Devise a way to measure/estimate the ultimate strength of a plastic pen. Try to get as accurate of
a measurement as possible of the geometry and explain your method. Run at least 4
tests/measurements of the same sample type. Include schematics and/or pictures of your set-up.
Write a brief report (~2 pages) summarizing your methods and findings, including sample
calculations. Include the following information:
a. Estimate the local maximum stress at failure for the rubber bands. Give the standard
deviation for these measurements, and show your calculation.
b. Explain the type of loading applied (bending, shear, axial, etc.) and discuss what would occur
in the other loading cases (test one, if possible).
c. Describe the sort of failure was observed (brittle, ductile, etc.)? Does it initiate at a particular
location consistently?
d. Research some common materials (at least 3) and properties for plastics/polymers used for
these applications. Give their properties and try to classify the material in your situation as best
as you can.
Sample Solution