Simulation Of Current Distribution And Lightning Protection In Composite Aircraft Grounding Grid

Composite materials is widely used in modern aircraft due to their advantages of high strength and light weight.However,composite materials have low electrical conductivity and low thermal sensitivity,and cannot replace traditional metal fuselages as ground points for onboard electronic/electrical systems.The metal ground grid structure in the composite area can replace the function of a traditional metal fuselage,meet the grounding requirements of airborne electronic/electrical equipment,provide a normal/fault current return path for airborne equipment,provide lightning protection,and high intensity electromagnetic fields Protection,its performance is related to the safe and stable operation of the aircraft.The composite aircraft grounding grid was taken as the research object,and the moment method is used as the theoretical analysis basis to analyze the electrical characteristics and lightning protection function of the grounding grid.First,a slab model and a track model was built to simulate the structural components of the ground grid.The current distribution characteristics on the slab structure and the coupling characteristics of the cables under the slab and track structure was analyzed.Secondly,a composite aircraft grounding grid model was built using the line model,and the current distribution mechanism in the grounding grid and the influence of the connection material between the composite and the skin on the current distribution in the grounding grid were analyzed when the current flowed into the grounding grid;By constructing a "cage-squirrel" grounding grid structure,the changes in grounding grid structural parameters,composite material skinning,software segmentation accuracy,and changes in interference voltages in the grounding grid when track components fail were analyzed.Finally,the lightning protection function of the ground plane of the composite aircraft is analyzed.The aircraft model and the single-orbit model were built to analyze the distribution of the lightning current injection/departure points to the fuselage current distribution and the electromagnetic field distribution inside the aircraft.The effect of the outer metal layer on the protection effect of the lightning indirect effects of the equipment inside the aircraft,and the lightning protection function of the metal ground grid structure was verified.The results show that when the frequency is low,the current distribution of the grounding grid is controlled by the resistance effect,and when the frequency is high,the current distribution is controlled by the inductance effect;different parameters of the grounding grid model will have a certain impact on the potential difference in the network,and the design of the grounding grid Relevant factors need to be considered during research and development;laying aluminum foil on the outer layer of the composite material can improve the protection effect of the lightning indirect effect of the whole machine,and the cables inside the machine should be laid under the concave track of the grounding network as much as possible.