Nonlinear ultrasonic imaging method for closed cracks using subtraction of responses at different external loads

Yoshikazu Ohara, Satoshi Horinouchi, Makoto Hashimoto, Yohei Shintaku, Kazushi Yamanaka

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

To improve the selectivity of closed cracks for objects other than cracks in ultrasonic imaging, we propose an extension of a novel imaging method, namely, subharmonic phased array for crack evaluation (SPACE) as well as another approach using the subtraction of responses at different external loads. By applying external static or dynamic loads to closed cracks, the contact state in the cracks varies, resulting in an intensity change of responses at cracks. In contrast, objects other than cracks are independent of external load. Therefore, only cracks can be extracted by subtracting responses at different loads. In this study, we performed fundamental experiments on a closed fatigue crack formed in an aluminum alloy compact tension (CT) specimen using the proposed method. We examined the static load dependence of SPACE images and the dynamic load dependence of linear phased array (PA) images by simulating the external loads with a servohydraulic fatigue testing machine. By subtracting the images at different external loads, we show that this method is useful in extracting only the intensity change of responses related to closed cracks, while canceling the responses of objects other than cracks.

Original languageEnglish
Pages (from-to)661-666
Number of pages6
JournalUltrasonics
Volume51
Issue number6
DOIs
Publication statusPublished - 2011 Aug 1

Keywords

  • Closed crack
  • Load dependence
  • Nonlinear ultrasound
  • Phased-array imaging
  • Subtraction

ASJC Scopus subject areas

  • Acoustics and Ultrasonics

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