Design Of Three-dimensional Woven Composite Superstructure And Research On Electromagnetic Wave Absorption Characteristic

With the rapid development of stealth technology,radar absorbing materials have become the focus of researchers.The artificial periodic element of metamaterials can make them have unique electromagnetic properties such as negative refraction and so on.Therefore,metamaterials are used in the design of radar absorbing materials.Based on this,a three-dimensional(3D)woven metacomposite with ferromagnetic microwires as electromagnetic functional elements was proposed in this study.Ferromagnetic microwires were woven with weft by using 2.5D angle-interlocking structure.The spacing of ferromagnetic microwires was controlled by adjusting the number of weft yarns.The effect of ferromagnetic microwire spacing on electromagnetic response of3 D woven metacomposites was analyzed and discussed through experimental test and CST Microwave Studio simulation.It was found that the high microwave absorption of3 D woven metacomposites with 2mm ferromagnetic microwire spacing can be attributed to the improved impedance matching,and the power loss of 3D woven metacomposites is caused by both dielectric loss and magnetic loss.In addition,the 3D ferromagnetic microwire structure can be regarded as a parallel RLC circuit in the multi-layer structure,so as to enhance the multiple reflection and absorption of electromagnetic waves between ferromagnetic microwires,and finally realize the high microwave absorption of 3D woven metacomposites.Experiments and CST Microwave Studio simulation were carried out for different angular arrangements of 90°～165° to reveal their electromagnetic response characteristics and microwave absorption mechanism in X and Ku bands.It was found that the arrangement angle of ferromagnetic microwires can adjust the complex permittivity.Due to dielectric resonance,the metacomposites with angles of 90° and105° in X band appears negative permittivity.The dielectric loss of 3D woven metacomposites mainly comes from multi polarization,including electric dipole polarization and relaxation polarization,and the magnetic loss mainly comes from natural resonance and exchange resonance.It was found that the threshold absorption angle is 135°,and the frequency range can be further enlarged by adjusting the thickness of metacomposite.In order to study the electromagnetic damage tolerance of 3D woven metacomposites and the effect of impact on its electromagnetic response,10 J impact energy was applied to 3D woven metacomposites,and three representative areas were selected,including impact center,impact edge and no impact.It is found that the 3D woven metacomposites before and after impact show negative permittivity in X band.The resonance frequency can be adjusted by the impact position.In Ku band,the permittivity moves in the positive direction and is less affected by the impact.The reconstruction of metamaterials is helpful to maintain their absorption capacity.Through simulation and equivalent RLC circuit analysis,it is found that the reconstruction of ferromagnetic microwires caused by impact can lead to circuit rearrangement,and the electromagnetic response and absorption after impact still maintain high efficiency and show high electromagnetic damage tolerance.