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Objective:

To verify the relationship between load and deflection for a simply supported beam with

a single concentrated central load.

(Note: You may find other objectives after doing the experiment)

Apparatus:

Knife edge supports, dial gauge, weights and weight carrier.

Method:

•

• 1 Mild steel bar

• 1 Brass bar

25.4mm x 4.76mm

25.4mm x 6.35mm

Set up each beam in turn centrally on knife edge supports near the ends of the beam.

Locate the dial gauge centrally between supports and set to zero.

•

Apply loads in 200 gram increments to 1600 grams, noting deflections.

• Repeat while removing loads.

NOTE: The beam should be vibrated gently before each reading is taken to ensure that it

is properly settled on the knife edges. You may take a picture of the setup for your report./nCalculations:

The equation for the deflection at the centre of the beam, for a simply supported beam

with a single concentrated central load, is as follows:

Given:

Where

y

L

I

E for Mild Steel Beam:

E for Brass Beam:

Deflection (m)

W - Load (N)

Length (m)

E-Young's Modulus (N/m²)

Second moment of Area [about the Neutral Axis] (m¹)

b

b (breadth of the beam)

d (depth of the beam)

Units

y =

m

WL³

48EI

Complete the following table by showing the relevant calculations:

m

207GPa

110GPa

Cross section of the beam

Mild Steel

Brass/nGraph:

Ploty / Deflection (mm) (Y-axis) vs. W / Load (N) (X-axis) for both beams in a single

graph.

Discussion:

• Is the deflection vs. load graph a straight line? Support your answer by (i) observing the

graph and (ii) with the help of the deflection equation.

• State three main errors that may have occurred in your assumptions and in the

measurements.

• Discuss why the brass beam is deflected less compared to the mild steel beam for the

same load in this experiment; support this with evidence.

Conclusion:

• Summarise key points/findings of the experiment

• Very briefly explains where this knowledge could be applied

Additional note:

• No more than 5 pages of report in total should be returned as additional pages will not

be marked. This does not include the cover page.

• Fonts should not be smaller than size 11.

The key for a good report is 5Cs - Clear, Concise, Complete, technically Correct and

Critical analysis

• Show your calculations to prove that you know how to do them

• Make the report looks nice and well-formatted - reuse the tables from the lab sheet

but feel free to make adjustments

Use diagrams or photos where appropriate (with figure number and description)

Fig: 1

Fig: 2

Fig: 3