Pulsed Eddy Current Detection And Automatic Scanning Realization Of Rivet Hole Cracks In Multi-layer Riveting Structure

The defect detection of multi-layer metal riveting structure has always been a difficult problem in the field of nondestructive testing.There are many interference factors in the process of detection,which makes the detection more difficult.This paper through the analysis of a large number of domestic and foreign scholars and research institutions for multilayer metal riveting structure defect detection method,choose the pulsed eddy current detecting technology in multi-layer metal riveting structure,designed and manufactured with a special sensor and automatic scanning system,put forward its own test method and a large number of experiments.In this paper,the detection device of rivet peripheral defect of multi-layer metal riveting structure is designed based on pulse eddy current detection technology.This device allows the probe to keep a certain distance from the center of the rivets,and the center of the rivets is rotated for 360 degrees.Experimental study on the probe excitation coil number of turns,test frequency and receiving sensor from the rivet from the effects of factors on test results and optimize the detection parameters,to improve the detection sensitivity of the entire detection device.Compared the traditional cylindrical rotating devices used single probe and rectangular single probe testing around the rivet crack,the sensitivity of the experiments show that the rectangular single probe test multilayer metal riveting structure on deep tiny crack sensitivity is higher than cylinder of the detection sensitivity of the single probe.Rotating at the same time detection transposed compared with manual rotation detection,experiment shows that rotation detection device stability is strong,can inhibit the manual test in the process of riveting influence on test results,reduce pseudo defects and improve the detection efficiency.Design and set up automatic scanning test system,this system can automatically by the pulsed eddy current generator synchronous trigger scanning frame with LabVIEW continuous acquisition system,to achieve synchronization acquisition and save the data,data that contains the information acquisition time also includes the location of the information collection.In this paper,using automatic scanning detecting system in multilayer metal around the rivet riveting structure defects,according to the method to detect surrounding the rivet crack rotating device,puts forward a kind of detection data processing algorithm based on automatic scanningsystem,to extract the rivet surrounding data,to realize the recognition of defects around the rivet and positioning.Finally,the whole research is summarized and the future research direction is put forward.