Research On Indirect Microwave Curing Of Carbon Fiber Reinforced Polymer Composites

Carbon fiber reinforced polymer composites have been widely used in aerospace industry because of its excellent performance.Traditional autoclave curing technology has disadvantages of poor process control ability,low heating speed and high energy consumption.Compared with autoclave curing of composites,microwave curing technology has better process control ability,higher heating speed and lower energy consumption.However,microwave curing technology has the problem that multidirectional carbon fiber reinforced polymer composites(CFRPs)can't be heated effectively and temperature distribution is uneven.Combined with the major needs of the National Natural Science Foundation and aviation enterprises,these problems are researched in this paper,and the results are shown as follows:(1)To solve the problem that multidirectional CFRPs can't be heated effectively,an indirect microwave curing process was proposed.The short carbon fiber reinforced polymer composite was used to absorb microwave and heat the part.On the basis,the microwave susceptive mold was designed,and the microwave absorption performance of the indirect microwave heating medium was systematically optimized especially.The curing process for both thin and thick composite component was designed,and the processing parameter for thick composite curing was analyzed and designed especially using simulation and experimental methods.(2)To adjust the temperature uniformity of the composite during microwave curing,a method based on time-varying electromagnetic field was presented.The method can generate a large number of electromagnetic field resonance patterns by adjusting the switch status and combination mode of microwave sources.The temperature uniformity was improved by the compensation effect between the heating modes corresponding to the different kinds of resonant state during microwave curing.The experimental results showed that the time-varying electromagnetic field in the microwave cavity can effectively improve the temperature uniformity of the composite.Compared with no adjusting and existing adjustment method,the temperature uniformity of the composite is increased by 39.9% and 24.7%.(3)The experiment about multidirectional CFRPs curing using indirect microwave heating was carried out,and the composite part was cured effectively.For thin composite laminate,compared with traditional thermal curing method,the time and energy consumption are reduced by 42.1% and 75.9% respectively during indirect microwave curing process.The mechanical properties of the composite parts including tensile strength,compressive strength and interlaminar shear strength(ILSS)is improved slightly.For thick composite laminate,compared with thermal curing,indirect microwave curing has excellent process followability.The damage caused by curing reaction exothermic is reduced significantly using the designed indirect microwave curing process,and the ILSS is increased by 1.38 times.