Fatigue

Steel wire ropes are mainly subjected to bending fatigue and fatigue caused by stretching, twisting, and vibration during use.

Bending fatigue

The steel wire rope is repeatedly flexed up and down in the pulley or drum. Numerous bends can easily cause the steel wire to fatigue, reduce its toughness, and ultimately lead to wire breakage. The fatigue broken wire appears on the outer wire on the side of the strand with the most bending degree. Under normal circumstances, the appearance of fatigue broken wire means that the wire rope is near the end of its use.

Fatigue caused by stretching, twisting and vibration

During the start and end of the crane wire rope, and before and after the bundled wire rope bears the load, the changing tensile stress will cause metal fatigue. In addition, the steel wire rope is often subjected to torsion and vibration, which is also the cause of fatigue.

The principle of fatigue damage is that under the action of variable stress, the surface of the thin steel wire first forms an initial crack due to various slippages, and then the crack tip is repeatedly plastically deformed under the action of shear stress, so that the crack propagates until it breaks. The broken wires caused by fatigue are generally flat, and most of them appear on the surface steel wire, and they are very regular.