【作者】 陈皓；

【导师】 左禹；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2014， 硕士

【摘要】 本实验以5428/T700碳纤维增强双马来酰亚胺树脂基复合材料和碳纤维纤维增强环氧树脂基复合材料,通过吸湿法、电化学交流阻抗法、傅里叶红外光谱仪、X射线光电子能谱仪和扫描电镜SEM等手段对碳纤维复合材料在酸雨环境中的失效过程进行分析。主要研究了不同浸泡条件、温度、阴极极化和树脂厚度对碳纤维复合材料的电化学特性、力学性能和微观形貌的影响,并结合有限元法对失效过程进行了分析。不同的浸泡条件对复合材料的老化过程有着不同的影响,吸湿法和电化学交流阻抗法均表明完全浸泡、干湿交替浸泡和湿热条件下复合材料的失效老化呈递增趋势,用两种方法均可推到出水分在碳纤维复合材料的扩散系数,且三种加速试验条件下试样的力学性能均有小幅度下降,成分测试可以看出失效破坏由树脂的吸湿引起,试样并未发生化学变化。在完全浸泡条件下在试样上加载一负的恒电位进行阴极极化可分析复合材料在服役时与其他金属部件发生的耦合效应可以通过电化学交流阻抗法发现试样出现较为明显的老化特征,其力学性能也发生较大的下降,通过成分分析和电镜观察可以发现复合材料中树脂基体发生了水解反应,从而引起树脂基体的裂纹与破损,树脂基体与纤维增强体间的界面结合受到破坏。碳纤维复合材料的树脂基体的厚度对复合材料的耐候性能的影响可通过交流阻抗法得出,树脂较厚的碳纤维复合材料对介质侵蚀的抵抗能力强于树脂较薄的碳纤维复合材料,在较厚的树脂层的保护下碳纤维复合材料的界面结构更不易受到破坏。通过有限元方法对复合材料的失效过程进行模拟可得出树脂的一部分膨胀由内应力导致,材料的两端最容易发生破坏,若在树脂表面加载一压头与复合材料发生机械接触可模拟树脂吸湿前与吸湿后与压头接触产生的力学响应,通过有限元方法对机械接触进行模拟分析并结合树脂表面的缺陷和缝隙的模拟,可得出缺陷处的应力分布和形变模式。更多还原

【Abstract】 In this paper, two kinds of CFRP were studied to analyze the failure process of CFRP in acid rain environment via moisture, electrochemical impedance spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. The research focused on the effects of different soaking conditions, temperature, cathodic polarization and thickness of resins to analyze the changing of electrochemical properties, mechanical properties and the microstructure to get a clear view of the failure mechanism. The research also combined the finite element methods to study the fatigue.Different soaking conditions had different impacts on the aging process of the composites, moisture absorption and electrochemical impedance spectroscopy showed that under completely soaked, wet/dry condition and hot/wet condition, composites experienced an increasing failure trend. There are two ways to determine the diffusion coefficient of CFRP, during three kinds of accelerated test, mechanical properties of the specimen fell slightly. Through component testing it could be seen that the failure damage was caused by moisture absorption of the resin, and there was no chemical in the resin.The sample loaded a negative constant potential of cathodic polarization under the condition of totally immerse could analysis the effects of the composites in service with the other metal parts. By electrochemical impedance method it was found that the specimen appeared more obvious aging characteristics, and its mechanical properties experienced a larger decline. Through the composition analysis and electron microscope the hydrolysis reaction in resin matrix could be found, which caused the crack and breakage of the resin, resin matrix and interface bond.The effects of resin thickness on weatherability were tested by electrochemical impedance method. CFRP with thicker resin had stronger erosion resistance ability than the thinner one. Under the protection of thick layer of resin, the interface structure of CFRP was less likely to damage.Through the finite element method simulating the failure process of the CFRP, it was concluded that the inflation of resin was caused by internal stress and the ends of the materials were the most prone to failure. Loading a mechanical contact on the resin before and after moisture absorption, the mechanical response was simulated. Via finite element methods for simulating mechanical contact analysis combining the simulation of defects and cracks on the surface of the resin, the stress distribution and deformation of defect mode were studied.更多还原