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Experiment No. 3, 4 Beam Deflection

Apparatus

Objective:

To investigate the relationship between the deflections and applied loads and the effect of

variations in length and cross-sectional dimensions on beam deflection

Theory:

When the load is applied on a simply supported beam, deflections are observed and these deflections vary

as the length and cross sectional dimensions are varied.

For this arrangement, it can be shown that the deflection under the load i.e. maximum deflection is:

=

48

Where

=

12

Procedure:

1. The apparatus consists of a rigid main support beam on which the hardened knife edge and

cantilever supports the test beam.

2. The test beam can be easily positioned using the edge and cantilever supports

3.

Hardened steel knife edge load hangers and the dial gauge support, which slides freely on themain beam, can be readily moved to the selected point where the deflection is to be measured.

4.

The load is varied and a set of readings are taken.

5. The experiment is repeated for a different specimen.

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Exercise 1 (Experiment 3)

= 500

Material:Mild Steel MS

Load (N) Deflection (mm)

5 3

10 5.8

15 8.7

20 Failure

Graph:

0

1

2

3

4

5

6

7

8

9

10

0 5 10 15 20 25

Deflection (mm)

Deflection (mm)

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Exercise 2 (Experiment 4)

= 400

Material:Mild Steel MS

Load (N) Deflection (mm)

5 1.58

10 2.88

15 4.26

20 5.70

25 7.19

Graph:

0

1

2

3

4

5

6

7

8

0 5 10 15 20 25 30

Deflection (mm)

Deflection (mm)

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Experiment No. 5, 6 Deflection of

Beams

Objective:

To investigate the relationship between loads applied and deflection produced for different

methods.

To investigate the relationship between length of beam and deflection produced for constant force

for different materials.

Theory:

The load applied is directly proportional to deflection produced for different materials to the deflection

produced for different materials. The relationship is same but the constant of proportionality changes.Also the deflection produced depends on the length of the beam: greater the length, larger the deflection

produced.

Procedure (Experiment 5)

1. Initially, use Brass

2. Set the bearers so that a span of 500mm is obtained.

3. A test specimen is placed on the bearers and the load device is mounted in the centre of test

specimen.

4.

Lowered the gauge and set the gauge zero.

5.

Loaded with weights and read off deflections.6.

The experiment is repeated for specimen of steel.

Procedure (Experiment 6)

1. Initially, use Brass

2. Set the apparatus as described in starting points above.

3. Keeping the force constant say 10N, changed the length and read off the deflection.

4. The experiment is repeated for a specimen of Steel.

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Exercise 1 (Experiment 5)

Material Load (N) Deflection (mm) (xE-2)

Brass

5 60

10 120

15 182

20 245

25 310

Steel

5 32

10 65

15 98

20 130

25 165

0

50

100

150

200

250

300

350

0 5 10 15 20 25 30

Brass

Steel

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Exercise 2 (Experiment 6)

Load = 10N

Material Length (mm) Deflection(mm) (xE-2)

Brass 300 25

400 65

600 222

Steel

300 15

400 37

600 114

Graph:

0

50

100

150

200

250

0 100 200 300 400 500 600 700

Brass

Steel