In the frame of FWO research project G099014N, Urszula Nawrot carried out her development of a novel patent pending strain enhancing transducer in the Optical Fibre Sensors team of B-PHOT, under the joint supervision of prof. Francis Berghmans and prof. Thomas Geernaert (VUB B-PHOT). She successfully defended her doctoral thesis on 3rd June 2019.
Vibration-based damage identification is a non-destructive method that enables health monitoring of civil engineering structures. It aims to detect the presence and growth of damage by measuring changes of natural frequencies, damping factors or modal displacements of these structures.
Modal strains have particular potential to local damage with a high sensitivity. However, under ambient excitation, the strain amplitudes in concrete civil structures can be in the sub-microstrain range (<1με). Commercially available strain sensor systems typically do not allow for quasi-distributed strain measurements below 1 με.
To leapfrog this hurdle we designed a novel strain amplifying transducer equipped with fiber Bragg grating-based sensors. The basic idea is to utilize a symmetric cantilever structure to enlarge the strain measured by the FBG sensor compared to the strain applied to the transducer itself by the bridge. After optimizing the technique in several lab tests, it was also applied to a high-speed rail viaduct of INFRABEL. Those results were published in the Structural Health Monitoring journal. The accepted version of the manuscript can be accessed here.
For inquiries: contact Prof. dr. ir. Thomas Geernaert.