Pulsed Eddy Current Detection of Rivet Hole Cracks in Multi-layer Metal Riveting Structure

Detection of the cracks in the rivet in the aircraft multi-layer metal riveting structure has been a difficult task and hot spot in the field of nondestructive testing. Based on the pulsed eddy current technology, this study designs probes and optimizes detection parameters:number of turns of excitation coil, frequency, distance between receiving sensor and rivet. A rotation device is also designed to enable probe to rotate around the rivet. The parameters of the detection probe and the changes of distance between the sensor and the rivet have a greater impact on the detection sensitivity. When the rotating device was used for detection, the number of excitation turns was 180 and the detection frequency was 100 Hz, when the distance between the probe and the rivet was 4 mm, the crack around the rivet hole with a length of 1,2 mm is better detected; for the cracks with length greater than 2 mm around the Rivet holes, detection sensitivity is higher when the distance between the probe and the rivet is 10 mm. At the same time, the results of rotation device test show that compared with pure manual detection, signal interference caused by the change of distance between probe and rivet was well restrained, false defects was reduced and detection efficiency was improved.