Free-edge delamination location and growth montoring with an embedded distributed fiber optic network

Abstract

Delamination is the most characteristic damage found in composite materials. Low velocity impacts may lead to delamination onset, likely to occur during manufacturing processes or in operating service life.Furthermore, areas near the free-edge of the structures,as well as ply drop off and integrated reinforcements have demonstrate a high vulnerability to impacts. This paper focuses on the delamination detection based on an embedded or fixed fiber optic network in a composite laminate. The sensor network uses the Rayleigh scattering through an Optical Backscatter Reflectometer (OBR)that it obtains a continuous strain monitoring on a bare opical fiber. For this purpose, several optical fibers were attached on the structure surface close to the free edge of the specimens in order to identify the first-ply failure and the delamination growth. Experimental results were compared to an ultrasonic C-Scan inspection which present a good agreement with the data of sensor network