Development and integration of a FBG optical sensor network for prognostics of electromechanical actuators.

This thesis was developed at the Mechanical and Aerospace Engineering Department (DIMEAS) of the Politecnico di Torino. With the strong development of the more-eletric philosophy for aircraft, EMAs (Electro- mechanical actuators) are increasingly being used and represent a critical safety element. The development of prognostic algorithms makes it possible to increase the safety levels of EMAs. In this scenario a key role is played by sensors that enable the acquisition of input data for prognostic algorithms. FBGs (Fiber Bragg gratings) are innovative sensors that are very adaptable to the aerospace environment. FBGs guarantee high performances in terms of accuracy and sensibilty and offer a number of advantages over traditional sensors: they are immune to the electromagnetic interferences, they are light and small, and can be installed in series on the same cable. The objective of this work is the development and integration of a FBG optical sensors network for prognostics on the Gearbox of an ex- perimental test bench reproducing an electromechanical servomechanism. The first step, before the installation of FBGs, was the design of a Load-module that can simulate an external load on the Gearbox, so that the FBGs can be used to evaluate the structural deformations caused by the load. Later, FBGs were installed together with strain gauges on the surface of the Gearbox made from PLA, which was connected to the motor shaft. The curved installation surface and the material of the Gearbox led to the development of a specific procedure for installing the sensors. Tests were carried out in order to evaluate the deformations measured by FBGs and strain gauges, when an external load is applied on the Gearbox through the Load module. Finally, the comparison of the data from the two types of sensors made it possible to calibrate and evaluate the FBGs as prognostic sensors for the electromechanical actuators.