APL Photonics (Mar 2020)

Multichannel fiber laser acoustic emission sensor system for crack detection and location in accelerated fatigue testing of aluminum panels

  • Caitlin R. S. Williams,
  • Meredith N. Hutchinson,
  • Joseph D. Hart,
  • Marriner H. Merrill,
  • Peter Finkel,
  • William R. Pogue III,
  • Geoffrey A. Cranch

DOI
https://doi.org/10.1063/1.5133040
Journal volume & issue
Vol. 5, no. 3
pp. 030803 – 030803-10

Abstract

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Detection and location of the source of acoustic emission in a thin aluminum panel is demonstrated using a multichannel fiber laser sensor system. Acoustic emission generated by a crack in an aluminum panel used as a test coupon in an accelerated fatigue experiment is detected and the location of the crack identified. Acoustic emission is detected over a bandwidth of around 0.5 MHz from a serially multiplexed array of four laser sensors and compared with measurements taken from four piezo-electric sensors co-located with the fiber laser sensors. The location of the crack is determined by first estimating time difference of arrival of signals at each sensor using a novel algorithm based on the cumulative distribution transform method with hyperbolic positioning. The fiber laser sensor is shown to match the signal-to-noise ratio of the industry standard (Mistras S9225) piezo-electric acoustic emission sensor.