar materials joined together to act as a unit in which the resulting system is stronger than the sum of its parts.

EXPERIMENT NO. - 8

AIM: - To find the compressive strength of given specimen.

Material and Equipment

Universal testing machine,

Compression pads,

Given specimen,

THEORY:-

This is the test to know strength of a material under compression. 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 varying height of member, keeping cross-sectional and the load applied

constant, there is an increased tendency towards bending of a member.

Member under compression usually bends along minor axis, i.e., along least lateral dimension. According

to column theory slenderness ratio has more functional value. If this ratio goes on increasing, axial

compressive stress goes on decreasing and member buckles more and more. End conditions at the time of

test have a pronounced effect on compressive strength of materials. Effective length must be taken

according to end conditions assumed, at the time of the test. As the ends of the member is made plain and

fit between two jaws of the machine, fixed end is assumed for calculation of effective length. Effective

length is taken as 0.5 L where L is actual length of a specimen

Compression Test

OBSERVATION:-

Cross sectional area of the specimen perpendicular to the load=A=……mm2

Load taken by the specimen at the time of failure, W=. …… (N)

Strength of the pin against shearing (σ) = [W/A] N/mm2

PROCEDURE:-1. Place the specimen in position between the compression pads.

2. Switch on the UTM

3. Bring the drag indicator in contact with the main indicator.

4. Select the suitable range of loads and space the corresponding weight in the pendulum and balance it if

necessary with the help of small balancing weights

Viva Voice:-1.Define: Column and strut. A column is a long vertical slender bar or vertical member, subjected to an axial compressive load and fixed rigidly at both ends. A strut is a slender bar or a member in an y position other than vertical, subjected to a compressive load and fixed rigidly or hinged or pin jointed at one or both the ends.

2. What are the types of column failure? a. Crushing failure: The column will reach a stage, when it will be subjected to the ultimate crushing stress, beyond this the column will fail by crushing The load corresponding to the crushing stress is called crushing load. This type of failure occurs in short column. b. Buckling failure: This kind of failure is due to lateral deflection of the column. The load at which the column just buckles is called buckling load or crippling load or critical load. This type of failure occurs in long column.

3. What is slenderness ratio (buckling factor)? What is its relevance in column? It is th e ratio of effective length of column to the least radius of gyration of the cross sectional ends of the column. Slenderness ratio = l eff / r l eff = effective length of column r = least radius of gyration Slenderness ratio is used to differentiate the type of column.Strength of the column depends upon the slenderness ratio,it is increased the compressive strength the column decrease as the tendency to buckle is increased.

4.Define beam? Beam is a structural member which is supported along the length subjected to external loads acting transversely. ie., perpendicular to the centre of the beam. Beam is sufficiently long as compared to external load.

5.What is meant by transverse loading on beams? If a load is acting on the beam which perpendicular to the support centre line Then it is called transverse loading.

6.How do you classify the beams according to its supports? The beam may be classified according to the support • Cantilever • Simply supported beam • Over hanging beam • Fixed beam • Continuous beam

7. What is cantilever beam? A beam with one end free and other end fixed is called Cantilever beam.

8. What is simply supported beam? A beam supported or resting freely on the supports at its both ends the its is called simply supported beam.

9. What is over hanging beam? If beam one or both end extend beyond the support limit then it is called as over hanging Beam10. Define Factor of Safety. It is defined as the ratio of ultimate tensile stress to the permissible stress (working stress)

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