Simulation Research On Lightning Indirect Effect Of Composite Aircraft

Lightning strikes are one of the main natural factors that threaten the safe flight of aircraft.Their impact on aircraft is divided into direct effects and indirect effects.The indirect effect refers to the transient electromagnetic field excited by lightning entering the avionics system through the coupling form,which in turn causes the electronic equipment to malfunction or even fail.In recent years,with the increasing proportion of advanced composite materials on new types of aircraft,coupled with the improvement of the accuracy of complex avionics equipment,the indirect effect of lightning has become increasingly prominent.This topic uses CST electromagnetic simulation software to conduct in-depth research on the lightning indirect effect of carbon fiber composite aircraft,mainly to complete the following work:(1)Firstly,the initial adhesion simulation model of B787 aircraft with 37 electrode positions was established in the CST EM studio with reference to the SAE ARP-5416 high voltage adhesion test.The initial attachment point of the lightning strike was determined based on the surface electric field intensity distribution of the aircraft.Further,the 1A partition is determined.(2)Secondly,the carbon fiber board material was defined in the CST cable studio and a carbon fiber material aircraft model was established.According to the initial adhesion results of lightning strikes,two current pulse injection models under lightning strike paths are established,and the conclusion that the lightning strike path will significantly affect the surface current distribution of the aircraft is obtained.The electromagnetic field values in the cockpit,passenger cabin and wing are obtained by the probe as the basis for determining the protection level of the indirect effect of the avionics system in the corresponding area.(3)Shielding is one of the main measures to solve the indirect effect of lightning.By comparing the simulation test on the two aspects of fuselage shielding and harness shielding,the following conclusions are drawn: the diamond with higher density has better shielding effect;deep and short The gap has the lowest weakening of the shielding performance;the optimal grounding mode of the single wire with the copper mesh shielding layer is double-ended balanced grounding;the wire harness can achieve better shielding effect by laying close to the metal structure surface or through the internal structure of the metal structure.This topic provides some reference for the design method of lightning indirect effect protection for composite aircraft.Based on the simulation,the optimization scheme of aircraft shielding performance is proposed.