Domination of self-heating effect during fatigue of polymeric composites

The following study focuses on investigation of influence of a self-heating temperature value on a fatigue process of polymeric composites and, in particular, on a criticality of this effect. A main goal of the study is to find a temperature value at which its growth becomes non-stationary (and thus dominates the fatigue processes) and investigate an influence of selected self-heating temperature values on fatigue life of a composite structure. The investigation is based on experimental studies, during which specimens were subjected to cyclic loading with simultaneous measurement of loading force, deflection velocity, surface temperature and acoustic emission. Such measurements allow for accurate evaluation of differences between particular loading cases as well as determination of characteristic points (moments) of degradation initiation, and finally analysis of all of the measured parameters within a number of cycles to failure. Based on the obtained results it was found that the self-heating effect is possibly dangerous to cyclically loaded composite structures even at relatively low self-heating temperature values and may significantly shorten their structural lifetime.