Mechanics of a Bent Rope

This paper describes the mechanics of what happens within a fiber rope when it is bent around a curved surface under tension. It explains how bending the rope causes: * motion between strand and yarns within the rope * abrasion within the rope structure. * increased tension and possible failure in strands on the outside of the bend. * decreased tension and axial compression fatigue in strands on the inside of the bend. These effects reduce the rope's breaking strength and shorten its service life. The paper pertains primarily to synthetic fiber ropes, but it is also applicable to wire ropes and cables. It discusses helical (twisted) structure rope, braided structure rope, and parallel strand rope. It discusses the effects of static and cyclic tension. The paper is of interest to rope designers and users. Knowledge of how the strands within a bent rope move or don't move help rope designers and users understand how internal wear and stress weaken the rope and lead to failure.