Study On Acoustic Emission Detection Method Of Landing Gear Of A Unmanned Aerial Vehicle

The steel used by BZk-005 Unmanned aerial vehicle for Under-carriage were be studed in this paper.Based on the analysis of external load damage of landing,a sample designed to simulate loading damage of the external cylinder of the landing gear cushion pillar.The grating acoustic emission(ae)and piezoelectric sensing acoustic emission(ae)detection system for loading damage are constructed,through stage stretching and whole process stretching loading,obtain related signals such as loaddeformation-acoustic emission.The research conclusion obtained:By comparing the acoustic emission signals collected by the sensor and piezoelectric sensor in the loading test,Grating sensor is more sensitive than piezoelectric sensor in acoustic emission event counting and signal amplitude,Especially in the signal's rising time,duration time and wave energy counting sensitivity,The ringing count of large crack growth is lower and the anti-interference ability is strong.In the elastic deformation stage of 30CrMnSi steel for landing gear of uav,the signal mainly comes from fixture friction,Signal frequency is low(< 50kHz),signal rise time and duration is long.During the transition from yield to uniform plastic deformation,the signal amplitude is relatively low,the average signal amplitude is 50dB,the signal rise time and duration time is short,and the signal frequency is concentrated at 150kHz.In the necking stage,at this point,the main fibers break between dimples,and the small cracks aggregate to form large cracks,and the large cracks expand to form radiative patterns.The acoustic emission time is very long and the signal amplitude is high(about 56dB).The signal duration and rise time are long,and the signal frequency is concentrated between 100kHz and 700kHz.The rising time and duration of fracture stage are short in fracture.In this paper,the acoustic emission characteristics corresponding to the four stages of elastic deformation,yield,uniform plastic deformation and neck contraction of the landing gear materials for uav are obtained.The advantages of the fiber grating sensor are demonstrated,which lays a method foundation for the detection of the landing gear structure health of uav.