Evaluation of critical self-heating temperature of composite structures based on analysis of microcrack development
Andrzej Katunin, Angelika Wronkowicz, Marcin Bilewicz
Quarterly No. 1, 2017 pages 9-13
DOI:
keywords: self-heating effect, microcracks development, crack density, degradation of composite structures
abstract The self-heating effect occurring during the cyclic loading of polymers and polymeric composites may initiate accelerated thermally induced fatigue processes, which causes a rapid increase in the self-heating temperature at a location of stress concentration and, as a consequence, sudden structural degradation. Therefore, it is essential to investigate this process and determine the criticality of the self-heating effect, i.e. the critical value of temperature which initiates accelerated degradation processes. In this paper, an aspect of microcrack formation and development was considered as an indicator which reflects the degradation degree of a structure. Microscopic observation of microcrack development at progressive temperature values was chosen due to its high sensitivity to the initiation of fracture processes among applied measurement techniques to evaluate structural degradation during fatigue tests. Appropriate image processing techniques as well as quantitative measures to describe microcrack development enable evaluation of the criticality of the self-heating effect using this approach and comparison of the obtained results with those obtained by other measurement techniques. The specified critical value of self-heating temperature allows determination of a safe temperature range for heavily loaded structures made of polymeric composites, which can be helpful both during the design stage as well as at the operating stage of composite structures.