Project

ME 323 Extra Credit Project- up to 20 additional bonus test points Due:10pm, Sat., Dec. 11th Calibrate Two Beams for Estimating Loads By Measuring Deflections (8 points) For two different beams, apply for 4 different loading levels of known weights and measure the deflection at a particular point. These can be different beam materials or the same beam under different support conditions. Document your work (pictures!) and develop a relationship between the measured deflection and the applied load, such that if an unknown weight were applied you could solve for it using the measured deflection. Explain how you got the theoretical deflection (source, derived, etc.). Show a sample calculation that you performed for each beam. Show the theoretical calculation for your beam deflection and the actual measured. Why are they different (explain any assumptions you used). Do these have any trends with load level, or is it pretty uniform? Plastic Pen Strength (8 points) 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.

Bridge Evaluation Report (6 points) Read over the attached National Transportation Safety Board report on the 2007 I-35W bridge collapse in Minnesota. In about 2 pages total, explain what went wrong. Start by briefly summarizing what occurred in the failure of this structure (where, when occurred, how long in service, what was happening at the time, etc.). Then, based on the analysis section of the report (pages 119-152), discuss the relative roles/contributions to the structure failure of each of the following topics. Explain the findings with respect to each topic, if this alone was enough to cause the failure, and what could have been done to prevent the issue.

o Design o Gusset plates o Environmental factors o Loading conditions o Inspection practices

Finally, end with your thoughts on what you’ve learned. What did you find most surprising? What was most interesting? How might this influence your future work in engineering?