Development of the Fiber Optic Distributed Strain Sensing System and its On-Board Monitoring of Aircraft during Flight Tests

Abstract

In this study, we develop a fiber optic distributed sensing technique to conduct aircraft structural monitoring during flights. The sensing system is based on optical frequency domain reflectometry that is capable of monitoring strain distributions with mm-order spatial resolution in real-time. We use fiber Bragg gratings (FBGs) with the maximum length of 5 m gauge length as a sensing element. We conduct flight tests using a jet flying test bed (Cessna Citation Sovereign). We bond the FBG to a stringer of the fuselage, and interrogate by the sensing system installed in the cabin. We monitor and record the real-time strain distributions on-board during flight tests. The system successfully monitored structural responses of the aircraft under various flight conditions.