Signal Characteristics in the Delaminated Composite Specimen with Fiber Optic Sensor

Delamination problems are one of the most important issues affecting the applications of composite laminates. Delamination reduces overall structural performance of composite laminates such as stiffness, strength, and buckling load. Therefore, it is necessary to identify the influence of delamination failure on composite laminates. The delaminated unidirectional composite specimens subjected to the compressive load were tested to study the characteristics of fiber optic sensor (FOS) signals when the buckling and the growth of delamination occurred. Extrinsic Fabry-Perot interferometers (EFPI) were used in this study. EFPI was embedded in the delaminated composite specimen or attached on the surface of specimen. As the specimens were buckled, the signals of FOS were analyzed. And also when the delamination growth occurred, the characteristics of FOS signal and data aliasing caused by the sampling time were investigated. The effects of the delamination length were discussed.