Study On Influence Mechanism Of Shielding Integrity On The ARINC429 Aircraft Bus

With the development of More-Electric-Aircraft(MEA),the avionics bus is widely used in signal transmission,as the neural network of the whole aircraft,the avionics bus plays a key role in transferring signal and distributing power.And the technology of the avionics bus becomes one of the most important technologies of avionics integration.Thus,various reliability parameters of the avionics bus have been extensively studied,such as electromagnetic interference,crosstalk,signal reflection and signal attenuation etc.With the increasing complexity of avionics systems,number of avionics bus is increasing gradually,and the electromagnetic environment in the cabin is also becoming complex,and the signal in transmission line will be affected by this complex electromagnetic environment.To suppress the coupling,a special structure is added outside the transmission line.When a MEA is flying,it will inevitably be affected by various disturbances and uncertainties,such as strong lightning stroke.In such a case,the friction between buses is often caused by the impact of vibration,and the shielding layer of avionics bus will be damaged with a decline of cable shielding capacity.If the damage on the cable is ignored in the aircraft maintenance process,it will degrade the system performance,and even make the system instable.To evaluate the integrity of shield,two aspects of the impact are analyzed in this paper.On the one hand,the transfer impedance mathematical modeling of the damaged shield is established.On the other hand,it is evaluated by analyzing the crosstalk between the cables.Otherwise,based on the finite element method,the geometrical modeling structural of the damaged cable shield is established,and the simulation results are obtained and compared with the theoretical model.Finally,the experimental platform is established to obtain the experimental results.In this paper,the integrity impact of damaged cable shielding is analyzed.The validity of the mathematic model is analyzed by theoretical analysis,finite element method and experimental verification method respectively.The model is established as a foundation for the state evaluation of the cable integrity impact.