Efficient phase shift migration for ultrasonic full-matrix imaging of multilayer composite structures. (15th July 2022)

• Record Type: Journal Article
• Authors: Ji, Kaipeng; Zhao, Peng; Zhuo, Chaojie; Jin, Haoran; Chen, Mu; Chen, Jian; Ye, Sheng; Fu, Jianzhong
• Is Part Of: Mechanical systems and signal processing. Volume 174(2022)
• Publication Date: 2022-07-15
• Subjects: Full matrix imaging -- Phase shift migration -- Multilayer structures -- Phased array -- Frequency-wavenumber space; Structural dynamics -- Periodicals; Vibration -- Periodicals; Constructions -- Dynamique -- Périodiques; Vibration -- Périodiques; Structural dynamics; Vibration; Periodicals; 621
• DOI: 10.1016/j.ymssp.2022.109114
• Languages: English
• ISSNs: 0888-3270

Abstract

Highlights: Double-square-root wavenumber is introduced in wavefield extrapolation directly. Imaging condition is directly applied in the frequency-wavenumber space. The method outperforms existing methods in computational complexity and efficiency. The method has great potential in online detection for large multilayer structures. The proposed method is well adaptable to the continuous-layered media. Abstract: Multilayer composite structures are essential for various fields but void defects inside will greatly reduce its mechanical properties. Ultrasonic full-matrix capture (FMC) is a useful imaging modality to detect defects in multilayer structures, but it also brings heavy computational burden. Though great progress has been made in the full-matrix imaging for homogeneous medium, most of these methods are invalid or inefficient for the cases of multilayer structures. To amend it, an efficient phase shift migration for ultrasonic full-matrix imaging of multilayer structures is proposed in this paper. The method regards FMC as data in three dimensions: receiver position, transmitter position and time, and transforms it into frequency-wavenumber ( f-k ) space by a three-dimensional fast Fourier transform. By downward extrapolating the wavefield on the surface, the wavefield at arbitrary depth in the measuring region is reconstructed, with a firstly introduced double-square-root vertical wavenumber. Then the imaging condition t = 0 is directly applied in the f-k space to produce the defect image. Computational complexity was reduced greatly, and the calculation time of the proposed method was only 1/6 of that of the well-established extended phase shift migration, in the case of the same resolution. Therefore, the proposed method has great potential in on-line ultrasound defect detection, especially for cases of large multilayer structures.