Monitoring Shape Change in Compliant Structures

Euan J. Rigg, R. R J Maier, James S. Barton, Andrew J. Moore, J. D C Jones, Scott McCulloch, Andrew Wallwork, Gary Burnell

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

We describe an optical system to monitor small long-term changes in the shape of a surface by using a network of optical fibre Bragg grating strain gauges, for applications in which space does not permit the use of techniques such as photogrammetry or structured light methods. Gratings are bonded to copper beryllium strips held under tension in contact with the test surface. The copper beryllium strips enable sufficient force to be transferred to the optical fibre from the compliant surface. Shape changes are revealed as strain changes in the sensor strips, inferred from wavelength shifts in the Bragg peaks. The optical signals are obtained in reflection by illuminating the sensor fibres with a broadband source and using a scanning Fabry-Perot filter to generate the spectrum with a wavelength resolution of 0.3pm over the range 1530 to 1570nm. Laboratory tests show that a strain resolution of 8 microstrain can be achieved with temperature compensation over the range 20 to 50 C, with a multiplexing capability of between 11 and 16 temperature - strain sensor pairs, depending on temperature gradients on the test surface. We present experimental measurements on a cylindrical test object subject to diametral loading, and show a comparison with a finite element model.

Original languageEnglish
Pages (from-to)206-217
Number of pages12
JournalProceedings of SPIE - the International Society for Optical Engineering
Volume5050
DOIs
Publication statusPublished - 2003
EventPROCEEDINGS OF SPIE SPIE - The International Society for Optical Engineering: Smart Structures and Materials 2003 Smart Sensor Technology and Measurement System - San Diego, CA, United States
Duration: 3 Mar 20035 Mar 2003

Keywords

  • Compliant structures
  • Fibre Bragg grating
  • Shape change
  • Strain measurement

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