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

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.