Health monitoring technique for composite materials utilizing embedded thermal fiber optic sensors

A thermal health monitoring technique is investigated based on thermography that uses optical fiber thermal sensors to detect damage within a laminated graphite epoxy composite specimen. Composite samples manufactured for testing have fiber optic sensors embedded between the layers while thermocouples are attached to the exteriors for verification. Teflon inserts are used to simulate delaminations and the sensitivity range of the embedded sensors is determined. A numerical model is developed to confirm the experimental findings and establish optimum sensor placement. Results indicate that this technique can detect down to a 20-mm delamination, possibly smaller. In addition, the sensors can typically locate a delamination up to 17 mm away. The purpose of this research is to advance standard thermography techniques for damage detection by utilizing fiber optic sensor technologies.