Thermal fatigue of polymeric composites under repeated loading

The paper deals with results of experimental study of thermal fatigue of polymeric composites caused by self-heating effect under repeating loading conditions. The tests were carried out on laboratory stand, which provides synchronization of all measured parameters. It was noticed that the process of thermal fatigue consists of three phases and the end of the second phase coincides with critical self-heating temperature, which causes rapid degradation until breakdown. During experiments, composite specimens were loaded for achieving a given temperature value, then cooled and loaded again. Based on experimental results, it was shown that the reloading caused cross-linking process, which causes hardening of a composite. The parametric analysis of self-heating curves was carried out for single-, double- and triple-loaded specimens, and fatigue life for investigated cases was determined and compared.