Bolt-hole corner crack inspection using the photoinductive imaging method

Cheng Chi Tai, John C. Moulder

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

We applied a laser-excited eddy current (EC) imaging technique, or so-called photoinductive (PI) imaging, to characterize corner cracks at the edge of a bolt hole. Crack images with excellent signal-to-noise-ratios were obtained. The PI signals revealed the geometrical shape of the electrical-discharge-machined (EDM) notches that were either triangular or rectangular. The results show that this technique is promising to characterize the length, as well as possibly the depth and shape, of corner cracks. In this paper we present measurement results of 0.25-mm, 0.50-mm, and 0.75-mm rectangular and triangular EDM notches. We also show measurement results of a very small notch (<0.25 mm) which would be difficult to detect with conventional eddy current techniques. The dependencies of PI signals on laser chopping frequencies and eddy current frequencies are also examined. To demonstrate the photoinductive imaging capabilities to image actual cracks, we display images of fatigue cracks grown in a Ti-6Al-4V hole specimen. Finally, we present comparisons of the photoinductive imaging results with usual eddy current images obtained from a 0.75-mm triangular EDM notch using a rotating bolt-hole scanner. This article intends to verify experimentally that the photoinductive imaging technique has a potential to become a useful nondestructive testing method.

Original languageEnglish
Pages (from-to)81-93
Number of pages13
JournalJournal of Nondestructive Evaluation
Volume19
Issue number3
DOIs
Publication statusPublished - 2000 Sept

All Science Journal Classification (ASJC) codes

  • Mechanics of Materials
  • Mechanical Engineering

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