Research On Detection Technique For Complex Structure Aircraft Cable Insulation Layer Defects Based On Ultrasonic Guided Waves

Aircraft is of self-evident importance to the modern aerospace field,which involves transportation,economy,production and people’s daily life.At the same time,it is also an important part of the modern military strategy of various countries.The safe operation of aircraft is concerned by the whole society.Aircraft cable,as an important medium of signal transmission of electronic and electrical system inside the aircraft,constitutes a whole of various communication equipment inside the aircraft.Because of the special environment inside the aircraft,the damage of the aircraft cable is inevitable and will lead to many serious consequences,which is a thorny problem that puzzles people for a long time.Special attention should be paid to the failure of aircraft cables that before the aircraft cable failure what is often observed is cable insulation damag.In order to ensure flight safety,it is necessary to detect whether there are defects in the insulation layer of aircraft cable.The existing detection methods have limitations such as low efficiency and offline detection.Therefore,this project proposes a defect detection method of aircraft cable insulation layer based on ultrasonic guided waves(UGWs).Compared with the traditional aircraft cable fault detection technique,UGWs is characterized by low loss and wide coverage.It can detect the insulation layer of aircraft cables when they are energized,and identify,locate,evaluate the possible defects.The technique will not be interfered by the complex electromagnetic environment and will not cause damage to the cable.In this paper,UGWs is applied to the integrity inspection of aircraft cable insulation layer,and a defect inspection system of aircraft cable insulation layer based on UGWs is built.The system can give early warning before the failure of aircraft cable,eliminate the potential risk of cable.In this paper,the propagation characteristics of UGWs in complex structure aircraft cable are studied,and the propagation characteristics of UGWs in complex structure aircraft cable are simulated by finite element analysis.Multi-strand cables,90° bent cables and 180°bent cables were detected by the aircraft cable insulation defect detection system,the detection signals of four kinds of defects are collected in the experimental study and the wavelet filtering method is used to preprocess the signals to improve the signal-to-noise ratio.The influence of defect type,defect size,defect location and bending on UGWs propagation characteristics in aircraft cable insulation layer was analyzed,and the defect type was determined by using VMD decomposition to extract the normalized energy of detection signal as its feature vector.