小口径管扭转模态导波在线检测

On-line Inspection of Small Diameter Tubes Using Torsional Guided Waves

采用扭转模态导波T(0,1)开展了小口径管在线检测研究。考虑管线服役环境及其结构特征,研制了一种适用于小口径管线在线检测的新型传感器阵列。传感器采用剪切型压陶瓷晶片作为敏感元件,具有柔性、轻质的特点。实验表明,环向布置的传感器阵列能够在管线中高效激励T(0,1)模态导波;通过提取回波信号中的各模态导波信息,实验系统能有效辨识管线中缺陷的状态变化;对于含有支撑结构的小口径管,比较并分析管线中导波散射信号及特征结构处回波信号的变化有助于辨识支撑结构附近区域损伤的产生及扩展。

The on-line inspection of small diameter tubes is studied by using torsional guided wave I （0,1）. Considering the service environment of tubes and their structural characteristics, a novel transducer array applicable to on-line inspection of tubes is developed. The transducer employs shear piezoelectric ceramic as the sensitive ele- ment, and has the characteristics of flexible and lightweight. Experimental results show that a ring of transducers can efficiently excite the T（0,1） mode guided wave in tubes. By extracting each of guided wave modes information in echo signals, the experimental system can effectively identify the state of the defects in tubes. For the tubes that contain support structure, comparing and analyzing the changes of scattered signal and echo signal from characteristic structure in tubes is contributed to identify the generation and extension of defects near the support region.