Using DIC To Conduct Large-Scale Structural Analysis
Conducting large-scale vibration analysis with traditional sensors can be tricky and expensive. It requires the application of many sensors over large areas, especially if you want to measure multi-axis movements accurately.
For an alternative to sensor-based structural analysis, researchers from the University of Grenoble in France used Digital Imaging Correlation (DIC). This non-contact technique uses high-speed cameras and specialized software to optically measure deformation, displacement and strain.
The researchers used DIC to conduct a full-field analysis of how large timber-framed structures respond to seismic activity.
Simulating Earthquakes. To capture the displacement of a full-scale house undergoing simulated earthquakes on a shake table, the researchers had to gather images with a high enough resolution that would allow them to clearly see the damage while gathering full-scale measurements.
To meet this need, the team used a Vision Research Phantom v641 camera at a maximum resolution of 2560 x 1600. At this resolution, each pixel represented 2.16 mm on a wall of the house. Thanks to an added 128 gigabytes of Phantom CineMag memory, a 40-gigabyte movie could be saved for each signal at 150 fps. For each simulated earthquake, the team acquired 7,599 images, tracking almost 4,000 pixels.
Out-Performing Contact Sensors. Researchers also added contact measurement devices to the structure to measure displacement. DIC analysis provided displacement measurements in the x and y axes. However, this multi-axis measurement wasn’t possible with the contact sensors. DIC also exposed an opening in infill material and provided information on the timber’s flexural behavior, which wasn’t observable through other means.
The researchers concluded that DIC field displacement measurements provided direct proof of the seismic-resistant behavior of a filled timber-framed structure.
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