Monitoring of fatigue damage of composite structures by using embedded intensity-based optical fiber sensors

Abstract

In this paper, the feasibility of real-time monitoring of the fatigue damage of composite laminates under fatigue loading using the embedded intensity-based optical fiber (IBOF) sensors was evaluated. The IBOF sensor system used in this study has a relatively simple sensing principle. Thus the system can be composed of inexpensive components compared with other optical fiber sensors such as Fabry-Perot and Bragg grating sensors. The performance of the fabricated IBOF sensors was evaluated by comparison with a surface-mounted extensometer. The process of conversion of the detected IBOF sensor signal into the stiffness was proposed. Experimental results showed that the sensing response of embedded IBOF sensors showed good agreement with that of the surface-mounted extensometer. The IBOF sensor system showed good potential as a health monitoring system which can give composite structures the capability of fatigue damage monitoring by detecting the stiffness change of the composite structures under fatigue loading. The IBOF sensors showed relatively good durability under fatigue loading compared with commercial electrical strain gages.