Aerospace (Jun 2024)

High-Resolution Wavenumber Bandpass Filtering of Guided Ultrasonic Wavefield for the Visualization of Subtle Structural Flaws

  • Lee Shi Yn,
  • Fairuz Izzuddin Romli,
  • Norkhairunnisa Mazlan,
  • Jung-Ryul Lee,
  • Mohammad Yazdi Harmin,
  • Chia Chen Ciang

DOI
https://doi.org/10.3390/aerospace11070524
Journal volume & issue
Vol. 11, no. 7
p. 524

Abstract

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Guided ultrasonic wavefield propagation imaging (GUPI) is useful for visualizing hidden flaws in aerospace thin-walled structures, but the need for subjective signal processing involving three-dimensional Fourier transformation to increase the visibility of subtle flaws hinders its wider acceptance. A high-resolution wavenumber bandpass filter capable of consolidating subtle flaw-relevant information from a wide frequency band using only two-dimensional Fourier transformation was proposed. The filter overturns the long-standing belief that modes must be separated based on narrow-band data acquisition or processing to achieve high flaw visibility. Its characteristics and advantages were experimentally demonstrated through enhanced visualization of hidden wall-thinning flaws of a plate specimen. Its strength was further demonstrated through the first GUPI visualization of a partially loosened bolt, with unprecedented clarity to discern bolt tightness levels. The results conclusively proved that the proposed filter significantly enhances the resolution of GUPI within a structured processing framework.

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