中国物理B ›› 2019, Vol. 28 ›› Issue (7): 74301-074301.doi: 10.1088/1674-1056/28/7/074301

• ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS • 上一篇    下一篇

Lamb waves topological imaging combining with Green's function retrieval theory to detect near filed defects in isotropic plates

Hui Zhang(张辉), Hai-Yan Zhang(张海燕), Meng-Yun Xu(徐梦云), Guo-Peng Fan(范国鹏), Wen-Fa Zhu(朱文发), Xiao-Dong Chai(柴晓冬)   

  1. 1 Shanghai Institute for Advanced Communication and Data Science, School of Communication and Information Engineering, Shanghai University, Shanghai 200444, China;
    2 School of Urban Railway Transportation, Shanghai University of Engineering Science, Shanghai 201620, China
  • 收稿日期:2019-03-07 修回日期:2019-04-22 出版日期:2019-07-05 发布日期:2019-07-05
  • 通讯作者: Hai-Yan Zhang E-mail:hyzh@shu.edu.cn
  • 基金资助:

    Project supported by the National Natural Science Foundation of China (Grant Nos. 11674214 and 11874255).

Lamb waves topological imaging combining with Green's function retrieval theory to detect near filed defects in isotropic plates

Hui Zhang(张辉)1, Hai-Yan Zhang(张海燕)1, Meng-Yun Xu(徐梦云)1, Guo-Peng Fan(范国鹏)1, Wen-Fa Zhu(朱文发)1, Xiao-Dong Chai(柴晓冬)2   

  1. 1 Shanghai Institute for Advanced Communication and Data Science, School of Communication and Information Engineering, Shanghai University, Shanghai 200444, China;
    2 School of Urban Railway Transportation, Shanghai University of Engineering Science, Shanghai 201620, China
  • Received:2019-03-07 Revised:2019-04-22 Online:2019-07-05 Published:2019-07-05
  • Contact: Hai-Yan Zhang E-mail:hyzh@shu.edu.cn
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Grant Nos. 11674214 and 11874255).

摘要:

A method of combining Green's function retrieval theory and ultrasonic array imaging using Lamb waves is presented to solve near filed defects in thin aluminum plates. The defects are close to the ultrasonic phased array and satisfy the near field calculation formula. Near field acoustic information of defects is obscured by the nonlinear effects of initial wave signal in a directly acquired response using the full matrix capture mode. A reconstructed full matrix of inter-element responses is produced from cross-correlation of directly received ultrasonic signals between sensor pairs. This new matrix eliminates the nonlinear interference and restores the near-field defect information. The topological imaging method that was developed in recent ultrasonic inspection is used for displaying the scatterers. The experiments are conducted on both thin aluminum plates containing two and four defects, respectively. The results show that these defects are clearly identified when using a reconstructed full matrix. The spatial resolution is equal to about one wavelength of the selectively excited mode and the identifiable defect is about one fifth of the wavelength. However, in a conventional directly captured image, the images of defects overlap together and cannot be distinguished. The proposed method reduces the background noise and allows for effective topological imaging of near field defects.

关键词: Lamb waves, topological imaging, cross-correlation, Green's function

Abstract:

A method of combining Green's function retrieval theory and ultrasonic array imaging using Lamb waves is presented to solve near filed defects in thin aluminum plates. The defects are close to the ultrasonic phased array and satisfy the near field calculation formula. Near field acoustic information of defects is obscured by the nonlinear effects of initial wave signal in a directly acquired response using the full matrix capture mode. A reconstructed full matrix of inter-element responses is produced from cross-correlation of directly received ultrasonic signals between sensor pairs. This new matrix eliminates the nonlinear interference and restores the near-field defect information. The topological imaging method that was developed in recent ultrasonic inspection is used for displaying the scatterers. The experiments are conducted on both thin aluminum plates containing two and four defects, respectively. The results show that these defects are clearly identified when using a reconstructed full matrix. The spatial resolution is equal to about one wavelength of the selectively excited mode and the identifiable defect is about one fifth of the wavelength. However, in a conventional directly captured image, the images of defects overlap together and cannot be distinguished. The proposed method reduces the background noise and allows for effective topological imaging of near field defects.

Key words: Lamb waves, topological imaging, cross-correlation, Green's function

中图分类号:  (General linear acoustics)

  • 43.20.+g
43.35.+d (Ultrasonics, quantum acoustics, and physical effects of sound)