纵向导波与管道中双缺陷相互作用的数值模拟

Numerical simulation on the interaction of longitudinal guided waves with double defects in pipes

利用导波技术检测管道缺陷,将不可避免地遇到多缺陷相互作用问题。针对此类问题,利用数值模拟方法研究管道中双缺陷相互作用规律,建立双缺陷管道的三维有限元波动数值模型,并通过与已有实验结果的对比验证所建立模型的正确性,在此基础上系统研究相同大小双缺陷相对位置对导波反射特性的响应机理。研究表明,对双缺陷管道而言,两缺陷的相对周向位置对缺陷总体反射的影响很小,反射系数几乎不随缺陷的周向间距变化而变化;两缺陷的相对轴向位置对总体反射有较大影响,反射系数随轴向间距呈周期性变化。此外,在一定轴向长度范围内的多个缺陷,其反射系数近似符合叠加原理,这对局部缺陷群的检测有重要意义。

In guided-wave based pipeline non-destructive inspection,it is inevitable that guided waves will interact with multiple defects,which makes damage identification more challenging.In this study,a numerical simulation was conducted to investigate the interaction of longitudinal guided waves with double notches in pipes.Firstly,a three-dimensional finite element model was established to simulate guided wave propagating in a pipe with a single notch.Then the established model was validated by comparing with existing experiments results.Based on the validated model,the guided wave reflection characteristics of two equal-sized notches of various relative positions were discussed systematically.The results show that,the relative circumferential positions of the two notches have little influence on the overall reflection,and the reflection coefficient rarely varies with the circumferential distance.However,the overall reflection of the two notches at the same circumferential location mainly depends on their axial positions,and the reflection coefficient varies periodically with the axial distance of the two notches.Moreover,the reflection coefficients of multiple notches within some axial range follow superposition principle approximately,which is very helpful for group corrosion detection.