基于角谱传播的管道超声导波成像检测研究

发布时间：2018-05-23 23:42

本文选题：管道超声导波 + 尺寸变化缺陷　；参考：《江苏大学》2016年硕士论文

【摘要】：管道在石油、天然气等易燃易爆物质的运输中应用广泛,对其的安全检测不容忽视。超声导波管道检测技术具有检测距离长、效率高的特点,非常适合里程巨大管线的检测。但现有导波检测所得结果均比较抽象,无法直观的得到缺陷信息,若能利用导波技术对管道进行成像检测,那么检测结果就可以用图像直观呈现,检测技术也就更容易被检测人员理解与掌握,从而使导波技术更快更好的应用于管道检测中。本文以超声导波理论为基础,结合角谱传播原理的声场成像理论,提出了基于角谱传播的管道导波成像方法,并通过数值模拟和试验的方式,成功对管道进行了成像检测,并利用所得图像对缺陷进行了定位和定量研究。本文的主要工作和结论有:1)阐述了超声导波理论和基于角谱传播原理的声场成像理论,根据导波检测的特点建立了基于角谱传播的管道导波成像的理论模型,并设计了成像算法。2)利用ANSYS有限元分析软件建立了管道导波成像检测的分析模型,研究了不同导波模态、激励信号、传感器布置、有效频带“BE”下的成像效果。结果表明,导波频散越小、波长越短,成像的轴向分辨率越好;周向均布的传感器个数越多,成像受干扰模态影响越小;有效频带“BE”达到一定值时,就可以获得与全频带基本相同的成像效果。根据以上结论确定了成像检测,使用T(0,1)模态、5周期汉宁窗调制正弦信号,激励节点个数为40个,75kHz的激励频率下,有效频带“BE”为35-115kHz。3)利用设计的成像算法得到了导波的角谱及其成像数据,研究了缺陷尺寸周向变化和轴向变化管道中导波的模态转换及其成像检测。对模态转换的研究发现,缺陷周向尺寸越大,转换产生的弯曲模态导波比重越大;而缺陷轴向尺寸的增加,弯曲模态导波比重未有明显的增多;T(0,1)模态转换产生的模态类型基本不随缺陷的变化而变化,主要为F(1,2)、F(2,2)、F(3,2)、F(4,2)等模态。对成像检测的研究发现,缺陷和管道特征的准确位置均能从检测图像中直接得到,周向定位精度可达±5°,轴向定位精度可达±12mm;对于周向尺寸大于所用导波波长的缺陷,可以利用3/4周向幅值宽来对其进行定量的判定。4)搭建了成像试验系统,对管道导波成像方法进行了试验验证研究。研究表明,所用成像方法可以对实际管道进行成像检测,检测图像准确反映了缺陷和管道特征的位置信息,周向缺陷的轴向定位精度可达±8mm;同时根据数值模拟所得结论,对周向缺陷进行了定量的试验研究。本文使用超声导波对管道进行成像检测,通过数值模拟与试验研究,验证了基于角谱传播的管道导波成像方法的正确性,研究工作为管道导波成像检测提供了理论与工程应用依据。
[Abstract]:Pipeline is widely used in transportation of flammable and explosive materials such as oil and natural gas. Ultrasonic guided wave pipeline detection technology has the characteristics of long detection distance and high efficiency, so it is very suitable for the detection of pipeline with huge mileage. However, the current results of guided wave detection are abstract and can not directly get the defect information. If the guided wave technology can be used to detect the pipeline, then the detection results can be presented directly by the image. The detection technology is easier to be understood and mastered by the detection personnel, so that the guided wave technology can be used in pipeline detection more quickly and better. Based on the theory of ultrasonic guided wave and the theory of acoustic field imaging based on the principle of angular spectrum propagation, a method of guided wave imaging of pipeline based on angular spectrum propagation is proposed in this paper, and the imaging detection of pipeline is carried out successfully by numerical simulation and experiment. The defect location and quantitative study are carried out using the obtained image. The main work and conclusions of this paper are as follows: (1) the ultrasonic guided wave theory and the acoustic field imaging theory based on the angular spectrum propagation principle are expounded. According to the characteristics of the guided wave detection, the theoretical model of the guided wave imaging based on the angle spectrum propagation is established. The imaging algorithm. 2) using ANSYS finite element analysis software, the analysis model of pipeline guided wave imaging detection is established, and the imaging effect under different guided wave mode, excitation signal, sensor arrangement and effective frequency band "be" is studied. The results show that the smaller the pilot-wave dispersion and the shorter the wavelength, the better the axial resolution of imaging, the more sensors distributed in the circumferential direction, the less the influence of interference modes on the imaging, and when the effective band "be" reaches a certain value, The imaging effect is basically the same as that of the whole frequency band. According to the above conclusions, the imaging detection is determined, and the sine signal is modulated by using the 5 period Hanning window of the TX 0 / 1 mode, and the excitation frequency is 40 kHz, the number of excitation nodes is 40 kHz, and the excitation frequency is 75 kHz. The effective band "be" is 35-115 kHz. 3) the angle spectrum of guided wave and its imaging data are obtained by using the designed imaging algorithm. The mode conversion and imaging detection of guided wave in pipeline with circumferential and axial variation of defect size are studied. It is found that the larger the circumferential dimension of the defect, the greater the specific gravity of the bending mode guided wave generated by the transformation, and the greater the axial dimension of the defect. The specific gravity of guided wave in bending mode does not increase obviously.) the modal types produced by modal transformation basically do not change with the change of defect. The study of imaging detection shows that the defect and the accurate location of the pipeline feature can be obtained directly from the detected image, the accuracy of circumferential positioning can reach 卤5 掳, and the accuracy of axial positioning can reach 卤12mm. for the defect whose circumferential dimension is larger than the wavelength of the guided wave used, the circumferential dimension is larger than the wavelength of the guided wave. The imaging test system can be set up by using 3 / 4 circumferential amplitude width to determine quantitatively. 4) the guided wave imaging method of pipeline is tested and verified. The study shows that the imaging method can be used to detect the actual pipeline, and the detection image accurately reflects the location information of the defect and pipeline characteristics, and the axial positioning accuracy of the circumferential defect can reach 卤8 mm. At the same time, according to the numerical simulation, the conclusion is obtained. A quantitative experimental study of circumferential defects was carried out. In this paper, the ultrasonic guided wave is used to detect the pipeline. Through numerical simulation and experimental study, the correctness of the guided wave imaging method based on angular spectrum propagation is verified. The research provides theoretical and engineering basis for pipeline guided wave imaging detection.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG115.285

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