Figure 16-29 shows the behavior of polypropylene, polyethylene, and acetal at two temperatures. We would like to produce a 12-in.-long rod of a polymer that will operate at 40°C for 6 months under a constant load of 500 lb. Design the material and size of the rod such that no more than 5% elongation will occur by creep.

Transcribed Image Text:

Stress (psi) 4000 3000 2000 1000 23°C Acetal 60°C Polypropylene 23°C 60°C Polyethylene -23°C 1 2 3 Strain (%) after 1000 h -60°C 4