板中超声导波弧形合成孔径阵列多帧满秩成像检测

Multi-frames Imaging Detection of Full Rank for Arc Synthetic Aperture Array of Ultrasonic Guided Waves in Plates

超声导波合成孔径阵列作为一种基本的成像方式,其"一发多收"阵列多帧满秩成像具有重要意义。针对板中超声导波弧形合成孔径阵列,运用波幅矩阵和渡时矩阵对弧形阵列接收孔径进行分析讨论,在依次变换发射阵元情况下,研究弧形合成孔径阵列多帧满秩成像和全帧满秩成像。研究结果显示,弧形合成孔径阵列多帧满秩成像可用以表征成像检测区域内散射体信息,弧形阵列自然焦点处多帧满秩图像灰度值基本一致,全帧满秩图像信噪比得到了不同程度增大。由于阵列阵元"边缘效应",阵列边缘阵元所对应的满秩图像背景灰度值增大约50%,全帧满秩图像对比度增大约200%。成像检测试验验证了成像原理的可行性,表明板中超声导波弧形合成孔径阵列多帧满秩成像可有效表征待检区域声场散射信息,研究工作可为深入开展超声导波非规则阵列成像检测研究与应用提供重要基础。

The synthetic aperture array of ultrasonic guided waves is a important imaging method, which multi-frames imaging detection of full rank is of great significance. Aiming at the arc synthetic aperture array of ultrasonic shear horizontal(SH) guided waves in plates, the receiving aperture of arc synthetic aperture array are analyzed by using the amplitude matrix and the flight time matrix. Under the condition of transforming the transmitting array elements in turn, the multi-frames imaging of full rank and whole-frame full rank imaging of the arc synthetic aperture array are all discussed. The research results show that the multi-frames imaging of full rank of arc synthetic aperture array could be used to characterize the scattering information in the testing area, the gray value of the multi-frames images of full rank at the natural focus of arc synthetic aperture array are according with each other, and the signal-to-noise ratio of the whole-frame image of full rank is increasing. Due to the "edge effect" of the array element, the background gray value of the images corresponding to the array edge element increases by about 50%, and the contrast value of the whole-frames image of full rank increases by about 200%. The imaging detection experiment verifies the feasibility of the imaging principle, which shows that the multi-frame full rank image of arc synthetic aperture array for ultrasonic guided waves in plates could characterize the scattering information of the area to be examined, and the research work proposed would provide an important basis for the further research and application of irregular array imaging detection of ultrasonic guided waves in plates.