Accurate measurement of closed cracks using subharmonic phased array

Yoshikazu Ohara, Setsu Yamamoto, Hiroaki Endo, Tsuyoshi Mihara, Kazushi Yamanaka

Research output: Chapter in Book/Report/Conference proceedingConference contribution


We developed a novel imaging method, subharmonic phased array for crack evaluation (SPACE), to measure closed-crack depth in the thickness direction. This implementation of the SPACE used a LiNbO3 single-crystal transmitter to generate the intense ultrasound required for subharmonic generation and a phased array sensor as a receiver for focusing on reception. We applied SPACE to closed fatigue and stress corrosion cracks and found that SPACE images can reduce the measurement error to approximately 1 mm. In addition, to explain the SPACE images, we propose a concept of localized subharmonic resonances.

Original languageEnglish
Title of host publicationNonlinear Acoustics - Fundamentals and Applications - ISNA18 - 18th International Symposium on Nonlinear Acoustics
Number of pages4
Publication statusPublished - 2008 Aug 15
Event18th International Symposium on Nonlinear Acoustics, ISNA18 - Stockholm, Sweden
Duration: 2008 Jul 72008 Jul 10

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


Other18th International Symposium on Nonlinear Acoustics, ISNA18


  • Closed cracks
  • Subharmonic resonance
  • Ultrasonic imaging

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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