Structural health monitoring of advanced grid structure using multipoint FBG sensors

Abstract

The authors have been developing a new lightweight composite grid structure equipped with a health monitoring system utilizing FBG (Fiber Bragg Grating) sensors for aircraft applications. A grid structure, comprising multiple interconnected ribs in a truss-like arrangement, has a very simple path of stress, which is easily detected with FBG sensors embedded in the ribs. In this study, manufacturing technology for embedding optical fibers into the grid structure was studied, in order to enable an embedded multi-point FBG sensor network. A total of 29 FBG sensors were embedded in a 525 x 550 mm test panel. A third test panel was also fabricated to evaluate effect of steering the optical fiber through the grid panel nodes. The strain data obtained from embedded FBG sensors were compared to ones from conventional strain gages in several loading conditions, which showed very good accordance. An appropriate arrangement of the grating wavelength of the embedded FBG sensors was also studied to show the feasibility a new lightweight composite grid structure with an excellent health monitoring system.