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Proceedings Paper

Broad-area detection of structural irregularities in composites using fibre Bragg gratings
Author(s): Claire E. Davis; Patrick Norman; Scott Moss; Colin Ratcliffe; Roger Crane
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Paper Abstract

The Structural Irregularity and Damage Evaluation Routine (SIDER) is a broadband vibration-based technique that uses features in complex curvature operating shapes to locate damage and other areas with structural stiffness variations. It is designed for the inspection of large-scale composite structures not amenable to more conventional inspection methods. The current SIDER methodology relies on impact excitation at a series of grid points on the structure and records the response using a small number of accelerometers to determine the operational curvature shapes. This paper reports on a modification to the SIDER technique whereby the acceleration measurements are replaced with in-plane strain measurements using Fibre Bragg Gratings (FBGs). One of the major challenges associated with using Bragg gratings for this type of response measurement is that the strains induced by structural vibrations tend to be low, particularly at higher frequencies. This paper also reports on the development of an intensity-based, swept wavelength interrogation system to facilitate these measurements. The modified SIDER system was evaluated on an E-glass/vinyl ester composite test beam containing a machined notch. The measurements accurately detected the presence and location of the notch. The distributive capacity of FBGs means that these sensors have the potential to replace the excitation grid with a measurement grid, allowing for single point or environmental excitation. The spatially separated measurements of strain can be used to provide the curvature shapes directly. This change in approach could potentially transition SIDER from an interval-based, broad-area inspection tool to an in-service structural health monitoring system.

Paper Details

Date Published: 1 April 2010
PDF: 9 pages
Proc. SPIE 7647, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2010, 76473M (1 April 2010); doi: 10.1117/12.848692
Show Author Affiliations
Claire E. Davis, Defence Science and Technology Organisation (Australia)
Patrick Norman, Defence Science and Technology Organisation (Australia)
Scott Moss, Defence Science and Technology Organisation (Australia)
Colin Ratcliffe, U.S. Naval Academy (United States)
Roger Crane, Naval Surface Warfare Ctr. (United States)

Published in SPIE Proceedings Vol. 7647:
Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2010
Masayoshi Tomizuka, Editor(s)

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