Design and development of a test bench for frequency analysis of FBGs optic sensors for prognostic techniques for aerospace applications

This thesis is one of the projects of the PHOTONEXT research group, carried on by professors and students of the DIMEAS, Mechanical and Aerospace Departments, of the Politecnico di Torino, and with the contribute of the ISMB, Istituto Superiore Mario Boella. The PHOTONEXT group works focus on the use of the fiber optic as a sensor in many aerospace applications: in particular it is trying to validate the Fiber Bragg Grating sensors in place of the traditional sensors. The purpose of this thesis is studying the dynamic effects on the FBGs optic sensors, in this way it will be also possible obtain their characterization. The use of the optic fiber as a sensor is a significative improvement in sensoristic applications: it is really light, it doesn’t need to be powered, it can transmits a great amount of data and it is immune to electromagnetic field, howewer, to read the data a laser interrogator is necessary. In order to study the dynamic behaviour of the fiber, a vibration source is needed: a piezoelectric actuator has been chosen. The actuator system has presented both advantages and disadvantages: the main advantage is the presence of its software, by means of is possible to command the actuator without using code lenguages, but it also have disadvantages, as the system attenuation and the frequency range limitations. The fiber dynamic behaviour has been analyzed comparing the measures obtained by the laser interrogator with the signal provided by the vibrations source .