γ辐照对GFRP拉-拉疲劳性能的影响

摘要

玻璃纤维增强树脂基复合材料(Glass Fiber Reinforced Plastic,GFRP)由于其良好的电绝缘性和力学性能,被作为北京正负电子对撞机束流管支撑法兰的制作材料.北京电子对撞机运行时,将对束流管及其支撑法兰产生大量γ和中子辐射.研究发现,玻璃纤维增强环氧树脂基复合材料长期处于γ辐射环境中,其力学性能会发生变迁.本文对由20 kGy、100 kGy、200 kGy剂量γ辐照前后的GFRP试件进行拉-拉疲劳实验研究,发现 γ辐照对低周疲劳阶段的疲劳寿命影响较为明显,而对于高周疲劳阶段疲劳寿命影响不大.基于Hwang和Han提出的假设,建立了拉-拉疲劳双参数疲劳寿命模型,并验证该疲劳寿命模型的准确性.利用扫描电镜对试件进行观察,发现辐照后环氧树脂基体出现碎片,环氧树脂与增强玻璃纤维的黏结界面受到破坏,但辐照对玻璃纤维影响程度较小.红外光谱图显示环氧树脂在辐照过程中降解反应较交联反应占优势.%Glass Fiber Reinforced Plastic (GFRP)is used as spare materials for the supporting flange of the BES III beam pipe in the Beijing Electron Positron Collimator(BEPCII)because of its excellent electrical insulating per-formance and mechanical properties.However,during the BEPC II operation,the beam pipe suffers a significant amount of γand neutron irradiation.When GFRP is exposed to γ irradiation,the material will become damaged, and its mechanical properties will vary.The tennsion-tension fatigue properties of GFRP laminated sheets before and after 20 kGy,100 kGy,200 kGy γirradiation were studied.The results show that the effect of γirradiation on the fatigue life in the low-cycle fatigue range is obvious,but it has little impact on the high cycle fatigue range.Based on the hypothesis of fatigue proposed by Hwang and Han,a two parameter fatigue life model was establishied.The mi-crostructure of GFRP laminated sheets before and after γirradiation were observed by SEM.The images show the glass fiber doesn't change obviously,but the epoxy degrades to pieces after irradiation.FTIR spectra indicate that the degradation reaction predominates over the crosslinking reaction of epoxy after γirradiation.