Aim
Performed tensile test on various materials and observe their stress and strain relation as they
undergo dierent stages of deformation and eventual failure.
Background
A tensile test subjects a material to a controlled load, it is pulled by that load until reaching
mechanical failure. By assessing the stress-strain relationship, the characteristic of the material can
be determined for appropriate application. In our experiment a universal testing machine will be
used to record load and elongation, which can then be converted to stress and strain. The machine
locks a sample into place with gripping section wider than the test section. This directs all the stress
to the gauge section where the cross section area can be used as reference.
Method
The dimensions of the materials are $rst taken to determine the cross sectional area.
Materials # Width(mm) Thickness(mm) Area (mm)^2
PMMA
1 13.02 2.9 37.758
2 13 3.01 39.13
3 12.44 2.77 34.4588
Nylon-6
1 12.45 2.07 25.7715
2 12.47 2.03 25.3141
3 12.55 2.04 25.602
Black Mild Steel
1 12.49 2.87 35.8463
2 12.43 2.83 35.1769
3 12.65 2.82 35.673
Aluminium Alloy
1 12.41 2.82 34.9962
2 12.62 2.81 35.4622
3 12.36 2.83 34.9788
4* 12.41 2.86 35.4926
* The 4th alloy sample is annealed
Tensile Test
For each piece of material
1. The machine is calibrated to the laboratory conditions.
2. The piece of material is placed into the universal testing machine with the two ends
secured into the grips.
3. Screen door is locked for protection
4. Data is entered into the computer, this includes the $le name and dimension of the
piece.
5. The test is started, with the data collected for later processing
6. Matlab is used to process the data
The same process apply for all specimens, however a heavy duty testing machine must be used for
the metal samples.
