On-line health monitoring of smart composite structures using fiber polarimetric sensor

Abstract

The sensitivity of the fiber polarimetric system for smart structure applications depends on various parameters such as pre-stress, input azimuth, fiber turns etc. The presence of the smart structure modifies the output characteristics of the highly birefringent (HiBi) fiber due to elastic properties of the structure. This differential lateral strain will produce a change in the birefringence of the fiber over this length, which manifests as the state of polarization change in the fiber output. These concepts are used in the defect detection of smart composite structures. Experimental procedures are repeated for bow-tie HiBi fibers with different optical configurations. A parameter sensitivity factor `Q' is proposed to characterize defects. A significant variation in Q-factor can be attributed to the presence of defects/delamination. This paper deals with the on-line defect detection of smart composites based on such concepts.