# Experiment Report

Aim

The aim of this experiment is to obtain and graph deflections and bending stresses for a cantilever beam under a point load and observe the affect that changing the mass of the point load has on the deflection and bending stress graphs.

Hypothesis

As the loading on the bar increases, the magnitude of deflection and bending stresses will become greater. Procedure

1. Clamp the strain gauge instrumented steel beam to the rig. Place the dial gauge at 200mm and zero it. 2. First acquire a reading with a zero load then load the beam with different weights (4 different weights is recommended) at 200mm. enter the mass into the corresponding box and ‘Acquire’ the data point. 3. Enter the parameters of the beam including the conversion factor to plot the theoretical deflection and stress curves. Note: to delete an individual data point, click on that row on that table and then click ‘delete row’. Remember to label your plot including units.

Diagram

Results

Discussion

The experiment has shown that as the loading mass is increased, the magnitude of the deflection and bending stress became greater, thus confirming the hypothesis. However there was a clear amount of error between the experimental and theoretical results. For deflection versus load the error was very small implying that the bar used for this investigation had not lost much of it original properties or suffered much permanent deformation prior to experimentation. The error incurred with this part of the investigation can be narrowed down to human error and uncertainties in measuring the equipment used.

For bending stress versus load the error was quite significant. There is a clear difference in the gradient of experimental and theoretical data. An average percentage error was calculated to be 64.15% (). As shown in the results, when the bar had a zero mass loading applied, there was still a stress force of 0.018 MPa, demonstrating...

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