厚壁管道超声导波检测方法与传感关键技术研究

As the major components bearing high temperature and pressure, the thick-wall pipe is commonly used in the main steam pipeline and the reheat steam heat section of the pipeline in the electric power industry. The thick-wall pipe health inspection is the top priority of the metal quality supervision in the power plants, because the included initial defects in base metal of the thick-wall pipe and the damage or cracks induced in the service stage directly affect the operation safety and result in a reduction in the service life of the structures. This project focuses on developing the corresponding propagation theory of the ultrasonic guided wave (UGW) in the thick-wall pipe, exploring the detection mechanism of the new-style array transducer and the breakthrough on the key technologies for the transducer design and manufacture. Therefore, the proposed guided wave inspection method based on novel transducers can be applied for the defect detection in the thick-wall pipe with high efficiency. The project will mainly emphasize on the following aspects: 1) to investigate the generation mechanism of ultrasonic guided waves considering the effect of the excitation sources, to establish the parameter optimization model for ultrasonic guided waves inspection method, and to research the propagation characteristics of ultrasonic guided waves in the thick-wall pipe and the interaction of ultrasonic guided waves with the defects.2) to research the inspection mechanism of the broad-band surface acoustic wave (SAW) transducer, the narrow-beam guided wave arrayed transducer with multi-element and its sidelobe suppression mechanism, and the fabrication of flexible hybrid transducer with multifunction. 3)to characterize the defect in the thick-wall pipe using the SAW or UGW, to plan the scanning path for defect detecion in global field, and to develop signal processing method for defects identification. As a result, a number of core technologies with the independent intellectual property rights are developed for inspecting the defects in the thick-wall pipe.

作为重要的高温高压承载部件，厚壁管道广泛应用在电力行业的主蒸汽、再热蒸汽热段管道等，是电厂金属监督检验的重中之重。厚壁管道母材的初始缺陷,在役过程中产生的损伤、缺陷及裂纹等直接影响厚壁管道整体结构的运行安全和使用寿命。本项目立足发展厚壁管道超声导波传播的相关理论，研究新型阵列传感器的检测机理,突破传感器设计与制造工艺的关键技术，提出基于新型传感技术的导波检测新方法，以实现厚壁管道缺陷的高效检测。研究重点为：1)激励源作用下厚壁管道中超声导波形成机理；超声导波检测参数的优化匹配模型建立；厚壁管道中超声导波传播特性及与缺陷的相互作用。2)宽带表面波传感器检测机理、窄声束导波阵列传感器及其旁瓣抑制机理、多功能一体化柔性导波传感器的集成与制造技术。3)厚壁管道缺陷表面波/超声导波表征方法；缺陷检测全场扫描路径规划；导波检测信号处理与缺陷特征识别。最终形成具有自主知识产权的厚壁管道缺陷检测成套技术。

作为重要的高温高压承载部件，厚壁管道广泛应用在电力行业的主蒸汽、再热蒸汽热段管道等，是电厂金属监督检验的重中之重。本项目立足于发展厚壁管道超声导波传播的相关理论，研究了新型阵列传感器的检测机理，突破了传感器设计与制造工艺的关键技术，提出了基于新型传感技术的导波检测新方法，实现了厚壁管道缺陷的有效检测。. 首先，发展了一种大频厚积情况下导波传播特性的计算方法，求解了厚壁管道中纵向、周向导波频散曲线，开发了相应的专用计算软件；初步诠释了激励源作用下超声导波的形成机理。揭示了厚壁管道中不同模态导波与不同类型缺陷的相互作用机理，提出了模态转换后复杂信号中微弱弯曲模态信号的分离方法；系统地研究了表面波在不同管径管道中的传播特性，提出了基于表面波反射/透射系数曲线的缺陷深度多频定征方法。其次，创新性地设计并实现了一种新型柔性非等间距梳状表面波宽带传感器；提出了一种任意激励函数下声场瞬态响应的求解方法；优化设计并研制了厚壁管道窄声束导波阵列传感器；研制了用于小径厚壁管检测的纵向导波电磁声传感器系列及高信噪比表面波电磁声传感器。再次，提出了一种基于时间反转多通道聚焦的信号增强方法，实现了对厚壁管道内外壁缺陷的有效检测和周向定位；首次提出了一种适于小径深比异型管道内壁周向缺陷检测的新方法；拓展了超声导波检测技术的应用范围，实现了热交换管内积碳层厚度的测量。最后，集成了一套厚壁管道表面波缺陷成像检测系统，研发了一套基于环向扫查器的磁致伸缩导波管道缺陷检测系统。

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