Large-scale Digital Image Correlation with VIC-3D as Bridge Repair Solution
The scientists at the University of Virginia in collaboration with the Virginia Transportation Research Council recently utilized the VIC-3D digital image correlation (DIC) system to measure the effectiveness of a steel beam end repair solution for bridges as described in this paper. The DIC system was used to measure the full-field strain distribution and buckling of the steel plate under a compressive load of 8 Kips (800 lbs force). The results were used to validate with finite element computer models and established a framework for more testing using DIC.
For many civil and mechanical engineering applications, the need to measure full-field deformation of large structures is becoming more and more prevalent because critical areas are identified and measured without any contact with the structure. In civil engineering, testing large specimens is vital to ensure buildings and bridges are designed to be structurally sound to withstand years of use and the forces of nature.
Measuring large structures presents challenges for digital image correlation systems due to nature of the size of the specimens being tested. DIC systems typically require longer standoff distances and baselines (distance between the stereo cameras), which presents challenges for the stereo calibration. For fields of view less than 3 meters, a single calibration target may be used and the calibration process is performed as usual by imaging the target with both cameras at the same time. For fields of view greater than 3 meters, a very large calibration target is no longer practical. To solve this problem, Correlated Solutions has developed a intelligent algorithms that calculate the two imaging sensors’ positions by analyzing the speckle pattern on the specimen’s surface which includes two points with a known distance. This unique method enables the VIC-3D system to measure an object of any size.
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