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Proceedings Paper

Photonic crystals for monitoring fatigue phenomena in steel structures
Author(s): Daniele Zonta; Andrea Chiappini; Alessandro Chiasera; Maurizio Ferrari; Matteo Pozzi; Lorenzo Battisti; Matteo Benedetti
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Paper Abstract

This paper introduces the concept and development of a strain sensing system for structural application based on the properties of photonic crystals. Photonic crystals are artificially created periodic structures, usually produced in the thinfilm form, where optical properties are tailored by a periodicity in the refractive index. The idea of using the crystal as a sensor is based on the observation that a distortion in the crystal structure produces a change in the reflected bandwidth. When a photonic crystal is designed to operate in the visible part of the spectrum, a permanent distortion of the film results in a change in its apparent color. This property makes photonic crystals suitable for permanent monitoring of structural elements, as any critical changes in the strain field can be promptly and easily detected by visual inspection. A simple and low-cost example of photonic crystals consists of opals synthesized by vertical deposition. In this contribution we introduce a target application for the fatigue monitoring of wind turbines, and then provide the reader with some basic information concerning modeling of the crystal architecture and fabrication of these structures. Next we discuss their application to strain measurement, specifying how reflection and transmission properties of the opals have to be designed to satisfy the expected strain response of the sensor. Finally, we present the preliminary results of a laboratory validation carried out on thin films applied to a rubber support.

Paper Details

Date Published: 30 March 2009
PDF: 10 pages
Proc. SPIE 7292, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2009, 729215 (30 March 2009); doi: 10.1117/12.814915
Show Author Affiliations
Daniele Zonta, Univ. of Trento (Italy)
Andrea Chiappini, CNR, Istituto di Fotonica e Nanotecnologie (Italy)
Alessandro Chiasera, CNR, Istituto di Fotonica e Nanotecnologie (Italy)
Maurizio Ferrari, CNR, Istituto di Fotonica e Nanotecnologie (Italy)
Matteo Pozzi, Univ. of Trento (Italy)
Lorenzo Battisti, Univ. of Trento (Italy)
Matteo Benedetti, Univ. of Trento (Italy)

Published in SPIE Proceedings Vol. 7292:
Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2009
Masayoshi Tomizuka, Editor(s)

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