海洋环境下G814/3233复合材料的老化机理及加速老化与自然老化的相关性

为探索航空用碳纤维增强树脂基复合材料（CFRP）的老化机理及实验室加速老化环境与真实服役环境间的相关性，以飞机常用的G814/3233复合材料为研究对象，以海洋环境为服役背景开展了实验室加速老化试验和随舰自然暴露试验，观测了老化前后CFRP试件的力学性能、微观结构、组织成分等；改进了传统的大样本统计方法，提出了确定自然老化方程的小子样方法，有效扩大了数据样本；提出了以纵横剪切强度保持率为基准的当量折算系数计算方法并开展了验证试验。结果表明：在加速老化1个月后，G814/3233复合材料的表面树脂及碳纤维/树脂界面遭到破坏，剩余强度、纵横剪切强度、玻璃化转变温度分别下降6.93%、7.30%、0.87%，室温条件下的储能模量升高约5 GPa；获得了该型CFRP在南海环境下的老化机理和纵横剪切强度中值曲线；确定了自然老化环境与加速老化环境之间的当量折算系数为7.25；所建立的实验室加速老化方法对自然老化方具有较好的加速性和重现性。

Aging mechanism of G814/3233 composite in marine environment and correlation between accelerated aging and natural aging

To explore the aging mechanism and the correlation between laboratory accelerated aging environments and real service environments of Carbon Fiber Reinforced Plastics (CFRP) for aviation, the G814/3233 composite commonly used in aircraft and the marine environment are taken as the research object and the service background, respectively. Laboratory accelerated aging tests and natural exposure tests on board were conducted, and the mechanical properties, microstructure and structural composition of the specimen before and after aging were observed. The traditional large sample statistical method was improved, the small sample method for natural aging equation determination proposed, and the data sample effectively expanded. The equivalent conversion coefficient calculation method based on the longitudinal-transverse shear strength retention rate was proposed, and the relevant verification test was carried out. The results show that the surface resin and the carbon fiber/resin interface of G814/3233 composite are destroyed after accelerated aging for one month. The residual strength, shear strength and glass transition temperature decrease by 6.93%, 7.30% and 0.87%, respectively. The storage modulus increases by about 5 GPa at room temperature. The aging mechanism and the median curve of longitudinal-transverse shear strength of this type of CFRP in marine environments were obtained. The equivalent conversion coefficient between the natural aging environment and the accelerated aging environment is 7.25. The laboratory accelerated aging method established in this paper has good acceleration, simulation and reproducibility for the natural aging.