Bending Moment Lab

MANUKAU INSTITUTE OF TECHNOLOGY
School of Mechanical Engineering & Trades
DIPLOMA IN MECHANICAL ENGINEERING

Beam Reactions

OBJECT

1. To determine both the theoretical and actual support reactions of a simple vertically loaded beam, showing that the loadings on the supports are directly proportional to the distances of the loads from the supports; thus illustrating the principle of the moments of forces.
2. To determine the beam support reactions for a horizontal beam carrying vertical loads at positions across the span.

APPARATUS

Two support stands, beam of uniform round bar, load hangers, known loads, two spring balances with suitable supports for beam.

1. PROCEDURE

• Assemble the apparatus as a simply supported beam with a span of 900mm. Adjust the equipment so that the beam is horizontal, the spring balances, and beam supports are vertical. Note the spring balance readings for each support with just the bar in place.
• Place a 10N load onto the load hanger and suspend it directly beneath one of the spring balances. Note both spring balance readings.
• Next move the mass hanger 100mm along bar and note both spring balance readings.
Repeat this procedure of incremental movement and readings until mass hanger is suspended directly under the spring balance at the opposite end of beam to the initial step.
• Calculate the theoretical beam reactions and use a graph to show the comparison of the two sets of data.

2. PROCEEDURE

• Suspend the beam to give a span of 900mm.
• Place loads as shown in the diagrams below and record the measured beam reactions.
• Calculate the theoretical beam reactions and use a graph to show the comparison of the two sets of data.
BEAM LOADING PATTERNS

a)

10N 20N 250mm 750mm

b)

20N 20N 500mm 750mm

c)

10N 15N 10N 150mm

400mm

800mm

RESULTS

Record the results for each part of the lab work into separate tables.

GRAPHS

Produce neat graphs for each part of the lab to show the results obtained. Use these graphs to draw conclusions about the results.

CONCLUSIONS

Discuss the findings from the graphs. It is not sufficient to simply say that the theory has been shown to be correct.