Ultrasonic phased array with surface acoustic wave for imaging cracks

Yoshikazu Ohara, Taro Oshiumi, Hiromichi Nakajima, Kazushi Yamanaka, Xiaoyang Wu, Tetsuya Uchimoto, Toshiyuki Takagi, Toshihiro Tsuji, Tsuyoshi Mihara

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


To accurately measure crack lengths, we developed a real-time surface imaging method (SAW PA) combining an ultrasonic phased array (PA) with a surface acoustic wave (SAW). SAW PA using a Rayleigh wave with a high sensitivity to surface defects was implemented for contact testing using a wedge with the third critical angle that allows the Rayleigh wave to be generated. Here, to realize high sensitivity imaging, SAW PA was optimized in terms of the wedge and the imaging area. The improved SAW PA was experimentally demonstrated using a fatigue crack specimen made of an aluminum alloy. For further verification in more realistic specimens, SAW PA was applied to stainless-steel specimens with a fatigue crack and stress corrosion cracks (SCCs). The fatigue crack was visualized with a high signal-to-noise ratio (SNR) and its length was measured with a high accuracy of better than 1 mm. The SCCs generated in the heat-affected zones (HAZs) of a weld were successfully visualized with a satisfactory SNR, although responses at coarse grains appeared throughout the imaging area. The SCC lengths were accurately measured. The imaging results also precisely showed complicated distributions of SCCs, which were in excellent agreement with the optically observed distributions.

Original languageEnglish
Article number065214
JournalAIP Advances
Issue number6
Publication statusPublished - 2017 Jun 1


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