Evaluation of UV Degradation of High-Strength Woven Fabric Material by Acoustic Emission Method

抄録

The acoustic emission (AE) method was applied to analyze the fracture mechanism of woven fabrics and evaluate the fracture mechanism of fabrics degraded by ultraviolet (UV) rays. The fracture mechanism of the woven poly-paraphenylene terephthalamide fabric was first estimated by monitoring its tensile strength using the AE method. Two different AE waveforms were detected during the tensile tests. Next, an experimental simulation was conducted. The two types of waveforms were found to be caused by fiber breakage in one case and friction in the other. Then, the fracture mechanism of woven fabric with UV degradation was investigated. The fracture strength and Young's modulus of the UV-exposed specimens decreased. This decrease in strength is assumed to be caused by the fiber strength of the UV-irradiated surface of the woven fabric, which breaks down and becomes brittle owing to hardening, as well as the increase of microcrack initiation by fiber friction resulting from the unevenness that occurs because of UV irradiation. Furthermore, during the tensile test, the UV-degraded fabrics were monitored using the AE method. It was found that the longer the UV exposure, the earlier the fiber breakage in the UV-degraded woven fabric, and the more the friction and pull-out between yarns.