Interaction of circumferential SH<sub>0</sub> guided wave with circumferential cracks in pipelines
Wenze Shi, Weiwei Chen, Chao Lu, Yao Chen
Abstract
This paper aims to provide a method for detecting the circumferential crack by analysing the two reflected SH0 guided wave from the front-edge and back-edge of the circumferential crack. We established a finite element model for the propagation of SH0 guided waves in the pipe, and the waves were generated by a periodic-permanent-magnet electromagnetic acoustic transducer (PPM EMAT). The influences of the geometric parameters of the circumferential crack on the two edge-reflected waves were investigated. Subsequently, the accuracy of crack’s circumferential extent estimation by the time-shift of the two edge-reflected waves was provided. Finally, the simulated results were verified by experiments. The results show that the peak of the crack’s front-edge wave shows a linearly increasing trend with the increasing cross-section area of the crack in the circumferential direction. The peak of the crack’s back-edge wave shows a roughly periodical variation when the circumferential extent of the through-thickness crack is increased. When the crack’s circumferential extent is no less than 10 mm, the relative deviation between the estimated circumferential extent and the actual extent is less than 5.1%. The relevant information of the two edge-reflected waves can provide an accurate and quantitative pipeline defect characterisations.