Packaging and testing of fiber Bragg gratings for use as strain sensor in rock specimens

Alvaro Castro-Caicedo; Pedro Torres; Ricardo Lain

doi:10.1117/12.2025678

18 November 2013 Packaging and testing of fiber Bragg gratings for use as strain sensor in rock specimens

Alvaro Castro-Caicedo, Pedro Torres, Ricardo Lain

Proceedings Volume 8785, 8th Iberoamerican Optics Meeting and 11th Latin American Meeting on Optics, Lasers, and Applications; 87852R (2013) https://doi.org/10.1117/12.2025678
Event: 8th Ibero American Optics Meeting/11th Latin American Meeting on Optics, Lasers, and Applications, 2013, Porto, Portugal

Abstract

This paper reports a packaging and calibration procedure for surface mounting of fiber Bragg grating (FBG) sensors to measure strain in rocks. The packaging of FBG sensors is performed with glass fiber and polyester resin, and then subjected to tensile loads in order to obtain strength and deformability parameters, necessaries to assess the mechanical performance of the sensor packaging. For a specific package, an optimal curing condition has been found, showing good repeatability and adaptability for non-planar surfaces, such as occurs in rock engineering. The successfully packaged sensors and electrical strain gages were attached to standard rock specimens of gabbro. Longitudinal and transversal strains under compression loads were measured with both techniques, showing that response of FBG sensors is linear and reliable. An analytical model is used to characterize the influences of rock substrate and FBG packaging in strain transmission. As a result, we obtained a sensor packaging for non-planar and complex natural material under acceptable sensitivity suitable for very small strains as occurs in hard rocks.

Citation Download Citation

Alvaro Castro-Caicedo, Pedro Torres, and Ricardo Lain "Packaging and testing of fiber Bragg gratings for use as strain sensor in rock specimens", Proc. SPIE 8785, 8th Iberoamerican Optics Meeting and 11th Latin American Meeting on Optics, Lasers, and Applications, 87852R (18 November 2013); https://doi.org/10.1117/12.2025678

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