Charlotte, North Carolina
June 20, 1999
June 20, 1999
June 23, 1999
4.470.1 - 4.470.15
Stretchy “Elastic” Bands II
Alan K. Karplus Department of Mechanical Engineering Western New England College Springfield, MA 01119-2684
Key Words: Elastics, Tension Tests
Prerequisite Knowledge: Have an idea about changes in the load an elastic loop holds as it is stretched and unloaded.
Objective: To work as a team member in the collection of data, to make plots for near constant rate loading and unloading of fabricated rubber loops, and to show features which are unique to these elastic products.
Equipment: 1. Collect fifteen three and one half inch long rubber “elastic” bands of 1/8 inch width, 0.034 inches thickness, and referred to as 33 rubber bands. These fifteen bands are required to build four group members: A) two bands each cut and tied with square knots at the cut ends to create a single 4 inch loop (this is equivalent to an uncut band in starting length), B) two bands each cut and tied with square knots at the cut ends to create a single 6 inch loop, C) four bands each cut and tied with square knots at the cut ends to create a single 12 inch loop, and D) six bands each cut and tied with square knots at the cut ends to create a single 18 inch loop. Then clearly designate the group as Group 33. Without the designator of elastic band size, “group” refers to the four members alone: loop size A, loop size B, loop size C, and loop size D. Most office supply houses have number 33 size elastic bands. 2. Fifteen foot long Tape measure. 3. Mounting board (3 in. by 1 in. by 30 inch) with a six penny nail inserted one inch from one end on the 3 inch by 30 inch face, and to which the twenty foot long scale can be attached. The 30 inch long board should be clamped to a table that is 15 feet long parallel to the long length. C- clamps can be used to secure the board and the tape measure once the tape measure has been wrapped with a protective material. The zero of the measure should be at the nail. 4. Safety Goggles 5. Heavy work gloves 6. Load scale for loads to 15 pounds or 7.5 kg. A scale with a capacity to 10 pounds or 5 kg. may be helpful, if available. 7. Micrometer or vernier caliper. 8. Data page with 25 lines and nine columns for each loop to be tested. For the loop size A the measurements are taken at one inch increments starting at a value of four inches and are to be listed in the first column. The next two columns are used in pairs to record load and unload for each elastic. Be sure to label columns and include units of measure selected. For the remaining
Karplus, A. K. (1999, June), Stretchy "Elastic" Bands Ii Paper presented at 1999 Annual Conference, Charlotte, North Carolina. https://peer.asee.org/7952
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