Effect of embedded optical fibers on the interlaminar fracture toughness of composite laminates

The effect of embedded optical fibers on the interlaminar fracture behavior of composite laminates was investigated. Double cantilever beam (DCB) tests and end notched flexure (ENF) tests were performed to obtain the mode I and mode II interlaminar fracture toughness, respectively. Two different stacking sequences of glass fiber-epoxy matrix composite laminates ([0(18){X}0(18)] and [0(6)/90(4)/0(8)/90{X}0(8)/90(4)/0(6)]) were studied, where {X} refers to the location of embedded optical fibers. It was shown that the mode I and mode II interlaminar fracture toughness values were in general little affected by the optical fibers embedded in the same direction as the crack propagation. In contrast, for composites with optical fibers embedded in the direction perpendicular to crack propagation, the mode I fracture toughness was generally lower than for those without embedded optical fibers, while the mode I fracture toughness showed large increases at the locations of optical fibers where the crack arrested. The failure mechanisms associated with the large diameter optical fibers are discussed.