Week 8

This week was very exciting for our team. After 7 long weeks of planning, adjusting and experimenting with the bioplastic material, it was finally time to put it through an ultimate tensile strength test. With help from Mr. Steve Pagano, Mr. Brian Wisner and Mr. Satish Rajaram, our team was able to observe our first tensile test in the Mechanical Engineering and Mechanics laboratory, as well as record the data and graphs displayed on the MARK-10 machines.

Figure 8.b: Preparing the test sample

Figure 8.a: Load weight displayed on MARK-10 screen

Figure 8.c: Slippage is evident through the lines seen on the

Setting up the machine seemed difficult initially, as the software and computer were slow. However, after several minutes of changing settings, we were finally able to place our sample in between the two grips. One of the biggest problems we faced was the slipping of our samples through the grips. When the sample would slip through, even just a little bit, the load value (expressed in Newtons) would be greatly affected. Thus, Mr. Wisner and Mr. Rajaram advised us to find a material to attach our samples to that would prevent them from slipping.

Figure 8.d: Brian and Satish in action

Even though we were not able to test all our samples and our collected data was quite different from what we expected, we were still able to make some good quantitative and qualitative observations. It seems that the less glycerol we mix into the plastic, the more brittle it becomes. The samples with the most amount of glycerol just kept stretching as far as the MARK-10 machine could go, while the ones with less glycerol would snap within seconds.

Figure 8.e: Stress-strain curve seen through the tensile test software