【作者】 王智；

【导师】 何存富；

【作者基本信息】 北京工业大学 ， 机械制造及其自动化， 2002， 硕士

【摘要】 管道的腐蚀、壁厚减薄等缺陷是石油、化工和水暖工业中面临的主要问题。这些缺陷既可能发生在管道外壁又可能发生在管道内壁，通常致使管道壁厚减薄。而传统无损超声检测技术是单点检测，因而，在检测长距离管道时，这种方法遇到很大困难。而利用纵向超声导波检测管道缺陷，激励导波沿管道传播，通过监测管道回波的变化，达到一次检测数十米的管道范围，并且是全范围检测。但是，由于导波的多模态特性及频散特性，往往使数据分析异常复杂，因此，选择和激励单一模态导波检测管道可大大简化问题分析的复杂性。本文正是针对这一课题深入研究了纵向超声导波技术及其检测管道缺陷的方法。首先，对当前本课题研究领域的进展作出综述，并简要介绍与超声导波技术相关的理论基础；其次，建立了一套有效的实验装置，在此实验装置基础上，重点研究了采用分布式PZT传感器在管中激励和接收特定模态超声导波的方法：根据在管状波导中传播的超声波具有频散现象及多模态特征，选择具有单一频率的特定信号激励超声导波，使其频散最小；同时采用分布式传感器抑制不同模态的波型。经大量实验验证，其实验结果与理论预测相吻合。在此基础上，进一步研究管道缺陷回波的特性，通过分析、处理接收到的管道中的缺陷回波特征，达到缺陷识别和定位的目的。更多还原

【Abstract】 Corrosion and pitting defects in pipe work are major problems in the oil, chemical, and other industries. These defects can occur at the outer or inner surface of the pipe and can lead to a serious loss of pipe wall thickness. Traditional Ultrasonic nondestructive testing techniques are single position measurements, therefore, they tend to be so slow that making long distance pipe inspection is almost impossible. An alternative to traditional pipe detection method is to excite stress waves, which can propagate along the pipe, and to monitor the response of the pipe for changes in the received signal at some remote positioa An ultrasonic inspection technique using guided waves was applied to detect and determine the exact location of flaws in long steel pipes. Since many modes of guided waves are generated due to guided waves’ multi-modes characteristic in the inspected pipe, to select and excite only single mode to detect 1he pipe can obviously simplify the analysis complexity. The project just do research on using certain guided wave modes to detect the pipe flaw. First, the development in this field was introduced. And the relative theories and basis were explained. Finally, some important conclusions were drawn, that is, using distributed PZT transducers, ultrasonic guided waves are generated and received in a pipe. Usually, there are many different modes of guided wave propagating in the pipe and these modes are generally dispersive, the specific exciting signal of a Harming windowed toneburst with a central frequency of 70kHz for decreasing the effect of dispersion was selected. And guided wave are generated using 16 distributed PZT transducers in a circumferential direction for suppressing flexural modes. The experimental results greatly agreed with the theoretical ones. On this basis, the flaw of the pipe can be detected and located by analysing the data from the receiving waves.更多还原