Article Article
Eddy Current Probability of Detection for Mid-Bore and Corner Cracks in Bolt Holes of Service Material

Fatigue cracks are prone to develop around fasteners found in multilayer aluminum structures on aging aircraft. Probability of detection (POD) studies using eddy current techniques within the bolt holes contribute to risk assessments used in evaluating the serviceability of these aircraft. Signal response to corner and mid-bore cracks by eddy current testing using standard split-D differential probes has been examined for in-service material from the horizontal stabilizer of a Hercules aircraft. Results are compared to data obtained from laboratory samples with drilled holes. Based on a logistic regression analysis, the results show no significant difference for a90/95 (90% of the cracks of size a will be detected 95% of the time) for mid-bore crack length of 0.60 mm in this study compared to 0.62 mm in earlier work on drilled holes. However, there was a substantial loss of sensitivity for corner cracks. In this study on in-service material, the a90/95 for corner cracks was 0.82 mm compared to 0.31 mm obtained from drilled holes. Decrease in sensitivity was attributed to damage at the hole’s corners of the in-service material, including rounding, folded metal, and burrs. Hole damage also significantly increased the risk of a false call.

  • A. Berens. Nondestructive Evaluation and Quality Control. ASM International Metals Handbook. Ninth Edition, Vol. 17, pp. 689–701.
  • United States Department of Defense. Nondestructive Evaluation System Reliability Assessment. MILHDBK-1823A. 7 April 2009.
  • H. Lemire, P. R. Underhill, T. W. Krause, M. Bunn, and D. J. Butcher. Research in NondestructiveEvaluation 21(3):141–156 (2010).
  • L. S. Rosado, J. C. Gonzalez, T. G. Antos, P. M. Ramos, and M. Piedade. Sensors and Actuators A197:96–105 (2013).
  • P. Y. Joubert, E. Vourc’h, and V. Thomas. Sensors and Actuators A 185:132–138 (2012).
  • P. R. Underhill and T. W. Krause. NDT&E International 44:513–518 (2011).
  • P. R. Underhill and T. W. Krause Journal of Nondestructive Evaluation 30(4), 237–245 (2011).
  • T. P. Theodoulidis and J. R. Bowler. IEEE Trans. Magn. 46:1034–1042 (2010).
  • J. R. Bowler and T. P. Theodoulidis. J. Phys. D: Appl. Phys. 39:2862–2868 (2006).
  • P. R. Underhill and T. W. Krause. Research in Nondestructive Evaluation 22(2):92–104 (2011).
  • J. Lattin, J. D. Carroll, and P. E. Green. Analyzing Multivariate Data. Brooks/Cole, Pacific Grove, CA (2003).
  • L. Gandossi and C. Annis. Probability of Detection Curves: Statistical Best Practices, ENIQ Report No. 41. ENIQ, Luxembourg, Germany (2010).
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