著者

甲嶋 秀平 梶井 憲弘 細井 厚志 川田 宏之

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.85, no.871, pp.18-00435, 2019 (Released:2019-03-25)

参考文献数

25

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Carbon fiber reinforced plastics (CFRPs) are widely used as components of marine structures. Thus, it is important to understand the degradation of the mechanical properties and its mechanism under seawater immersion. The object of this study is the influence of seawater immersion on the mechanical properties of plain woven CFRP laminates. Static tensile test and tensile fatigue test were carried out on the CFRP immersed different time under seawater for 300, 2500 and 5400 hours. The mechanical properties immersed for 300 hours was almost the same value compared with those of no immersion. However, the tensile strength immersed for both 2500 and 5400 hours reduced by 22.5% compared with that of no immersion. Then, from the fatigue results, in the low-cycle fatigue region, the fatigue strengths decreased as immersion time was longer, on the other hand, in the high-cycle fatigue region, the fatigue strength did not change significantly regardless of immersion time. As a result, the inclination of S-N curves became gentle as immersion time was longer. From observation of fracture surfaces by scanning electron microscopy (SEM), it was shown that the fiber/matrix interface deteriorated remarkably after seawater immersion. Moreover, the difference of damage growth behaviors due to immersed in seawater under fatigue loading was investigated using soft X-ray photography. On specimen immersed in seawater, the accumulation of damage expanded more widely due to interface degradation compared with that of no immersion. Considering these results, it was suggested that the static tensile strength depended on load transmission efficiency between fiber and matrix, on the other hand, the fatigue strength in high cycle fatigue region depended on the strength of fiber along 0° that had small influences by seawater immersion.