Optical sensor based on combined GI/DSPI technique for strain monitoring in crucial points of big engineering structures

Dariusz Łukaszewski; Leszek Sałbut; Małgorzata Kujawińska; Krzysztof Malowany

doi:10.1117/12.889582

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27 May 2011 Optical sensor based on combined GI/DSPI technique for strain monitoring in crucial points of big engineering structures

Dariusz Łukaszewski, Leszek Sałbut, Małgorzata Kujawińska, Krzysztof Malowany

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Proceedings Volume 8082, Optical Measurement Systems for Industrial Inspection VII; 80823P (2011) https://doi.org/10.1117/12.889582
Event: SPIE Optical Metrology, 2011, Munich, Germany

Abstract

The data from a monitored structure/object should be easy acquired, processed and sent to the user, who can assess the health of a structure in short time and schedule necessary maintenance in order to prevent accidences. Systems which provide such information are fundamental for Structural Health Monitoring (SHM). In the paper novel optical sensor designed for in-plane displacement and strain monitoring in crucial points of a big engineering and civil structures is presented. It combines two techniques: Grating Interferometry (GI) and Digital Speckle Pattern Interferometry (DSPI). GI requires specimen grating attached to the surface of an object under test. It is the unique technique which may provide the information about fatigue process and increased residual stresses. DSPI works with a rough object surface but due to differential measurements cannot be simply used for long time monitoring but to explore the actual behavior of a structure. The sensor which combines these techniques provides user with wide possibilities concerning functionality, measuring range, object surface and environmental conditions. The crucial issue in implementation of this sensor is the choice of its location(s) at the investigated structure. Therefore it is proposed to be as one of the elements of hierarchical sensors net, which gives complete information about structure state. As the method for supporting the choice of GI/DSPI sensor location we proposed the system based on 3D digital correlation method. The paper presents mechanical and optical sensor design along with laboratory tests of main component such as sensor heads in form of monolithic (plastic) and cavity waveguides. Finally the possible application of proposed sensor in combination with 3D DIC system is presented.

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Dariusz Łukaszewski, Leszek Sałbut, Małgorzata Kujawińska, and Krzysztof Malowany "Optical sensor based on combined GI/DSPI technique for strain monitoring in crucial points of big engineering structures", Proc. SPIE 8082, Optical Measurement Systems for Industrial Inspection VII, 80823P (27 May 2011); https://doi.org/10.1117/12.889582

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