Abstract
The helical cord is a unique machine element with high tensile stiffness and low bending stiffness, and therefore is used in various types of rubber belts as a tension member. However, the fatigue failure initiation site of the rubber belts is often the inside of the helical cord. In this study, the fatigue failure mechanism of the hybrid cord, which consists of the carbon fibers and the glass fibers, was investigated caring out some experiments and the mechanical analysis. Especially, the failure morphology of the damaged cords was observed using a three-dimensional X-ray CT scan.