Abstract
Synchronous belts are rubber-composite materials with rubber, helical cords and facing fabrics. The helical cord is the tension member of the belt and is made of glass fibers, aramid fibers, or steel wires. The recent trend is high stiffness for the rubber belts, because of the stability under high loading conditions. The use of carbon fibers is considered to be an effective way to achieve the high stiffness for the helical cords. The purpose of this paper is to improve the bending fatigue strength of the hybrid cords, where the core strand is made of carbon fibers, and the outer strands are made of glass fibers. The optimum cord composition for high bending fatigue durability was discussed following some bending fatigue tests of the cord and mechanical analysis using a simplified mechanical model. The simplified mechanical model explained reasonably the fatigue failure initiation site in the hybrid cords. Then, it is expected to obtain a better cord construction for the bending fatigue strength using the proposed mechanical model.
