Lightning strike protection and electromagnetic interference shielding for composite structures using metallic submicrofilm and nanofilm

Abstract

Carbon fiber composites are very much imperative to future-generation aircraft structures. However, lightning strike protection (LSP) and electromagnetic interference (EMI) are one of the main concerns of today's aerospace industries. Carbon fibers have very good mechanical properties with the best strength-to-weight ratios, but they are very poor conductors of electricity. These fibers must be reinvented to increase the electrical conductivity of an aircraft structure and to increase the surface conductance of the composite. This present study deals with preparing composite sandwich structures of carbon and glass used for commercial nacelle applications subject to lightning strike effects with different metallic nanofilms of gold (Au), copper (Cu) and submicrofilms of silver (Ag), and aluminum (Al) measuring approximately 100 nm used on the top layers of the aircraft structure. Initial lightning strike results for a composite sandwich structure using gold nanofilm were obtained to observe lightning strike damage and structural tolerance necessary to observe the damage tolerance capability. Results were correlated with microstructure analysis. Resistance of composite panels with metallic submicro and nanofilm under various strains was studied. It was found that resistance of the metallic submicro and nanofilm increased under strain. The voltage was found to be low; hence, an increase in current would help to reduce the damage on composite panels due to lightning strikes, and the same theory would be applicable to EMI. No EMI was absorbed or reflected in the submicro and nanofilm using the P-static test. When lightning strikes were applied to composite coupons, the resulting damage from the currents was reduced on those with metallic submicro and nanofilms. C-scan results for the area of damage were correlated with results pertaining to lightning strikes and electromagnetic inference.