DOI: 10.5176/2301-394X_ACE18.52
Authors: Niranjan Desai and Joel Poling
Abstract:
Structural health monitoring (SHM) assists engineers in maintaining structures, making them safer and more cost effective. Digital image correlation (DIC) techniques applied to SHM are non-contact, fast, and accurate techniques that are easy to apply. This investigation determined the minimum resolution of the state-of-the-art, OpenSource DIC – based tool “Improved DIC”. Initially undetected damage at low strains in connections of a real-world bridge motivated this investigation, whose detection would have restricted its spread, leading to lower repair costs. A cantilevered plate specimen was transversely loaded in the laboratory, and the longitudinal strain was measured at six different locations, using the OpenSource DIC-based tool. The DIC strains were compared against those measured by traditional strain gauges. Strains as low as 0.015% were measured accurately using the OpenSource tool. Additionally, this study demonstrated that small out-of-plane specimen movements that inadvertently occurred even in controlled laboratory conditions led to noise in the DIC-based strain measurements. Hence, it was also concluded that prior to implementing this technique in a real structure to detect small strains, it is desirable to determine the limits of out-of-plane specimen displacement within which it is practical to use this technique to measure strain.
Keywords: Structural Health Monitoring, Digital Image Correlation, OpenSource
Structural health monitoring (SHM) assists engineers in maintaining structures, making them safer and more cost effective. Digital image correlation (DIC) techniques applied to SHM are non-contact, fast, and accurate techniques that are easy to apply. This investigation determined the minimum resolution of the state-of-the-art, OpenSource DIC – based tool “Improved DIC”. Initially undetected damage at low strains in connections of a real-world bridge motivated this investigation, whose detection would have restricted its spread, leading to lower repair costs. A cantilevered plate specimen was transversely loaded in the laboratory, and the longitudinal strain was measured at six different locations, using the OpenSource DIC-based tool. The DIC strains were compared against those measured by traditional strain gauges. Strains as low as 0.015% were measured accurately using the OpenSource tool. Additionally, this study demonstrated that small out-of-plane specimen movements that inadvertently occurred even in controlled laboratory conditions led to noise in the DIC-based strain measurements. Hence, it was also concluded that prior to implementing this technique in a real structure to detect small strains, it is desirable to determine the limits of out-of-plane specimen displacement within which it is practical to use this technique to measure strain.
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