Resolution Enhancement of Total Focusing Imaging Combining with Autoregressive Spectral Extrapolation

被引：0

作者：

Lin L. ^{[1
]}

Shi S. ^{[1
]}

Sun X. ^{[1
]}

Ma Z. ^{[1
]}

Zhang X. ^{[2
]}

Liu L. ^{[3
]}

Jin S. ^{[1
]}

机构：

[1] NDT & E Laboratory, Dalian University of Technology, Dalian

[2] Nuclear Industry Research and Engineering Co., Ltd., Beijing

[3] China Nuclear Industry 23 Construction Co., Ltd., Beijing

来源：

Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | 2020年 / 56卷 / 22期

关键词：

Autoregressive spectrum extrapolation; Imaging resolution; Total focusing method; Ultrasonic detection;

D O I：

10.3901/JME.2020.22.008

中图分类号：

学科分类号：

摘要：

The defects with close spacing are difficult to be distinguished by ultrasonic imaging with total focusing method(TFM). Autoregressive spectrum extrapolation with low-order and wide effective frequency band is introduced to compress the pulse width in time domain, achieving subwavelength resolution imaging of TFM. Two preset side-drilled holes having 1.8 mm center distance and 1.3 mm diameter in the simulated model of carbon steel are detected by array probe with 2.25 MHz center frequency and 32 elements. Focusing on full matrix capture, taking 2-order and the width of frequency window represented a 14 dB drop from the maximum amplitude of spectrum, and the autoregressive model is established to extrapolate the high-frequency and low-frequency components beyond effective frequency band. Then, the delay-and-sum algorithm is implemented on the processed full matrix capture data to obtain the TFM image. The simulated results indicated that the combination of TFM and autoregressive spectrum extrapolation with low-order and wide effective frequency band had high robustness and accuracy, so as to effectively separate adjacent defects with center distance of 0.7λ(λ is ultrasonic wavelength). The positioning error is no more than 0.73% while retaining the lateral resolution. Finally, side-drilled holes having 1.8 mm center distance are calculated with the same testing parameters in experiment, and the positioning error is no more than 1.06%, effectively improving imaging resolution of TFM. © 2020 Journal of Mechanical Engineering.

引用

页码：8 / 13and23

页数：1315

共 19 条

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