Quote:
Originally Posted by tasdrouille
re fatigue failure:
according to wikipedia "fatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading".
Now what is cyclic loading? In the case at hand, one could probably argue that it happens at every rotation of the wheel at the contact patch, and probably even every time there is a tire warm up cycle. Constant higher pressure does not look like cyclic loading to me, but I might be way off.
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The issue isn't the pressure. The issue is the stress in the tire - and it changes as an individual section of the tire revolves through the contact patch. That's the cycle.
Quote:
Originally Posted by tasdrouille
re fatigue failure:
From my understanding of it, hysteresis plays the biggest role in tire fatigue. This seems to be demonstrated by the fact that tires which have been run at low pressure for extended periods of time are prone to cord failure and tread separation. So reducing sidewall hysteresis by means of increased pressure would appear like a good way to reduce the occurrence of fatigue failure.
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That would br true up to a point. But we are discussing way beyond that point.
Normally, the problem with hysteresis is that the heat generated changes the properties of the rubber - and that causes the failure in the form of a separation between plies. You will hardly ever see actual fabric fatigue in a tire, but if you do, it will be caused by the cord going into compression. It's sort of like pushing on a rope - the rope doesn't work very well that way.