Hysteretic heating, fatigue behavior

Opp and co-workers (14) attempted to extend the universal slopes equation to predict the behavior of polymer fatigue. However, in their attempts they showed that a form of equation 6 was not useful for predicting polymer behavior and instead developed a model to predict the low cycle fatigue behavior based on hysteretic heating. And in this sense is consistent with those presented in equation 3 and References 15-17. 

Semicrystalline Polymers. As a class, semicrystalline polymers tend to exhibit superior fatigue resistance, relative to that of amorphous polymers, both in terms of a-N behavior and FCP rates (2,4,169), as long as tests are conducted at frequencies low enough to minimize excessive hysteretic heating. This is so, even allowing for variations, due to molecular weight. Indeed even though performance in a standard S-N test at 30 Hz may be relatively ppor, many such... 

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