Smart composite structures are those that exploit the muscular characteristics offered by electro-rheological fluids, piezo-electric materials, and shape memory metals and also sensing capabilities offered by optical fiber sensors, for examples. Optical fiber sensors, as sensing materials for detecting and monitoring of damages of composite laminates, have been receiving much attention due to its characteristic advantages. Optical fiber sensors have a number of specific advantages over other types of sensors for the application to smart structures. Optical fiber sensors can be directly embedded within the materials such as advanced composites to provide sensing networks for the damage detection or health monitoring of smart structures. However because the diameter of optical fiber is much larger than the diameter of reinforcement fiber, a comprehensive study about the effect of the presence of embedded optical fibers on the mechanical properties of host materials is necessary. The effects of embedded optical fiber sensors on delamination, which is one of the main failure mechanisms in composite materials, are investigated in this study. Firstly, optical fibers were embedded at the interface which is thought to be delaminated by low-velocity impact and then impact tests were performed with these specimens. Then buckling tests to study the effect on delamination buckling were also performed with pseudo-specimens which simplify delamination as one- dimensional crack and the differences of critical load and delamination crack propagation were examined. The coupled effects were observed from the buckling tests with low-velocity-impacted specimens not with pseudo-specimens.
It is found from the experiments that the effect of the embedded optical fibers can be neglected in macroscopic view. However it is observed that the embedded optical fibers cause matrix cracking and retard the delamination under impact loading. The embedded optical fiber sensors can also cause the retardation of crack propagation in buckling test.
