Structural health monitoring of composite materials with FBG sensors: damage detection and remaining useful life prediction

Official URL: http://192.168.1.20/record=b1505279 (Table of Contents)

Advanced composites are widely employed in load bearing structures due to their high strength-to-weight ratios, stiffness, corrosion resistance and fatigue performance. Monitoring the manufacturing process and detecting the damage during service are rather troublesome. In this study, practicality and feasibility of fiber optic based sensors are evaluated for monitoring the state or the structural health of the composite materials from manufacturing phase to service phase continuously. 2D and 3D composite structures were designed and manufactured by resin transfer molding (RTM) method. A novel ingress/egress technique is utilized to embed the fiber optic sensors. The capabilities of fow and cure monitoring of fiber Bragg grating (FBG) sensors are presented. The strain and the temperature sensitivity of the embedded FBG sensors was calculated. Following the calculation of the sensitivities, a manufactured composite with embedded FBG sensor is subjected to cantilever beam experiments. To be able to show that the FBG sensor is capable of detecting damage formation in composites, the composite plate was drilled to create artificial defects of different size. The wavelength shift of the FBG was monitored as a function of the size of the hole and wavelength measurements are compared with those of sound structure to conclude on the health of the structure. Technique for prediction of remaining useful life (RUL) of composite materials with embedded FBG sensors is demonstrated and fatigue testing of composite materials are performed to verify this technique.