Research On Weak Fault Characteristics And Diagnosis Method Of Aircraft Cables

Aircraft cables are an important part of the aircraft,and they provide channels for power and signal transmission of various systems on the aircraft.Their performance determines whether the various systems of the aircraft can cooperate normally to ensure the safe flight.At present,the diagnosis technology of aircraft cable open circuit and short circuit fault has been very mature,but there is still no stable and reliable detection method for weak fault caused by local damage or structural change of aircraft cable.Therefore,it is of great significance to study the weak fault of aircraft cable to ensure safe flight.Firstly,the transmission characteristics of aircraft cable based on the transmission line theory is analyzed,and the impedance of parallel double-wire single-core unshielded cables and coaxial cables according to the actual cable parameters are calculated respectively,and the corresponding aircraft cable model are established by using ANSYS electromagnetic simulation software.By changing the size parameters of the local position of the aircraft cable model to simulate the weak fault caused by the cable structure and shape changes,the distribution parameters and characteristic impedance changes of the aircraft cable under different degrees of fault are analyzed.Secondly,the augmented spread spectrum time domain reflectometry(ASSTDR)is proposed,which uses the improved variational mode decomposition to decompose the results of traditional spread spectrum time domain reflectometry and eliminate the noise interference caused by the environment and signal acquisition equipment,Then,the time-frequency transform is used to process the intrinsic mode components with fault information.On this basis,the spectrum is reassigned based on the time or frequency shift invariance and energy conservation characteristics of reassigned spectrogram,and then the weak fault of aircraft cables can be detected and located based on energy.Finally,the effectiveness and stability of ASSTDR are verified and analyzed by designing the experimental scheme,building the experimental platform,and making detailed cable fault diagnosis experiments with different fault degrees.The research results show that the ASSTDR proposed in this paper can effectively detect and locate the weak fault of the aircraft cable,and solve the problem that the traditional SSTDR,which cannot detect the weak fault of the cable,and ASSTRD has great engineering application value for the early weak fault detection of the cable.