| In the field of aerospace, carbon fiber reinforce plastic (CFRP), which has theexcellent properties of light weight, high strength and high stiffness, plays animportant role. In order to satisfy the need of stealthy technology in the modernwarfare, more and more attention has been paid to the radar absorbing properties ofCFRP. Among the wave absorbing materials, structural radar absorption CFPR withimproved absorbing properties as well as the carrying capacity, therefore, has beenwidely used.In this paper, based on the theory and experiments, periodic structural layupdesigned with continuous carbon fiber has been used on the surface of CFRP torealize the modulation of surface impedance of the material, leading to thestructural absorbing property in the band of8-12GHz as well as good mechanicalproperties. Moreover, the feasibility of non-contact stain measurement has beenstudied, and the aim to absorb the microwave in the frequency range of1-4GHz hasbeen realized by altering the structure of the material properly.Firstly, based on the principle of structural wave absorption, periodic structurallayer designed with continuous carbon fiber has been introduced to the surface ofCFRP. Using the software Ansoft HFSS, the regularities of the surface impedanceand the wave absorbing property of the composite material, which has the layer ofunidirectional carbon fiber, of single grid pattern and other arrangementsrespectively, have been studied. Meanwhile, the relationship between the structureparameter and the absorbing property has been set up. The influence of the types ofcarbon fibers has also been discussed. The results show that the CFRP withunidirectional carbon fiber layer on the surface could not achieve the desiredabsorption effect, however, the one with grid pattern behaved well in the range of8-12GHz. For the composite material with single grid pattern layer, the resonancefrequency decreased as the width and the distance of carbon fibers increased.Combined with these two parameters, the reflection peak could reach-18dB at10.4GHz with single grid layer in which the width and distance of carbon fiber are4mm and11mm respectively. The attenuation of electromagnetic wave is mainly the electrical loss caused by electric resonance.Secondly, optimizing the structure with the simulation analysis, three sampleswith different surface layers has been prepared. The absorbing properties of thesamples have been tested and compared with the simulation results in order toverify the accuracy of the calculation. The results demonstrated that considering thescattering process of the interfaces, the test results are larger than the calculationresults, and the bandwidth are also wider. However, the position of the resonancepeak had little distinction. Furthermore, by connecting the carbon fiber on thesurface and the electric substrate, the resonance frequency has been reducedsubstantially, which appeared during4-8GHz.Finally, primary research has been made on the non-contact strainmeasurement and the absorbing properties of the low-frequency stage of thematerial. The variations of the resonance frequency under series of strains indifferent directions have been simulated by Ansoft HFSS, the results illustrated thatwhen applied the stretching force along the direction of electric field of the incidentelectromagnetic wave on the sample with single grid pattern surface, the variationsand the strains could be fitted as a straight line strictly, and the variations can betested in the accuracy range of the instrument. Therefore, it could be used in thenon-contact strain measurement. On the other side, connected the carbon fiber onthe surface and the electric substrate of the material, as well as enlarged the size ofthe cell and the width of the surface carbon fiber, we could get the absorbingproperty of the composite material in the range of1-4GHz with the resonance peakunder-10dB. Similarly, the property could be modulated by adjusting the structuralparameters. |
PDF Full Text Request