In this study the effect of the presence of embedded optical fiber sensors on the matrix crack spacing of cross-ply laminates was investigated. The matrix crack spacing of cross-ply laminates with embedded optical fiber sensors was predicted using modified shear-lag analysis and compared with experimental values. Specimens were fabricated with transparent glass fiber/epoxy prepregs to observe matrix cracking and other damage processes such as delamination and bleeding of laser signal directly and visually. Specimens with different number of embedded optical fiber sensors were tested under the tensile loading using 10-ton MTS servohydraulic testing machine.
It has been found that at specimens with one and three embedded optical fiber sensors, the matrix crack spacing was not affected by embedding of optical fiber sensors. But in case of seven embedded optical fiber sensors, matrix crack spacing was found to decrease at the same stress level because of the debonding of transverse ply by close interaction of two adjacent resin-rich areas. Also, the effect of coating of optical fiber and the relation between the damage of cross-ply laminates and the laser intensity were investigated.
