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.

摘要

本文旨在通过分析从圆周裂纹前缘和后缘反射回来的两个SH ₀导波，提供一种检测圆周裂纹的方法。我们建立了 SH ₀传播的有限元模型管道中的导波，这些波是由周期永磁电磁声换能器 (PPM EMAT) 产生的。研究了圆周裂纹几何参数对两种边缘反射波的影响。随后，通过两个边缘反射波的时移提供了裂纹周向范围估计的准确性。最后，通过实验验证了模拟结果。结果表明，裂纹前沿波的峰值随着裂纹截面面积在圆周方向上的增加呈线性增加趋势。当全厚度裂纹的周向范围增加时，裂纹后缘波的峰值显示出大致的周期性变化。当裂纹的圆周范围不小于 10 mm 时，估计圆周范围与实际范围的相对偏差小于5.1%。两个边缘反射波的相关信息可以提供准确和定量的管道缺陷表征。