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I've been working with a team of 'designers' that are highly concerned over a potential failure mode of ABS plastic. Their theory is that under a static load well under the yield point of the material that a plastic ABS part will eventually stretch and fail.

The specific example is a handle that I've calculated to hold over 190 lbs before yielding is being loaded to 30 lbs and held there for seven plus days.

The only type of failure I can think of that this could be would be creep, but since we're working at constant room temperature, constant load, evenly distributed load over a wide surface (3 square inches) and so far below the yield point I can't imagine that this test would produce any useful results.

Can anyone think of anything this test would show? Is there a failure mode that I'm not thinking of (specific to ABS or not)? Or is this more likely a test in futility?

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  • $\begingroup$ Where will the part be used? Is it subject to changes in temperature when in the "real" world? Will it be in sunshine - will that cause ageing etc? $\endgroup$ – Solar Mike Jan 26 '18 at 21:05
  • $\begingroup$ The test conditions are as close to the working conditions as possible. In door, constant temperature constant load, cylical loading but low low cycles 20 a day maybe at 20 lbs max, no weird chemicals in the air constant moisture content too $\endgroup$ – Diesel Jan 26 '18 at 21:22
  • $\begingroup$ If you really want to test this you should actually cyclically load it. $\endgroup$ – agentp Jan 27 '18 at 1:46
  • $\begingroup$ Agreed, I can think of about a dozen tests I'd LIKE to do that would produce results I'd be interested in, but I'm wondering if this test does anything at all. Other than confirm it can hold a weight way below the yield point. $\endgroup$ – Diesel Jan 27 '18 at 15:46

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