Abstract
Fatigue failure mechanism of synchronous belts has been investigated focussing on the bending fatigue failure in helical cords. The fatigue damage is initiated as a de-bonding between strands in the cords. The de-bonding is initiated by a shearing stress along the strands. The author has proposed a geometrical parameter S, which is useful to estimate the extent of the shearing stress. In this study, the effect of strand radius and the cord construction on the parameter S is discussed. The shearing stress is low in the cords in which the strand radius is small. Moreover, the extent of the shearing stress is compared between the helical cords and a plaited cord.
