超声导波在管道中的传播特性的研究

采用超声导波技术可以对管道进行快速检测,因此工程应用上的前景非常广阔.在长距离管道检测过程中,经常会遇到环形焊缝和弯管,二者对对导波能量的反射较强.当导波能量出现较大衰减时,就会影响其有效检测范围.本文采用纵向和扭转模态导波,对导波在连续穿越七条环形焊缝和一段弯管的传播特性进行了研究,对其在检测凹槽、焊疤、支路等缺陷或管道特征方面的能力进行了对比.结论表明:(1)检测方向上的环形焊缝不超过4个才能充分保证检测结果的可信性.(2)最优频率的选择对非频散波的产生至关重要.

Study on Propagation Characteristics of Ultrasonic Guided Waves along the Pipe

Ultrasonic guided waves can be used to evaluate integrity of pipeline rapidly and its application in the field of non-destructive pipeline inspection is broad and promising.When geometry features of the pipe were changed,much energy of guided waves would be reflected and inspection distance may decrease.In this paper,longitudinal wave L(0,2) and torsional wave T(0,1) were used to study propagation characteristics of guided waves along a mild steel pipe.Research was carried out on energy attenuation of guided waves when it passes seven girth welds and a piece of elbow.Comparison of the two guided waves on sensitivity and location precision of defects or geometry features on the pipe,such as notch,burr and branch was given.The experimental results show:(1) girth welds in the inspection direction should be no more than 4 in order to receive reliable inspection result;(2) optimum frequency tuning is important in non-dispersive guided wave generation.