Robust vibration-based damage identification with a novel high-accuracy strain measurement system.

Vibration-based damage identification of existing infrastructure currently suffers from the low sensitivity of natural frequencies and modal displacements to certain types of damage while the sensitivity to environmental influences may be sufficiently high to completely mask the effect of severe damage. Modal strains and curvatures are much more sensitive to local damage, but the direct monitoring of these quantities in a dense grid is not possible with current measurement techniques due to the very small strain levels occurring during ambient, or operational, excitation. In this project, the Structural Mechanics Section of KU Leuven and the B-Phot team of VUB will combine their unique expertise and develop a novel strain measurement system, based on optical fiber Bragg grating (FBG) technology,that offers the precision, resolution and flexibility required for accurate and quasi-distributed dynamic strain monitoring in operational conditions. This will be pursued through the development of an innovative sensitivity-increasing FBG package and of novel photonic crystal fibers. The influence of environmental changes on modal strains and curvatures will be thoroughly investigated and eliminated with advanced nonlinear system identification techniques. Finally, robust damage detection algorithms, that account for the uncertainty of the extracted modal characteristics, will be developed.