焊接板结构中缺陷的非规则超声SH导波阵列成像检测研究

Comparing with regular arrays, the irregular arrays including non-line arrays, sparse arrays and arbitrary arrays break through the restrictions of weld’s diversity, complex and industrial rigid testing conditions, and so the irregular arrays are more adapted for imaging and testing of ultrasonic guided waves for defects in plate with welded structures. In this project, based on the characteristic of elliptical cluster tracks, the model of synthetic aperture focusing imaging of ultrasonic SH guided waves for defects in plate with welded structures by irregular arrays will be established, which may reveal imaging regulation of irregular arrays with imaging algorithm. The relationship between the gradient matrix of elliptical clusters and the position angle matrix of array elements will be discussed, and the resolution analyzing criterion of irregular array imaging and testing for ultrasonic guided waves will be proposed. The influence of boundary scattering and weld scattering on the imaging and testing of ultrasonic guided waves will be studied, according to which the imaging algorithm will be improved. Furthermore, the dominant roles of main frame image in more frame images of irregular arrays will be studied, and the fusion algorithm of more frame images of irregular arrays will be presented. For the purpose of promoting and facilitating the further development of theory and application of imaging and testing of ultrasonic guided waves for defects in plate with welded structures and structure health monitoring, there is no doubt that the results obtained in this project will have important significance for imaging and testing of circumferential ultrasonic guided waves in hollow cylindrical structures.

与规则阵列相比，非直线型、稀疏型和任意型等非规则阵列突破了焊缝形式多样性、复杂性和工业现场苛刻检测条件限制，更适合于焊接板结构中缺陷的超声导波成像检测。项目将基于椭圆簇轨迹特征建立焊接板结构非规则超声SH导波阵列合成孔径聚焦成像模型，揭示其成像算法运用于非规则阵列的成像规律；探讨成像时散射体处椭圆簇斜率矩阵与阵元方位角矩阵的关系，建立用于分析判定非规则超声导波阵列成像检测分辨率的判据；揭示焊缝散射对板中非规则超声导波阵列成像检测的影响机理和影响规律，改进焊接板结构非规则超声导波阵列成像算法；探讨主帧图像在非规则阵列多帧导波图像中的主导作用，提出非规则阵列多帧导波图像融合处理算法。项目拟开展的研究工作和预期成果，可进一步丰富和发展焊接板结构中缺陷的超声导波成像检测理论、方法和技术，对焊接管结构周向超声导波阵列成像检测研究与应用也具有重要的借鉴意义。

焊接板结构常用于土木工程、石油储运等工业领域中，对其进行超声导波成像检测需求日益迫切。项目对以下问题进行了研究。.基于阵列成像椭圆簇轨迹特征，提出了超声导波合成孔径多帧变秩成像模型，探讨将其用于非直线阵列成像检测，讨论了接收矩阵的秩不同时多帧图像在灰度、信噪比、对比度、成像耗时等方面的关联特性，将为焊接板结构超声导波非规则阵列成像检测提供更为丰富的基础图像数据。.基于阵列成像椭圆簇轨迹特征，提出了超声导波合成孔径多帧满秩成像模型，探讨将其用于非规则阵列成像检测，讨论了不同帧序满秩图像在灰度、信噪比、对比度等方面的关联特性，将为焊接板结构超声导波非直线阵列成像检测结果分析与判别提供支持。.将焊缝散射因子和散射矩阵用来分析量化焊缝散射，从导波阵列信号和阵列成像机理出发，探讨了焊缝散射因子和散射矩阵在阵列成像的中的作用，从而揭示出焊缝散射对超声导波阵列成像检测的影响规律，有助于深入开展焊接板结构超声导波非规则阵列图像处理和图像识别。.将散射回波矩阵和散射渡越时间矩阵用于描述声波散射，运用散射因子来定量表征声波散射时的回波信号特征，从合成孔径阵列成像算法和成像机理出发，研究了声波散射在阵列成像中的作用机制，明确了焊缝散射与边界散射之间的关系，可为深入开展焊接板结构超声导波非规则阵列成像算法改进提供支持。.为揭示接收孔径对超声导波合成孔径阵列成像检测的影响机制，提出将接收矩阵作为分析工具对超声导波合成孔径阵列成像原理展开研究。通过运用波幅接收矩阵和渡越时间接收矩阵来定量描述接收孔径，重点以满秩接收孔径、半秩接收孔径和单秩接收孔径对影响超声导波合成孔径阵列成像的机理进行了研究，可为改进超声导波非规则阵列成像方法提供支撑。.项目研究工作，可进一步丰富和发展焊接板结构中缺陷的超声导波非规则阵列成像检测相关理论、方法和技术，对焊接管结构周向超声导波非规则阵列成像检测研究与应用也具有重要借鉴意义。