Research On Array Pulsed Eddy Current Inspection Of Riveted Multilayer Metal Structure In Aircraft

Riveted multilayer metal structure is widely used in aircraft and an important part of fuselage skin.Because of the influence of rivets and other disturbing factors,it is a difficult problem to detect the rivet hole defects in riveted structure.Array pulsed eddy current testing is one of the developing eddy current non-destructive testing techniques.It has the characteristics of rich pulse spectrum detection and simple detection,and has the advantage of high array scanning efficiency.This paper used this technique to build the relevant detection scheme,to make experiments and carry out researches.The main work was to design array probe and write programs to automatically scan the corrosion defects and multilayer plate cracks in real time using the automatic scanning rack.Defects include rivet hole cracks and corrosion between riveted plates.By referring to the related experiments and analysis of a large number of domestic and foreign scholars' references,appropriate magnetic sensor TMR was selected as the device to receive signals,and amorphous alloy was used as the magnetic core of the probe.For the rivet hole cracks in plannar multilayer metal riveting structure,rectangular probe with linear array were designed and manufactured,the spacing of signal receiving device was optimized,and the effect of geomagnetic field was eliminated by signal processing,the test block was detected by rotary scanning method.The experiments results showed that there were an optimal detection angle between the defect and the array axis.,and the rotary scanning has significant detection effect on the defects around the rivet hole.For the rivet hole cracks in curved multilayer metal riveting structure,a flexible linear array probe was designed and manufactured,and the probe parameters were optimized to improve the detection sensitivity.The rotating scanning method was also used to detect the test bolck.The experimental results showed that the flexible probe has high sensitivity for detecting the rivet hole cracks in curved test bolck.The multi-channel automatic scanning real-time imaging detection system was designed and built with LabVIEW software and automatic scanning frame.The probe was installed on the automatic scanning rack.When the pulsed eddy current generator triggers synchronously,the automatic scanning begins.At the same time,the software parts extracted the differential signal eigenvalues of each channel of the linear arrayrectangular probe and constructed the eigenmatrix to realize the automatic scanning real-time imaging.Finally,the whole research was summarized and puted forward the future experimental direction and suggestions for the shortcomings of the existing research.