• CN:11-2187/TH
  • ISSN:0577-6686

机械工程学报 ›› 2019, Vol. 55 ›› Issue (4): 25-32.doi: 10.3901/JME.2019.04.025

• 仪器科学与技术 • 上一篇    下一篇

基于相位相干性的厚壁焊缝TOFD成像检测研究

陈尧1,2, 冒秋琴1, 石文泽1, 陈果1, 林莉3, 金士杰3, 甘勇1, 吴霞1, 卢超1   

  1. 1. 无损检测技术教育部重点实验室(南昌航空大学) 南昌 330063;
    2. 中国科学院声学研究所声场声信息国家重点实验室 北京 100190;
    3. 大连理工大学无损检测研究所 大连 116085
  • 收稿日期:2018-06-05 修回日期:2018-12-05 出版日期:2019-02-20 发布日期:2019-02-20
  • 通讯作者: 卢超(通信作者),男,1971年出生,博士,教授,硕士研究生导师。主要研究方向为超声检测与仪器。E-mail:luchaoniat@163.com
  • 作者简介:陈尧,男,1984年出生,博士,讲师。主要研究方向为材料超声无损检测与评价。E-mail:chenyao1984@foxmail.com
  • 基金资助:
    国家自然科学基金资助项目(51705232,51265044,51705231)、声场声信息国家重点实验室开放课题研究基金(SKLA201806)和江西省自然科学基金(20171BCB24008)资助项目

Research on Ultrasonic TOFD Imaging Inspection for Heavy-walled Weld Based on Phase Coherence Characteristics

CHEN Yao1,2, MAO Qiuqin1, SHI Wenze1, CHEN Guo1, LIN Li3, JIN Shijie3, GAN Yong1, WU Xia1, LU Chao1   

  1. 1. Key Lab. of NDT, Ministry of Education, Nanchang Hangkong University, Nanchang 330063;
    2. State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190;
    3. NDT & E Laboratory, Dalian University of Technology, Dalian 116085
  • Received:2018-06-05 Revised:2018-12-05 Online:2019-02-20 Published:2019-02-20

摘要: 将相位相干成像(Phase coherence imaging,PCI)后处理算法应用于厚壁焊缝超声TOFD检测,有效改善低信噪比和水平分辨力问题。首先,利用合成孔径聚焦(Synthetic aperture focusing technique,SAFT)算法对TOFD-B图像的孔径数据集进行延时叠加处理。然后,基于PCI算法通过孔径数据集中各路信号的相位信息构建相干因子,用以表征B-SAFT图像中各像素点的相位相干性。最后,通过构建的相位相干因子对B-SAFT图像进行加权处理。结果表明,PCI算法能够通过放大相位分布对像素点幅值的贡献,有效抑制噪声和提高信噪比,使壁厚78 mm奥氏体不锈钢焊缝中3个φ3边钻孔平均信噪比达到30 dB以上,较TOFD-B图像提高了20 dB。此外,PCI算法还可增强孔径波束指向性提高分辨力,使48 mm壁厚CV焊缝中缺陷半波高水平宽度较TOFD-B图像缩小70%以上。

关键词: TOFD, 超声, 焊缝, 厚壁, 相位相干成像

Abstract: To improve the signal to noise ratio (SNR) and lateral resolution, phase coherence imaging (PCI) post-processing algorithm is presented and applied in ultrasonic time-of-flight diffraction (TOFD) inspection for heavy-walled welds. Firstly, delay and sum operation for the aperture data of TOFD-B image is implemented by synthetic aperture focusing technique (SAFT). Secondly, phases of aperture data were used to establish phase coherence factor which represented the phase dispersion for each pixel in the B-SAFT image. Finally, the B-SAFT image is dynamically weighted by phase coherence factor. The results show the PCI is capable of suppressing structure noise and enhancing SNR by amplifying the contribution of phase information. For austenitic weld with 78 mm thickness, the average SNR of three φ3 side drilled hole were more than 30 dB, higher 20 dB than TOFD-B image. Furthermore, the PCI could improve the lateral resolution by enhancing aperture beam directivity. Compared to TOFD-B image, the half lateral width of defect in processed images were decreased by more than 70 percent for a 48mm thickness CV weld.

Key words: heavy-walled, PCI, TOFD, ultrasonic, weld

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