Advanced Signal Processing for reliable FBG measurements and structural condition monitoring

Signal distortion in FBG sensors embedded in composites

FBG sensors generally provide output optical signals with a pulse-like shape in the wavelength domain, with the position of the pulse-peak (the so called Bragg-Wavelength) associated with the physical measurand. When FBGs are embedded in composite materials, the shape of their optical signal can be distorted, e.g. due to manufacturing issues.

Distorted FBG signals are more complicated to process with conventional techniques and decrease the reliability of the measurements. The developed Fast Phase Correlation Technique can overcome these issues, allowing accurate, precise, robust and fast FBG measurements.

Condition monitoring using strain based operational modal analysis tools

Embedded FBG sensors can be used for condition monitoring purposes, i.e. using the sensors to measure dynamic strains, and to estimate and track changes in the structural modal parameters, such as natural frequencies, damping ratios and strain mode shapes. The occurrence and propagation of structural damages, such as delaminations or debonding, induce modi-fications of the modal parameters and can therefore be detected and assessed. The combination of Fast Phase Correlation technique with advanced system identification methods leads to an improvement of the FBG damage detection capabilities.