Study On The Curing Behavior Of Civil Aircraft Composite Based On Ultrasonic On-line Monitoring

Studying the curing process of composite maintenance, using the online monitoring curing process of ultrasonic technology and analyzing the impact of different parameters on the properties of cured after curing, have the important meaning to develop the curing process of repair better and achieve the controllable curing process.In this paper, Friedman (FR), Flynn-Wall-Ozawa (FRO), Kissinger-Akahira-Sunose (KAS), three kinds of non-model methods, have been used to calculate and draw the relation curve graph of WHUT-Esys208epoxy resin system, which include the curing rate, the activation energy and the curing degree. The data has been analyzed to reveal the curing reaction stage and curing behavior of epoxy resin system. The research shows that the curing reaction is gradually from the catalytic reaction mechanism into N order reaction mechanism, which is basically consistent of the model fitting results. The curing behavior of the system can be characterized by these three kinds of model fitting method:the KAS method can accurately reflect the curing behavior of the system, while the result of FWO method is only a slight deviation, but for the FR method only the trend is consistent with the other two methods.The online monitoring method of ultrasonic has been used to monitor the curing process of WHUT-Esys108room-temperature-curing epoxy resin system. The experiments show that when the system is curing, the ultrasonic amplitude value and the energy values have been constantly changing, the curing process of the resin system can reflected by the plotted curves in a certain extent. The formula of ultrasonic attenuation has been used to calculate in the curing process, and the data has been used to draw the curve graph. The curve graph of ultrasonic attenuation can significantly distinguish different stages of curing reaction, which combines ultrasonic wave amplitude variation with characterization of the curing reaction process.The effect of different curing temperature and heating rate on the mechanical properties of the composites after curing has been studied with the help of optical microscope, which has been used to reveal the relationship between curing parameters and microstructure. The research shows that there should be a best curing temperature for the resin:with the holding time of60min and the heating rate of2℃/min, the optimum temperature is120℃in this experiment, and the composites tensile property has been certainly effected by different heating rate, which shows that the slower heating rate, the better mechanical properties of the composite, but the specific reason is unknown.