面向飞机蒙皮的碳纤维预浸料吸波承载一体化层合结构设计

Design of carbon fiber prepreg electromagnetic wave absorbing and load-bearing integrated laminated structure for aircraft skin

针对现有飞机复合材料蒙皮设计难以兼顾承载性能和吸波性能的问题,凭借碳纤维预浸料独特的力电特性,基于阻抗渐变原理设计了具有优异吸波性能的梯度碳纤维阵列,赋予结构吸波性能;利用碳纤维底板优异的承载性能,进行力学性能的增强设计。通过玻璃纤维层合结构(Glass fiber laminated structure,GFLS)电磁和承载性能的双增强设计,构造了吸波/承载一体化层合结构(Integrated laminated structure,ILS)。电磁仿真和试验结果表明:结构实现了薄厚度下(<5 mm)宽频段(5~18 GHz)、大角度(0°~70°)、高强度(平均吸收率>94%)的吸波效果。通过吸波机制研究发现了结构的谐振频率与碳纤维宽度成反比,碳纤维宽度逐层渐变的设计使结构在较宽频段范围内产生多个相近的强吸收频点,从而实现了宽频高强吸波。弯曲性能试验结果表明,一体化层合结构的比弯曲强度和比刚度相较同尺寸的玻璃纤维层合结构分别提升了86.8%和76.3%。本文通过在玻璃纤维预浸料铺层中引入碳纤维预浸料并进行结构构型设计,可实现结构吸波性能和承载性能的大幅增强,为飞机蒙皮的轻质隐身承载一体化设计提供了一种新的解决方案。

In response to the difficulty in balancing load-bearing and electromagnetic(EM)wave absorbing performance in the design of existing aircraft composite skin,the unique mechanical and electrical characteristics of carbon fiber prepreg were utilized to enhance the mechanical and electrical properties of glass fiber laminated structure(GFLS).Gradient carbon fiber arrays were designed with excellent absorbing performance based on the impedance gradient principle,endowing the structure with EM wave absorbing performance;Carbon fiber reinforced polymer(CFRP)back sheet with excellent load-bearing performance was utilized to achieve enhanced design of mechanical properties.By enhancement design of both magnetic and mechanical properties of GFLS,the EM wave absorbing and load-bearing integrated laminated structure(ILS)was finally constructed.EM simulation and experiment show that the ILS realizes a broadband(5-18 GHz),multiangle(0°-70°),and efficient(average absorptivity>94%)absorption effects for EM wave under thin thickness(<5 mm).Through study of absorption mechanisms,it is discovered that the resonant frequency of a structure is inversely proportional to the width of carbon fibers.The layer-by-layer gradual change of the width of the carbon fibers in the ILS is designed to produce multiple adjacent strong absorption frequency points in a wide range of frequency band,which achieves a broadband and strong EM wave absorption.The mechanical experiment results show that the specific bending strength and specific stiffness of the ILS have increased by 86.8%and 76.3%respectively,compared to the GFLS of the same size.Through the introduction of carbon fiber prepreg in glass fiber prepreg layup and structural design in this paper,the EM wave absorbing and load-bearing performance of the GFLS have significantly been enhanced,providing a novel solution for the EM wave absorbing and load-bearing integrated design of aircraft composite skin.