厚壁管道周向超声导波缺陷检测研究

厚壁管道在特种承压设备领域中广泛使用,常规无损检测技术难以实现其快速有效地检测。本文采用数值模拟与实验相结合来研究周向导波快速检测厚壁管道的方法。首先,利用有限差分软件研究了不同角度激励下外径269mm、壁厚32mm的厚壁管道中周向导波的传播特性,优化了探头激励角度范围;然后分别制作了55°和45°的斜楔,并搭建了实验系统,研究了周向导波与厚壁管道壁厚方向不同位置缺陷的相互作用规律。研究结果表明,周向导波适用于厚壁管道快速检测。检测时需选择角度适中的探头。激发角度过小时,厚壁管中形成的周向导波模式较多,使得波包宽度较大,影响检测分辨率;而角度过大时,会使得盲区增大,导致靠近内壁区域缺陷漏检。本文的研究结论为厚壁管道缺陷周向导波的实际检测应用提供了指导。

On the Defect Detection of Thick-Walled Pipe by using Circumferential Ultrasonic Guided Wave

Thick-walled pipes are widely used in the field of special pressure equipment industry.Conventional nondestructive testing technique is difficult to achieve fast and effective detection.In this paper,both numerical simulation and experiment are adopted to study the rapid detection of thickwalled pipe by using circumferential guided wave.Firstly,finite difference software was used to study propagation characteristics of circumferential guided wave excited at different angles in a thick-walled pipe with 269mm outside diameter and 32mm wall thickness,and the excitation angle range was optimized.Then,two kinds of wedge with apex angle of 55° and 45° were fabricated respectively,and the experimental system was established.The interaction between circumferential guided wave and defects located at different positions along wall thickness direction in a thick-walled pipe was experimentally studied.Experimental results show that circumferential guided wave is suitable for rapid detection in thick-walled pipes.In defect detection,it is necessary to select probe with appropriate angle.If the excitation angle is too small,the circumferential guided wave modes formed in thick walled pipe will be increasing,which leads to the large width of wave packet and lower detection resolution.On the other hand,too large excitation angle will lead to increase of blind area and the defects close to the inner wall may be undetected.Above results may provide reference for practical defect detection application of thick-walled pipe by using circumferential guided wave.