Experimentation of fiber optic FBG sensors in a CFRP aerospace component

This paper describes experimental activities performed on specimens representative of an aerospace component to demonstrate the possibility of monitoring aerospace components using Fiber Bragg Gratings FBG sensors, embedded inside composite materials and to test the survivability of the fibers in an industrial environment. The tests have been carried out in the Alenia Aermacchi factory in Venegono Superiore (Varese), in collaboration with DIAEE and DICMA Departments of Sapienza University of Rome. The specimen used for the tests were realized during internal testing activities performed by Alenia Aermacchi, and were intended to be used for destructive tests after a simulated ‘aging’ (submerged in water at T=70°C for 31 days) of the material. Two specimens carrying 8 embedded FBG sensors each were manufactured. The FBG sensors were also used to monitor the stress of the material after the curing in an autoclave. Non-Destructive Tests (ultrasonic scan, X-rays) were performed to check the positions of the fibers inside the specimens. Three other specimens were monitored with FBG sensors glued on the external surfaces. The FBG sensors were positioned close to Resistive Strain Gages, so that the readings from the two kinds of sensors could be compared. The results are discussed in the paper.