Highly Dynamic Material Test Analysis in Civil Engineering
Doctoral candidate: Laura Camila Duran Vergara
This project is the continuation of subproject C1 of the Research Training Group GRK2250 funded by the German Research Foundation. The aim is to increase the precision and reliability of the estimation of the mechanical properties of different concrete compositions in highly dynamic tests. By using ultrahigh-speed cameras with the ISIS (in situ storage image sensor) sensor architecture, which combines features of CCD and CMOS image sensors, an increase in spatio-temporal resolution is achieved. This allows observing concrete deformation after impact and before fracture. As the concrete specimens are accelerated at high rates, the time interval to rupture is microseconds or even nanoseconds at very high strain rates.
© ipf
Video: Deformation in the impact direction of a compression test before and after the main crack formation. The deformation is represented by the displacement in the X-direction and the main crack formation by the principal strain. The test was carried out with a Kirana 7M camera (924 ×768 px; 1,500,000 fps) and processed with the GOM Correlate Pro Software.
However, due to the high frame rate without the loss of the dimensional component, there are some challenges in image acquisition: low image recording capacity, low sensor sensitivity, image lag effect, and fixed pattern noise effect. This is largely due to the fact that the signals in each pixel are loaded and stored during the image acquisition time. As a result, the image quality and thus the determination of the image coordinates used for deformation analysis are affected by the low fill factor, an insufficient charge transfer efficiency, and radiometric errors.
Considering the aforementioned challenges, the one-dimensional wave equation theory is applied to the displacement vector field representing the deformation of the specimen. This allows the estimation of the velocity of the longitudinal wave, which is mainly responsible for the rupture of the concrete.
Link to project website: https://www.grk2250.de/
Link to the Kirana camera website: https://www.specialised-imaging.com/products/video-cameras/kirana
2024
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Ultrahigh-speed imaging for high-impact concrete deformation analysis in pre- and post-cracking stages, 8 Jan 2024, In: Applied Optics. 63, 2, p. 467-482, 16 p.Electronic (full-text) versionResearch output: Contribution to journal > Research article
2023
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Analysis of the Accuracy Potential of a Stereo High-Speed Camera System in 3D Measurements in Highly Dynamic Experiments, 14 Feb 2023, In: Sensors (Switzerland). 23, 4, p. 1-26, 26 p.Electronic (full-text) versionResearch output: Contribution to journal > Research article
This information is provided by the FIS.