Defect Detection in Cylindrical Cavity by Electromagnetic Ultrasonic Creeping Wave

Internal defect, especially the parts of the cavity structure defect, is a challenging task in the field of non-destructive testing and often is falsely detected or undetected in the testing process. Creeping wave is a type of compressional wave, which propagates below the curved surface and is sensitive to surface and near-surface defects. Creeping wave detection provides a possibility to recognize internal defect. In this paper, the detection of cylindrical cavity defect by using the electromagnetic ultrasonic creeping wave was studied through the finite-element method. The sensitivity of creeping wave detection was improved through the design of coil parameters, which concentrate the energy and reduce the oblique incidence beamwidth of shear wave. Three common crack defects were analyzed in the structure of cavity. The results show that creeping wave detection can be used to recognize the defects which are more difficult to be detected in the cavity and the features of the defect are obvious, which provides a novel method for the internal cavity defect detection.