A curvature based approach in dynamic monitoring using long-gage fiber optic sensors

Fiber Bragg grating (FBG) sensors offer a significant advantage for structural health monitoring due to their ability to simultaneously monitor both static and dynamic strain while being durable, lightweight, capable of multiplexing, and immune to electro-magnetic interference. Drawing upon the benefits of FBG sensors, this research explores the use of a series of long-gage fiber optic sensors for damage detection of a structure through dynamic strain measurements and curvature analysis. Curvature and strain based analysis may be a more reliable means for structural monitoring as they show more sensitivity to damage compared to modal parameters such as displacement mode shapes and natural frequency. Small scale experimental testing was performed using an aluminum beam instrumented with a series of FBG optical fiber sensors. Dynamic strain measurements were obtained as the beam was subjected to various support and loading conditions and damage was simulated by creating imperfect support constraints. From this, a normalized parameter based on the strain and curvature from the dynamic strain measurements has been developed as a potential means of damage detection. The results demonstrated the potential of FBG long-gage sensors to facilitate dynamic monitoring at both the local and global scale, thus allowing assessment of the structures health.