Open-Ended Engineering Experimental Project II
EGN 4930 - Foundations of Engineering (Fall 1999)
Goal/Purpose
Apply some of the fundamentals of engineering to a group experimental project similar to an experiment that a quality engineer would perform at a manufacturing plant to determine the quality of their product.
Objective
Perform an experiment to evaluate the deflection and stiffness of rubber bands. Specifically, each group will test rubber bands by different manufacturers (two) and different sizes (two). The experiments will also be performed under different environmental conditions (five), that is,
· New (out of the package),
· Heated (microwave or oven),
· Cooled (frozen or iced),
· Armor-Alled, and
· Fifth condition at each group's discretion.
Each group will be responsible for developing an experimental set-up such that data can be accurately taken and replicated.
Experimental Parameters, Measurements, and Calculations
The following experimental parameters, measurements, and calculations should be closely adhered to:
· The free length or un-stretched length, width and thickness should be accurately measured for each rubber band. Note that plastic calipers can be purchased at a reasonable price.
· Each rubber band should be labeled and documented.
· 5 rubber bands should be tested for each trial. Note that a trial consists of a specific rubber band size from a specific manufacturer under a certain environmental condition. This results in a total of 100 rubber bands being tested [i.e., (# of manufacturers = 2) X (# of sizes = 2) X (# of environmental conditions = 5) X (# of rubber bands tested for each trial = 5) = 100.
· No rubber bands should be used twice (i.e., don't use the same rubber bands from one trial to the next).
· For each test, the deflection of the rubber band under a specified load (e.g., 1 to 2 pounds should be adequate depending on rubber band size) should be measured. Be creative in measuring your load and applying it. For instance, the load can easily applied using a 16-oz. can of beans, duct tape and a paper clip.
· Also, 2 rubber bands for each trial should be stretched until they fail to determine their ultimate load. This will result in an additional 40 tests.
· Once all of the data is taken, statistics should be performed to determine mean and standard deviation of deflection or ultimate load for each trial. Excel can be used to tabulate date and perform the statistics.
· The stiffness (assuming a linear relationship between load and deflection) of the rubber bands for each trial can then be easily determined from k = F/x where k is stiffness, F is load and x is deflection.
· Note that you are performing a scientific experiment and everything should be recorded (e.g., room humidity, room temperature, heating temperature and time, etc.).
Presentation (date to be determined by section professor)
Each group will demonstrate their experimental set-up and make a short (time to be determined by section professor) formal presentation on the experimental set-up, data taken, statistical results, conclusions, etc.
Technical Report (due date is determined by section professor)
A technical report presented as an executive summary in memorandum format to the professor is required. The report (no longer than 3-4 pages) should include problem statement, description of experimental set-up, tabular data taken, statistical results, conclusions, etc.
Grading
Grading of the project is up to the section professor but will be based on a pass/fail policy