The tensile test was preformed on the following commonly used materials; 836 Cold Rolled Steel, T351-2024 Aluminum, 110 Copper, Grey Cast Iron, and HDPE Plastic. The first objective was to examine the stress-strain curves in order to calculate and identify the significant mechanical properties of these materials. The curves are also used to give a better understanding of what these mechanical properties mean. The second objective was to compare the mechanical properties and physical appearance of these materials. In order to get the stress-strain curves, each specimen was placed in the tensile testing apparatus. The load frame slowly stretches the specimen until it breaks. The extensometer, was placed directly on the specimen and was hooked up to a computer program that collected all of the data, which was used to make the stress-strain curves.
First a punch was used to mark off a two inch section on each specimen. This section was marked off so that it could be used as a reference in finding the elongation of the specimen.Then, using a caliper, the diameter of each was measured and recorded. Now the mechanist calipers were set up in increments of 0.05 inches starting at 2.05 inches. Next the specimen was loaded into the tensile testing apparatus, the extensometer was put onto the specimen, and the data-acquisition program was turned on. The extensometer had to be taken off the specimen once it has reached its proportional limit. Once it was taken off the mechanist calipers were used. As soon as the length in between the two marks on the specimen lined up with the caliper length the data for the live load was recorded. This was done until the material fractured. Next the two halves were removed from the…...