Experiment Mo5 -Elastic Modulus

City University of Hong Kong

Student number: 50925348
Course number: AP2240
Section number: L01

Title:

Experiment M05 – Elastic Modulus

Objective:
1. To investigate the bending of flat bars as a function of:

a) the applied force
b) the thickness of the bar
c) the width of the bar
d) he distance between the points of support

2. To determine the modulus of elasticity for steel, aluminum and brass.
Introduction:
If the extension or compression in a member due to a load disappears on removal of the load, then the material is said to be elastic. Elastic materials, with some exceptions, obey Hooke’s law, which states that: the strain is directly proportional to the applied stress.

E, Young’s modulus, relates to stiffness or rigidity of a material since the higher its value the greater the load required to produce a given extension.

Deflection is a term that is used to describe the degree to which a structural element is displaced under a load. The deflection of a member under a load is directly related to the slope of the deflected shape of the member under that load and can calculated by integrating the function that mathematically describes the slope of the member under that load.

[pic]

Where F is the weight of the hanging mass
          L is the distance between two supports
          λis the distance bent by the bar
          a is the width of the bar
          b is the thickness of the bar
          E is the Young’s modulus

Data and analysis:
  A. λ vs F – Young’s modulus
Steel
a = 10.14 mm
b = 1.56 mm
Distance L = 483 mm
Data table:

|Force, F / N                                 |0               |0.098           |0.196           |0.588           |0.784           |0.980           |
|Corresponding bending, λ / mm               |0               |missing         |0.42           |1.61           |2.41           |3.09           |

Aluminum
a = 9.25 mm
b = 1.99 mm
Distance L = 483 mm
Data table:

|Force, F /...