Development of Photonic Smart Veil for Structural Health Monitoring

Abstract

The use of fiber optics as structural health monitoring (SHM) systems is now widespread. This technology is ideal for the creation of monitoring algorithms thanks to the creation of individual Bragg grating sensors (FBGS) or arrays of sensors, the small size, durability, real-time monitoring capabilities, and the ability to place these elements within composite structures. One of the issues in using FBG sensors is the placement of these local transducers at the point where measurement is to be made, during the composite component creation process. Positioning a sensor array along a complex path in the lamination sequence and ensuring that the position of the sensors is maintained during the autoclave curing process is a decisive challenge to enable this technology to spread rapidly in the market. Starting with the configuration of the Quick Pack, a thin membrane that incorporates optical fiber, methods of manufacturing the component were improved by minimizing its size to reduce its invasiveness. New materials to incorporate the optical fiber and different configurations to reduce its stiffness were considered. Configurations with different degrees of polymerization of the constituent materials were studied to improve the adhesion of the component to the composite structure. To validate the performance improvement, specimens were created in order to perform peel tests (ASTM D 3167-10). The results demonstrate the improvement in adhesion and the advantage of including the partially cured element in the lamination sequence. Further prototyping identified the minimum degree of polymerization required to hold the optical fiber in place. This new transducer, Photonic Smart Veil, allows FBG sensors to be properly inserted in the desired positions and locked in place during the production of composite components, improving their performance.