Closed-crack imaging and scattering behavior analysis using confocal subharmonic phased array

Azusa Sugawara, Kentaro Jinno, Yoshikazu Ohara, Kazushi Yamanaka

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)


To solve the underestimation of closed-crack depth, we have developed an imaging method, subharmonic phased array for crack evaluation (SPACE). However, a single-array SPACE can image only the vicinity of a transmission focal point (TFP) when the TFP is fixed. In this study, we have developed a confocal SPACE that defines multiple TFPs for imaging closed cracks over a wide area. We demonstrated its usefulness by measuring a stress corrosion crack (SCC). Moreover, we proposed a radarlike display that shows single-focus images with a line indicating the incident direction. By applying it to the SCC specimen, a moving crack response (MCR) was observed with varying incident angles. To analyze this behavior, we performed a simulation using a finite-difference time-domain (FDTD) method with a damped double node (DDN) model. Furthermore, we examined the ratio of the subharmonic to fundamental responses depending on the stress ratio between input wave stress and crack closure stress (σc).

Original languageEnglish
Article number07HC08
JournalJapanese journal of applied physics
Issue number7
Publication statusPublished - 2015 Jul 1

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)


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