The Failure Behavior And Mechanism Of Carbon Fiber Composites In Simulated Acid Rain

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.