Intensity-Based Demodulation Approach for the Measurement of Strains Induced by Structural Vibrations using Bragg Gratings

摘要

The Structural Irregularity and Damage Evaluation Routine (SIDER) is a broadband vibration-based technique that uses features in the complex curvature operating shapes of vibrating structures to locate damage and other areas with structural stiffness variations. Historically SIDER has determined these shapes using out-of-plane acceleration measurements, however it may also be possible to determine these complex curvature operating shapes by using arrays of fibre Bragg gratings to measure the dynamic strain profile of the vibrating structure. This report outlines a review of commercially available FBG demodulation systems with the requirements of SIDER in mind. Three commercially available systems were assessed in the Laboratory and found to be unsuitable for this study. Hence in order to achieve a suitable outcome a purpose-built demodulation system was developed by DSTO. This report describes the assessment of the commercial systems as well as the development and evaluation of the DSTO purpose-built demodulation system.